Study On Ultrasonic-resin Extraction Method Extracting The Extracellular Polymer Substances From The Activated Sludge

Extracellular polymer substances (EPS) were the most important components of activated sludge, which have important effect to flocculation ability, settlement ability and dewatering ability of activated sludge. However, there were no extracting method which was commonly applied, because these methods have some shortcomings, such as low efficiency and serious chemical pollution, etc. In the dissertation, the ultrasound extraction method was systemically studied, using G6PD activation estimating the lysis of bacteria because of extraction process. Applying homemade cation exchange resin(CER), the extraction strategy of the CER was studied. Combining the ultrasound and CER extraction methods, the ultrasound-CER extraction method was brought forward, which have many merits, such as low chemical pollution and bacteria lysis, high extraction efficiency. The main conclusions of the study are as follows:①In the course of ultrasonic extraction, the ice bath was suggested , and added blend was not needed. The materials of extraction containers affect extracting effect. Borate glass containers were suggested. The best frequency for extracting EPS was 21 kHz, and the best scope of the power was from 32W to 40W, the sonic time was suggested to not pass 3 minute. The solid retention time affected the EPS, the EPS of the low SRT sludge was easy to extract, but the bacteria was easy to lysis by the effect of ultrasonic.②While using homemade cation resin to extract EPS, .001×7 cation exchange resin was better than D001 cation exchange resin. The pH of the liquid affected extracted amount of the EPS through the extraction. While value of pH was from 5.8 to 7.8, the extracted amount of the EPS was stable. Furthermore, the similar amount of EPS could be got, using pH balance distilled water, compared to pH 7.0 phosphate buffer. The regular centrifuge followed by the draw filtrate can get more humic substances than ultracentrifuge to separate EPS from sludge, which was more fitted to separate EPS. The proper strategy of the extraction was 80g/g VSS of the addition amount of resin ,500rmp of the speed of blend and 1h～3h of blending time.③Combining ultrasonic and cation resin could get high extracted amount of EPS, in premise of avoiding largely lysis. In three different combining ways, ultrasonic -cation resin was the best, which also was more efficient and secure than heating method and EDTA method. For different sludge, ultrasonic-cation resin was also more efficient, and the amount of EPS extracted was about 8% to 13% of the volatile matter of sludge.