Civil Vi Environmental Engineering i [10cv61] Notes

Environmental Engineering – I

10CV61

ENVIRONMENTAL ENGINEERING-I Subject Code : 10CV61 Part - A Unit - 1 INTRODUCTION: Human activities and environmental pollution. Water for various beneficial uses and quality requirement. Need for protected water supply. 2 Hours DEMAND OF WATER: Types of water demands- domestic demand indetail, institutional and commercial, public uses, fire demand. Percapita consumption –factors affecting per capita demand, populationforecasting, different methods with merits &demerits- variations indemand of water. Fire demand – estimation by Kuichling‟s formula,Freeman formula & national board of fire underwriters formula, peakfactors, design periods & factors governing the design periods 6 Hours Unit - 2 SOURCES: Surface and subsurface sources – suitability with regardto quality and quantity. 3 Hours COLLECTION AND CONVEYANCE OF WATER: Intake structures –different types of intakes; factor of selection and location of intakes.Pumps- Necessity, types – power of pumps; factors for the selectionof a pump. Pipes – Design of the economical diameter for the risingmain; Nomograms – use; Pipe appurtenances. 6 Hours Unit – 3 QUALITY OF WATER: Objectives of water quality management.wholesomeness& palatability, water borne diseases. Water qualityparameters – Physical, chemical andMicrobiological.Sampling ofwater for examination. Water quality analysis (IS: 3025 and IS: 1622)using analytical and instrumental techniques. Drinking waterstandards BIS & WHO guidelines. Health significance of Fluoride,Nitrates and heavy metals like Mercury, Cadmium, Arsenic etc. andtoxic / trace organics. 6 Hours Unit – 4 WATER TREATMENT: Objectives – Treatment flow-chart. Aeration - Principles, types of Aerators. 2 Hours SEDIMENTATION: Theory, settling tanks, types, design. Coagulantaided sedimentation, jar test, chemical feeding, flash mixing, and clariflocculator. 4 Hours

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Environmental Engineering – I

10CV61 Part - B

Unit - 5 FILTRATION: Mechanism – theory of filtration, types of filters, slowsand, rapid sand and pressure filters including construction, operation,cleaning and their design – excluding under drainage system – backwashing of filters. Operational problems in filters. 6 Hours Unit - 6 DISINFECTION: Theory of disinfection, types of disinfection,Chlorination, chlorine demand, residual chlorine, use of bleachingpowder. UV irradiation treatment – treatment of swimming pool water 4 Hours SOFTENING – definition, methods of removal of hardness by limesoda process and zeolite process RO & Membrane technique. 3 Hours Unit - 7 MISCELLANEOUS TREATMENT: Removal of color, odor, taste, useof copper sulfate, adsorption technique, fluoridation anddefluoridation. 4 Hours DISTRIBUTION SYSTEMS: System of supply, service reservoirs andtheir capacity determination, methods of layout of distribution systems

Unit - 8 MISCELLANEOUS: Pipe appurtenances, various valves, type of firehydrants, pipefitting, Layout of water supply pipes in buildings. TEXT BOOKS: 1. Water supply Engineering –S.K.Garg, Khanna Publishers 2. Environmental Engineering I –B C Punima and Ashok Jain 3. Manual on Water supply and treatment –CPHEEO, Minstry ofUrban Development, New Delhi. REFERENCES 1. Hammer, M.J., (1986), Water and Wastewater Technology –SIVersion, 2ndEdition, John Wiley and Sons. 2. Karia, G.L., and Christian, R.A., (2006), Wastewater Treatment –Concepts and Design Approach, Prentice Hall of India Pvt. Ltd.,New Delhi. 3. Metcalf and Eddy, (2003), Wastewater Engineering, Treatmentand Reuse ,4th Edition, Tata McGraw Hill Edition, Tata McGraw HillPublishing Co. Ltd. 4. Peavy, H.S., Rowe, D.R., and Tchobanoglous, G.,(1986),Environmental Engineering– McGraw Hill Book Co. 5. Raju, B.S.N., (1995), Water Supply and WastewaterEngineering, Tata McGraw Hill Pvt. Ltd., New Delhi. SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I

10CV61

Table of Contents Unit – 1 INTRODUCTION

(06 – 25)

1. Human activities and environmental pollution. 2. Water for various beneficial uses and quality requirement. 3. Need for protected water supply.

DEMAND OF WATER 1. Types of water demands- domestic demand in detail, institutional and commercial, public uses, fire demand. 2. Per capita consumption –factors affecting per capita demand, 3. population forecasting, 4. different methods with merits &demerits- variations in demand of water. 5. Fire demand – estimation by Kuichling‟s formula, Freeman formula & national board of fire underwriters formula, 6. peak factors, 7. design periods & factors governing the design periods

Unit – 2 SOURCES

(26 – 49)

1. Surface and subsurface sources 2. Suitability with regard to quality and quantity.

COLLECTION AND CONVEYANCE OF WATER: 1. 2. 3. 4. 5. 6. 7.

Intake structures – different types of intakes; factor of selection and location of intakes. Pumps- Necessity, types – power of pumps; factors for the selection of a pump. Pipes Design of the economical diameter for the rising main; Nomograms – use; Pipe appurtenances.

Unit – 3 QUALITY OF WATER

(50 – 69)

1. Objectives of water quality management. 2. wholesomeness& palatability, water borne diseases. 3. Water quality parameters Physical Chemical and Microbiological. 4. Sampling of water for examination. 5. Water quality analysis (IS: 3025 and IS: 1622) using analytical and instrumental techniques. 6. Drinking water standards BIS & WHO guidelines. 7. Health significance of Fluoride, Nitrates and heavy metals like Mercury, Cadmium, Arsenic etc. and toxic / trace organics. SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I Unit – 4 WATER TREATMENT

10CV61 (70 –99)

1. Objectives 2. Treatment flow-chart. 3. Aeration - Principles, types of Aerators.

SEDIMENTATION 1. 2. 3. 4. 5. 6. 7.

Theory Settling tanks, types, design. Coagulant aided sedimentation Jar test chemical feeding flash mixing clariflocculator.

Unit - 5 FILTRATION 1. 2. 3. 4. 5.

Unit – 6 DISINFECTION 1. 2. 3. 4. 5.

(100 – 118)

Mechanism – theory of filtration Types of filters, slow sand, rapid sand and pressure filters including construction Operation, cleaning and their design Back washing of filters Operational problems in filters.

(119 – 132)

Theory of disinfection Types of disinfection Chlorination, chlorine demand, residual chlorine Use of bleaching powder. UV irradiation treatment – treatment of swimming pool water

SOFTENING 1. 2. 3. 4.

Definition Methods of removal of hardness by lime soda process Methods of removal of hardness by zeolite process Methods of removal of hardness by RO &Membrane technique.

Unit – 7 MISCELLANEOUS TREATMENT

(133 – 137)

1. Removal of color, odor, taste 2. Use of copper sulfate, adsorption technique 3. Fluoridation and defluoridation.

DISTRIBUTION SYSTEMS 1. System of supply 2. service reservoirs and their capacity determination 3. methods of layout of distribution systems SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I Unit – 8 MISCELLANEOUS 1. 2. 3. 4. 5.

10CV61 (138 – 142)

Pipe appurtenances Various valves Type of firehydrants Pipefitting, Layout of water supply pipes in buildings.

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Environmental Engineering – I

10CV61

Unit1 - INTRODUCTION Water is a chemical compound and may occur in a Liquid solid gaseous form. All these three Forms of water are extremely useful to man, full filling his basic necessities of life.No life can exist without water since water is as essential for life. It has been estimated of water is absolutely essential not only for survival of human being but also for animals, plants and all other living creatures further it is necessary that the water required for their needs must be safe in all respects and it should not contain unwanted impurities or harmful chemical compounds or bacteria‟s in it therefore in order to ensure the availability of sufficient quantity of good quality water it becomes imperative in modern society to plan and build suitable water supply schemes which will provide potable (safe for drinking) water to the varies sections of community in accordance with then demands and requirements. The provision of such a scheme shall ensure a constant and a reliable water supply to that section of the people for which it has been designed such a scheme shall not only help in supplying safe whole some water to the people for drinking cooking, bathing, washing, etc.., so as to keep the diseases away and there by promoting better health, but would also help and thus helping in maintaining better sanitation and beautification of surroundings. Besides promoting overall hygiene and public health it shall ensure a safety against fire by supplying sufficient quantity of water to extinguish it. The existence of such a water supply scheme shall further help in attracting industries and thereby helping in industrialization and modernization of the society and consequently reducing unemployment and ensuring better living standards such schemes shall therefore help in promoting health wealth and welfare of entire community as a whole. Various important and pathogenic organisms (disease causing organisms) due to these diseases like typhoid Asiatic cholera Amoebiasisgiavdisis etc..may spread. These diseases are called WATER borne DISEASES and therefore it will be harmful to health. The pathogenic organisms (pathogens) do not multiply in water like that in milk but they do survive i.e water may be considered as a carrier for bacteria and not multiplier thus the control of pathogens is possible by simple disinfection principles (process). (If we control the purity of H2O completely, the chances of outbreak water borne communicable diseases will be much less). Besides communicable diseases certain other diseases like goiter, dental flourosis and skeletal flourosis are attributable to chemical impurities present in water.

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Environmental Engineering – I

10CV61

HUMAN ACTIVITIES AND ENVIRONMENTAL POLLUTION Increasing human population numbers are putting great pressure on many of these limited resources and deplete those resources which cannot be renewed. Many different natural processes occur within those ecosystems influencing humans. Some of these processes include atmospheric quality. soil generation and conservation, energy flow, the water cycle, waste removal and recycling. Human activities are altering the equilibrium involved in these natural processes and cycles. If these changes due to human activities are not addressed, the stability of the world's ecosystems may irreversibly affected. Humans damage ecosystems by harvesting trees that are homes to hundreds of different organisms. We damage the atmosphere by releasing greenhouse gases when we drive cars or use electricity. We pollute water with chemicals and waste products from factories. We can't reverse the damage, but we can help prevent new damage by changing our lifestyles to be less wasteful and more conservative with our resources. I'd love to tell you all about it(I live very green) but it would take a long time. Basically, just remember Reduce, Reuse, and Recycle. Any little change you can make does help the problem, even if it's just a minor change like switching to energy saving lightbulbs.

POINTS TO BE CONSIDERED FOR A PROTECTED WATER SUPPLY SCHEME (WSS) The following factors should be kept in view in water supply for particular place. i)

THE SOURCE: Source should be selected which may sufficiently provide the water in all the seasons. The sources may be wells steams, natural lakes, deep ponds in rivers, reservoirs, perennial rivers etc…

ii)

QUANTITY OF WATER: It can be estimated by considering need for present population and future population growth during the design period also some quantity of water will be required for fire fighting, public conveniences street washings and horticultural purposes. In addition to these some water is usually wasted by the consumers. Thus the total quantity way of water may be estimated for a particular locality considering all the above factors.

iii)

CHECK CALCULATION: After the above calculations are completed, designer should again confirm whether the source of water will provide the required amount of water especially in summer season of the driest year.

iv)

DISTANCE AND DIFFERENCE IN ELEVATION: The designer should see distance and difference in elevation in a town with respect to source of water. As far as possible the water should be under enough pressure in service pipes so that it may reach upto 10-15m.

v)

IMPOUNDING RESERVOIR: May only be provided if its provision at higher elevation is not economical.

vi)

QUALITY OF WATER: After this the quality of water should be tested the treatment units should be installed according to degree of pollution in the source.

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Environmental Engineering – I vii)

10CV61

METHODS OF PURIFICATION: The methods of purification of water for drinking purposes may be divided into 5 parts viz. a) SCREENING: in which the fine and coarse particles, rags, papers, etc… are separated through fine and coarse screens. b) PLAIN SEDIMENTATION: in which the sedimentation of set liable solids in large tanks is affected. c) COAGULATION OR CHEMICAL PRECIPITATION: This is adopted when there is much turbidity. The alum solution is generally mixed in water and the precipitation is formed which is later separated. d) FILTRATION: in which water is passed through layers of stones and sand. e) DISINFEC TION: in which the pathogenic bacteria are destroyed.

NOTE: In addition to these some special methods like softening, aeration, iron removal etc….. are also resorted to remove colour, bad taste smell etc…. viii)

SERVICE RESERVOIR: Pure water may be stored at a higher elevation in the town which is called a service reservoir. From these reservoir the water may be supplied in the hours of peak demand

ix)

DISTRIBUTION SYSTEM: the water from the service reservoir is served to consumers through a network of mains, sub mains, laterals called as distribution network system.

ARRANGEMENT OF WATER SUPPLY (FLOW CHART OF WATER SUPPLY SCHEME) 1- Intake structures 2- Pumping station 3- Screens 4- Coagulants dosing tank 5- Sedimentation tank 6- Filters 7- Chlorine dosing tank 8- Clear water reservoir 9- Pumping station 10- Overhead tank 11- Distribution network systems.

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Environmental Engineering – I

10CV61

DEMAND FOR WATER VARIOUS TYPES OF WATER DEMAND Which planning a water supply scheme, it is necessary to find out not only the total yearly water demand but also to assess the required average rates of flow (or draft) and the variations in these rates. The following quantities are therefore, generally assessed and recorded. i) ii) iii) iv) v)

Total annual volume (V) in liters or million liters. Annual average rate of draft in liters per day, i.e V/365 Annual average rate of draft in liters per day per person i.eliters per capita per day or lpcd called PER CAPITA DEMAND (q) or RATE OF DEMAND. V 1 × Average rate of draft in liters per day per service i.e 365 No of services Fluctuations in flows expressed in terms of percentage ratios of maximum or minimum yearly, monthly, daily or hourly rates to their corresponding average values.

It is difficult to precisely assess the quantity of water demanded by the public, since there are many variable factors affecting water consumption certain thumb rules and empirical formulas are therefore generally used to assess this quantity, which may give fairly accurate results. The use of a particular method or a formula for a particular case has therefore, to be decided by the intelligence and fore sightedness of the designer. The various types of water demands, which a city may have, may be divided into the following classes. i) ii) iii) iv) v)

Domestic water demand Industrial and commercial water demand Demand for public uses Fire demand Water required compensating losses in wastes and thefts.

As correctly as possible the total water demand of a particular section of the community, all these demands must be considered and suitable provision made depending upon the needs of those people for whom the water supply scheme is to be designed. DOMESTIC WATER DEMAND: This includes the water required in private buildings for drinking, cooking, bathing, lawn sprinkling, Gardening, sanitary purposes etc…. This amount varies according to the living conditions of the consumers on an average this domestic consumption under normal conditions in a Indian city is expected to be around 135 litres /day/person as per Id:1172,1971. The total domestic consumption generally amounts to 5060% of the total water consumption.

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Environmental Engineering – I

10CV61

AVERAGE DOMESTIC WATER CONSUMPTION IN A INDIAN CITY USE Drinking cooking Bathing Washing of clothes Washing of utensils Washing and clearing of houses and residences TOTAL

CONSUMPTION IN LPCD 5 5 55 20 10 10 30 135 lpcd

INDUSTRIAL AND COMMERCIAL WATER DEMAND This includes the quantity of water required to be supplied to offices, Factories, different industries, hospitals, hostels, etc…. This will vary considerably with the nature of the city and with the number and types of industries and commercial establishment there is no direct relation of this consumption with the population and hence the actual requirements for all industries should be estimated. The water requirements for buildings other than residences as per is standards are as follows.

