Using a biological aerated filter to treat mixed water-borne volatile organic compounds and assessing its emissions

A biological aerated filter (BAF) was evaluated as a fixed-biofilm processes to remove water-borne volatile organic compounds (VOCs) from a multiple layer ceramic capacitor (MLCC) manufacturing plant in southern Taiwan.The components of VOC were identified to be toluene,1,2,4-trimethylbenzene,1,3,5-trimethylbenzene,bromodichloromethane and isopropanol (IPA).The full-scale BAF was constructed of two separate reactors in series,respectively using 10-cm and 15-cm diameter polypropylene balls as the packing materials and a successful preliminary bench-scale experiment was performed to feasibility.Performance results show that the BAF removed over 90% chemical oxygen demand (COD) from the influent with (1188 ± 605) mg/L of COD.A total organic loading of 2.76 kg biochemical oxygen demand (BOD)/(m~3 packing·d) was determined for the packed bed,in which the flow pattern approached that of a mixed flow.A limited VOC concentration of (0.97 ± 0.29) ppmv (as methane) was emitted from the BAF system.Moreover,the emission rate of VOC was calculated using the proposed formula,based on an air-water mass equilibrium relationship,and compared to the simulated results obtained using the Water 9 model.Both estimation approaches of calculation and model simulation using Water 9 evaluating VOC emissions reveal that 0.1% IPA (0.0031-0.0037 kg/d) was aerated into a gaseous phase,and 30% to 40% (0.006-0.008 kg/d) of the toluene was aerated.