A Look at How Waste Management Uses Bioreactor Technology

A Look at How Waste Management Uses Bioreactor Technology

wastemanagementlogoWhile recycling and waste reduction are playing increasingly important roles in managing waste, landfills remain a significant means of handling it. Waste Management, an Ohio-based company, has proposed several innovative models for landfill management that could make this method of waste disposal viable for years to come.

According to Waste Management, small changes in the way landfills are managed could bring about substantial economic and environmental benefits. The company envisions transforming landfills from waste disposals to waste treatment centers, thus eliminating their threat to the environment.

Waste Management is working on several new landfill innovations, such as the following:

Aerobic-anaerobic bioreactor

This model combines aerobic and anaerobic attributes to speed up waste degradation. The anaerobic stage breaks down food and other quickly degradable waste, which reduces the production of organic acids in the aerobic stage and brings about methanogenesis more quickly. This model merges the simplicity and efficiency of the aerobic and anaerobic processes and has the potential to destroy volatile organic compounds created in waste.

Anaerobic bioreactor

Anaerobic bacteria do much of the work in landfills, breaking down organic wastes into organic acids and then into methane and carbon dioxide. Conditions for anaerobic bacteria occur naturally in a landfill, but an anaerobic bioreactor would speed up the anaerobic breakdown process by adding more moisture, thus optimizing the conditions for the process. The accelerated waste breakdown, however, produces more gases, so anaerobic bioreactors must be capable of handling a higher peak volume of gases.

Aerobic bioreactor

aerobic bioreactor tankThis model optimizes the conditions for aerobes, which are organisms that need oxygen for cellular respiration, to increase the rate of waste degradation. This is typically achieved by injecting oxygen into the waste mass, but the process also can require large amounts of water to offset the metabolic heat produced in the process.

Facultative bioreactor

This landfill technology combines the anaerobic process with a system that controls the high amount of ammonia produced when water is added to the waste mass. The process converts ammonia to nitrate, which facultative bacteria and other organisms can use for respiration. This also removes nitrogen from the system.

Engineers at Waste Management are confident that these new systems can be created and implemented into landfills. They cite three reasons why they believe these innovations and projected results can be accomplished:

1)  Many landfills are designed with effective pollution controls already, and waste degrades naturally within the system. Waste Management’s solutions will speed up the degradation process, which currently takes many years, and will control the moisture and gases these accelerated processes require and produce. Engineers imagine a process where natural decomposition takes years instead of decades and where environmental protection is more advanced.

2)  The most important ingredient for accelerated waste degradation is moisture, and now engineers can increase moisture to the waste mass through landfill leachate, storm water runoff, water, sewer sludge, and gas condensate.

3)  The benefits of bioreactor landfills are significant, which could increase interest in them and, in turn, the implementation of bioreactor processes. For example, the waste mass stabilizes more quickly when the degradation process is sped up, which allows landfills to be used for other purposes more quickly. Space in the landfill is also recovered at a quicker rate, leaving more room for additional waste. Another benefit is that producing more methane in a shorter amount of time decreases the amount of greenhouses gases the landfill will produce over its lifetime.

Waste Management is evaluating the four types of bioreactor technology, including how they could work for retrofitting existing landfills and which technology is best for new landfills. The company is particularly focused on how geography and climate impact the bioreactors’ performance, how to manage nitrogen in landfills, and what regulatory changes would affect bioreactors. It also wishes to discover other sources of moisture and water for the waste mass and to establish geotechnical stability for landfills.

At its 10 waste disposal sites throughout the United States and Canada, Waste Management is examining how to manage bioreactor processes as well as their environmental and economic impacts. Such projects include the King George and Maplewood landfills in Virginia, where researchers are studying the benefits of adding liquid to solid waste, and a landfill in Mount Holly, New Jersey, where air and leachate are being injected into a closed part of the landfill to treat contaminates in the waste.

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