Type of building

Age consumption in lpcd 45

1.Factories a) where bathrooms are required to be provided b) where no bathrooms are required 30 to be provided 2.Hospitals (including laundry) per bed a) Number of beds < 100 340 b) Number of beds > 100 450 3.Nurse homes and medical quarters 135 4.Hostels 135 5.Hotels (Per bed) 180 6.Restauvants (Per seat) 70 7.offices 45 8.Cinemas, Auditoriums and theatres (per 15 seat) 9.Schools a) Day schools 45 b) Residential school 135

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Environmental Engineering – I

10CV61

DEMAND FOR PUBLIC USES (MUNICIPAL CONSUMPTION) This includes the quantity of water required for public parks, gardening, washing and sprinkling on roads, use in public fountains etc….. A nominal amount not exceeding 5% of the total consumption may be added to meet this demand on an arbitrary basis or else the consumption of water for municipal purposes as given below may be considered. PURPOSE

WATER CONSUMPTION

Public parks

1.4 litres/m2/day

Road watering

1-1.5 litres/m2/day

Sewer cleaning

4.5 litres/head/day

Extinguishing for is very small in a year but the rate of consumption is large. The scheme should provide the necessary peat demand of water for firefighting (although fire hydrants with separate water mains at about 100-150m apart are provided) The water requirements for extinguishing fire depends on bulk, congestion and fire resistance of buildings. Indirectly we can say, it ,mainly depends on the population. The minimum limit of fire demand is the amount and rate of supply that are required to extinguish the largest probable fire that may occur in a town. Which designing public water supply schemes the rate of fire demand is sometimes treated as a function of population and is worked out on basis of certain empirical formulas which are as follows. EMPIRICAL FORMULAS FOR FIRE DEMAND A) KULCHILING’S FORMULA : It states that Q 3182 p (at a demand rate to be maintained at hydrants of 1-1.5 kg km2 lasting For 3 hrs) where Q = amount of water required in litres/min P = population in thousands. B) FREEMAN FORMULA : It states that p Q=1136.5 10 and 10

y 2.8 p Where y = period of occurrences of fire in years Q and „p‟ are same as above

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Environmental Engineering – I

10CV61

C) NATIONAL BOARD OF FIRE UNDERWRITER’S FORMULA FCPA central congested high valued city i. When population is 2,00,000 Q = 4637 p 1 D.D1 p ii. When population is > 2,0,000 a provision for 54600 litres/ min may be made with an extra additional provision of 9100 to 30400 litres/min for a second fire. For a Residential City 1. Small low buildings = 2200 litres/min 2. Large and higher buildings = 4500 litres/min 3. High value Residences apartment and tenements = 7650-1350 litres/min 4. Three storeyed buildings = 27,000 litres/min D) BUSTON’S FORMULA - It states that Q = 5663 p All the above formulae suffer from the drawback, that they are not related with the type of area served. These formulas therefore give equal results for industrial and non industrial areas, although the possibility of occurrence of a fire with of given duration is more for an industrial area as compared to the non-industrial area.WATER REQUIRED TO COMPENSATE IN THEFTS, WASTES, etc.. It includes the water lost in leakage due to bad plumbing or damaged meters, stolen water due to unauthorized water connections and other losses and wastes, etc…. These losses should be taken into account while estimating the total requirement. These losses can be reduced by careful maintenance and universal metering. Even in the best managed water works this amount is usually taken as 15% of the total consumption. DESIGN PERIOD A Water supply scheme includes huge and costly structures like dams, reservoirs, treatment works, penstocks etc…., which cannot be replaced or increased in their capacities, easily and conveniently for example. The water mains including distribution pipes are laid underground and cannot be replaces or added easily without digging the road or disrupting the traffic. In order to avoid these future complications of expansions, various components of w.s.s are purposely made larger, so as to satisfy the community meets for a reasonable years to come. The future period or the number of years for which a provision is made in designing the capacities of the various component of the w.s.s. is known as DESIGN PERIOD. It should be neither too long nor should it be too short. Normally 20-30 years is considered for distribution system. PER CAPITA DEMAND (RATE OF DEMAND) (Q) It is the annual average amount of daily water required by one person and includes the domestic use, industrial and commercial use, public use, wastes, thefts, etc… SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I

= Per capita Demand in litres/day/head = q

10CV61 Total yearly water requirement of the citty in Litres 365 Design population

V 365P

For an Average.Indian town. As per I.S recommendations the per capita demand may be taken as given in table below. USE

CONSUMPTION (LPCD)

Domestic use

135

Industrial use

50

Commercial use

20

Civic or public use

10

Waste, theft. Etc…

55

Total

270 lpcd

The above figure or 270 lpcd when multiplied by the population at the end of the design period shall give the total annual average water requirement of the city/day. When multiplied by 365 will give the volume of the yearly water requirement in litres. Generally the per capita demand valuesranges between 10-300 lpcd. These variations in total water consumption of different cities or towns depend upon various factors. FACTORS AFFECTING PER CAPITA DEMAND 1. 2. 3. 4. 5. 6. 7. 8. 9.

Size and type of city Climatic conditions Class of consumers Quality of water Pressure in the distribution system Sewerage Facilities System of supply Policy of metering system Cost of water

PROBLEM ON RATE OF DEMAND Work out the rate of demand of water for an average Indian city. Make your own assumptions wherever necessary. Soln: The total requirement of water for various purposes is worked out separately as under.

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Environmental Engineering – I PURPOSE 1.DOMESTIC Drinking Cooking Bathing Washing Clothes and utensils Washing and Cleaning of houses Flushing of latrines

10CV61 CONSUMPTION (lpcd) 5 5 55 30 10 30 135

2. CIVIl or PUBLIC A. Road washing b. Sanitation purpose c. ornamental purpose d. fire demand 3. Industrial purposes 4. commercial purposes 5. waste, theft, etc… Total

5 3 1 1 10 50 20 55 270 Lpcd

VARIATIONS IN DEMAND There are wide variations in the use of water in different seasons, in different months of the year, in different days of the month and in different hours of the day. Seasonal or monthly variation are prominent in tropical countries like India rate of consumption reaches maximum in summer season due to greater use of water for street and lawn sprinkling etc… It goes down in winter months. The fluctuation in the rate of consumption may be as much as 150% of the average annual consumption. HoURLYVARIATIONS

Avg. Demand on a maxm. Day

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Environmental Engineering – I

10CV61

TIME IN HOURS. Daily and hourly Fluctuations depend on the general habits of people, climatic conditions etc… more water demand will be on Sundays and holidays due to more comfortable working, etc…. as compared to other working days. Peak hours may be 6 a.m to 10a.m and 10a.m to 4.p.m minimum flow and between 10.p.m to 4.a.m it is very less. The above graph shows the hourly variation in demand of water or rate of consumption 20% of average hourly demand

ASSESSMENT OF NORMAL VARIATIONS The maximum demands (monthly, daily or hourly) are generally expressed as ratios of their means. The following figures are generally adopted. 1. MAXIMUM DAILY CONSUMPTION is generally taken as 180% of the average, therefore Maximum daily demand(MDD) = 1.8 Average daily demand (^DD) = 1.8 q 2. MAXIMUM HOURLY CONSUMPTION is generally taken as 150% of its average hooray consumption of maximum day, there fore Maximum hourly consumption = 1.5 (150%) Average hourly consumption of the maximum day or of the maxm. Day.(Litres/day) peak demand MDD 1.5 (Litres/hr) 24

1.8 q (Litres/hr) 24 2.7 q (Litres/hr) 24 Therefore, Maximum hourly consumption of the maximum day = (2.7 Annual Average hourly demand) 1.5

The formula given by GOODRICH is also used for finding out the rather of peak demand rates to their corresponding average values. GOODRICH FORMULA P=180 t 0.10 Where, P = % of annual average draft for the time„t‟ in days 1 T = Time in days from to 365 24 SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I

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When t= 1 day (For daily variations)

1

P = 180

0.10

P = 180% MDD ADD

180%

When t = 7 days (For weekly variations) P = 180

(7)-0.10

P = 148% MWD AWD

148%

T = 30 days (For monthly variations) P = 180 (30)-0.10 P =128% MMD 128% AMD Maxm monthly Demand 128% Avg.MonthlyDemand PROBLEMS 1. The design population of a town is 15000 Determine the Average daily, Maximum hourly demand under suitable assumptions Soln: Assuming Average percapita demand as 270 Lpcd i.

ADD = design population Avg. per capita demand = 1500 270 = 4050000 Litres/day ADD = 4050 m3/day

ii.

MDD = 1`.8 Average daily demand = 1.8 4050 MDD = 7290 m3/day

iii.

Maximum hourly demand of maximum day = 2.7 Annual Avg. hourly demand q = 2.7 24

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Environmental Engineering – I 4050 24 = 455.625 m3/hr = 10935 m3/day

10CV61

= 2.7

or

EFFECTS OF VARIATION 1. The sources of supplies such as wells etc… may be designed for MDD 2. The pipe mains taking water from the source upto the service reservoirs may be designed for MDD. 3. The filter and OTHER UNITS at water treatment plant may also be designed for MDD. Sometimes an additional provision for reserve is also made for break down and repairs therefore they may be designed for twice the ADD instead of MDD. 4. The pumps may be designed for MDD plus some additional reserve (say twice the ADD) When the pumps do not work for all the 24 hrs such as in small town supplies, the design draft should be multiplied by

24 Number of hours in the day foe which the pumps are running 5. The distribution system is generally designed for the maximum hourly demand of the maximum day or coincident draft whichever is more. 6. Service reservoirs are generally designed for 8 days consumption. COINCIDENT DRAFT It is extremely improbable that a fire may break out when water is being drawn by the consumers at maximum hourly draft. Therefore for general community purposes, the total draft is not taken as the sum of maximum hourly demand and fire demand but is taken as the sum of MDD and fire demand ort the maximum hourly demand whichever is more. The MDD when added to fire demand for working out TD (Totaldraft) it is known as coincident draft. COINCIDENT DRAFT = MAXM DAILY DEMAND (MDD) + FIRE DEMAND (FD) Problem 1.A water supply screen has to be designed for a city having a population of 1,50,000 Estimate the important kinds of drafts which may be required to be recorded for an Avg. consumption of 250Lpcd. Also record the required capacities of the major components of the proposed water works system for the city using a river as the source of supply. Assume suitable figures and data where needed. Soln: i. Average daily demand ADD = (per capita Avg consumption in Lpcd) population = 250 150000 SJB Institute of Technology, Department of Civil Engineering

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= 37500000 Litres/day = 37.5 106Litres/day = 37.5 Million Litres/day or ADD = 37.5 Mld ii.

Maximum daily draft May be assumed as 180% of annual average daily draft. MDD = 1.8 37.5 MDD = 67.5 Mld

iii.

Maximum hourly demand of maximum day May be assumed as 270% of annual average daily draft. 37.5 24 MHD= 2.7 24 MHD = 101.25Mld iv. Fire demand Using national board of fire under writer‟s formula, when population is less than or equal to 2 lakhs we have

Q

4637 p 1 0.01 p 4637 150 1 0.01 150 49835.92 Litres / min 71763724.35 Litres / min 71.76 106 Litres / min

Q 71.76 Mld . COINCIDENT DRAFT

= MDD + Fire draft = 67.5 + 71.76

= 139.26Mld.

CAPACITY OF VARIOUS COMPONENTS 1. The intake structure for fetching water from the stream may be designed for MDD i.e for 67.5Mld. 2. The pipe mains carrying the water from the intake to the treatment plant and then to service reservoir. May be designed for MDD Required capacity = MDD (67.5 Mld) 3. The filters and other units at the treatment plant may be designed for MDD plus some reserve (say twice the ADD) Required capacity = 2 ADD = 2 37.5 = 75 ld. SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I 4. The Lift pumps may be designed for twice the ADD = 2 pumps are operating for all the 24 hours)

10CV61 37.5 = 75 Mld (Assuming

5. The distribution system including the pipes carrying water from service reservoir to the distribution system may be designed for coincident draft with fire or maximum hourly demand, whichever is more. The required capacity = 139.26 Mld. POPULATION FORECASTING When the design period is fixed, the next step is to determine population in various periods because the population of the towns generally goes on increasing. The population is increased by births, decreased by deaths, increased or decreased migration. The correct present and past population can be obtained from census office. The WSS are not designed for the present population the future population expected by the end of the design period may be estimated by various methods. The method to be adopted to a particular town or city depends on the factors discussed in these methods. The various methods of forecasting the population are 1. Arithmetical increase method 2. Biometrical increase method 3. Incremental increase method 4. Decreasing rate of increase method or decreasing rate method 5. Simple graphical method 6. Comparative graphical method 7. Master plan method or Zoning method 8. Ration method or Apportionment method 9. Logistics curve method. ARITHMETICAL INCREASE METHOD This method is based upon the assumption that the population is increasing at a constant rate, ie. The rate of change of population with time is constant. If the present population of a particular town is „P‟ and the average increase in population for past decade „Ia‟ the future population „Pn‟ at the end of „n‟ decades will be Pn = P+ nIa This method gives low results for developing areas, which develop faster than the post this method of limited value may be useful for smaller design periods or for old and very large cities SJB Institute of Technology, Department of Civil Engineering

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with no industries and which have practically reached their maximum development or approaching saturation GEOMETRICAL INCREASE METHOD This method assures that the percentage increase in population from decade to decade is constant. This method gives high results for young cities expanding at faster rates and useful for old developed cities. If the present population of the city is „P‟ and the Average percentage increase/ decade „Ig‟ then the population „Pn‟ at the end of “n‟ future decades will be

Ig Pn = P I 100

n

INCREMENTAL INCREASE METHOD This method is a combination of the above two methods and therefore gives the advantages of both arithmetic and Geometric increase methods and hence gives satisfactory results. In this method the Average increase is first determined by the arithmetical increase method and to this added the average of the net incremental increase once for every future decade. n(n 1) p p nI L n o a i 2 PROBLEMS 1. Estimate the population by 2001 by Arithmetic and geometric progression method using the following census, which method is ideal and why? YEAR 1951 1961 1971 1981 POPULATION 19800 42000 75000 110000 Soln:

I)

YEAR

POPULATION

1951 1961 1971 1981

19800 42000 75000 110000

INCREASE DELADE 22200 33000 35000

PER % INCREASE PER DECADE 112.12 78.57 46.67

Ia = 30067

Ig = 79.116

By ARITHMETICAL INCREASE METHOD The population by 2001 is given by P2001 = P1981 + nIa

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n= 2 decades Ia = 30067 P2001 = 100000 + 2(30067) P2001 = 170134 II)

By GEOMETRICAL INCREASE METHOD The population by 2001 is given by P2001 = P1981

Ig = 1 100

79.116 110000 1 100 P2001 = 352908

n

2

In this case AIM is ideal because, GIM gives very high results.

2.

The census record of a town is as follows YEAR 1940 POPULATION 81420

1950 125000

1960 170000

1970 220000

1980 230000

Workout the populationafter three decades by AIM, GIM, and IIM Solution: YEA POPULATIO INCREASE/DECAD %INCREASE/DECAD R N E E 1940 81420 43580 53.52 1950 125000 45000 36 1960 170000 50000 29.41 1970 220000 10000 4.55 1980 230000 Ia = 37145 Ig = 30.87

I)

By ARITHMETICAL INCREASE METHOD Population after 3 decades i.e by the year 2010 P2010 = P1980 + nIa = 230000+3(37145) P2010 = 341435

II)

By GEOMETRICAL INCREASE METHOD populationafter 3 decades P2010 = P1980

= 1

Ig 100

INCREMENTA L INCREASE 1420 5000 40000

Ii = -11194

n

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3

By INCREMENTAL INCREASE METHOD Population by 1990 P1990 = P1980 +Ia +Ii = 230000+37145-11194 P1990 = 255951 P2000 = P1990 +Ia +Ii = 255951+37145-11194 P2000 = 281902 P2010 = P2000 +Ia +Ii = 281902+37145-11194 P2010 =307853

3) The census data of population of a town are as follows Estimate the population by the year 2011 by AIM GIM and IIM. Which method is ideal and why? 1961 YEAR POPULATION 80

YEA R 1961 1971 1981 1991

Solution: POPULATIO N (in thousand) 80 120 145 160

1971 120

1981 145

INCREASE/DECAD E

%INCREASE/DECAD INCREMENTA E L INCREASE

40 25 15

50 20.83 10.34

-15 -10

Ia = 26.667

Ig = 27.056

Ii = 12.5

I)

By ARITHMETICAL INCREASE METHOD P2011 = P1991 + nIa = 160+2(26.667) P2011 =213.334(In Thousands)

II)

By GEOMETRICAL INCREASE METHOD P2011 = P1991

1991 160

Ig = 1 100

n

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2

27.056 100 1 100 P2011 =258.29(In Thousands)

III)

By INCREMENTAL INCREASE METHOD P2001 = P1991 +Ia +Ii = 160+26.667-12.5 P2001 =174.167(In Thousands)

P2011 = P2001 +Ia +Ii = 174.167+26.667-12.5 P2011 =198.334 (In Thousands) IIM is IDEAL because GIM and AIM have lorger values. IIM gives a constant value.

