The OT-L Series Leachate Treatment System® exploits the metabolic function to deal with large quantity of microorganisms suspending in the leachate or attached to special microorganisms and contributes to the highly effective removal of pollutants. The OT-L Series Leachate Treatment System® comprehensively adopts the processing technology of “biochemical treatment + physical treatment + low-pressure membrane separation”. With this technology, the biochemical process can degrade and eliminate the pollutants effectively, and the membrane separation process can separate and remove non-biochemical-process residues of the pollutants.