Assessment on extraction methods of EPS from hybrid membrane bioreactor

Four methods, including high-speed centrifugation, ultrasonication, cation exchange resin, heating, were employed for extracting EPS of activated sludge from HMBR. Chemical analysis method was combined with excitation-emission matrix (EEM) and gel-permeating chromatography (GPC) to estimate the four methods. The experimental result revealed that heating method employing 60°C for 30 minutes showed the best extracting effect and caused little damage to the cell. The EEM spectra showed that four methods all had good extract effect on fulvic-acid-like substances. As to humic-like and protein-like substances, heating was prior to other three methods. Gel-permeating chromatography showed that the molecule weight distribution of EPS extracted by four methods got little difference. The molecule weight (MW) of EPS distributed from 100 to 1000000, mainly concentrating between 100 and 10000.