CONTROL OF VOLATILE ORGANIC-COMPOUND EMISSIONS USING A COMPOST BIOFILTER

Laboratory and field experiments were conducted using a pilot-scale co mpost biofilter (approximately 5.7 m(3)/min) to determine the potentia l of using biofiltration for removing volatile organic compounds (VOCs ) from gas streams at publicly owned treatment works. Six compounds co mmonly found in wastewaters (benzene, trichloromethane, dichloromethan e, 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 p ressure drops of 0.1 to 0.7 kPa. Removals of aromatic VOCs averaged gr eater than 80% during an 8.5-month field study and were typically grea ter than 90 to 95%, despite highly variable inlet concentrations. Remo vals of chlorinated VOCs were inconsistent and ranged from none to mor e than 60%. Low removals of the chlorinated compounds were believed to be due, in part, to the low inlet airstream concentrations, which wer e generally less than 70 ppb. Removal of H2S and odors was excellent t hroughout the studies. consistent with the findings of other investiga tors.