The characteristics of membrane fouling in the process of A2/(O-MBR) treating municipal wastewater.

摘要

In order to understand and control membrane fouling in the membrane bioreactor (MBR), the characteristics of membrane fouling in the process of A2/(O-MBR) treating municipal wastewater was investigated. A pilot-scale A2/(O-MBR) reactor was operated at a flux of 14.5 Lm-2h-1 over a period of 100 days. The transmembrane pressure (TMP) rise to 40 kPa and the membrane foulants attaching on the membrane surface formed cake layer. The distribution of the cake layer is uneven. It is usually found cake layer near the potted end of membrane fibers. Properties of cake layer were examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectroscopy, etc. SEM images indicated cake layer is so thick and compact that totally covered the pores of membrane surface. The properties of membrane surface, such as pore and porosity, have been changed by the cake layer. Due to the pore area for transmitting water molecule reduced, the filtration resistance increased. EDX analysis suggests C and O are the main elements in cake layer. In addition, inorganic elements, such as Fe, Na, Al, Si, P and Ca, are also found in the cake layer. The components of the membrane foulants are complex including organic and inorganic matter. According to the analysis of FTIR spectra, polysaccharide and protein are major forms of the organic matter in the cake layer. Therefore, removing cake layer on the membrane surface, especially removal of polysaccharide and protein in the cake layer, is good for controlling membrane fouling in the process of A2/(O-MBR).