Study On The Characteristics Of SMP And EPS In The Mbr+ssbwr Combined System

Membrane Bioreactor(MBR) has quite a lot of advantages compared with the traditional wastewater treatments, so it has an extremely wide application prospect. However, Membrane fouling problem is an obstacle that affecting the popular application of MBR technology. It's well documented that SMP and EPS are the dominating pollutants in the operation of MBR.The Static Sequencing Batch Worm Reactor(SSBWR) is a special sludge reduction concept in which the aquatic oligochaete(worms) were immobilized in a carrier material and was surrounded by the activated sludge mixed liquor. The characteristics of the sludge mixed liquor will be changed after the predation of worms. Therefore, we combined the MBR wastewater treatment process with the SSBWR sludge reduction process through sludge backflow, and the contrast experiment was also carried out at the same time in order to compare the membrane fouling conditions. Meanwhile, the change conditions of SMP and EPS were recorded in the MBR+SSBWR combined system during the experiment, so as to study the influences of SSBWR coupling to the membrane fouling.After the 100 days, operation of MBR-A and MBR-B+SSBWR combined system, we found that the TMP of MBR-A rose fastly and the membrane module was contaminated seriously. In contrast, the TMP of MBR-B only had a small rise and the membrane module stayed clean. It indicated that the SSBWR coupling could alleviate membrane fouling.Observing the change conditions of SMP and EPS in the MBR-B+SSBWR combined system, we could find that the concentration of SMP in the upper water had a small rise, and that of EPS decreased greatly. Compared with MBR-A, the decrease of EPS concentration in MBR-B counteracted the increase of SMP, so we concluded that the SSBWR coupling could reduce the amount of membrane pollutants and alleviate the membrane fouling effectively.The amount of substances weighting 20,000 Da in SMP grew while substances weighting 5,000 Da droped after worms, predation, but no significant differences of the molecular weight distribution were observed between MBR-A and MBR-B. The amount of EPS in different molecular weight distributions decreased at varying levels. After the analysis of FT-IR, we found that the intensity of polysaccharose and proteins peaks in MBR-B were less than those in MBR-A, in addition, the amount of proteins in membrane pollutants decreased, owing to the sludge backflow.The predation had a great effect on the three-dimensional Characterizations of SMP and EPS in the combined system. The amount of tryptophane and tyrosine in SMP increased after the worms, preadition, but the former had a larger rise. Both the two types of proteins in EPS decreased at different levels, and I(B)/I(A) also had a certain drop. Compared with MBR-A, all the SMP peak intensities of MBR-B declined greatly in the sludge, upper water and membrane pollutants because of the sludge backflow. In addition, both the two types of proteins in EPS also decreased.The results of the experiment indicated that the characteristics of SMP and EPS were greatly changed due to the SSBWR coupling. As a result, the membrane fouling was alleviated effectively.