Bioreactor Landfill

BIOREACTOR LANDFILLS: A REVIEW

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INTRODUCTION 

This This bior biorea eact ctor or conc concep eptt dif differs fers from from the the trad tradit itio iona nall “dry “dry tomb” municipal landfill approach.

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A bioreacto ctor land andfill operate ates to rapidly trans ransfform and degrade organic waste. The increase in waste degradation and stabi stabiliz lizat ation ion is acco accomp mplis lishe hed d thro through ugh the the addi additio tion n of  qu an a r o en ance m cro a pro processes.

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40-60 gallons of added liquid per ton of solid waste increases the water content of the waste from about 20% to about 40-50%. The liquids create optimum conditions for the microorganisms to rapidly degrade the solid waste. 2 7/27/2012

BENEFITS

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BIOREACTOR L ANDFILL: TYPES  Aerobic-Anaerobic: 

The aerobic-anaerobic bioreactor is designed to accelerate waste degradation by combining attributes of the aerobic and anaerobic bioreactors.

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The objective is to cause a rapid biodegradation of  aerobic stage to reduce organic acids in the anaerobic stage resulting in the earlier   methanogenesis.

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In this system, the uppermost lift of waste is aerated while the lifts below receive liquids. Horizontal wells, installed in each lift during construction, are used to transport landfill gases, liquids and air. 7/27/2012

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BIOREACTOR L ANDFILL: TYPES

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BIOREACTOR L ANDFILL: TYPES

The aerobic process is much accelerated and typically requires less than two years for full biodegradation. 7/27/2012

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BIOREACTOR L ANDFILL: TYPES

In this system, leachate containing high levels of  ammonia is treated using the biological process of  nitrification. 7/27/2012

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GENERATION OF L ANDFILL GASES 

Initial Adjustment Stage 

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Transition Phase 

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3months to 3 years

Methane Fermentation Phase 

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1-6 months

Acid Phase 

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Few hours or one week

8-40 years

Maturation Phase 7/27/2012

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LEACHATE RECIRCULATION 

Liner system

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LEACHATE RECIRCULATION 

Drainage System

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Leachate collection pipe

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Volume of liquid V= MpAT where V= volume of liquid Mp= additional % of moisture  A= area of waste T= thickness of waste mass.

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It is influenced by 

actual moisture content

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Heterogenety

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Compaction 7/27/2012

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LEACHATE RECIRCULATION Methods of recirculation 

Prewetting

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Horizontal trenches

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Surface Ponds

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Spray irrigation

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Vertical Injection Wells

The radius of influence for the well is given by R=Kw/Kr  Where, R is radius of influence and Kw and Kr are hydraulic conductivity of surrounding material and waste. 

Horizontal Injection wells 7/27/2012

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LEACHATE RECIRCULATION

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LEACHATE RECIRCULATION The advantages of leachate recirculation are: 

Landfills that use leachate recirculation experience a decrease in the concentration of the leachate compared to landfills without recycle treatment. This reduced the amount of leachate treatment that is needed it and therefore costs are also reduced.

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The increased moisture content within the solid waste decomposition of organic matter in the landfill.

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The organic matter in the leachate receives further  treatment each time it recycled through the landfill. This reduced treatment costs of the landfill.

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The reducing environment within the landfill removes inorganics in the leachate through precipitation and sorption. 7/27/2012

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LEACHATE RECIRCULATION 

Leachate recirculation stabilizes the biological system in the landfill and this reduced the environmental threats of the landfill, and reduces the amount of  post closure monitoring that is re uired. It also rovides the o ortunit for landfill mining and space reclamation.

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Leachate recirculation increases the rate at which the waste decomposes and this increases the rate of methane production.

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Leachate recirculation is a leachate management method that is relatively simple and inexpensive. 7/27/2012

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LEACHATE RECIRCULATION The disadvantages of leachate recirculation are: 

Since landfills are heterogeneous, the leachate may find discrete channels to travel through. This makes it difficult to insure that the leachate is reacting with all of  the waste and is thoroughly treated.

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The risk of environmental exposure when leachate is .

