Long-term operation of a full scale intermittent MBR

The paper describes a real example of municipal wastewater treatment and reuse by a membrane bioreactor combined with the alternate cycles process. Focusing mainly on the membrane system, almost every detail of the first year operation regarding loading, membrane cleaning, long-term behaviour, fouling control and power consumptions has been analyzed in details. Long-term operation was carried out with permeate flux of 26 LMH, solid concentration in the membrane tank of 8÷11 g L and specific aeration for membrane scouring in the range 0,12÷0,19 Nm m h. The membranes were routinely cleaned in place once a week with hypochlorite solution (300 mgCl L), and this practice seemed to play a key role for a good control of the membrane fouling. The membrane permeability was in the range 230÷240 LMH bar.The system suffered from short-term loading peaks, on the contrary was able to face well the long-term seasonal fluctuations. The automatic control of the aeration and the operating strategy for the biological process contributed to power requirements in the range 0.44÷0.57 kWh m.