Water Quality and Treatment

Table Summary of various Unit Operations and Processes Unit Operation and Process Trash rack (UO) Coarse screen (UO) Microstrainer (UO) Aeration (UP) Mixing (UO) Coagulation (UP) Flocculation (UO) Sedimentation (UO) Filtration (UO) Recarbonation (UP) Demineralization (UP) Ion-exchange (UP) Reserve Osmosis (RO) (UO)

Description and Principal Applications. Provided at the intake gate for removal of floating debris. Mechanically cleaned screen provided at the intake or in the sump well ahead of pumps for removal of smaller objects. Removal algae and plankton from raw water. Strips and oxidizes taste and odour producing volatile organics and gases and oxidize iron and manganese’s. Provides uniform and rapid distributions of chemicals and gases into water. Coagulation is the additional and rapid mixing of coagulation resulting in destabilized of the colloidal particles and formation of micro flocs. Flocculation ins aggregation of destabilized turbidity and colour causing particles to form a rapid setting macro flocs. Gravity separatation of suspended solids or flocs produced in treatment process. Removal of particulate matter by percolation through granular media. Restore the chemical balance of water after softening Bubbling of Co2 converts Ca and Mg into more soluble forms. Involves removal of dissolved salts from the water supply. Demineralization may be achieved by ionexchange, membrane processes, distillation and freezing. The cations and anions in water are selectively removed when water is percolated through beds containing cation and anion exchange resins. Semi – permeable membranes are used to permeate high-quality water while rejecting the passage of dissolved salts.

Table Health effects of water quality parameters Paramete r

BIS BIS Guidelines 1983 value (Maximum) 2000 mg/L 3000

BIS 1991

WHO

General & Health effects

2000

1000

6.5-8.5

6.5-9.2

6.5-8.5

6.5-8.5

Alkalinity Hardness

600 mg/L 600 mg/L

600

600 600

500

Calcium

200 mg/L

200

200

Magnesiu m

100 mg/L

100

100

100

Iron

1.0 mg/L

1.0

1.0

0.3

Manganes e Aluminum

0.3mg/L

0.5

0.5

0.1

0.2mg/L

-

0.2

0.2

Copper

1.5 mg/L

1.5

1.5

1.0

Zinc

15 mg/L

15

15

5

Ammonia

-

Nitrate

-

Nitrate

100 mg/L

45

100

45

Sulfate

400 mg/L

400

400

400

Undesirable taste; gastro intestinal irritations; corrosion or incrustation. Affects mucous membrane; bitter taste; affects aquatic life. Boiled rice turns yellowish Poor lathering with soap; deterioration of the quality of clothes; scale forming; skin irritation; boiled meat and food become poor in quality. Poor lathering and deterioration of the quality of clothes; incrustation in pipes; scale formation. Poor lathering and deterioration of clothes; with sulfate laxative. Poor or sometimes bitter taste, color and turbidity; staining of clothes materials; iron bacteria causing slime. Poor taste, color and turbidity; staining; black slime. Neurological disorders; Alzheimer’s disease. Liver damage mucosal irritation, renal damage and depression; restricts growth of aquatic plans. Astringent taste; opalescence in water; gastro intestinal irritation; vomiting, dehydration, abdominal pain, nausea and dizziness. Indicates pollution, growth of algae. Forms nitrosamines which are carcinogenic. Blue baby disease (methemoglobineamia), algal growth. Taste affected, laxative effect,

Total dissolved solids PH

-

-

Chloride Fluoride

1000mg/L 1.5 mg/L

1000 1.5

1000 1.5

250 1.5

Phosphate Arsenic

0.05 mg/L

0.05

0.05

0.05

Mercury

0.001 mg/L

0.001

0.001

0.001

Cadmium

0.01 mg/L

0.01

0.01

0.01

Lead

0.05 mg/L

0.1

0.05

0.05

Chromium

0.05 mg/L

0.05

0.05

0.05

Pesticide

0.001 mg/L

Detergent

-

------

0.001 -----

gastrointestinal irritation. Taste affected, corrosive. 1.5 mg/L-Dental and skeletal fluorosis, non-skeletal manifestations. Algal growth Toxic, bio-accumulation, central nervous system affected, carcinogenic. Highly toxic, causes`minamata’ diseaseneurological impairment and renal disturbances, mutagenic. Highly toxic, causes `itai-itai’ disease-painful rheumatic condition, cardio vascular system affected, gastro intestinal upsets and hyper tension. Causes plumbism-tiresness, lassitudes, abdominal discomfort, irritability, anaeminal, biocumulation, impaired neurological and motor development, and damage to kidneys. Carcinogenic, ulcerations, respiratory problems and skin complaints. Affects central nervous system. Undesirable foaming.