Sometimes, it is not possible to stop all of the contaminants from coming into a landfill. The water -- even rainwater -- with dissolved contaminants that slips through the trash is called "leachate," and it is acidic. Part of landfill management requires collecting, containing and treating the leachate to protect surface and groundwater in areas near the landfill.
Perforated pipes placed throughout the landfill collect leachate. The leachate then drains into a pipe and afterward into a leachate collection pond. The pipes and containers that transport or hold leachate must be made of special materials that prevent leakage and hold up to the acidity of the liquid. The collection pond or lagoon is tested for acceptable levels of chemicals like magnesium, organic chemicals, sulfate and iron. After the water is tested, it is treated like any other sewage and discarded on-site or off-site. Sometimes it is circulated again and then treated afterward.
Finding sustainable ways to manage leachate is the goal of many landfill managers. Engineers are looking into ways to destroy all of the contaminants in leachate at one time without having to produce harmful byproducts in the process. For example, the sun can oxidize pools of leachate for free, at least enough to then safely dispose of the liquid in a sanitary sewer system [source: Meeroff].
Another solution that's being used in some communities is to capture the leachate and recycle it back into the landfill to wet the garbage. This helps speed up decomposition and traps the methane gas created by the process to convert it to power [source: Buie]. This process is used in bioreactor landfills and is considered both a solution to leachate management and a way to speed up biodegrading of waste. Advanced versions of bioreactor technology are biocells, which use waste as a resource, and biocaps, which control and convert gas emissions from surfaces of landfills and leachate ponds [source: Hettiaratchi].
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