Abstract: The nanofiltration(NF) and reverse osmosis(RO) concentrated landfill leachate was pretreated by electrolytic process. The COD removal effect of nanofiltration concentrate under different electrolytic conditions was investigated and the optimal parameters of electrolytic pretreatment were determined. The AO-MBR process was adopted, the salinity acclimated sludge with tolerance of 30 mg/L NaCl was incubated as seed sludge, the electrolytic treated NF and RO concentrated liquid mixture was used as the treatment object, and the removal efficiencies of COD, ammonia and total nitrogen were investigated. The result indicated that under the optimum electrolysis conditions of treatment time of 2 hours, current density of 10 mA/cm2, and inter-electrode distance of 1 cm, the removal efficiency of COD and salinity were 65%-75% and 24%, respectively. When the mixing ratio of electrolytic treated NF and RO concentrate in influent was less than 1∶1, the removal efficiencies of ammonia and total nitrogen were above 92% and 86%, respectively. But those efficiencies decreased to 50% and 60% when the mixing ratio was above 2∶1. It was found that the mixing ratios of electrolysis of NF and RO concentrate in influent did not affect the removal efficiency of COD significantly.

Key words: leachate, membrane concentrate, electrolysis, AO-MBR, salt acclimated sludge, mixing ratio, removal efficiencies