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Leachate Plant

Leachate is generated when the moisture-holding capacity of the refuse in the landfill is exceeded. Leachate percolates down through the refuse where it is collected on the bottom liner and is directed to sumps using a series of pipes and trenches.

From the sumps, leachate is pumped to a 9,200-gallon equalizer tank in the pre-treatment facility. The tank aerates the leachate and provides interim storage and flow equalization prior to entering the chemical treatment unit.

The first step of pre-treatment is to remove metals and solids. The second step uses an aerobic tower to reduce biological oxygen demand while degrading volatile organic compounds.

From the equalization tank, water is pumped to a three-chamber chemical treatment unit.
  • Unit one is a coagulation tank where Ferric Chloride is added so that the suspended solids are electrically neutralized. This allows the solids to agglomerate together.
  • In unit two, sodium hydroxide is added to increase pH above 9.0, precipitating metals into insoluble hydroxide ions.
  • In the third unit, anionic polymer is added, causing the particles to collide and further agglomerate into floc.

The leachate then flows into a solids separator, where the floc drops to the bottom. The liquid rises through an inclined plate separator and into a pH adjustment tank. Sulfuric acid is added in the adjustment tank to re-adjust pH to neutral.

The flow then proceeds to a lift tank where it is pumped to the bottom of a bio-tower and is evenly distributed upward through random packed plastic media. The leachate is fortified with phosphoric nutrients to feed the microbes in the bio-tower. The up flowing leachate comes in contact with a thin microbial film, which converts the organics to carbon dioxide and water from the top of the bio-tower, leachate gravity flows to the effluent tank, and is pumped out of the facility and into the county sewer system.
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