Microcosm experiments on a coconut-fibre biofilm treatment system to evaluatewaste water treatment efficiencies

Abstract

Interest in utilization of locally available biomasses as biofilm support media for wastewater treatment in developing countries is increasing. In this study, microcosm experiments on a coconut-fibre biofilm treatment system were carried out to evaluate wastewater treatment efficiencies in the laboratory using two wastewaters, synthetic sewage and leachate, with different pollutant loads. Three coconut-fibre conditions were set as a single bundle (low fibre density: LFD), two bundles (high fibre density: HFD), and no coconut fibre (blank). The wastewater was first circulated in the system for six weeks (circulation stage) and then discharged from the treatment tank for 7-24 weeks (treatment stage). Water quality parameters of effluents, pH, DO, EC, BOD, COD, TC, and TN, were measured at one-week intervals, and the sedimented sludge in each treatment tank was collected to determine C, N, and P contents. Results showed effective reductions in BOD and COD in the LFD and HFD conditions for the synthetic leachate, indicating that the coconut fibre contributed to the treatment of wastewater. On the other hand, the fibre density had less or no effect on the reduction of water quality parameters in the synthetic sewage. For both synthetic sewage and leachate, the C and N consumptions generally increased in the order of blank, LFD, and HFD. In particular, sludge sedimentation contributed to C consumption under the HFD condition.