Characteristics of MBR Oily Sludge and Its Influence on Membrane Fouling under Two Aeration Modes

A membrane bioreactor (MBR) with ordinary aeration (reactor R1) and a MBR with microporous aeration (reactor R2) are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling. The results indicate that the order of membrane fouling rate from high to low is: reactor R1 dissolved oxygen (DO) (1 mg/L) > reactor R2 DO (1 mg/L) > reactor R1 DO (4 mg/L) > reactor R2 DO (4 mg/L). Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling. The soluble microbial products (SMP) are examined by three-dimensional excitation-emission matrix (3DEEM) fluorescence spectra. 3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein, fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L, respectively. The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling, and membrane fouling accelerates as the ratio increases.