In the process of stacking and landfill, a kind of liquid with high concentration of organic or inorganic components is produced under the action of precipitation and groundwater seepage due to the biochemical degradation effects such as compaction and fermentation, which is called landfill percolate or percolate.There are many factors affecting the percolate production, including the rainfall situation in the landfill area, the nature and composition of the garbage, the anti-seepage treatment of the landfill site, and the hydro-geological conditions of the site.
Landfill percolate has complex water quality and contains a variety of toxic and harmful inorganic and organic substances. percolate also contains non-chlorinated aromatic compounds such as naphthalene and phenanthrene, chlorinated aromatic compounds, phosphoric acid vinegar, phenolic compounds and aniline compounds which are difficult to biodegrade.
The maximum concentration of CODcr and BOD5 in landfill percolate can reach thousands to tens of thousands, which is much higher than that of urban sewage. Therefore, percolate can not be directly discharged into urban sewage treatment pipeline without strict treatment and disposal.In general, CODcr, BOD5, BOD5/CODcr decreased with the "age" of the landfill, and the alkalinity content increased.
