Bioreactor Landfill

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IOREACTOR

IOREACTOR

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ANDFILLS

ANDFILLS

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REVIEW

REVIEW

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NTRODUCTION

NTRODUCTION

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 ThThis is bibiororeaeactctor or coconcncepept t didifffefers rs frfrom om ththe e trtradadititioionanal l “d“dryry tomb” municipal landfill approach.

tomb” municipal landfill approach.

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 A A bbiioorreeaactctoor r llananddffiilll l ooppeerratatees s tto o rraappiiddly ly ttraransnsffoorm rm aandnd degrade organic waste. The increase in waste degradation degrade organic waste. The increase in waste degradation and

and stastabibilizlizatation ion is is acaccocompmplislishehed d ththrorough ugh ththe e adaddiditiotion n of of  q

qu u aan n a a r r o o een n aanncce e mm ccrro o a pra proocceesssseess..

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 4400--660 0 ggaalllloonns s oof f aaddddeed d lliiqquuiid d ppeer r ttoon n oof f ssoolliid d wwaassttee increases the water content of the waste from about 20% to increases the water content of the waste from about 20% to about 40-50%. The liquids create optimum conditions for the about 40-50%. The liquids create optimum conditions for the microorganisms to rapidly degrade the solid waste.

microorganisms to rapidly degrade the solid waste.

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B

ENEFITS

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IOREACTOR

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YPES

 Aerobic-Anaerobic:

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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

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IOREACTOR

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 ANDFILL

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YPES

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IOREACTOR

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YPES

The aerobic process is much accelerated and

typically requires less than two years for full

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IOREACTOR

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YPES

In this system, leachate containing high levels of 

ammonia is treated using the biological process of 

nitrification.

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ENERATION OF

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 ANDFILL GASES

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Initial Adjustment Stage

 Few hours or one week

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Transition Phase

 1-6 months

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Acid Phase

 3months to 3 years

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Methane Fermentation Phase

 8-40 years

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EACHATE

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ECIRCULATION

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Liner system

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L

EACHATE

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ECIRCULATION

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Drainage System

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Leachate collection pipe

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

 Heterogenety

 Compaction

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EACHATE

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ECIRCULATION

 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

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EACHATE

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ECIRCULATION

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EACHATE

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ECIRCULATION

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.

 The increased moisture content within the solid waste

decomposition of organic matter in the landfill.

 The organic matter in the leachate receives further 

treatment each time it recycled through the landfill. This reduced treatment costs of the landfill.

 The reducing environment within the landfill removes

inorganics in the leachate through precipitation and sorption.

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EACHATE

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ECIRCULATION

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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

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EACHATE

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ECIRCULATION

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.

 The risk of environmental exposure when leachate is

.

 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.

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EACHATE

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ECIRCULATION

 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.

 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.

 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.

 Since the target of bioreactor landfills is to maintain a high

moisture content, gas collection systems can be effected by

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 ACTORS AFFECTING GENERATION OF

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 AS

Moisture content

Nutrient Content

pH Level

Bacterial Content

Temperature

Oxygen Content

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ONVENTIONAL 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.

 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

.

 Gas production rate is notably increased and more than

conventional (about 14%)

 Average solids content decreased from 54% to 31% and it

proves active decomposition.

 BOD:COD ratio increases initially but decreases considerably

afterwords while pH first decreases then increases and

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ONVENTIONAL 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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UMMARY

 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.

 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.

 A bioreactor landfill site requires specific management activities and

operational modifications to enhance and accelerate microbial .

 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 pre-disposal and post-pre-disposal conditioning, and temperature management, may also serve to optimize the bioreactor process.

 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. 20

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UMMARY

 Advantages of Bioreactor Landfill can be summarized as follows:

 Enhance the LFG Generation Rates

 Reduce Environmental Impact

 Production of End Product that does not Need Land

filling

 Overall Reduction of Land filling Cost

 Reduction of leachate Treatment Capital and Operation

Cost

 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 ₂₁

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EFERENCES

 C.H. Benson. (2007). “Practice review of five bioreactor/recirculation landfills”.

Waste Management Vol 27 Page 13–29.

 Ertan Durmusoglu. (2005). “Landfill Settlement with Decomposition and Gas

Generation”. Journal Of Environmental Engineering © ASCE. Page 1311-1321

 M. A. Warith. (2003). “Solid Waste Management: New Trends In Landfill Design”.

Emirates Journal for Engineering Research, vol 8 (1), page 61-70.

 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.

 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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HANK YOU

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