Macropollutants removal from compost leachate using membrane separation process

Abstract

Advanced treatment of a biologically pre-treated compost leachate was carried out in this study. The leachate was fed to a membrane-based bioreactor and then its supernatant effluent was purified by a hollow fiber membrane (HFM) and a flat sheet membrane (FSM) separately. Macropollutants including biological oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS) were monitored in the reactor feed and permeate after the system reaches to a steady-state condition which lasted 280 d. The values of pH and total dissolved solids (TDS) were also measured routinely. Both the membranes were thoroughly rinsed with permeate and then immersed individually in hypochlorite solution for 30 min occasionally. Among the experiments, total COD values ranging from 50 to 2,200 mg/l in the feed were decreased to 32.5 and 4 mg/l in the HFM and FSM permeate, respectively. Average TSS content in the effluent of the HFM was 2.5 mg/l and that in the FSM effluent was 0.26 mg/l. Also, produced BOD5 in the HFM and in the FSM effluents were 1.3 and 0.2 mg/l, respectively. TDS concentration in the membranes' feed were varied from 4,567 to 14,811 mg/l, whereas, there were no significant decreases in the membranes' permeate. The results demonstrated that the FSM was more suitable module than the HFM in terms of providing high quality permeates.