Aquatic environment

Performances of biological aerated filter employing hollow fiber membranesegments of surface-improved poly (sulfone) as biofilm carriers


SHEN Ying-jie , WU Guang-xia , FAN Yao-bo , ZHONG Hui , WU Lin-lin , ZHANG Shao-lai , ZHAO Xian-hong , ZHANG Wei-jun

DOI:

Received September 08, 2006,Revised January 18, 2007, Accepted , Available online

Volume 19,2007,Pages 811-817

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Using the surface of poly (sulfone) hollow fiber membrane segments as grafted layer, the hydrophilic acrylamide chain was grafted on by UV-photoinduced grafting polymerization. The gained improvement of surface wettability for the modified membrane was tested by measuring the contact-angle as well as FTIR spectra. Then correlation between the hydrophilic ability of support material and the biofilm adherence ability was demonstrated by comparing the pollutant removal rates from urban wastewater via two identical lab-scale up-flow biological aerated filters, one employed the surface wettability modified poly (sulfone) hollow fiber membrane segment as biofilm carrier and the other employed unmodified membrane segment as biofilm carrier. The experimental results showed that under the conditions of influent flux 5 L/h, hydraulic retention time 9 h and gas to liquid ratio (G/L) 10:1, the removal rates of chemical oxygen demand (COD) and ammonium nitrogen (NH4 +-N) for the modified packing filter and the unmodified packing filter was averaged at 83.64% and 96.25%, respectively, with the former filter being 5%–20% more than the latter. The e uent concentration of COD, NH4 +-N and turbidity for the modified packing filter was 25.25 mg/L, 2 mg/L and 8 NTU, respectively. Moreover, the ammonium nitrogen removal performance of the filter packing the modified PSF was compared with the other bioreactor packing of an e cient floating medium. The biomass test indicated that the modified membrane matrixes provided better specific adhesion (3310–5653 mg TSS/L support), which gave a mean of 1000 mg TSS/L more than the unmodified membrane did. In addition, the phenomenon of simultaneous denitrification on the inner surface of the support and nitrification on the outer surface was found in this work.

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