Environmental Engineering Reference
In-Depth Information
3. Aerobic-anaerobic bioreactor landfills
The Aerobic-Anaerobic Bioreactor is designed to accelerate waste degradation by
combining attributes of the aerobic and anaerobic bioreactors. The objective of the sequential
aerobic-anaerobic treatment is to cause the rapid biodegradation of food and other easily
degradable waste in the aerobic stage in order to reduce the production of organic acids in the
anaerobic stage resulting in the earlier onset of methanogenesis.
In this system the uppermost lift or layer of waste is aerated, while the lift immediately
below it receives liquids. Landfill gas is extracted from each lift below the lift receiving
liquids. Horizontal wells that are installed in each lift during landfill construction are used
convey the air, liquids, and landfill gas. Figure 3 shows a cut-away view of an aerobic-
anaerobic bioreactor.
The principle advantage of the hybrid approach is that it combines the operational
simplicity of the anaerobic process with the treatment efficiency of the aerobic process.
Added benefits include an expanded potential for destruction of volatile organic compounds
in the waste mass.
C. Features Unique to Bioreactor Landfills
The bioreactor accelerates the decomposition and stabilization of waste. At a minimum,
leachate is injected into the bioreactor to stimulate the natural biodegradation process.
Bioreactors often need other liquids such as stormwater, wastewater, and wastewater
treatment plant sludge to supplement leachate to enhance the microbiological process by
purposeful control of the moisture content and differs from a landfill that simple recirculates
leachate for liquids management. Landfills that simply recirculate leachate may not
necessarily operate as optimized bioreactors.
Figure 3. Aerobic-Anaerobic Bioreactor Landfill (U.S EPA 2004)
