Bioreactors Landfills

Bioreactor Defined

“……a sanitary landfill operated for the purpose of transforming and stabilizing the readily and moderately decomposable organic waste constituents within five to ten years following closure by purposeful control to enhance microbiological processes. The bioreactor landfill significantly increases the extent of waste decomposition, conversion rates and process effectiveness over what would otherwise occur within the landfill.”

Why Operate a Landfill as a Bioreactor?to increase potential for waste to

energy conversion, to store and/or treat leachate, to recover air space, and to ensure sustainability

Status

1993 - less than 20 landfills recirculating leachate

1997 - ~ 130 landfills recirculating leachate

My estimate - ~ 5-10% of landfills

Regulatory Status

EPA permits recirculation of indigenous liquids into landfills with Subtitle D liners

Some states more stringentEPA is considering nonindigenous

liquid addition

Europe

The European Union Council Directive on Landfilling of Waste has identified the need to optimize final waste disposal methods and ensure uniform high standards of landfill operation and regulation throughout the European Union (EU).

Essential Needs for a BioreactorComposite linerAppropriate density of MSWAppropriate daily coverLeachate recirculation systemActive gas collection systemAppropriate final cover systemCompetent landfill operator

Leachate Recirculation

Ponding Water

Gas Flow

PreferentialChannels

Impermeable Cover

Heterogeneity

Waste

Impact of Waste Processing

Gas Collection

Year

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

Cu

bic

mete

rs L

FG

0 10 20 30 40 50

LFG Generation Curves

Half-Life = 1.35 yr

Half-Life = 3.68 yr

Half-Life = 20 yr

LFG Collection From Operating Landfills

HorizontalCollectors

Sub-Cap Collector

Leachate Collection System - LFG Collector Network

o

o

o

o

o

oo

Odor Potential

Cover Issues

- 8 - 6 - 4 - 2 0 2 4 6 8

H o r i z o n t a l C o - o r d i n a t e , m

0

2

4

6

8

1 0

1 2

1 4

Was

te H

eigh

t, m

D a ily

M a te ria lC o v e r

Leachate Outbreaks

Alternative Daily Cover

Waste Compaction

Landfill Stability

Recovery of Composted Materials

Research Issues - Aerobic BioreactorHow much air is needed?How can air be delivered?What is the impact on the water

balance?How are landfill fires prevented?What are the economic

implications?

Economic Impacts

BenefitsEnhanced gas

productionRecovered spaceReduced env.

impactReduced post-

closure care

CostsCapital costsOperating costs

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Last updated July 2004 by Dr. Reinhart