The majority of landfills create methane gases that escape into the surrounding atmosphere if they are uncontrolled. The gases have an obnoxious odor and can harm the environment in many ways. The Environmental Protection Agency (EPA) has recently released new solid waste regulations and a draft of New Source Performance Standards (NSPSs) which could significantly increases the number of landfills that are now required to employ active LFG collection systems. Landfill gas condensate is a by-product of these collection systems.
Landfill gases are produced within the refuse pile of a landfill as organic matter decomposes. If left alone, the gas may migrate within the landfill, ultimately escaping at the landfill's surface into the atmosphere. Under the new EPA regulations, LFG collection systems will be installed in currently active and previously closed landfills; as well as part of the procedure for closing a landfill. An LFG collection system generally includes a series of gas extraction wells. The wells are typically formed by drilling a hole into the refuse pile and inserting a perforated pipe into the hole. The space around the pipe is typically backfilled with a porous material to facilitate gas flow. The wells are connected together by a series of collector pipes. The collector pipes are connected to a fan which provides the necessary vacuum to extract the LFG from the refuse pile. The LFG is then fed into a flare which burns the gas.
The temperature of the gas within the refuse pile can achieve temperatures as high as 90.degree. fahrenheit (F) to 140.degree. F. depending on the type and moisture content of organic matter in the refuse pile, as well as the other site specific conditions. The amount of gas produced also depends on these factors and on the age of the landfill. Generally, a landfill will produce its maximum amount of gas between three and seven years after it is closed. When the gas being drawn up through the wells reaches the collector piping on the surface, it is cooled by the ambient temperature of the air. As the gas cools, condensation forms on the inside of the piping. The piping is pitched to allow the condensate to flow to a collection point or dump. If the piping system has a plurality of collection points, the condensate is pumped by conventional means to a central collection or accumulating tank.
Until now, the condensate formed in the gas collection piping was released back into the landfill. Under-the new Subtitle D Regulations for municipal solid waste facilities, landfill gas condensate must be collected unless the landfill gas collection system is operated within a landfill equipped with both composite base liner and leachate collection systems. The current methods of disposal include discharging the condensate into an on-site leachate treatment system or transporting the condensate to an industrial wastewater treatment facility. Only a limited number of landfills can make practical use of the aforementioned solutions. Many landfills, due either to their design or location, cannot economically use these solutions. Smaller landfills located in rural areas are in great need of an economical solution. An alternative solution for these and other landfills is needed.
It is an object of this invention to provide a method and apparatus for the onsite disposal of LFG condensate. It is a further object of the present invention to incinerate the contaminants in the LFG condensate by using the waste heat generated by burning LFG in an onsite flare.