SIMPLE GRAPHICALMETHOD In this method a graph is plotted from the available data, between time and population the curve is then smoothly extended up to the desired year. The method, however, gives very approximate results, as the extension of the curve is done by the intelligence of the curve is done by the intelligence of the designer. PROBLEM: 1. YEAR 1900 POPULATION 35000

1920 40000

1940 44000

1960 49000

1980 55000

Calculate the population at various decades like 2000, 2020, and 2040. By GRAPH population in the year, 2000 = 60300 2020 = 65750 2040 = 70000 Comparative graphical method In this method the cities having conditions and characteristics similar to the city under consideration are selected. It is assumed that the city under consideration will also develop in similar fashion of the selected cities. The population growth curve of the city under consideration is drawn using the available data as shown in the figure. Decrease in sale of increases method or decreasing sale method Simi rate of increases in poplin goes on reducing as a city reaches towards etc. saturation value this method which makes use of decreases in the % increases is wed & gives a rational result in this method the average decreases in the increases is worked out & then subtracted from the latest increases for each successive decade. SJB Institute of Technology, Department of Civil Engineering

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Pn

10

Ig (n 10) Id Pn 100

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10

Master plan or zoning method By & metropolitan cities are generally not allowed to develop in a haphazard & natural way but are allowed to develop only in planned ways The master plan prepared for such cities, divides the city into zones & thus to separate the residential, commend & industrial area‟s from each at The poplin densities are also fixed. It is very easy to calculationdesign poplin using master plan because it will give us as to when & where the given no of houses, industries etc..Would be developed. Ratio method & apportion method In this method the cities poplin record is ex as %age of poplin of the whole country. At the feat, the rations of local to national poplin are worked out for past 4-5 decades. A graph in plotted l/w tone & there ratios to design period to calculation future population. Graph If the poplin of a town is plotted w.r.t time, the curve so obtained under normal condition are be as in figure & is called as ideal growth curve or logistics curve The rarely growth of the city is shown by IK & is an increasing rate of

dp P The growth l/w K dt

dp = const dt This transitional curve „KM‟ also pass through the point of inflection „L‟ Later the growth from dp M to N shows the decreasing in rate ie Ps P where „P‟ is the poplin of town @ T from J ds & Ps value of saturation The „S‟ shaped curve JKLMN is logistic curve

& M follows

Ps

P H

Ps

P0 P0

Now let Ps P0 P0 z

KPs

log e 1

KPs t

m

n

Ps 1 m log e 1 nt Which is the required eq… P

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If 3 pairs of char values P0 , P1 & P2 @ time t0 , t1 , t2 which extend over the range of t0 0, t1 & t2 2t1 are known as the saturation value Ps M & n can he found

Ps m n

2 P0 PP P12 ( P0 1 2 P0 P2 P12 Ps

P2 )

P0 P0

P P P 2.3 log10 0 5 1 t1 P1 Ps P0

2. The details of a town‟s population are given below.Find its population in 2001 Year Population sol

Ps m n

2 P0 P1 P2 P12 ( P0 P0 P2 P12 Ps

P0 P0

1961 35000 P0 =35000

1971 78000 P1 =78000

1981 115000 P2 = 115000

t 0 =0

t1 10

t2

P2 )

20

138271

2.9506

P P P 2.3 log 0 s 1 t1 P1 Ps P0 0.1338

t 1961 2001 t 40 Ps P 1 m log e 1 nt 136364

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UNIT 2 - SOURCES OF WATER SUPPLY CLASSIFICATION OF SOURCES OF WATER SUPPLY The various sources of water available on earth can be classified into the following two categories PRECIPITATION

1. 2. 3. 4.

Surface sources such as Sub surface sourcessuch as Lakes(natural) 1.Springs Streams and Rivers 2.Infiltration galleries Storage(impounded)reservoir 3. Infiltration wells Oceangenerally not used for water supplies at present 4. Wells&Tubewells(Borewells)

SURFACE SOURCES are those sources of water in which water flows over the surface of the earth and is thus directly available for water supplies NATURAL PONDS AND LAKES: The quantity of water available from pond or lake is however generally small though they are not considered as principal sources of water supply. It depends on the catchment area of the Lake Basin, annual rainfall and geological formations. The quality of water in lake is generally good and does not need much purification. Larger and older lakes however provide comparatively pure water then smaller and new lakes. Self purification of water due to sedimentation of suspended matter bleaching of colour, etc… makes the lake water pure and better when compared to stream or river waters. STREAMS AND RIVERS: The quantity or discharge of the streams is generally low, sometimes even go dry in summer season. Therefore they may be considered as source of water supply only for small villages. The quality of water in streams is normally good except the first runoff. But sometimes runoff water while flowing over the ground is mixed with silt, clay, sand and other mineral impurities. This can be removed in a sedimentation basin upto certain extent. (Rivers are formed when the discharge of large number of springs and streams. Combine together. Rivers (Perennial) are the most important sources of water for public w.s.s. Therefore most of the cities are situated on the banks of the rivers the rivers may be perennial or nonperennial (seasonal). Perennial rivers flow throughout the year getting their waters during summer from snow and from rain in winter. Perennial rivers may be considered as water supply sources directly where asnon perennial rivers can be used as public water supplies by providing storage barriers across these rivers.

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IMPOUNDED RESERVOIRS: During summer the water which is flowing in the river may not be sufficient to feed the town and on the other hand during rainy season it may be difficult to operate due to flood waters. Therefore hydraulic structures are constructed across these river valleys forming impounded reservoirs. The quality of water in these reservoirs is not much different from that of lake water while top waters prove to develop algae, bottom layers of water may be high in turbidity Co2, iron and manganese and on occasions H2S. UNDER GROUND SOURCES (OR) SUB-SURFACE SOURCES They are nothing but sub-surface sources with regard to their quantity and quality aspect rainwater percolating into the ground and escaping beyond the reach of vegetation and either collecting in underground basins or flowing underground in sub-surface streams constitutes a ground water source. Generally ground water is clear and colorless but is harder than the surface water of the region in which they occur. In lime stone formation, ground water is very hard and dispositive nature in pipe lines. In granite formations, they are soft. The water as it seeps down comes in contact with organic and inorganic substances during its passage through the ground and acquires chemical characteristics representative of the starter it passes. Bacteria logically, ground water is much better than surface water except where sub-surface pollution exists. FACTORS” GOVERNING THE SELECTION OF A PARTICULAR SOURCE OF WATER The following important factors are generally considered. 1. 2. 3. 4. 5.

The quantity of water available The quality of water available Distance of the source of supply Elevation of source of supply Cost.

1. QUANTITY OF WATER AVAILABLE = Quantity of water available must be sufficient to meet the various demands during the entire design period. If the available source found is not sufficient. The additional source which is available in the nearby (vicinity) is considered. 2. QUALITY OF WATER AVAILABLE = water available must not be toxic, poisonous or in any other way injurious to health.) It should contain minimum impurities so that their removal does not require costly treatment processes. 3. DISTANCE OF THE SOURCE = The source of supply must be near to the town in order to minimize the length of conduits required to transport water. 4. COST = The selection of source should be such that the overall cost of water supply project is brought down to the minimum.

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VARIOUS FORMS OF UNDER-GROUND SOURCES INFILTRATION GALLERY Infiltration gallery or horizontal or nearly – horizontal tunnels constructed at shallow depths (3-5m) along the bank of the river through the water bearing strata as shown in the figure. They are sometimes called as horizontal wells. These galleries are constructed of masonry walls with concrete roof slab and derive their water from the aquifer by various drain pipes. These pipes are generally covered with gravel so as to prevent the entry of sand particles into the pipe. These tunnels are laid at a slope and water collected in them, is taken into a sump from where it is pumped to the treatment plant and distributed to the public. These are very helpful when sufficient quantity of water is available just below the ground level or so. In order to obtain large quantity of water, a series of shallow wells are sunk in the banks of the river. The wells are constructed of brick masonry with open joints and are closed at top and open at the bottom. The water infiltrates through bottom sand bed and gets purified to some extent. For inspection a manhole cover is usually provided in roof slab. These various infiltration wells are connected to a common sump well by porous drain pipes. This sump well is called JACK WELL. The water from this jack well is lifted to the treatment plant. SPRINGS A natural outflow of ground water at the earth surface is said to form a spring a pervious layer sandwiched between two impervious layers gives rise to a natural spring. The springs are generally capable of supplying very small quantities (amounts) of water and therefore generally not regarded as sources of water supply. FORMATION AND TYPES OF SPRINGS Springs are usually formed under 3 general conditions of geological formations They are i. Gravity springs ii. Surface springs iii. Artesian springs.

YIELD AND SPECIFIC YIELD The volume of ground water extracted by gravity drainage from the saturated water bearing material is known as YIELD and when it is expressed as the ratio of the volume of water that can be drained by the gravity to the gross volume of the soil then it is known as SPECIFIC YIELDA Therefore volume of water obtained by gravity drainage SPECIFIC YIELD= gross volume of the soil. Values of specific yield are dependent on soil” particle size, shape and distribution of pores and degree of compaction of the soil. SJB Institute of Technology, Department of Civil Engineering

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SPECFIC RETENTION OR FIELD CAPACITY The quantity of water retained by the materials against the pull of gravity is termed as specific retention or field capacity. This is also expressed as the percentage of total volume of materials drained.

AQUIFER AND THEIR TYPES AQUIFER = An Aquifer is an water bearing stratum or formation capable of transmitting water in quantities sufficient to permit development. AQUICLUDE = It is an impermeable stratum that may contain large quantities of water but whose transmission rates are not high enough to permit effective development. AQUIFUGE = It is a formation that is impermeable and divide of water. AQUIFERS may be considered as falling into two categories. i. Unconfined or Non-Artesian Aquifer ii. Confined or Artesian Aquifer, depending on whether or not the water table or free water surface exists under atmospheric pressure. i. UNCONFINED AQUIFER OR NON ARTESIAN AQUIFER The top most water bearing stratum having no confined impermeable over burden (Aquiclude) lying over it, is known as an unconfined aquifer or non-Artesian aquifer. The ordinary gravity wells of 2-5m dia which are constructed to tap water from the top most water bearing strata i.e from unconfined aquifer are known as unconfined or Non Artesian wells. The water levels in these wells will be equal to the level of water table. Such wells are therefore known as water table wells. ii.

CONFINED or ARTESIAN AQUIFERS When an aquifer is confined on its upper and under surface by impervious rock formations and is also broadly inclined so as to expose the aquifer somewhere to the catchment area at a higher level for the creation of sufficient hydraulic head, it is called a confined or an artesian Aquifer. A well excavated through such aquifer yields water that often flown out automatically under the hydrostatic pressure thus even rise or gush out of the surface for a reasonable height.

PERCHED AQUIFER It is a special case which is sometimes found to occur within a confined Aquifer. If within a zone of saturation an impervious deposit is found to support a body of saturated material then this body of saturated material which is a kind of Aquifer is known as perched Aquifer. The top surface of the water held in this perched aquifer is known as perched water table.

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SPECIFIC CAPACITY = Specific capacity of a well is the measure of the effectiveness of the well and is defined as the yield of the well per unit draw down. Therefore

Q yield L draw down Specific capacity of a well is not constant but decreases as discharge increases SPECIFIC CAPACITY =

WATER TABLE:- The uppermost layer of soil or top soil at ground level is generally pervious. The rainwater which is directly percolated through this top soil is contained by it. The upper surface of free water in top soil is termed as water table or ground water level. The water table is the surface of a water body which is constantly adjusting itself towards an equilibrium condition. If there were no recharge or outflow from the ground water in a basin, the water table would eventually become horizontal.

WELLS CLASSIFICATION OF WELLS The wells may be classified as i. Open wells ii. Tube wells i.

OPEN WELLS or DUE WELLS Smaller amount of ground water has been utilized from ancient times by open wells. They are generally open masonry wells having compensatively higher diameters and are suitable for low discharge (18m3/hr). The dia of open wells may be 2-9m and they are generally less than 20m in depth. The walls of an open well may be built by brick or stone masonry or precast concrete rings. The open wells may be classified into the following 2 types i. Shallow wells ii. Deep wells The nomenclature of shallow and deep is purely technical and has nothing to do with the actual depth of the well. A shallow well might be having more depth than the deep well. YIELD OF AN OPEN WELL The term yield of the well is used to indicate the rater of with drawl of water without causing failure of well. It is the rate at which a well can supply the water. The factors which influences the yield of an open well are: 1. 2. 3. 4. 5.

Well dimensions Location of nearby wells Porosity of aquifers Quantity of water available in aquifers Slope of water table

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6. Coefficient of permeability of soil. 7. Rate of pumping water. CO-EFFICIENT OF PERMEABILITY (k) It is defined as the velocity of flow which will occur through the total cross sectional area of soil (or Aquifer) under a unit hydraulic gradient. CO-EFFICIENT OF TRANSMISSIBILITY It is defined as the rate of flow of water in m3/day through a vertical strip of the aquifer of unit width and extending the full sanitation height under unit hydraulic gradient at a temperature of 600F. T = BK Where B = Aquifer thickness DARCY’S LAW The percolation of water through soil was fist studied by darcy(1856) who demonstrated experimentally that for laminar. Flow conditions in a saturated soil, the rate of flow or the discharge per unit time is proportional to the hydraulic gradient. i.e Q = Ki.A Q V = = Ki A WHERE, Q = Discharge K= Darcy‟s Co-efficient of permeability i = hydraulic gradient A = Total C/S area of soil V = Flow velocity. EXPRESSION FOR YIELD OF AN OPEN WELL OR DISCHARGE FROM AN UNCONFINED AQUIFER Let, H= depth of water before pumping h= depth of water after pumping i = slope of hydraulic gradient - dy dx

r = radius of well R = Radius of circle of influence K= coefficient of permeability S = draw dawn at the well. Consider any point „P‟ on the draw down curve (cone of depression) whose co-ordinates are(x,y). THEN from DARCY‟S law Q = KM.Ax ix

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Where Ax = Area of C/S at the saturated part of Aquifer at „P‟ Ax = (2 x)y = 2 xy Ix = hydraulic gradient at „P‟ = dy dx

Substituting „Ax‟ and „ix‟ in the above eqn. Q = K .2 ny Q

dx x

dy . dx

2k y dy

Integrating between the limits „r‟ & „R‟ for „x‟ and (H,h) for „Y‟ we get. R H dx Q 2 k y dy x r h

Q log e x Q Q

y2 R k 2

R r

k H

2

h

H

h

2

log e ( R / r ) 1.36k H 2 h 2 log10 ( R / r )

If there are two observation wells at radial distances „r1‟ and „r2‟ and if the depths of water in them are „h1‟ and „h2‟respectively then

Q

1.36k h22 h12 log10 ( R2 / r1 )

YIELD OR DISCHARGE FROM A CONFINED OR ARTESIAN AQUIFER Let B = thickness of the Aquifer in „m‟ 2.72bk H h Q log e ( R / r )

TEST FOR YIELD OF A WELL The yield of an open well can be found or tested by the following methods 1. Constant level pumping test a. Pumping in test b. Pumping out test 2. Recuperation test.

