Study On A Submerged Membrane Bioreactor Using Pectinate Hollow Fiber Membrane With Free End And Its Applications

Membrane Bioreactor( MBR) is a kind of technics in Wastewater treatment, which combines membrane separation techonolgy with microbiology and biochemical. It uses the great effective separation of membrane techonolgy to replace the secondary sedimentation tank in activated sludge process, and increases the MLSS concentration of the bioreactor evidently, so that SRT is prolonged, the residual sludge is reduced, the water quality is increased significantly, specially for the removal of the suspend solid, pathogenetic bacteria and virus.But the main problem of MBR is the membrane fouling, which limites its applications. Aimed at the problem, in order to control and reduce the membrane fouling, this paper investigated a submerged hollow fiber membrane bioreactor and its applications systematically. The membrane module of this SMBR is a kind of polypropylene(PP) pectinate hollow fiber membrane with free end. Compared to immersed hollow fiber membrane,it had a free end and lower tightness with more gap between the membrane fiber, which could enhanced the degree of response to air scouring. So it had more fiber amplitude and displacement, which could reduce the possibility of contamination attachment and the thickness of cake layer easier. Then the improvement in membrane flux and fouling control could be seen.This paper investigated the result and technics of Wastewater treatment of this SMBR using pectinate hollow fiber membrane with free end. When the influent COD_cr is 240-500 mg/L, the effluent COD_cr is lower than 20 mg/L after 1 d of running, the percent of removal is higher than 95% stably. It compared the membrane fouling of two membrane modules with different tightness degree, and it was found that the module B did better in membrane fouling control in short term of running. The long term of running with membrane module B was studied, when the suction pressure was between 0.015 MPa⁰.037 MPa, MLSS was between 7500-10500 mg/L, aeration rate was 200 L/h and suction time/suspended time is 9 min/l min, it can kept a membrane flux of 6.4-8.0 L/(m²h) with 46 days of running continuously. The effects of initial suction pressure, the transmembrane pressure, aeration rate, suctiontime/suspension time, MLSS concentration on membrane flux of SMBR with membrane module B were also studied. And the cleaning method after membrane fouling was discussed, which contained the enhancement of aeration rate, water cleaning, chemical cleaning, ethanol soaking, and the combination of these methods. At last, the optimal method was made out.