Hazardous waste landfill leachate treatment using an activated sludge-membrane system.

This research was aimed to investigate the capability of a combined system of activated sludge and microfiltration processes with backflushing technique to reduce organic carbon and nitrogen compounds in hazardous landfill leachates. The experiments included acclimation, batch and continuous processes. The continuous process was conducted with a 24 hour HRT (Hydraulic Retention Time), and the SRT (Solid Retention Time) ranged from 16 to 36 days. The aeration basin volume was 5 L and the membrane filter used was a hollow fiber module made from polypropylene with pore size of 0.2 microm. The batch process (without membrane separation) achieved its steady state condition over a period of 33 days. The removal of COD, BOD5 and ammonia-N were 52.5%, 94.3% and 75.5%, respectively. The kinetic parameters obtained are as followed: the maximum specific growth rate constant (microm): 0.96/day and the saturation substrate constant (Ks): 16,445.32 mg/L. The high value of Ks indicated that the leachate was not easily biodegraded. The continuous process revealed that the system with SRT of 32 days was more stable than that of 16 and 24 days. The reduction of COD, BOD5 and ammonia-N were 31.3%; 66% and 98%, respectively. The stable flux was achieved around 5 L/m2 x hour.