Abstract: Urban recycled water has been used as water supplement in coal-fired power plants for water conservation. The membrane bio-reactor (MBR) might be a prime choice to avoid the potential pollution. The predominant fouling substances in submerged MBR system and the effect of the operation cycle on membrane fouling degree are studied through the analysis on the fouling constituent and SEMs of the membrane module taken out from a long term operating MBR system. The results show that the pollutants in the submerged MBR membrane system are mainly organics. With the performance life prolonging, the pollutants are gradually developed into irreversible fouling layer, which leads to membrane pore getting narrower and cleaning efficiency getting lower. Therefore, this paper suggests that the cleaning cycle should be shortened and the cleaning process should be optimized. In addition, the cleaning should be conducted when the pressure difference between the membranes increases substantially in its early stage so as to achieve good cleaning effect.

Key words: urban recycled water, membrane bio-reactor(MBR), membrane fouling, scanning electron microscope(SEM), chemical cleaning, membrane flux