THE EFFECTIVENESS OF AERATION RECIRCULATION IN CONTROLLING VOC EMISSIONS FROM PUBLICLY OWNED TREATMENT WORKS

The effects of aeration recirculation on oxygen transfer and the fate of five volatile organic compounds (VOCs) commonly found in publicly o wned treatment works (POTWs) influent are studied using various modeli ng approaches. The five compounds are benzene, chloroform, methylene c hloride, toluene, and trichloroethylene. The models predict that the o verall oxygen transfer efficiency can be increased by 96.7% at 50% aer ation recirculation with only a 9.6% drop in oxygen transfer rate. The emission reductions and biodegradation improvements are compound spec ific; for the compounds investigated here, about 40% emission reductio ns and 16% biodegradation increases can be achieved at 50% aeration re circulation. The temperature effect on the VOC fate mechanisms is also investigated. Overall, the model predictions reveal that up to 50% ae ration recirculation is effective in controlling VOC emissions.