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CONSTANT LEVEL PUMPING TEST In this test the rate of pumping is so adjusted that water level in the well remains constant. As and when the condition is reached the rate of inflow will be equal to the rate of pumping since it is difficult to maintain constant level in the well this test is generally not adopted to determine the yield.

RECUPERATION TEST In the Recuperation test the water from the well is pumped at a faster rate and its level is depressed to certain level is depressed to certain level pumping is then stopped. The time taken for the water to come to its normal level (Recuperate) is recorded. Let, H1 = initial depression head after pumping stopped (in m) H2 = depression head in the well at a time(T) after pumping stopped(in m) A = Sectional area of the well (m2) C = specific capacity of the well in m3/hr/ m2 of the area under in depression head

2.303 A H log10 1 m3 / hr / m(m 2 of Area) H 2 T Yield of the well Q = CH C

PROBLEMS 1) During the recuperation test, the water level in an open well was depressed by 2.5m after pumping and is recuperated by 1.6m in 70mins. Calculate the specific yield of the well. Also determine the yield from the well of 3m diameter under a depression head of 3.5m

Solution:

C =

1 2.303 A log10 H H2 T

2.303 70

32

4

log 10

2.5 0.9

60 C 6.191 m3 / hr / m (m 2 of area ) yield Q = ch = 6.191 3.5 Q

21.67m3 / hr

2) A 30cm dia well penetrates 25m below the static water table (SWT). After 24hrs of pumping at 5400 lit/min, the water level in a test well at 90m is lowered by 0.53m and in a well 30m away the draw down is 1.11m. What is the transmissibility of the aquifer. SJB Institute of Technology, Department of Civil Engineering

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For an unconfined aquifer, discharge 1.36 K ( H 22 h12 ) Q = r log10 2 r1

But, T = kh or k = T 1.36 T Q =

H

log10 1.36 T 5.4

2 2

(h r2

H

h12 )

r1

(24.47 2 23.892 ) 25 log10 90 30

2.576 T 25 38.146 T 1.69m 2 / min . 3) Design an open well in fine sand for a yield of 0.004 cusecs under a depression head of 3.5m. the value of „C‟ is 0.5m3/hr/ m2 of area/m drawsone. Solution: Q = 0.004 m3/sec Q = 14.4 m3/hr C = 0.5 m3/hr/m drawdown. A We have for the discharge, Q = CH Q= C A H A

14.4 d2 d d

0.5

d2 3.5 4

10.477 3.24m 3.25m

4) A 20cm well penetrates 30m below SWL. After a long period of pumping at a rate of 1800lit/min, the drawdown‟s in the observation wells at 12m and 36m from the pumped well are 1.2m and 0.5m respectively. i) Determine the transmissibility of aquifers ii) The drawdown of the pump well assuming R = 300m. iii) Specific capacity of the well. Solution: SJB Institute of Technology, Department of Civil Engineering

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We have Dupuit‟s Equation 1.36 K (h22 h12 ) Q = r log10 2 r1 h2 = H – S2 = 30 – 0.5 = 29.5m h1 = H – S1 = 30 – 1.2 = 28.8m. 1800 lit/min = 1.8m3/min

1.36 K (29.52 28.82 ) 1.8 = log10 86 12 K 0.00155m / min

iii)

i)

TRANSMISSIBILITY OF AQUIFER T = KH = 22.28 * 30 T = 6668.47m2/Day

ii)

DISCHARGE 2.72 KHS Q = log10 R r 2.72 0.155 30 5 1.8 log10 300 0.2 S 4.52m

Sp.capacity of the well

yield(Q) drawdown s Q S

1.8 60 4.52 6.637 10 3 m3 / sec/ m

5) A Tube well taps an artesian aquifer. Find its yield in lit/hr for a drawdown of 3m, when the dia of well is 20cm and thickness of the aquifer is 30m Assume the Co-efficient of permeability to be 35m/day. If the dia of well is doubled. Find the percentage increase in the yield, the other conditions remaining the same Assume the radius of influence ® as 30m in both cases.

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Solution: We have for an Artesian Aquifer. 2.72T ( H h) Q = log10 R r where T Kb

2.72kb( H h) log10 R r 2.72 35 30 30 27 log10 300 0.1 3 Q 2464.11 m / day Q 102677.14lit / hr 1 Q log10 R r (other things remaining the same) „Q‟ be the yield of the doubled well „r‟ be the radius of the doubled well = 0.2m log10 R 1 Q r 1 Q log10 R r log10 300 102671.14 0.2 300 Q1 log10 0.1 1 Q 112402.31 lit / hr Q

PERCENTAGE INCREASE IN THE YIELD Q1 Q 100 Q

112402.31 102671.14 102671.14 9.48%

100

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COLLECTIONAND CONVEYENCE OF WATER INTAKE STRUCTURES Intakes or intake structures are masonry or concrete structures whose function is to provide calm and still water, free from floating matter for water supply. Intakes consists of the opening, strainers or gratings through which the water enters and the conduit for conveying the water, usually by gravity to a sump well. From the well the water is pumped to the treatment plant. SELECTION OF A SITE FOR INTAKE CONSTRUCTION While selecting a site for intakes, the points to be kept in mind are. i) ii) iii) iv) v) vi) vii) viii) ix)

Intake work should provide good quality water so that its treatment may become less exhaustive Heavy water currents should not strike the structure directly Approach to the intakes should be easy As far as possible intakes should not be selected in the vicinity of sewage disposal Selection of site should be nearer to the treatment plant so that it reduces the cost of conveyance of water They should not be located in navigation channels In meandering rivers, the intakes should not be located on curves or at least on sharp curves Intake must be located at a place from where it can draw water even during the driest periods of the year. Site should be such as to permit greater withdrawal of water, if required of a future date.

TYPES OF INTAKES Depending on the source of water the intake works are classified as follows. i. Lake intake ii. River intake iii. Reservoir intake iv. Canal intake For obtaining water from lakes mostly submersible intakes are used. These intakes are constructed in the bed of the lake below the low water level so as to draw water in dry seasons also. It consists of a pipe laid in the bed of the river, one end of which is provided with bell mouth opening with fine screens. The water enters through the bell mouth opening and flows under gravity.

ADVANTAGES I. No obstruction to navigation II. No danger from floating bodies III. No trouble due to ice. SJB Institute of Technology, Department of Civil Engineering

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RIVER INTAKE It is a circular masonry tower of 4 to 7 meter in diameter constructed along the bank of the river at such place from where required quantity of water can be obtained even in the dry period. The water enters in the lower portion of the intake known as sump well from penstocks the penstocks are fitted with screens to check the entry of floating solids and are placed on the downstream side so that water free from most of the suspended solids may only enter the lack well. Number of pen stock openings is provided in the intake tower to admit water at different levels. The opening and closing of penstock values is done with the help of wheals provided at the pump-house floor. RESERVOIR INTAKE It is mostly used to draw the water from earthen dam reservoir. It consists of an intake tower constructed on the slope of the dam at such place from where intake can draw sufficient quantity of water even in the driest period. Intake pipes are fixed at different levels so as to draw water near the surface in all variations of water level. These all inlet pipes are connected to one vertical pipe Indies the intake well screens are provided at the mouth of all intake pipes to prevent the entrance of floating and suspended matter in them. The water which enters the vertical pipe is taken to the other side of the dam by means of an outlet pipe. At the top of the intake tower sluice values are provided to control the flow of water. The value tower is connected to the top of the dam by means of a foot bridge gangway for reaching it. CANAL INTAKE Canal intake is a very simple structure constructed on the bank. It consists of a pipe placed in a brick masonry chamber constructed partly in the canal bank on one side of the chamber an opening is provided with coarse screen for the entrance of water. The end of the pipe inside chamber is provided with a bell mouth fitted with a hemispherical fine screen. The outlet pipe caries the water to the other side of the canal bank From where it is taken to the treatment plants one sluice value is operated by a wheel from the top of the masonry chamber provided to control the flow of water in the pipe.

PUMPS AND PUMPING STATIONS PURPOSE I. To lift the water from source to the treatment plant which is at higher level compared to the source II. To lift the treated water to the elevated tanks III. To increase the pressure in the distribution system. IV. To lift the water at the treatment plant if sufficient natural ground slope is not available as to cause gravitational flow between different units of treatment plants.

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Classification of pumps

Based on their Principal of Based on the type of power required service

Based on the type of operation

i. Displacement pumps

i.Electrically driven pumps

ii.Centrifugal pumps

ii. Gasoline pumps

iii. Airlift pumps

iii. Steam engine pumpsiii.Deep well pumps

iv. Impulse pumps

iv.Diesel engine pumps

i. Low lift pumps ii.High lift pumps

iv. Boosters

v. Stand by pumps Under most of the situations in water supply scheme, displacement and centrifugal pumps are commonly used. Displacement pumps i. Reciprocating pumps ii. Rotary pumps PUMPING STATIONS The location of a pumping station is primarily governed by the place where it is to recerive water. The points to be kept in mind while selecting a suitable site are. i.

The site should be away from all the sources of contamination or pollution

ii.

The site should be above the HFL of the river.

iii.

Its future growth and expansion is easily possible

iv.

Possibility of fire hazards is also to be considered

FACTORS AFFECTING THE SELECTION OF A PARTICULAR TYPE OF PUMP 1. Capacity of pumps 2. Importance of WSS 3. Initial cost of pumping arrangement 4. Maintenance cost 5. Space requirements for locating the pumps 6. Number of units required SJB Institute of Technology, Department of Civil Engineering

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7. Total life of water required 8. Quantity of water to be pumped. HEAD POWER AND EFFICIENCY OF PUMPS The total head against which a pump works is made up of i. ii. iii.

The suction Head(Hs) The Delivery Head(Hd) The Head loss due to friction entrance and exit in the rising main(Hf)

The suction HEAD is the difference in elevation between the low water level and center line of pump. Delivery HEAD is the difference in elevation between the pump center line and point of discharge Total HEAD (H) =Hs+Hd+Hf The work done by the pump in lifting „Q‟ cumecs of water by a head(H) =WQH kg-m/sec. Where, W = Specific weight of water, 1000 kg/m3 Q = discharge to be pumped, m3/sec. The water horse power of the pump is given by WHP(out put) = WQH/75 If „n‟ is the efficiency of the pump then BRAKE HORSE POWER of the pump is given by BHP(INPUT) + WQH/75n ECONOMICAL DIAMETER OF THE RISING (PUMPING) MAIN The economical diameter is a particular size of the pumping or rising main which while passing a given discharge of water gives the total annual expense to be minimum. If the diameter chosen is more than the economic dia, it will lead to higher cost of the pipe line on the other hand, if the dia of the pipe is less than the economical dia, the increased velocity will lead to higher friction headless and require more HP for the required pumping and the cost of pumping shall be much more than the resultant saving in the pipe cost. LEA FORMULA An empirical formula given by LEA Connecting the dia and discharge is given by D = 0.97 to 1.22 Q Where D = economical diain‟m‟ Q = Discharge to be pumped in „cusecs‟ SJB Institute of Technology, Department of Civil Engineering

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This relation gives optimum flow velocity varying between 0.8 to 1.35m/sec FOR RIGOROUS ANALYSIS The total cost of pipe and pumping should be woeked out at different assumed velocities (b/w 0.8 to 1.8m/sec) and a graph plotted between the annual cost and the size of the pipe. The economical size is one which gives the least annual cost. PROBLEMS 1. Determine the capacity of pump required for the following data Population = 3lakhs Daily demand of water = 140lped Water level in the source = 100m Level of the treatment plant = 125m Pumping hours = 24hours a day Dia of the Rising main = 90cm Distance between the source and Treatment plant = 2km Coefficient of friction = 0.01 Solution: Total daily demand = 300000 140 (TDD) = 42000000 lit/day TDD = 42000m3/day 42000 Discharge = 24 60 60 Q = 0.486m3/sec Static head(Hs) = 125-100=25m

FLQ 2 Head loss(Hf) = 3d 5 0.01 2000 (0.486) 2 3 (0.9)5 HF 2.67m Total head = 25+2.67 H = 27.67m WQH BHP 75n 1000 0.486 27.67 75 0.75 BHP 239.07 HP 2. A town with prospective population of 60000 is to be supplied with water from a river 4.8km away and 30.5m below the level of town. Design the economical section of rising SJB Institute of Technology, Department of Civil Engineering

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main and pumping unit where electrical power is available. Take water supply rate as 150lped and f=0.01. Assume other relevant details. Solution: Total daily demand = 60000 150 (TDD) = 9000000 lit/day = 9000m3/day TDD = 0.1042m3/sec Assuming 18hrs of pumping is done a day 0.1042 24 18 0.1389 m3 / sec The economical dia of rising main using LEA FORMULA 1.2 Q

1.2 0.1389 0.447m 0.45m dia rising main STATIC HEAD = 30.5M FLQ 2 Head loss(Hf) = 3d 5 0.01 4800 (0.1389) 2 3 (0.45)5 HF 16.728m Total head = 30.5+16.728 Total head = 47.23m Assuming efficiency of motor (nm) as 90% Assuming efficiency of pump (nP) as 80% (Since electrical power is used) WQH Capacity of the pump required 75nm n p

BHP

1000 0.1389 47.23 75 0.9 0.8 121.49 HP

3 3. A centrifugal pump is to lift 4m of water per sec to a height of 10m. Assuming total loss of head in pipes as 0.5m calculate the H.P of driving engine to run the pump it its efficiency is 75%.

Solution: Q = 4m3/sec Total head = H = 10+0.5 = 10.5m SJB Institute of Technology, Department of Civil Engineering

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Assuming that the efficiency of driving engine is 90% WQH BHP 75nP nm

BHP

1000 4 10.5 75 0.75 0.9 829.63HP

HYDRAULIC DESIGN OF PRESSURE PIPES DETERMINATION OF LOSS OF HEAD IN PIPES The head loss in the pipe can be determined by the following formula: a) MANNING‟S FORMULA This formula is usually used in determining the loss of head in the gravity conduits n2V 2 L HL R 4/3 Where n = Manning Rugosity (roughness) coefficient L = Length of pipe V = Velocity of flow in pipe R = Hydraulic mean depth(HMD) A Wetted area R= P wetted perimeter

d2 4

When circular pipe flowing full = A = P=

d2

A R= P

d

d 4

4 D

When circular Pipe flowing halffull = = A = P= d

R=

d

d2 8

2

2

d

8 2

d 4

B) HAZEN WILLIAM’S FORMULA V= 0.85 CH R0.63 S0.54 CH= Hazen – william‟s coefficient (100 -140) S = Slope c) DARCY – WEISBACH FORMULA

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4 FLV 2 flQ 2 2 gd 3d 5 F = dimensionless friction factor, varies between 0.0075 to 0.03 G = acceleration due to gravity The appropriate value of „F‟ can be determined by the following empirical formula hL

a)FOR NEW PIPES 0.02 1

1 35d

b)FOR OLD PIPES 1 35d WHERE, d = diameter of pipes 0.04 1

4. A town population 1.5 lakh is to be supplied with water. The water works to be located at a lower elevation of 10m than the water level of the source. Find the size of the gravity main to convey the water from the source to the water works which is located at a distance of 30km. The per capita demand of water is 150lit/day. Solution: Qty of water required by the town = 150000 150 (TDD) = 22500000 lit/day = 22500m3/day TDD = 0.2604m3/sec

Assuming 12hrs of pumping per day

0.2604 24 12 0.5208 m3 / sec We have Discharge = Area * Velocity Q AV

V

Q

A 0.5208 V d2 4 0.663 V d2 Using Darcy – Weis bach formula SJB Institute of Technology, Department of Civil Engineering

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4 FLV 2 Hf = 2 gd Assuming of = 0.0075

0.663 2 ) d2 3 9.81 d

0.075 30000 ( HF

114.68 0.663 d d2 5.04 d5

HF HF

2

Cosidering all the available head lost in overcoming the friction 5.04 100 d5 d 0.55m

