Performance of Soluble microbial products in hybrid membrane bioreactor with suspended carriers

Soluble microbial products (SMP) would accumulate in membrane bioreactor (MBR) and result in membrane fouling due to the membrane rejection. A new hybrid membrane bioreactor with porous suspended carriers (HMBR) explored by author was effective in controlling membrane fouling. The behaviors of SMP in HMBR were investigated in such aspects as concentration variation with operation time, molecular weight distributions (MWDs), hydrophobicity, specific cake resistance of supernatant. UV254 absorbance indicated that SMP in HMBR increased with operation time. The MWDs experiments revealed that the distribution of SMP showed a double peaks curve, the two peaks appeared in high-molecular weigh (>100 kDa) and low- molecular weigh (< 2kDa), and the latter was far higher than the former. However, the former had an increasing tendency with operation time. The hydrophobicity of SMP in HMBR and MBR gradually increased with time, and the former had a higher increasing rate. The dead-end filtration tests were used to indicate the SMP effect on membrane fouling and the specific cake resistance of supernatant in HMBR and MBR were determined. The results showed that the specific cake resistance of supernatant had a large increasing tendency.