Biological Treatment of Photoprocessing Wastewaters

The activated sludge and anaerobic digestion processes were used for the biological treatment of photoprocessing wastewaters from two commonly used photoprocesses, namely KODAK Flexicolor Process C-41 and KODAK Ektacolor Process RA-4. Photoprocessing wastewaters were simulated in the laboratory and fed to fill-and-draw activated sludge reactors at loading levels less than or equal to 100% v/v along with a synthetic base feed. Up to 68% photoprocessing wastewater-derived COD removal was achieved by the fill-and-draw activated sludge reactors. Ammonia removal was achieved by all reactors, although some degree of nitrification inhibition -- manifested by the accumulation of nitrite -- was observed in some of the photoprocessing wastewater treating reactors. The performance of digesters fed with activated sludge generated in the presence of photoprocessing wastewaters (up to 50% v/v levels) matched or even surpassed that of the control digester (fed activated sludge without any photoprocessing wastewaters present). Digester failure -- accompanied by a cessation of gas production, increase in volatile fatty acids and lowering of the pH - was observed for only the digestion of activated sludge produced from the aerobic treatment of 100% photoprocessing wastewaters, primarily due to inhibition of methanogenesis. However, with prolonged incubation, digester recovery was observed.