5. Determine the size of water main required to carry water from a source 2.15KM away from the town the yield from the source is 1500lit/min Head lost in friction is 50.50m. Assume F = 0.01 Solution Discharge = 150Lit/min = 1.5m3/min Q = 0.025 m3/sec We have

0.025 V

Q = AV d2 V 4 0.0318 d2

By, DARCY – WEISBACH FORMULA

4 FLV 2 HF = 2 gd

SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I 0.0318 4 0.01 2150 d2 50.50 2 9.81 d 5 d 8.77733 10 5 d 0.15441m d 15.44cm d 16cm

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2

6. Water is to be supplied to a town of 3laks population from a source 2km away. Percapita demand of town is 180lped. If the town is situated at a higher elevation than the source and the difference in elevation b/n the lowest water level in the source to the point of inlet at the water war‟s is 30m, Determine the size of rising main and HP of the pump, The value of Solution: Quantity of water required by the town = 500000*180 = 90 *106litres/day Q = 90MLD Q = 1.042 m3/sec 0.63 0.54 V = 0.85 CHR S

Q AV 42

1.042

0.85 110

4

d 2 1.2

1.05 4

1.051

0.63

5

0.54

S 1.495 10 3 S Lin 688 CH - 110 and the pump works for 18hours Solution: Qty of water required by the town = 300000 180 (TDD) = 54000000 lit/day = 54000m3/day Q = 0.625m3/sec The discharge required for 18 hours of pumping per day 0.625 24 Q 18 Q 0.833m3 / sec Assuming the velocity of flow through pipe as 1.2 m/sec

SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I The c/s area of pipe (A) = A

Q V

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0.833 1.2 0.694m2

Dia of the rising main d2 0.694 4 d 0.94m Using Hazen – William‟s equation

V

0.85CH R 0.63 S 0.54

Where HL S L R

d

4

0.94 4

0.235

V

0.85 110

0.235

1.2

0.85 110 0.235

0.63

0.63

S 0.54

S 0.54

S

1 in 587.84 HL S L 1 HL 587 2000 H L 3.41m

The head difference between LWL to water works point of inlet = 30m (static head) Total head = 30 + 3.41 = 33.41m Assuming the efficiency of the pump 75% WQH BHP HP 75nP

BHP

1000 0.8333 33.41 75 0.75 494.94 HP

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CONVEYANCE OR TRANSMISSION OF WATER VARIOUS TYPES OF PRESSURE PIPES Depending on the construction material the pipes are of the following types i. C.I pipes ii. Steel pipes iii. RCC pipes iv. Hume steel pipes v. Vitrified clay pipes vi. Asbestos cement pipes vii. Miscellaneous pipes such as wrought iron pipes, PVC pipes. PIPE JOINTS For facilitating in handling transporting and placing in positions pipes are manufactured in small lengths of 2-6m. These small pieces of pipes are then joined together after placing in position, to make one continuous length of pipe the design of these joints mainly depend on the pipe material, internal pressures and the condition of support. VARIOUS TYPES OF JOINTS are i. Bell and spigot joint ii. Expansion joints iii. Flanged joint Mechanical joint iv. Mechanical joint v. Flexible joint vi. Screwed joint vii. Collar joint

BELL AND SPIGOT JOINT Design of pipes using monograms For the known design discharge. The pipe dia are assumed in such a way that the velocity of flow varies from 0.6 to 3m/sec smaller velocity is assumed for pipes of smaller dia& larges velocity for pipes of larger dia. The loss of head in the pipe is then cal using hydraulic formulas. Out of these formulas Hagen – William formula is more commonly used. The use of Hagen Williams formula however involves trial & error sol & in order to avoid this monogram of Hagen Williams formula has been developed. These are in all four variably 1. Discharge Q in m3/min or lit/sec 2. Dia of pipe in mm 3. Loss of heat in m/1000m light of pipe 4. Velocity of flow in m/sec

SJB Institute of Technology, Department of Civil Engineering

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If out of 4 quantities any 2 are known. The other 2 can be found from the monogram. The monogram should in fig is valid for a value of roughness co-eff. C4 = 100. For any other value of CH the head loss obtained from the monogram is multiplied by the factor CH/100 For example Let the flow rate he 10m3/min & the dia of pipe he 400mm. It is required to find the head for a pipe of 800 m length. Mark a point A corresponding to Q = 10m3/min discharge line & point B corresponding to dia = 400m the dia line from point A & B by means of straight be prolong the line AB to cut the head loss line at per velocity line at point „D‟ this we get head loss 1000m light = 7m Hence the head loss for 800m length

800 7 the velocity of flow comes to the 1.38m/sec. 1000

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UNIT3 - QUALITY OF WATER WHOLE SOME WATER – Absolutely pure water is never found in nature absolutely pure water is the water which contains 2parts of „H‟ and 1part of oxygen by volume but the water found in nature contains a number of impurities in varying amounts. The rain water which is originally pure also absorbs various gases dost and other impurities while falling. This water when moves on ground picks up silt, agonic and inorganic impurities. Complete, removal of these impurities becomes costly and on other hand, certain impurities cause the water tasteful and our body needs certain elements and if no present in water their removal is not necessary such a water which does not contain harmful impurities and thus contain other salts and impurities either good or unharmful to health is called wholesome or potable water Following are the requirements of wholesome water 1. 2. 3. 4. 5. 6.

Should be free from bacteria‟s which may cause diseases. Should be colourless and sparkling which may be accepted by the public It should be tasty, adourfree and cool. Should not corrode pipes Should be free from all objectionable matter. Should have dissolved oxygen (DO) and free from carbonic acid so that it may remain.

PALATABILITY To be palatable, water must be significantly free from colour, turbidly, taste and Adour and of moderate temperature in summer and winter and well aerated. At least 4 human perceptions respond to these qualities.

IMPURITIES IN WATER Impurities in water may be organic, inorganic and living organisms. Both organic and inorganic impurities may be in the form of suspended, colloidal, sett liable and dissolved state.

SUSPENDED IMPURITIES includes silt, clay, Algae, Tung, organic and inorganic matters and mineral matters etc…. They neither settle down nor dissolve in water and are microscopic and make water turbid. Bacteria cause diseases while silts, clay, Algae, protozoan‟s cause turbidity, odor and colour in water. The concentration of suspended matter in water is measured by turbidity. SJB Institute of Technology, Department of Civil Engineering

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COLLOIDAL IMPURITIES Colloids are particles in a finely divided state. They are neither in suspension nor insolvable but in condition midway between the two. These particles are so small that their removal in a sedimentation tank is impossible at reasonable overflow rates and detention time. They are not visible to the naked eye and are electrically charged and repel cash other. The size of these particles is between 1 minor to 1 mille micron. They impart colour to the water.

DISSOLVED IMPURITIES Their numbers may be very large because water is a very good solvent and can dissolve all the salts to which it comes in contact. Salts of calcium, magnesium when dissolved in water cause taste, hardness, alkalinity, etc….

IMPURITIES A)INORGANIC a. Suspended b.Dissolved

IMPURITIES B) ORGANIC I. Suspended a.vegetable b.animal II.Dissolved a.vegetable

CAUSES EFFECTS Particles of silt and clay Turbidity I)Carbonates and bicarbonates of Hardness & alkalinity calcium and mg. ii)Sulphates and chortles of ca Hardness and corrosion and mg. iii)carbonates and bicarbonates of Alkalinity sodium iv)Nitiates Excess over 50mg/lit Methenoglubanemiao r blue babies. v)chlorides of „Na‟ Brackish taste vi)Fluorides of „Na‟ Excess over 1.5mg/L causes Fluor sis. vii)Iron oxide Taste colour and hardness viii)Manganese Taste and odour

CAUSES

EFFECTS

Decayed leaves, Acidity, taste and colour algae,Fungi,etc.. Contamination Dead animals, hairs, insects, etc.. Bacteria.

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b.Animal

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Large quantities of albuminoidal nitrogen with Pathogens, contamination due little quantities of ammonia to sewage. Etc… and chlorides. Large quantities of Albuminoidal nitrogen

WATER BACTERIA May bacterias are found in water most of them are of no sanitary significance. Few in numbers are pathogenic. These include bacteria causing typhoid fever, Para typhoid, Dysentery, Gastro enteric diseases, etc… Water bacteria may be classified in 4 ways. 1) According to Oxygen Demand a. Aerobic bacteria = those which require light and free oxygen for their living and development. b. Anaerobic bacteria = those which do not require light and free oxygen for their living and development. c. Facultative bacteria = those which can exist in presence or absence or light and free oxygen. They grow more in absence of oxygen. 2) According to Shape a. Cocci bacteria = Cells are round or spherical. b. Bacilli = Cells are rod shaped. c. Spirilla = Spiral shaped cells. 3) According to their diseases producing characteristics a. Pathogenic bacteria = those which are harmful to human life. They causes diseases like typhoid, Dysentery, cholera, etc… b. Non-pathogenic bacteria = those do not cause diseases to human. 4) According to the Temperature Flourish a. Psycryophilic bacteria = which can persist at low temperature only Range 10 – 200C. b. Mesophillic = which can thieve within the temperature range of 200C to 400C. c. Thermophillic = It is most effective in the temperature range of 40-650C. WATER BORNE DISEASES are those which are transmitted by contaminated water. Water is a very good carrier of micro organisms. Communicable diseases which may be transmitted by water include bacterial, viral and protozoan infections The diseases caused by bacterial infections are a. Typhoid fewer b. Para-Typhoid c. Bacillary dysentery SJB Institute of Technology, Department of Civil Engineering

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d. Cholera e. Solmonellosis f. Shigellosis Viral infections a. Infectious hepatitis(jaundice) b. Polio myelitis Protozoan infections a. Amoebic dysentery (Amoebiasis) b. Giardiasis.

CHARACTERISTICS AND EXAMINATION OF WATER OBJECTS OR ADVANTAGES OF ANALYSIS OF WATER 1. By knowing the results of analysis, the outline of the treatment process may be framed. 2. Daily operation of the treatment plant is based on this analysis report. 3. To ascertain the quality of raw water to suggest the type of treatment to be given and the degree of treatment necessary. 4. Water must also be analyzed at the end of the treatment to find out the efficiency or performance of the treatment plant. PHYSICAL CHARACTERISTICS AND EXAMINATIONS The various physical characteristics and examinations are i. Temperature ii. Colour iii. Turbidity iv. Taste and odour Temperature: The most desirable temperature for public water supply scheme is 100C. Temperature above 260C are undesirable and above 370C are unfit for P.W.S.S. as they are not palatable Colour:Colour in water is usually caused by the presence of organic matter in colloidal and dissolved state. The colour can be measured by comparing the colour of water sample with other standard glass tubes called NESLER‟S TUBES containing solutions of different standsrdcolour intensities) The standsrd unit of colour is that which is produced by one milligram of platinum – cobaltus chloride dissolved in 1-litre of dist5illed water. For domestic supplies the permissible limit is 20 colour units (CU) on platinum cobalt scale and should be preferably less than To. For precise determination of small colour intensities, compact instrument properly lighted from inside called TINTOMETER is used. Turbidity: It is the measure of inter frame given by insoluble process of soil organics, mionoorganisms and other materials for the passage of light through water the standard unit is SJB Institute of Technology, Department of Civil Engineering

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that which is produced by 1 milligram of finely divided silico in one litre of distilled water the permissible limit of turbidity is 5 to 10units on silica scale. The turbidity may be measured in the laboratory by following instruments i. Turbidity Rod ii. Jackson‟s Turbidity meter iii. Nephelo Turbidity meter iv. Baylis Turbidity meter v. Hellige Turbidity meter JACKSON’S TURBIDITY METER It is the std. instrument for measuring turbidity. It essentially consists of a calibrated glass tube, a metallic container tube (or holder), a standard candle and a metallic stand. The glass tube is placed in the container and the candle or standard source of light is placed below the container. The water sample B poured slowly in the glass tube until the outline of the candle flume is no longer visible. Readings in terms of Jackson turbidity unit (JTU) are then taken directly from the calibrated tube. TASTE AND ODOUR The dissolved organic materials and inorganic salts or dissolved gases impart taste and odors to the water but for the drinking water it must not contain any undesirable or objectionable taste and odors. It is measured in terms of odors intensity which is related with the threshold number. The Threshold number represents the dilution ration at which the odors is hardly detectable. For domestic purpose the threshold odors umber is limited between 1 and 3 CHEMICAL CHARACTERISTICS AND XAMINATION Chemical analysis involves test for determining total solids P‟ value hardness, chronicle content, and nitrogen content, from and manganese, residual chlorine, toxic metals, etc…. Total solids =these include the solids in suspension, colloidal and dissolved state. The quantity of suspended solids is determined by filtering the sample of water. Through a fine filter and drying and weighing. The quantity of dissolved and colloidal solids is determined by evaporating the filtered water and weighing the residue. The total solids can be directly determined by evaporating the water sample and weighing the residue. The amount of total solids should be less than 500milligram/Lit and should never exceed 1000 mg/Lit.

P H VALUE P H value of water indicates the log of reciprocal of hydrogen ion concentration present in water. It is thus indicator of the acidic and alkaline nature of water.

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Log

1 H

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Log H

Since P H is the reciprocal of Log H

the higher values of P H means, lower

loons

H

concentration and thus represents alkaline solutions, where as the lower values of P H means higher

H

ion concentration and thus represents acidic solutions. Pure water is a balanced

combination of positively charged

H

ions and negatively charged

OH

concentration. Therefore in water it has been found that the product of combinations of ion and 10

14

ion H

ions in a water solution B constant. This constant has been found to be equal to

OH

moles/lit. Therefore if

H

lon and

OH

ion concentrations are equal, virtually each

will have Concentrations equals to 10 14 i.e 10 7 moles/lit in neutral water will therefore have a 1 1 P H Log log10 H 10 7

log 10

7

( 7) log10 7 (1) 7 Hence if the P of water is more than „7‟ it will be alkaline and if it is less than „7‟ acidic. The permissible limit of „ P H ‟ values for drinking water may e 6.62 to 8.5 H

PROBLEM 1. In a water treatment plant, the P H values of incoming and outgoing waters are 7.2 and 8.4 respectively. Assuming a linear variation of P H with time, Determine the Average P H value of water. Solution: We have 1 P H log H H P of incoming water PH

1

7.2

log10

1 H1

P H of outgoing water

SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I PH

8.4

2

1 H2

log10

log10 H1

7.2

H1

10

7.2

H2

10

8.4

lll ly ,

H1

Avg.Value of H 10

Avg.Value of P H

log log

H

1.2

H2 2 10

2 3.35 10

H

P

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8.4

8

1 H 1 3.35 10

8

7.477

2) If the concentration of OH

lons in a water solution is 0.008 find the value of P H

Solution: By the law of mass action, we have H OH 10 14

10 14 0.008 1.25 10

H H PH

log log

PH

12

1 H 1 1.25 10

12

11.90

3) If a sample of water contains a 0.000001g.m of H

ion/lit what is HS P H value.

Solution :

SJB Institute of Technology, Department of Civil Engineering

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Environmental Engineering – I PH

log

PH

6

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1 1000000

Determination of P H P H value may be determined by instrumental or colorimetric method or P H paper method (narrow or wide ranged)

INSTRUMENTAL METHOD = this method is very quick and automatic method of recording P H values. In this potentiometer is used to measure electrical pressure exerted by positively charged H ions. A meter is connected to the electric acquit which directly indicates the P H value of water. COLORIMETRIC METHOD = some indicators or chemicals are added to the sample of water and the colour so obtained is compared with standard colours of known P H value. The usual indicators are benzol yellow, methyl red, brown phenol etc… for P H range 0-7 and Thymol blue, Tolylred and phenol red for P H values above 7.

