ANAEROBIC BIODEGRADATION POTENTIAL OF PHOTOPROCESSING WASTEWATERS

The anaerobic biodegradation potential of photoprocessing effluents an d their effect on the anaerobic digestion of biological sludge generat ed from the aerobic treatment of photoprocessing wastewaters were inve stigated. Simulated C-41 photoprocessing wastewaters were subjected to an anaerobic toxicity test using the serum bottle technique. Unacclim ated, anaerobic sludge inocula were used and the test solutions consis ted of photoprocessing wastewaters and readily degradable organic subs trates. Concentrations of photoeffluents considerably higher than thos e expected to reach municipal wastewater treatment plants initially de pressed the production of methane, mainly because of competition betwe en sulfate reducing and methanogenic bacteria. After prolonged incubat ion, methanogenesis recovered. Biological sludge generated by laborato ry-scale activated sludge reactors with and without photoeffluents was fed to anaerobic digesters without adverse effects. The digesters fed sludge from the aerobic treatment of photoeffluents achieved about 14 % higher digestibility than did the digester fed with sludge never exp osed to the photoeffluents. For photoeffluent levels expected to reach municipal wastewater treatment plants, no adverse effects on anaerobi c digestion are expected.