Study Of Characteristics Of Heavy Metals In Leachate Through A~2/O Treatment Process

This article aims at the heavy metals in landfill leachate from Shenyang Laohuchonglandfill site and analyses the variation of characteristics of these5heavy metals(Pb, Ni, Cu,Zn, Cr) with higher content and microbial toxicity in leachate in the process of bio-treatment.The research is carried out though the A~2/O treatment process and studies the influence ofsome main factors on the heavy-metal removal rate and the change of the adsorption andmigration of these heavy metals, with which founds a multi-component competitiveadsorption model having a good fitting with actual situation. In consideration of the toxicityof heavy metals, the research studies the influence of the concentration of heavy metals on theeffects of system’s treatment efficiency and the toxic effects to activated sludge. The resultsshow that, through the A~2/O treatment process, the total removal rate of these5heavy metalsis over80%and3(Cu, Zn, Pb) of them can be as much higher as90%. Because the heavymetals mainly exist in dissolved form in landfill leachate, the majority of these metals can beremoved in biological-process units but the adsorption equilibrium time of each unit is not thesame and the time in each tank is90,60and30min, respectively. There are obviouscompetitive adsorption phenomena throughout the adsorption process by drawing adsorptionisotherm, which shows the effect of Ni is the most. The research studies the toxicity of theseheavy metals to anaerobic and aerobic activated sludge through Anaerobic ToxicityAssay(ATA) and ETS activity experiment. It reveals that, with the rise of the concentration ofheavy metals, the removal rate of heavy metals decreases through the A~2/O treatment processapparently and the resistance of aerobic activated sludge is higher than that of anaerobicactivated sludge under the same concentration of heavy metals.