AEROBIC BIODEGRADATION POTENTIAL OF PHOTOPROCESSING WASTEWATERS

Currently, over 99% of all photoprocessing laboratories in the U.S. di scharge directly to publicly owned treatment works (POTWs) after using various recovery methods. The purpose of this research was to investi gate any potential adverse effects of photoprocessing effluents on the activated sludge process. Effluents from two commonly used photoproce sses were tested. These effluents were simulated in the laboratory and fed to fill-and-draw activated sludge reactors at loading levels less than or equal to 20% by volume along with a synthetic base feed. Conv entional wastewater treatment parameters along with major photoeffluen t constituents, such as ethylene diamine tetraacetate (EDTA), sulfur, and nitrogen species, were monitored. Results indicate that EDTA was r ecalcitrant and accounted for a significant fraction of the effluent C OD. A significant fraction of the reduced sulfur species were oxidized to sulfate resulting in alkalinity consumption and a pH reduction. Al l activated sludge reactors showed a decrease in influent ammonia conc entration and production of nitrate or nitrite. Up to 61% photoeffluen t COD removal was achieved by the fill-and-draw activated sludge react ors. Such results demonstrate the potential of aerobic biological proc esses in the treatment of photoprocessing wastewaters and warrant furt her study.