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Bioreactor landfills are a relatively new technology. For  the newly developed bioreactor landfills initial monitoring costs are higher to ensure that everything important is discovered and properly controlled. This includes gases, odours and seepage of leachate into the ground surface. 7/27/2012

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LEACHATE RECIRCULATION 

The increased moisture content of bioreactor landfill reduces the structural stability of the landfill. The landfill can become too soft too quickly and end up collapsing in on itself due to its weight.

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Another consequence of rapid decomposition is the rapid accumulation of landfill gases, primarily methane. Traditional landfills have exhaust pipes dug into them to release methane as it is produced. Bioreactor landfills may are not be able vent them, causing an explosion.

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In addition, the types of gases bioreactor landfills produce in excess compared to traditional landfills, such as H2S, have excessively putrid smell (H2S smells like rotten eggs). Hence, there is a chance that bioreactor landfill land may not be used for other projects due to the presence of these odorous gases.

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Since the target of bioreactor landfills is to maintain a high moisture content, gas collection systems can be effected by the increased moisture content of the waste. 7/27/2012

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F ACTORS AFFECTING GENERATION OF L ANDFILL G AS 

Moisture content

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Nutrient Content

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pH Level

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Bacterial Content

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Temperature

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Oxygen Content 17

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CONVENTIONAL VS BIOREACTOR LANDFILL  A case study of north America landfills shows following result for  bioreactor landfill. 

Leachate generation rate are mostly similar in case of  bioreactor is similar or decreased.

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Leachate depths and liner/leachate temperatures: Raise in the leachate depth is found which ranged from 50mm to 600mm.An elevated temperature may damage the liner system .

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Gas production rate is notably increased and more than conventional (about 14%)

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Average solids content decreased from 54% to 31% and it proves active decomposition.

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BOD:COD ratio increases initially but decreases considerably afterwords while pH first decreases then increases and 18 stabilize in range7-8. 7/27/2012

CONVENTIONAL VS BIOREACTOR LANDFILL Settlement in bioreactor landfill conventional reactor is much higher that is 2-3 fold due higher  weight and rapid degradation.

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SUMMARY 

A bioreactor landfill is a sanitary landfill site that uses enhanced microbiological processes to transform and stabilize the readily and moderately decomposable organic waste constituents within 5 to 8 years of bioreactor process implementation.

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The bioreactor landfill significantly increases the extent of organic waste decomposition, conversion rates and process effectiveness over those that otherwise occur within the traditional landfill sites.

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A bioreactor landfill site requires specific management activities and operational modifications to enhance and accelerate microbial .

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The single most important aspect for effective operation is liquid addition and management. Other strategies, including waste shredding, pH adjustment, nutrient addition and balance, waste predisposal and post-disposal conditioning, and temperature management, may also serve to optimize the bioreactor process.

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The successful operation of bioreactor landfill also requires the development and implementation of focused operational and development plans to ensure that optimal conditions for  bioprocesses exist and to allow the system to function effectively. 7/27/2012

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SUMMARY  Advantages of Bioreactor Landfill can be summarized as follows: 

Enhance the LFG Generation Rates

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Reduce Environmental Impact

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Production of End Product that does not Need Land filling

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Overall Reduction of Land filling Cost

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Reduction of leachate Treatment Capital and Operation Cost

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Reduction in Post-Closure care, maintenance and Overall reduction of contaminating life span of the landfill due to a decrease in contaminant concentrations during the operating period of the bioreactor landfills 7/27/2012

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REFERENCES 

C.H. Benson. (2007). “Practice review of five bioreactor/recirculation landfills”. Waste Management Vol 27 Page 13–29.

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Ertan Durmusoglu. (2005). “Landfill Settlement with Decomposition and Gas Generation”. Journal Of Environmental Engineering © ASCE. Page 1311-1321

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M. A. Warith. (2003). “Solid Waste Management: New Trends In Landfill Design”. Emirates Journal for Engineering Research, vol 8 (1), page 61-70.

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Ma. C. Hernández-Berriel. (2010). “Influence of Recycling Different leachate Volumes on Refuse Anaerobic Degradation”. The Open Waste Management Journal, vol 3, page 155-166.

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Pin-jing Hea. (2006). “Dissolved organic matter (DOM) in recycled leachate of  bioreactor landfill”. Waterr Research, vol 40, page 1465 – 1473.

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THANK YOU y ??? 23

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