BIOFILTRATION OF ODORS, TOXICS AND VOLATILE ORGANIC-COMPOUNDS FROM PUBLICLY OWNED TREATMENT WORKS

Increasing federal and state regulation has made it necessary to apply air pollution control measures at publicly owned treatment works (POT Ws). Traditional control technologies may not be suitable for treating the low and variable contaminant concentrations often found in POTW o ff-gases. An alternative control technology, biofiltration, was studie d. An experiment using bench- and pilot-scale reactors established opt imal operating conditions for a full-scale conceptual design. The wast e airstream contained ppmv levels of hydrogen sulfide and ppbv levels of specific volatile organic compounds (VOCs). Granular activated carb on (GAG) and yard waste compost (YWC) were tested impossible biofilter media with and without pH control. The 16-month field study bench rea ctors achieved 99% removal of hydrogen sulfide, 53 to 98% removal of a romatic hydrocarbons, 37 to 95% removal of aldehydes and ketones, and 0 to 85% removal of chlorinated compounds. The GAC and YWC pilot react ors removed more than 80% and 65% of the total VOCs at 17 second and 7 0 second empty bed retention times, respectively. The YWC reactors per formed poorly at empty bed retention times of 30 and 45 seconds, remov ing less than 40% of total VOCs. Declining pH had little negative effe ct on contaminant removal suggesting costly control measures may not b e necessary. Biofiltration appears to be a feasible alternative to tra ditional control technologies in treating off-gases from POTWs.