CONTROL OF VOLATILE ORGANIC-COMPOUND EMISSIONS USING A COMPOST BIOFILTER

Laboratory and field experiments were conducted using a pilot-scale compost biofilter (approximately 5.7 m(3)/min) to determine the potential of using biofiltration for removing volatile organic compounds (VOCs) from gas streams at publicly owned treatment works. Six compounds commonly found in wastewaters (benzene, trichloromethane, dichloromethane, toluene, tetrachloroethene, and trichloroethene) were selected for quantitative evaluation of removal efficiency. Gas fluxes through the biofilters ranged from 0.3 to 1.8 m(3)/m(2) . min with corresponding pressure drops of 0.1 to 0.7 kPa. Removals of aromatic VOCs averaged greater than 80% during an 8.5-month field study and were typically greater than 90 to 95%, despite highly variable inlet concentrations. Removals of chlorinated VOCs were inconsistent and ranged from none to more than 60%. Low removals of the chlorinated compounds were believed to be due, in part, to the low inlet airstream concentrations, which were generally less than 70 ppb. Removal of H2S and odors was excellent throughout the studies. consistent with the findings of other investigators.