These days many people are asking whether household garbage be safely discarded at the municipal landfill or will it end up polluting the environment. Here is a simplified explanation of how landfills are designed and the pro's and con's.
The primary environmental risks associated with the municipal landfills are due to the leachate and gases produced from the interaction of diverse waste components, rain water, and organic degradation.. Regarding the composition of the waste, the U.S. EPA estimates that approximately 50% is paper products and yard waste, roughly 40% is metals, food waste, and plastics, and the rest is mostly wood, rubber, leather, textiles, and miscellaneous inorganic materials. The mixture also contains household hazardous waste from cleaning products, pesticides, paints and finishes, paint thinners, adhesives, and automotive maintenance products. Small businesses such as dry cleaners, machine shops, and automotive repair shops add degreasers, oils, and solvents to the mix. Rain water filtering through the waste produces a solution high in heavy metals and volatile organic compounds (VOCs). The microbial decomposition of organic material produces a landfill gas comprised primarily of methane and carbon dioxide.
In the past, municipal landfills were treated as all-purpose dumping grounds but were not designed to contain the leachate coming from the waste or to prevent gas build-up. They were often situated in old gravel pits or wetlands where contaminants were rather easily transferred to the groundwater with the possibility of getting into drinking water.
The leachate from municipal landfills has been found to contain high levels of heavy metals such as lead, cadmium, arsenic, and nickel. Exposure to these metals may cause blood and bone disorders, kidney damage, decreased mental capacity, and neurological damage. Movement of these metals in the soil and groundwater is slow due to binding to the soil particles. VOCs such as benzene and chlorinated benzenes, tetrachloroethylene, trichloroethylene, xylene, vinyl chloride, and toluene also tend to show up in the leachate. Exposure to these compounds has been associated with cancer, leukemia, and liver and neurological damage. They are more of a potential hazard once in the groundwater since they have relatively high mobility. Also, in the old landfills, the methane gas formed was not vented to the outside and this increased the possibility of explosions or fires.
Landfill regulations that have come into effect over the last few years involve much stricter design, siting, and operational requirements. Landfills are now being required to have liners, groundwater monitoring, and leachate collection as well as gas removal systems. Thus, the risk of release of toxic metals and VOC's to the environment is decreasing. However, the best way to prevent environment is decreasing. However, the best way to prevent environmental pollution from landfills is to keep toxic substances (e.g., batteries, household hazardous waste) out of your trash by using less toxic products and by increasing recycling and reuse.
This page was updated on August 01, 2004