HARDNESS Definition: Hardness is the property of water which prevents the formation of lather or foam and needs large quantities of soap”. It forms scales in not water pipes, heaters, boilers where the temperature of water is increased. CAUSES It is caused by “DIVALENT METALLIC CATIONS” the principal hardness causing cations are calcium and magnesium there are two types of hardness temporary and permanent hardness TEMPORARY HARDNESS Caused due to presence of carbonates and bicarbonates of calcium and magnesium this can be removed by boiling or by adding lime solution in water. Temporary hardness is also called carbonate hardness. PERMENET HARDNESS of water is caused due to the presence of sulphates, chlorites and nitrates of calcium and magnesium. They cannot be removed by simple boiling and require special treatment of water softening it is also called as Non-=carbonate hardness.

DETERMINATION OF HARDNESS Hardness is generally defined as the caco3 equivalent of ca and Mg ions present in water and expressed in mg/llitas caco3 Hardness can be determined by EDTA titrometric method ( EthyleneDiamine Tetra acidic acid), Ferrochrome black – T is used as indicator SJB Institute of Technology, Department of Civil Engineering

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Erichrome Black + water = Less stable ions (Blue colour) (Ca++,Mg++) (wine red colour) EDTA + Less stable ion = Erichrome black T + more stable lon (TITRANT) (Blue colour) Colour change = Wine red to purple to blue Water are commonly classified interms of degree of hardness. Milligram / Litre CaCo3 0 - 75 75 -150 150 - 300 300 and a bove

as Degree of hardness Soft Moderately soft Hard Very hard

However the permissible Units of hardness for potable water ranges between 75 – 115 mg/lit as CaCo3. CHLORIDES Chlorides in combination with other elements are always found in water. Nacl is normally found in water the presence of nacl may be due to water coming in contact with saltish layer or sewage entering into it for potable water the amount of chlorides is limited to 250mg/lit. Chlorides may be readily measured by means of volumetric procedures employing indicator solution. For most purposes the MOHR method employing silver nitrate as indicator solution (yellow – brick red) is used. NITROGEN CONTENT The presence of nitrogen in water is an indication of organic matter present in water and they may occur in any of the following a. Albuminoid Nitrogen b. Free ammonia c. Nitrate d. Nitrate (stabilized end product of nitrogen) Presence of above indicate the degree of pollution of water. Permissible limits of Nitrate is 45PPm IRON AND MANGANESE These metals at very low concentrations are highly objectionable in water supplies for domestic or industrial use. Fe and Mm in concentration greater than 0.3ppm and 0.05ppm respectively stain plumbing fixtures and laundered clothes moreover they cause incrustation of water main due to deposition of ferric hydroxide and Mno. Foul taste and odours are produced by growth of fe bacteria in water distribution mains. Fe and Mn may be determined either by precipitation Technique if they are present in large amounts or by colorimeter or spectra

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photometer. In they are present in small amounts (Phenol chlorine and per sulphate method respectively) Public water supplies should not contain more than 0.3ppm of Iron and 0.05ppm of manganese. If they exceed the above limits they can be oxidized by oxidizing agents like oxygen, chlorine and potassium permanganate (KMno4) or by simple aerator Technique by adjusting P H 9-10 the manganese gets precipitated.

RESIDUAL CHLORINE The important purpose of chlorinating public water supplies is to prevent the spread of water borne diseases chlorine is used in water treatment for disinfection, prevention and H destruction of odours, Iron and colour remover. At optimum P and temperature of water its bactericidal efficiency is very high. In order to ensure no bacterial growth even in the distribution, chlorination is necessary. Therefore residual chlorine of 0.2ppm is required to be maintained in the distribution system to ensure no further bacterial contamination. Residual chlorine is determined by STARCH – IODIDE method or ORTHOTOLIDINE METHOD.

FLUORIDES Excessive fluoride ions in drinking water cause DENTAL FLUOROSIS or MOTLING OF TEETH. On the other hand, communities whose drinking water contains no fluoride have a high prevalence of dental caries optimum fluoride concentrations provided in public water supplies generally in range of 1-1.5mg/lit reduce dental caries to a minimum without causing noticeable dental fluorosis. Several fluoride compounds are used in treating municipal water all of these dissociate readily yielding fluoride ions (fluoridation). Excessive amounts of fluoride lons drinking water can be removed by defluoridation. The two current treatment methods for defluoridation use either activated alumina are bone char. In india “NALAGONDA TECHNIQUE OF DEFLUORIDATION” is most widely used as it is easier and convenient to use in rural areas. BIOLOGICAL CHARACTERISTICS AND EXAMINATION SIGNIFICANCE OF TERMS BACTERIA, E-coli and B - Coli Sewage contains many barn ----------- which are discharged through excremental matter of intestines of man and warm blooded animals these organisms were used to be called colon – bacilli and are known as coli forms. It is a full group of bacteria, but out of them “ESCHIRICHIACOLI” (E – coli) are the most important The E-coli bacteria are harmless organisms of coli form group, live longer in water than pathogenic bacteria, it is generally presumed that the water will be safe and free from pathogens if no coli form bacteria are present.

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The term BACTERIUM –COLL (B-coll) used to indicate a group of organisms that include. The whole “Coli – aero gens” group. TEST OF BACTERIA a. Total count b. Coli – Form count Total count = More popularly known as „PLATE COUNT‟ or „AGAR COUNT‟. Test procedure consists of placing “1ml” or some other portion of water to be tested on a sterialelish “100m” in diameter. To this a sterile nutrient medium is added and the plate is incuvated at 200C for 48 hours” or at 370C for 24 hours Each bacterium would have formed am colony which can be seen on the plate and counted using a colony counter for POTABLE WATER the total count should not exceed 100 colonies/cc of water. COLIFORM COUNT (Determination of coliform or B-coli) COLIFORMS are defined as that group of organisms which includes all the aerobic facultative, grain stain negative, non-spore forming bacteria. This group of organisms ferments lactose with gas. Formation at 310C within 48hours. The multiple tube fermentation Technique is used for the determination of coli forms. It consists of a. Presumptive test b. Confirmatory test c. Completed test DETERMINATION OF BACTERIAL NUMBERS The preferred method for bacterial enumeration is membrane filter techniques in this procedure. i) A measured volume of water is drawn through a cellulose acetate of glass fibre filter with the openings less than 0.5ill ii) The bacteria present in the sample will be retained upon the filter iii) The filter is rinsed with sterile buffer solution placed upon a pad saturated with suitable nutrient medium and incubated at an appropriate temperature. iv) The bacteria which are able to grow upon the nutrient medium will produce visible calories which can be counted. v) Each colony departs one bacterium in the original sample. MOST PROBABLE NUMBER (MPN) In order to arrive at the number of coli forms in a water sample, it is necessary to know the positive results from various size portions of a sample. The MPN of coli forms in the water is obtained by applying the laws of statistics to the results of test.

DEFINITION MPN of coli forms or B-coli is defined as that bacterial density which if actually present in the sample under examination would requently give the observed analytical results SJB Institute of Technology, Department of Civil Engineering

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In other words MPN indicates the bacterial density which is most likely to be present in water. The standard sample for potable water is 5 of 10mc portions. If all these are negative, the MPN is zero. If only 1 out of 5 is true, then MPN is two. THOMAS EQUATION OF DETERMINATION OF MPN Thomas has suggested the following approximate equation for calculation of MPN 100 Number of tve portions

MPN

ml in all -ve portions

ml of all portions

PROBLEMS:1. If 1 out of 5-10ml portions is +ve and 1 out of 5-1ml portions is tve calculate MPN Solution: 100 1 1 MPN = 40+4 50+5

4.07 4

MPN

2. Calculate the MPN for the following tabular columns. Comment on the result. Sample size 10ml 1ml 0.1ml 0.01ml Portions 5 5 5 5 Positive No 5 4 2 1

100

MPN =

1+0.3+0.04

5 4 2 1 50+5+0.5+0.05

139.087 MPN 139 COMMENT: The MPN index of coli form bacteria should be „o‟ or „ MnCl2 + Cl2 + 2H2O

Figure 1: Carl Wilhelm Scheele discovered chlorine in 1774 Scheele discovered that chlorine gas was water-soluble and that it could be used to bleach paper, vegetables and flowers. It also reacted with metals and metal oxides. In 1810 sir Humphry Davy, an English chemist who tested fundamental reations of chlorine gas, discovered that the gas Scheele found must be an element, given that the gas was inseperable. He named the gas „chlorine‟ (Cl), after the Greek word „chloros‟, which means yellow-greenish and refers to the color of chlorine gas (White, 1999. Watt, 2002) Chlorine can be found on many different locations all over the world. Chlorine is always found in compounds, because it is a very reactive element. Chlorine can usually be found bond to sodium (Na), or in kitchen salt (sodium chloride; NaCl). Most chlorine can be found dissolved in seas and salty lakes. Large quantities of chlorine can be found in the ground as rock salts or halite. The properties of chlorine Chlorine (Cl2) is one of the most reactive elements; it easily binds to other elements. In the periodic chart chlorine can be found among the halogens. Other halogens are fluorine (F), bromine (Br), iodene (I) and astatine (At). All halogens react with other SJB Institute of Technology, Department of Civil Engineering

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elements in the same way and can form a large quantity of substances. Halogens often react with metals to form soluble salts. Chlorine atoms contain 17 negative electrons (negatively charged particles). These move around the heavy core of the atom in three shells. Within the inner shell there are two electrons, within the middle shell there are eight and within the outer shell there are seven. In the outer shell there is space left for another electron. This causes free, charged atoms, called ions, to form. It can also cause an extra eletron to form (a covalent bond; a chlorine bond), causing the outer shell to complete.

Figure 2: chlorine atoms contain 17 electrons Chlorine can form very stable substances, such as kitchen salt (NaCl). Chlorine can also form very reactive products, such as hydrogen chloride (HCl). When hydrogen chloride dissolves in water it becomes hydrochloric acid. The hydrogen atom gives off one electron to the chlorine atom, causing hydrogen and chlorine ions to form. These ions react with any kind of substance they come in contact with, even metals that are corrosion resistant under normal circumstances. Concentrated hydrochloric acid can even corrode stainless steel. This is why it is stored either in glass or in plastic. Chlorine is a very reactive and corrosive gas. When it is transported, stored or used, safety precautions must be taken. In Holland for example, chlorine is transported in separate chlorine trains. Watery chlorine should be protected from sunlight. Chlorine is broken down under the influence of sunlight. UV radiation in sunlight provides energy which aids the break-down of underchloric acid (HOCl) molecules. First, the water molecule (H2O) is broken down, causing electrons to be released which reduce the chlorine atom of underchloric acid to chloride (Cl-). During this reaction an oxygen atom is released, which will be converted into an oxygen molecule: 2HOCl -> 2H+ + 2Cl- + O2 Chlorine is produced from chlorine bonds by means of electrolytic or chemical oxidation. This is often attained by electrolysis of seawater or rock salt. The salts are dissolved in water, forming brine. Brine can conduct a powerful direct current in an electolytic cell. Because of this current chlorine ions (which originate from salt dissolving in water) are transformed to chlorine atoms. Salt and water are divided up in sodium hydroxide (NaOH) and hydrogen gas (H2) on the cathode and chlorine gas on the anode. These cathode and anode products should be separated, because hydrogen gas reacts with chlorine gas very agressively.

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To produce chlorine, three different electrolysis methods are used. 1. The diaphragm cell-method, which prevents products to mix or react by means of a diaphragm. The electrolysis barrel contains a positive pole, made of titanium and a negative pole, made of steel. The electrodes are separated by a so-called diaphragm, which is a wall that only lets fluids flow through, causing gasses that form during a reaction to be separated. The application of the countercurrent principle prevents hydroxide ions from reaching the positive pole. However, chlorine ions can pass through the diaphragm, causing the sodium hydroxide to become slightly polluted with chlorine. This causes the following reactions to take place: + pole : 2Cl- -> Cl2 + 2e- pole : 2 H2O + 2 e- -> 2OH- + H2 2. The mercury cell-methode uses one mercury electrode, causing the reaction products to be purer than those of the diaphragm cell-methode. With this method an electrolysis barrel is used which contains a positive titanium pole and a negative flowing mercury pole. On the negative pole a reaction with sodium (Na+) takes place, causing sodium amalgams to be formed. When the amalgams flow through a second reaction barrel, sodium reacts with water to sodium hydroxide and hydrogen. This causes the hydrogen gas to remain separated from the chlorine gas, which is formed on the positive pole. Within the electrolysis barrel the following reactions take place: + pole : 2 Cl- -> Cl2 + 2e- pole : Na+ + e- -> Na second reaction barrel: 2Na + 2H2O -> 2 Na+ + 2OH- + H2 3. The membrane-method resembles the diaphragm method. The only difference is that the membrane only allows positive ions to pass, causing a relatively pure form of sodium hydroxide to form. During the mercury electrolysis process a solution containing 50 mass-% of sodium hydroxide is formed. However, during the membrane and diaphragm processes the solution must be evaporated using steam. Sixty percent of the European chlorine production takes place by means of mercury electrolysis,whereass 20% takes place in the diaphragm process and 20% takes place in the membrane process. Chlorine can also be produced by means of hydrogen chloride oxidation with oxygen from air. Copper(II)chloride (CuCl2) is used as a cathalyser during this so-called „Deaconprocess‟: 4HCl + O2 -> 2H2O + 2Cl2 Finally, chlorine can be produced by means of molten salts electrolysis and, mainly in laboratories, by means of hydrochloric acid and manganese dioxide oxidation: MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2 When gaseous chlorine is added to water the following hydrolysis reaction takes place: Cl2 + H2O = H+ + Cl- + HOCl

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Chlorine applications Chlorine is applied on a massive scale. Chlorine is a very reactive element, causing it to quickly form compounds with other substances. Chlorine also has the ability to develop a bond between two substances that do not normally react with one another. When chlorine bonds to a substance that contains carbon atoms, organic substances are formed. Examples are plastic, solvents and oils, but also several human body fluids. When chlorine chemically binds to other elements, it often replaces a hydrogen atom during a so-called substitution reaction. Multiple hydrogen atoms in the same molecule can be replaced by chlorine atoms, causing new substances to form one after another. Chlorine plays an important role in medical science. It is not only used as a disinfectant, but it is also a constituent of various medicines. The majority of our medicines contain chlorine or are developed using chlorine-containing byproducts. Medical herbs also contain chlorine. The first anaesthetic used during surgery was chloroform (CHCl3). The chemical industry creates ten thousands of chlorine products using a small number of chlorine containing chemicals. Emaples of products which contain chlorine are glue, paints, solvents, foam rubbers, car bumpers, food additives, pesticides and antifreeze. One of the most commonly used chlorine-containing substances is PVC (poly vinyl chloride). PVC is widely used, for example in drainpipes, insulation wires, floors, windows, bottles and waterproof clothes.

Figure 3: products containing chlorine Chlorine-based bleach is applied as a disinfectant on a large scale. The substances are also used to bleach paper. Bleaching occurs as a result of chlorine or hypochlorite oxidation. About 65% of industrialized chlorine is used to produce organic chemicals, such as plastics. About 20% is used to produce bleach and disinfectants. The remaining chlorine is used to produce inorganic compounds from chlorine and several different elements, such as zinc (Zn), iron (Fe) and titanium (Ti). Chlorine as a disinfectant Chlorine is one of the most widely used disinfectants. It is very applicable and very effective for the deactivation of pathogenic microorganisms. Chlorine can be easily applied, measures and controlled. Is is fairly persistent and relatively cheap. Chlorine has been used for applications, such as the deactivation of pathogens in drinking water, swimming pool water and wastewater, for the disinfection of household areas and for SJB Institute of Technology, Department of Civil Engineering

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textile bleaching, for more than two hundred years. When chlorine was discovered we did not now that disease was caused by microorganisms. In the nineteenth century doctors and scientists discovered that many diseases are contagious and that the spread of disease can be prevented by the disinfection of hospital areas. Very soon afterward, we started experimenting with chlorine as a disinfectant. In 1835 doctor and writer Oliver Wendel Holmes advised midwifes to wash their hands in calcium hypochlorite (Ca(ClO)2-4H2O) to prevent a spread of midwifes fever. However, we only started using disinfectants on a wider scale in the nineteenth century, after Louis Pasteur discovered that microorganisms spread certain diseases. Chlorine has played an important role in lengthening the life-expectancy of humans. For more information about pathogens in aquatic systems, please take a look at pathogens in freshwater ecosystems Chlorine as a bleach Surfaces can be disinfected by bleaching. Bleach consists of chlorine gas dissolved in an alkalisolution, such as sodium hydroxide (NaOH). When chlorine is dissolved in an alkalic solution, hypochlorite ions (OCl-) are formed during an autoredox reaction. Chlorine reacts with sodium hydroxide to sodium hypochlorite (NaOCl). This is a very good disinfectant with a stable effect. Bleach cannot be combined with acids. When bleach comes in contact with acids the hypochlorite becomes instable, causing poisonous chlorine gas to escape. The accompanying underchloric acid is not very stable.

