Treatment of Oil-containing Sewage Wastewater Using Immobilized Photosynthetic Bacteria

Abstract

Removal of cooking oil from the domestic wastewater was carried out by immobilized photosynthetic bacteria, Rhodobacter shaeroide S (S) and R. shaeroides NR-3 (NR-3). The microorganisms were immobilized in sodium alginate (2%) or agar (2%). We treated 50 g of cooking oil suspended in artificial sewage wastewater under anaerobic dark conditions in a 15 l acrylic vessel. Results show that after 6 days of batch treatment, 74.2, 58.2 and 15.8% of oil was removed with the alginate-immobilized S, NR-3, and control, respectively. Relatively larger accumulations of volatile fatty acids such as propionic and acetic acids were observed in the control experiment compared with that in the immobilized cell (alginate and agar) experiment. In addition, continuous treatment of oil-containing wastewater was carried out with agar-immobilized S at a fixed dilution rate of 0.4/day. These results indicate that 96% of the oil was removed from the wastewater, and the maximum removal rate of oil reached approximately 3.83 kg oil/m3/d.