The Apply Of The MBR-PAC Combination Technology In Landfill Leachate Treatment

Landfill leachate is one kind of high concentration organic wastewater. Its componentis very complex and it contains large amounts of deleterious and its treatment is difficulty.Membrane bioreactor (MBR), which combines membrane separation technology andbiological treatment technology, has been widely used in high strength waste watertreatment. The membrane fouling results in lots of problems such as decrease of thetreatment capacity and management difficulties and shortening useful life cycle of themembrane. In the paper, based on experiments of MBR dealing with landfill leachate, theeffects of power activated carbon (PAC) on MBR had been investigated in fields of effluentquality, sludge mixed liquor and membrane fouling.The activated sludge was domesticated by the stepped influent mode. At the end of thedomestication, CODCrof the landfill leachate was3700mg/L, BOD5was1700mg/L,nitrogen was450mg/L, TN was600mg/L, TP was40mg/L, color degree was2500. Theexperiment went into the stabilization stage after domestication stage. The activated sludgecould commendably adapt to the environment through a long period domestication. Thepurification efficiency was high, but the concentration of contaminants was still high. Theeffluent could not reach relevant national standard unless the effluent would be processed bythe subsequent process. The water-quality indicators of MBR effluent: the average of CODCr,BOD5, nitrogen, TN, TP, color degree were550mg/L,120mg/L,50mg/L,170mg/L,7.5mg/L,1200. The water-quality indicators of PAC-MBR effluent: the averages of CODCr, BOD5,nitrogen, TN, TP, color degree were500mg/L,100mg/L,45mg/L,160mg/L,7mg/L,1000.All these showed that adding PAC could help improve the MBR system effluent quality. ButPAC-MBR did not have obvious advantage with MBR in effluent quality.PAC had a profound effect on the sludge mixed liquor. The concentration of activatedsludge of PAC-MBR grew more rapid than that of MBR. On the28th day after the bothsystem startup, MLSS of MBR was13000mg/L. MLSS of PAC-MBR was16000mg/L. ThePAC could bring the EPS down. The EPS of MBR, maximum of which was75.38mg/g hada comparatively large fluctuation. And the average was59.78mg/g. However, EPS ofPAC-MBR was at the steady state. The maximum of it was57.18mg/g and the average was49.32mg/g. At the domestication stage, due to the higher content of SMP of MBR, the bothsystems had relatively large differences in SMP. At the stable stage, the SMP of MBR and PAC-MBR quite accorded with each other. Meanwhile, the PAC slowed the TMP growthand reduced the frequency of cleaning, mitigating membrane pollution and extendedmembrane lifetimeIn the situation that the membrane resistance of the both reactors was negligible, thetotal membrane resistance, cake layer resistance, pore adsorption resistance were determined.The results showed that: the dosing of PAC reduced the total membrane resistance and cakelayer resistance. Cake layer resistance was suggested to account for upwards of90percentof the total membrane resistance and was the primary reason for the falling of membraneflux. After physical and chemistry cleaning, the membrane flux renewal of MBR andPAC-MBR reached93.6%and95.7%respectively.