Study On Representative POPs Treatment In Landfill Leachate With An Innovative BBF Process

Landfill leachate, which was produced from the process of landfilling, contains a large amount of poisonous contaminants. It may contribute severe environmental hazards when discharged without correct treatments. Too many studies on the removal of pollutants such as high concentrations of COD and ammonium nitrogen by conventional biological techniques had been done. Nowadays, studies on the trace and hazardous persisit organic pollutants in the process of leachate treatment process have been paid great attention.An innovative process which was a combination of coagulation and the two-staged sequencing batch biofilm reactors(BBF) with plant netted fiber carrier had been carried out in this paper, and the removal effects of COD, NH₄⁺-N, TP and representative POPs in the start-up period and the steady operation period were also studied.The results indicated that the new process had good removal effects on landfill leachate treatment. The average removal efficiency of COD in the two-staged BBF was 63.54%, while the first BBF was the main place for its removal. The average removal efficiency of NH₄⁺-N in the two-staged BBF was 63.54%, and the process had a greater anti-impulsion to changes of high concentration of NH₄⁺-N in influents. By mixing leachate with water for dilution as influents in the process, the removal efficiency of TP in the first BBF was 51.38%, but that in the second BBF was unsteady. The limited removal capability of the two-staged BBF on some non-biodegradable organic matters in landfill leachate was confirmed by the changes of UV₂₅₄ in influents and effluents.The results also indicated that the removal efficiency of coagualtion to representative POPs was closely allied to concentration of SS. The total removal efficiencies to PCBs in leachates from Erfei Shan and Liufang in the two-staged BBF were 22.05% and 39.80%, respectively, and the removal of the second BBF was higer than that of the first BBF. The removal of PCBs was mainly achieved by the removal of three chloro-PCB homologs. And the concentrations of PCBs in last effluents were all above 1000ng/L. DDTs were removed by different extents in the biological treatment. No obvious removal law of HCHs was found, but it had something to the improved water qualities, which needed further studies to be done. The contents of PCBs, DDTs and HCHs in sludge in the two-staged BBF were studied as follow: residual sludge of the second BBF,residual sludge of the first BBF,raw activated sludge, which was consistent with the conclusion that the removal of representative POPs in the second BBF was higher than that in the first BBF.