Figure 4: chlorine is often used as a bleach Bleaching powder (CaOCl2) can also be used. This is produced by directing chlorine through calcium hydroxide (CaOH). The benefit of bleaching powder is that it is a solid. This makes it easier to apply as a disinfectant in medical areas, next to its use as a bleach. When bleaching powder dissolves, it reacts with water to underchloric acid (HOCl) and hypochlorite ions (OCl-). Chlorine disinfection Chlorine kills pathogens such as bacteria and viruses by breaking the chemical bonds in their molecules. Disinfectants that are used for this purpose consist of chlorine compounds which can exchange atoms with other compounds, such as enzymes in bacteria and other cells. When enzymes come in contact with chlorine, one or more of the hydrogen atoms in the molecule are replaced by chlorine. This causes the entire molecule to change shape or fall apart. When enzymes do not function properly, a cell or bacterium will die. When chlorine is added to water, underchloric acids form: Cl2 + H2O ->HOCl + H+ + ClSJB Institute of Technology, Department of Civil Engineering

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Depending on the pH value, underchloric acid partly expires to hypochlorite ions: Cl2 + 2H2O ->HOCl + H3O + ClHOCl + H2O -> H3O+ + OClThis falls apart to chlorine and oxygen atoms: OCl- ->Cl- + O Underchloric acid (HOCl, which is electrically neutral) and hypochlorite ions (OCl-, electrically negative) will form free chlorine when bound together. This results in disinfection. Both substances have very distinctive behaviour. Underchloric acid is more reactive and is a stronger disinfectant than hypochlorite. Underchloric acid is split into hydrochloric acid (HCl) and atomair oxygen (O). The oxygen atom is a powerful disinfectant. The disinfecting properties of chlorine in water are based on the oxidising power of the free oxygen atoms and on chlorine substitution reactions.

Figure 5: the neutral underchloric acid can better penetrate cell walls of pathogenic microorganisms that the negatively charged hypochlorite ion The cell wall of pathogenic microorganisms is negatively charged by nature. As such, it can be penetrated by the neutral underchloric acid, rather than by the negatively charged hypochlorite ion. Underchloric acid can penetrate slime layers, cell walls and protective layers of microorganisms and effectively kills pathogens as a result. The microorganisms will either die or suffer from reproductive failure. The effectivity of disinfection is determined by the pH of the water. disinfection with chlorine will take place optimally when the pH is between 5,5 and 7,5. underchloric acid (HOCl) reacts faster than hypochlorite ions (OCl-); it is 80-100% more effective. The level of underchloric acid will decrease when the pH value is higher. With a pH value of 6 the level of underchloric acid is 80%, whereass the concentration of hypochlorite ions is 20%. When the pH value is 8, this is the other way around. When the pH value is 7,5, concentrations of underchloric acid and hypochlorite ions are equally high.

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Underchloric acid (left) : hypochlorite ions (right) When chlorine is added to water for disinfection purposes, it usually starts reacting with dissolved organic and inorganic compounds in the water. Chlorine can no longer be used for disinfection after that, because is has formed other products. The amount of chlorine that is used during this process is referred to as the 'chlorine enquiry' of the water. Chlorine can react with ammonia (NH3) to chloramines, chemical compounds which contain chlorine, nitrogen (N) and hydrogen (H). These compounds are referred to as 'active chlorine compounds' (contrary to underchloric acid and hypochlorite, which are referred to as 'free active chlorine') and are responsible for water disinfection. However, these compounds react much more slowly than free active chlorine. When dosing chlorine one has to take into account that chlorine reacts with compounds in the water. The dose has to be high enough for a significant amount of chlorine to remain in the water for disinfection. Chlorine enquiry is determined by the amount of organic matter in the water, the pH of the water, contact time and temperature. Chlorine reacts with organic matter to disinfection byproducts, such as trihalomethanes (THM) and halogenated acetic acids (HAA). Chlorine can be added for disinfection in several different ways. When ordinary chlorination is applied, the chlorine is simply added to the water and no prior treatment is necessary. Pre- and postchlorination means adding chlorine to water prior to and after other treatment steps. Rechlorination means the addition of chlorine to treated water in one or more points of the distribution system in order to preserve disinfection. Breakpoint chlorination consists of a continual addition of chlorine to the water upto the point where the chlorine enquiry is met and all present ammonia is oxidized, so that only free chlorine remains. This is usually applied for disinfection, but it also has other benefits, such as smell and taste control. In order to reach the breakpoint, a superchlorination is applied. To achieve this, one uses chlorine concentrations which largely exceed the 1 mg/L concentration required for disinfection.

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Chlorine gas can be obtained as fluid gas in 10 bar pressure vessels. It is highly water soluble (3 L chlorine/ 1 L water). To kill bacteria little chlorine is required; about 0,2-0,4 mg/L. the concentrations of chlorine added to the water are usually higher, because of the chlorine enquiry of the water. Nowadays chlorine gas is only used for large municipal and industrial water purification installations. For smaller applications one usually ads calcium or sodium hypochlorite. Factors which determine chlorine disinfection effectively: Chlorine concentrations, contact time, temperature, pH, number and types of microorganisms, concentrations of organic matter in the water. Table 1: disinfection time for several different types of pathogenic microorganisms with chlorinated water, containing a chlorine concentration of 1 mg/L (1 ppm) when pH = 7,5 and T = 25 °C The reaction of the human body to chlorine depends on the concentration of chlorine present in air, and on the duration and frequency of exposure. Effects also depend on the health of an individual and the environmental conditions during exposure. When small amounts of chlorine are breathed in during short time periods, this can affect the respirational system. Effects vary from coughing and chest pains, to fluid accumulation in the lungs. Chlorine can also cause skin and eye irritations. These effects do not take place under natural conditions. When chlorine enters the body it is not very persistent, because of its reactivity. Pure chlorine is very toxic, even small amounts can be deadly. During World War I chlorine gas was used on a large scale to hurt or kill enemy soldiers. The Germans were the first to use chlorine gas against their enemies. Chlorine is much denser than air, causing it to form a toxic fume above the soil. Chlorine gas affects the mucous membrane (nose, throat, eyes). Chlorine is toxic to mucous membranes because it dissolves them, causing the chlorine gas to end up in the blood vessels. When chlorine gas is breathed in the lungs fill up with fluid, causing a person to sort of drown. Forms of application of chlorine 1. 2. 3. 4.

Bleaching powder or hypochlorite Chloramines Free chlorine gas Chlorine dioxide Bleaching powder or calcium hypochloric is a chlorinated lime . It is not stable and loses its strength during storage or exposure of air. It is therefore used only on small installations or under emergency conditions. The process of chlorination with hypochlorites is known as hypochlorination. Hypochlorites are applied to water as a solution by means of hypochlorites feeding apparatus. The dose of the solution is adjusted by means of an adjustable punch clamp.

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Ultraviolet Radiation (UV) treatment of swimming pool water The disinfectant ability of radiation from the ultraviolet section of the electromagnetic spectrum is well established. UV treatment has been used in drinking water, industrial and effluent applications. The primary action of UV is to kill bacteria, viruses, moulds and spores, thus reducing the risk of transmission of stomach, skin and respiratory tract infections to pool users. UV has an important secondary action: it initiates photochemical and photo-oxidation reactions which destroy chloramines. This is particularly important in leisure pools where features such as water slides and waves give a greater surface area for the release of chloramines into the air. UV reduces the burden, making the atmosphere safer and more pleasant. The limiting factor tends to be the water clarity, as dissolved and suspended material inhibits UV penetration. Filtration will remove some of these solids from swimming pool water; but to optimise the effectiveness of the UV it is important that the full flow of water returning to the pool is exposed to the ultraviolet radiation. This will ensure the pool water is treated on a regular and continuous basis. An automatic wiper removes solids that settle onto the quartz thimble around the UV arc tube. A chlorine or bromine based disinfectant must be used in conjunction with UV systems to maintain a disinfectant residual in the pool. UV radiation inactivates bacteria and helps break down chloramines and other pollutants. Water Softening

Soda lime is a process used in water treatment to remove Hardness from water. This process is now obsolete but was very useful for the treatment of large volumes of hard water. Addition of lime (CaO) and soda (Na2CO3) to the hard water precipitates calcium as the carbonate, and magnesium as its hydroxide. The amounts of the two chemicals required are easily calculated from the analysis of the water and stoichiometry of the reactions. The lime‐ soda uses lime, Ca (OH)2 and soda ash, Na2CO3, to precipitate hardness from solution.

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Soda lime water softening process

Carbon dioxide and carbonate hardness (calcium and Magnesium bicarbonate) are complexed by lime. In this process Calcium and Magnesium ions are precipitated by the addition of lime (Ca(OH)2) and soda ash (Na2CO3). Following

are

the

reactions

that

takes

place

in

this

process:

As slacked lime is added to a water, it will react with any carbon dioxide present as follows: Ca(OH)2+CO2→CaCO3 ↓ +H2O....(1)

The lime will react with carbonate hardness as follows: Ca(OH)2 + Ca(HCO3)2 →2CaCO3 ↓ +2H2O.....(2) Ca(OH)2 + Mg(HCO3 )2 →MgCO3 + CaCO3 ↓ +2H2O.....(3) The product magnesium carbonate in equation 3 is soluble. To remove it, more lime is added: Ca(OH)2 + MgCO3 →CaCO3 ↓ +Mg(OH)2 ↓.....(4) Also, magnesium non-carbonate hardness, such as magnesium sulfate, is removed: Ca(OH)2 + MgSO4 →CaSO4 + Mg(OH)2 ↓.....(5) SJB Institute of Technology, Department of Civil Engineering

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Lime addition removes only magnesium hardness and calcium carbonate hardness. In equation 5 magnesium is precipitated, however, an equivalent amount of calcium is added. The water now contains the original calcium non-carbonate hardness and the calcium non-carbonate hardness produced in equation 5. Soda ash is added to remove calcium non-carbonate hardness: Na2CO3 + CaSO4 → Na2SO4 + CaCO3 ↓.....(6) To precipitate CaCO3 requires a pH of about 9.5; and to precipitate Mg(OH)2 requires a pH of about 10.8, therefore, an excess lime of about 1.25 meq/l is required to raise the pH.

The amount of lime required: lime (meq/l) = carbon dioxide (meq/l) + carbonate hardness (meq/l) + magnesium ion (meq/l) + 1.25 (meq/l)

The amount of soda ash required: soda ash (meq/l) = non-carbonate hardness (meq/l) After softening, the water will have high pH and contain the excess lime and the magnesium hydroxide and the calcium carbonate that did not precipitate. Recarbonation (adding carbon dioxide) is used to stabilize the water. The excess lime and magnesium hydroxide are stabilized by adding carbon dioxide, which also reduces pH from 10.8 to 9.5 as the following: CO2 + Ca(OH)2 →CaCO3 ↓ +H2O CO2 + Mg(OH)2 →MgCO3 + H2O Further recarbonation, will bring the pH to about 8.5 and stabilize the calcium carbonate as the following: CO2 + CaCO3 + H2O→Ca(HCO3)2 It is not possible to remove all of the hardness from water. In actual practice, about 50 to 80 mg/l will remain as a residual hardness.

Limitation of Soda Lime Process: Lime soda softening cannot produce a water at completely free of hardness because of the solubility (little) of CaCO3 and Mg(OH)2. Thus the minimum calcium hardness can be achieved is about 30 mg/L as CaCO3, and the magnesium hardness is about 10 mg/L as CaCO3. We normally tolerate a final total hardness on the order of 75 to 120 mg/L as CaCO3, but the magnesium content should not exceed 40 mg/L as CaCO3 (because a greater hardness of magnesium forms scales on heat exchange elements).

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Zeolite process

Some materials that are insoluble in water, called 'Zeolites', have the property of combining with certain harmful ions in a solution and, at the same time producing other harmless ions. Zeolites are referred to as 'Ion Exchange Resins' and are complex compounds of sodium, aluminium, silicon and oxygen. When water containing Ca 2+ and Mg 2+ ions, is passed through Zeolite beds, these ions are picked up by the Zeolite which then replaces them with harmless sodium ions … Na+ . If we represent the Zeolite as a letter 'Z', the equation can be shown as follows: Ca (2+) + Na2Z ===>CaZ + 2(Na+) This indicates that the calcium ions have come out of solution and are replaced by sodium ions in the solution. This process is called 'Water Softening by Ion Exchange' as follows: Hard water Containing 'Ca' and 'Mg' ions ===> Water treatment plant Containing Sodium Zeolite beds which attract the Ca& Mg ions ===> Treated (softened) water Containing harmless 'Na' ions When the Zeolite is 'saturated', (all Na ions used up), it is regenerated by passing a concentrated salt (NaCl) solution through the Zeolite bed. This forces the Ca and Mg ions out of the Zeolite back into the water and replaces them with sodium. The solution containing the Ca and Mg is disposed of. The sodium salts remaining in the treated water are harmless and will not form deposits of scale.

Reverse Osmosis A technique used in processes requiring high-quality, purified water, such in semiconductor processing or biochemical applications, is reverse osmosis. It can be used to treat boiler feedwater, industrial wastewater, or process water. Reverse Osmosis is a water purification technique that reduces the quantity of dissolved solids in solution (Kucera, 54). It was first developed in the 1950's by the US SJB Institute of Technology, Department of Civil Engineering

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government to provide fresh drinking water for the Navy, and since then, advances have made it much more feasible for obtaining purified water from wastewaters produced in many industrial applications. RO uses waterline pressure to push raw wastewater against a special semipermeable membrane. It is essentially a molecular squeezing process which causes H2O molecules to separate from the contaminants. The separated water molecules then pass thru to the inside of the membrane on to a holding reservoir. The contaminants are washed from the membrane and disposed of. Recently, RO has been used in treating boiler feedwater, in addition to industrial and process wastewaters. Boilers are found throughout the chemical processing industry and the primary method to treat boiler wastewater is an ionexchange based demineralization. However, RO has been demonstrated to be more cost effective than this demineralization process Problems With Reverse Osmosis: It is necessary to establish feedwater quality guidelines to optimize system performance and prevent the three main problems associated with RO: scaling, fouling, and degradation of ROmembranes These problems tend to decrease system productivity because they reduce wastewater purity. Scaling occurs on RO membranes when the concentration of scale-forming species exceeds saturation, producing additional solids within the RO feedwater. Scalants include such chemical species as calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and reactive silic). Since these species have very low solubilities, they are difficult to remove from RO membranes. Scaling decreases the effectiveness of the membranes in reducing the solids and causes more frequent cleanings. A scale on a membrane provides nucleation sites that increase the rate of formation of additional scale

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UNIT7 – MISCELLANEOUS TREATMENTS Removal of colour, odour and taste The water to be supplied in the public water supply scheme should be free from odour, colour& taste. The objectionable taste and odours may be due to the following 1. 2. 3. 4. 5.

Organic and vegetable matter. Industrial waste and domestic sewage. Dissolved gases Dissolved mineral matter Micro –organisms such as moulds, iron and sulphur bacteria.

The different methods that can be adopted for the removal of colour, odour and taste are 1. 2. 3. 4. 5. 6. 7.

