a b s t r a c tOily wastewater treatment through membrane separation is remarkably effective, but the high operation cost and poor resource recovery potential of this method necessitate the application of an integrated physical/chemical-biological oily wastewater treatment. In this study, aerobic granular sludge was applied for oily wastewater treatment from the ultrafiltration (UF) effluent of a twostage UF-reverse osmosis process. The removal efficiencies of the sludge for oil and chemical oxygen demand reached 94.1% and 85.6%, respectively. The protein concentration of extracellular polymeric substances (EPS) increased to 34.6 mg/g MLSS, and the relatively high protein/polysaccharide ratio was found to be closely related to the formation of aerobic granular sludge. In addition, protein in loosely bound-EPS was converted to tightly bound-EPS (TB-EPS), which indicated that the protein in TB-EPS could be the major factor affecting the granulation process. Separate sludge incineration could be achieved due to the lower heating value of granules was as high as 8.5 MJ/kg. Furthermore, the proposed process could enhance the treatment efficiency of the sludge incinerator and increase the amount of heat energy that could be recycled.

The authors investigated the possibility to reduce aeration time in one of the cycles of sequencing batch activated sludge reactors. It is known that there are microorganisms in activated sludge which can store organic materials temporarily in such forms as polyhydroxyalkanoate (PHA). It was expected that removal of organic materials in the cycle with reduced aeration was supplemented by the microbial activities to store organic materials temporarily. The authors operated sequencing batch reactors with 6 cycles/day with synthetic wastewater, and reduced aeration in one of the cycles. Short-term experiments were conducted to see the effects of aeration reduction for one time, and long-term experiments were conducted to see the effect of long term implementation of operation with aeration reduction. In both experiments, removal of DOC was greater than 92%, and no significant adverse effect was observed. The more aeration was reduced, the more PHA was carried over to the following cycles. It was estimated that about 17% to 50 % of PHA was carried over to the cycles following the cycles in which aeration was reduced. The operation with one-cycle reduced aeration was successfully implemented in the experiments. There is a big room to explore wastewater treatment technologies in the direction to flexibly control energy consumption.