Coagulation followed by filtration Prechlorination Superchlorination Chloramines treatment Use of chlorine dioxide Ozonation Removal of iron and manganese

Other special methods are 1. Treatment by activated carbon. 2. Use of copper sulphate.

Use of copper sulphate Copper sulphate is generally available in powder form or in crystals form. It may be applied either directly in the distribution pipes or in open reservoirs. The dose may vary from 0.3 to 0.6 p.p.m. For its application to the reservoirs, it is ground in fine powder and sprinkled on the water surface .The amount of copper sulphate necessary to kill various algae may be troublesome because of taste and odours will be temporarily increased. Hence smaller amounts are often successful as prophhylatic doses to prevent trouble. Chemical and physical adsorption Adsorption is a fundamental process in the physicochemical treatment of municipal wastewaters, a treatment which can economically meet today's higher effluent standards and water reuse SJB Institute of Technology, Department of Civil Engineering

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requirements. Activated carbon isthe most effective adsorbent for this application. Expanded-bed contact systems permit most efficient use of granular carbon for waste treatment. The adsorption process is enhanced by in-situ partial regeneration effectedby biological growth on the surfaces of the carbon. Physicochemical systems using adsorption with activated carbon consistently produce high levels of treatment and have a high degree of stability and reliability. Advantages overbiological treatment systems include: lower land area requirements: lower sensitivity to diurnal flow and concentration variations and to toxic substances: potential for significant heavy metal removal; greater flexibility in designand operation; and, superior removal of organic wastes. Chemical adsorption (chemisorption)analysis techniques provide much of the information necessary to evaluate catalystmaterials in the design and production phases,as well as after a period of use.Although a catalyst and the reactants andproducts can be of many forms, this article onlywill address solid catalysts and gas or vaporreactants and products. A distinctive characteristic of a solid material is a distribution of weak surface energysites. Gas or vapor molecules can become bound to these sites. This generally describesthe adsorption phenomenon.The quantity of molecules taken up by thesurface depends on several conditions andsurface features including temperature,pressure, surface energy distribution, and thesurface area of the solid. A plot of the quantityof molecules adsorbed versus pressure at constant temperature is called the adsorptionisotherm. Physical adsorption is the result of relativelyweak Van der Waal's interaction forces betweenthe solid surface and the adsorbate- a physicalattraction. Physical adsorption is easilyreversed.

Flouridation It has been found that a fluoride concentration of 0.7 to 1.2 p.p.m in water is beneficial for the Prevention of dental caries in children. The allowable level of the fluoride is determined by the annual average of the maximum daily air temperature. Higher levels of fluoride have responsible for mottling of teeth. However in areas where water is of low fluoride content, dental caries is high. The fluoride compounds that are adopted in fluoridation as sodium fluoride,sodiumsilicofluride and hypoflusilic acid. The application of fluorides in water may be either in water may be either in powder form or in solution form. However in solution form is preferred. In powder form sodium fluoride or sodium fluosilicate is toxic and must be contained in dust tight hoppers and containers.

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Defluoridation Excess concentrations of fluoride causes dental flurosis,when the concentrations is morethan 1 to1.5ppm. it should be removed from water. The process of removing fluoride concentration of water is known as defluoridation. The principal methods of defluoridation are i. ii. iii. iv. v. vi. vii. viii.

Calcium sulphates Bone charcoal Synthetic tri- calcium phosphate Flourex Ion-Exchanger Lime Aluminium compounds Activated carbon

Distribution systems Thedistribution system consists of network of pipes with appurtenances, for transporting water from purification plant to the consumers tap. A good distribution systems should satisfy the following requirements. 1. The systems should be capable of supplying water at consumers tap at reasonable pressure head. 2.It should meet the fire demand simultaneously 3.It should be easy to operate and maintain Methods of distribution system 1. Gravity system. 2. Combined gravity and pumping systems 3. Pumping system. Systems of water supply. 1. Continuous systems In the continuous water is available to the consumers for all the 24 hours of a day.In this system water is not stagnant any point of time and fresh water is available.

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2. Intermittent systems In this system water is supplied to the consumers only during some fixed hours of the day. This method is adopted when there is less pressure and insufficient quantity of water.

Service reservoir Clear water storage reservoirs are required for storage of filtered water until it is pumped in to the service reservoir or distribution reservoirs. They are to meet the widely fluctuating demands often imposed on a distribution system,to provide storage for fire fighting and emergencies and to equalize They serve the following purposes 1.They absorb the hourly variation in demand. 2. If pumps are used, the provision of reservoirs makes it possible to run the pumps at uniform rate. 3.Their provision results in an overall reduction in the sizes of pumps, pipes and treatment units. 4.They serve as storage for emergencies such as outbreak of fire, failure of pumps or bursting of mains. Capacity of distribution reservoir The storage capacity of the distribution reservoir is based on the following three requirements i. ii. iii.

Balancing or equalizing reserve. Breakdown reserve Fire reserve

Layout of distribution systems There are four principal methods of laying our distribution systems 1. 2. 3. 4.

Dead end or tree systems Grid iron system or reticulation systems Circular systems or ring system Radial systems.

Dead end or tree systems: In this system, one main pipe line runs through the centre of the populated area and sub mains taken off from this to both sides. There are no cross connections SJB Institute of Technology, Department of Civil Engineering

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between the branches and sub mines. Due to several dead ends there is accumulation of sediment there and stagnation of water. However the flow rate in each pipe is easily known due to which the pipe diameters can be found. Grid iron or reticulation systems: If the dead ends of the previous systems are interconnected, water can be made to circulate continuously through the whole of the distribution systems. This systems is there also known as the interlaced systems. The branch lines interconnect all the submains. The systems is ideal for cities laid out on rectangular plan resembling a grid-iron. Circular systems or ring system: In this systems, the supply main forms a ring around the distribution district. The branches are connected cross wise to the mains and also to each other.The systems is most suitable for the town or area having well planned streets and roads.The systems possesses the same advantage and disadvantage as those of grid iron systems. Radial system: This systems is just the reverse of the circular system. In this systems the whole area is divided in to a number of distribution districts, Each district has a centrally located distribution reservoir from where distribution pipes run radially towards the periphery of the distribution district. This system gives quick service without much loss of head. Design of distribution system 1. 2. 3. 4. 5.

Surveys and maps Tentative layout Discharge in pipe line Calculation of pipe diameter Computation of pressures

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UNIT 8 - MISCELLANEOUS Pipe appurtenances Pipe is a circular closed conduit through which the water may flow either under gravity or under pressure. Pipes are made of 1. Cast iron 2. Wrought iron 3. Steel 4. Galvanized iron 5. Cement concrete 6. Asbestos cement 7. Plastic 8. Lead 9. Copper 10. Wood. Cast iron pipes: they are used in great majority of water distribution mains. Cast iron pipes are manufactured by two methods (1) Ordinary sand moulding (2) Centrifugal process. Wrought iron: they are manufactured by rolling flat plates of the wrought iron to the proper diameter and welding the edges.Such pipes are much lighter than the CI pipes& can be more easily cut, thread and worked. Steel pipes: It can be made from solid but large sizes are made by riveting or welding together the edges suitably curved plates, sockets being formed later in pres. The joints may be either transverse and longitudinal or transverse and spiral. Cement pipes: Cement concrete pipes may be either in plain or reinforced, and are best made by spinning process. They are either precast or may be prepared at the sites. Water tightness of high pressure concrete pipe may be obtained by insertion of a thin steel cylinder in the pipe walls either with or without prestressed reinforcement. Asbestos cement pipes: They are manufactured fiber and Portland cement combined under pressure to form a dense homogeneous structure having strong bond between cement and the fibre. Such a pipe is considered to be impervious. Copper and lead pipes: Copper pipes are very costly and their use is restricted for conveyance of hot water in the interior of buildings and for making gooseneck in the service connections. Wood pipes: They are prepared of staves or planks of wood held together by steel bands. They have been used for many years for water supply pipes, though they were replaced due to lack of capacity. SJB Institute of Technology, Department of Civil Engineering

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Pipe appurtenances 1. 2. 3. 4. 5.

Sluice valve Air valve Reflux valve Altitude valves Scour valve

Sluice valve: They are extensively used in the distribution systems to shut off the supplies whenever desired. They are helpful in dividing water mains into suitable sections. They are also placed at street corners or where two pipe lines meet or intersect. The possess the advantage over most other types of valves of combing relatively low cost and offering almost no resist Air relief : The water flowing through the pipe lines always contain some air. This air tries to accumulate at high points and may interfere with the flow. Air relief valves are therefore provided at the summits along the water pipe to provide an exit for such accumulated. Reflux valves: Reflux valves are also known as check valves or non return valves. It is an automatic device which allows water to flow in one direction only. They are placed in water pipes which obtain water directly from the pumps. When the pump is stopped the water in the pipe line does not rush back and damage the pump Altitude valves: They are mainly used on those lines which supply water to elevated tanks or stand pipes. They are close automatically when the tank is full and open when the pressure in the pump side is less than that on the tank side of the valve. Scour valve They are also called as blow of valve or washout valves are ordinary sluice valve hat are located either at the dead ends or at lowest points in the mains. They are provided to blow off or remove the sand and silt deposited in the pipe line, They are operated manually. Fire Hydrants are an integral part of private fireline construction and public water pipeline main systems. Fire hydrants are basically outlets that release large quantities of pressurized water to extinguish fires. Public fire hydrants are typically supplied by municipal potable water pipeline mains; whereas private fire hydrants are typically located behind a detector check and specifically only used for fire suppression and is not typically drinking water. Public fire hydrants are usually designed and spaced to be installed in a new construction setting approximately every 500 ft. They are usually located along a street, in the sidewalk at a certain distance away from the curb. Each public fire hydrant typically includes a gate valve on the branch off the municipal water pipeline supply. Fire hydrant outlet sizes and number of outlets are determined by local zoning requirements and local fire department codes. Fire hydrants are designed with an operating valve for each outlet. SJB Institute of Technology, Department of Civil Engineering

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Outlets can range in size from 2 ½ to 4 ½ inches in diameter. Outlets range from two to three outlets, in most cases. As mentioned, private fire hydrants are located behind a check valve. These fire hydrants are used specifically for fire suppression and are typically connected to a system that feeds a building's fire sprinkler system. Their location and quantity vary depending on what type of structure or property they are servicing. There are generally two types of fire hydrants used in most instances. Whether serving public or private systems, they are either wet barrel or dry barrel fire hydrants. Wet barrel fire hydrants are pressurized up to their outlets and each outlet can be operated individually. Dry barrel fire hydrants are not pressurized up to their outlets. Instead, there is only one internal valve, generally located at the base of the fire hydrant bury, that when opened, will pressurize all outlets at the same time. Another difference between the two fire hydrant types is that the dry barrel, if struck or hit and separated from the base, will allow the valve in most cases to close, thereby not allowing water to be discharged. In contrast, wet barrel fire hydrants, if struck, do not have this feature. To combat this, several municipalities have introduced the use of a break-off check valves located just below the head of wet barrel fire hydrants. Pipe fitting is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and repair of leaks. .Fitters work with a variety of pipe and tubing materials including several types of steel, copper, iron, aluminium, and plastic. Pipe fitting is not plumbing; the two are related but separate trades. Pipe fitters who specialize in fire prevention are called Sprinklerfitters, another related, but separate trade. Materials, techniques, and usages vary from country to country as different nations have different standards to install pipe.

Steel pipe Steel pipe (or black iron pipe) was once the most popular choice for supply of water and flammable gases. Steel pipe is still used in many homes and businesses to convey naturalgas or propane fuel, and is a popular choice in fire sprinkler systems due to its high heat resistance. In commercial buildings, steel pipe is used to convey heating or cooling water to heatexchangers, air handlers, variableairvolume (VAV) devices, or other HVAC equipment. Steel pipe is sometimes joined using threaded connections, where tapered threads (see NationalPipeThread) are cut into the end of the tubing segment, sealant is applied in the form of thread sealing compound or thread seal tape (also known as PTFE or Teflon tape), and it is then threaded into a corresponding threaded fitting using a pipe wrench. Beyond domestic or light commercial settings, steel pipe is often joined by welding, or by use of mechanical couplings SJB Institute of Technology, Department of Civil Engineering

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made by companies such as Victaulic or Grinnell that hold the pipe joint together via a groove pressed or cut (a rarely used older practice), into the ends of the pipes. Other variations of steel pipe include various stainless steel and chrome alloys. In high-pressure situations these are usually joined by TIG welding. In Canada, with respect to natural gas (NG) and propane (LP gas), black iron pipe (BIP) is commonly used to connect an appliance to the supply. It must however be marked (either painted yellow or yellow banding attached at certain intervals) and certain restrictions apply to which nominal pipe size (NPS) can be put through walls and buildings. With propane in particular, BIP can be run from an exterior tank (or cylinder) provided it is well protected from the weather, and an anode-type of protection from corrosion is in place when the pipe is to be installed underground.

Copper pipe Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or solder. Copper offers a high level of resistance to corrosion, but is becoming very costly. Soft copper

Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing. While the work hardening of the drawing process used to size the tubing makes the copper hard/rigid, it is carefully annealed to make it soft again; it is therefore more expensive to produce than non-annealed, rigid copper tubing. It can be joined by any of the three methods used for rigid copper, and it is the only type of copper tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in split-system air conditioners and heat pumps. Flare connections

Flare connections require that the end of a tubing section be spread outward in a bell shape using a flare tool. A flare nut then compresses this bell-shaped end onto a male fitting. Flare connections are a labor intensive method of making connections, but are quite reliable over the course of many years. Rigid copper

Rigid copper is a popular choice for water lines. It is joined using a sweat, compression or crimped/pressed connection. Rigid copper, rigid due to the work hardening of the drawing process, cannot be bent and must use elbow fittings to go around corners or around obstacles. If heated and allowed to slowly cool, called annealing, then rigid copper will become soft and can be bent/formed without cracking. SJB Institute of Technology, Department of Civil Engineering

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Soldered connections

Solder fittings are smooth, and easily slip onto the end of a tubing section. The joint is then heated using a torch, and solder is melted into the connection. When the solder cools, it forms a very strong bond which can last for decades. Solder-connected rigid copper is the most popular choice for water supply lines in modern buildings. In situations where many connections must be made at once (such as plumbing of a new building), solder offers much quicker and much less expensive joinery than compression or flare fittings. The term sweating is sometimes used to describe the process of soldering pipes. Compression connections

Compression fittings use a soft metal or thermoplastic ring (the compression ring or "olive") which is squeezed onto the pipe and into the fitting by a compression nut. The soft metal conforms to the surface of the tubing and the fitting, and creates a seal. Compression connections do not typically have the long life that sweat connections offer, but are advantageous in many cases because they are easy to make using basic tools. A disadvantage in compression connections is that they take longer to make than sweat, and sometimes require retightening over time to stop leaks. Crimped or pressed connections

Crimped or pressed connections use special copper fittings which are permanently attached to rigid copper tubing with a powered crimper. The special fittings, manufactured with sealant already inside, slide over the tubing to be connected. Thousands of pounds-force per square inch of pressure are used to deform the fitting and compress the sealant against the inner copper tubing, creating a water tight seal. The advantages of this method are that it should last as long as the tubing, it takes less time to complete than other methods, it is cleaner in both appearance and the materials used to make the connection, and no open flame is used during the connection process. The disadvantages are that the fittings used are harder to find and cost significantly more than sweat type fittings.

Aluminium pipe Aluminium is sometimes used due to its low cost, resistance to corrosion and solvents, and its ductility. Aluminium tube is more desirable than steel for the conveyance of flammable solvents, since it cannot create sparks when manipulated. Aluminium tubing can be connected by flare or compression fittings, or it can be welded by the TIG or heliarc processes.

Glass pipe Tempered glass pipes are used for specialized applications, such as corrosive liquids, medical or laboratory wastes, or pharmaceutical manufacturing. Connections are generally made using specialized gasket or O-ring fittings.

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