| Landfill leachate, produced in the process of landfill disposal, is one kind of organic wastewater of high concentration and difficult treatment, which is very difficult to treat because of its variable quantity and quality and much toxic and harmful ingredient in it. Because it may hazard environment badly, it has been one of the critical problem of pollution control to treat landfill leachate in the nowadays and a long time later. The membrane bioreactor (MBR), a combined process of biological treatment with advanced membrane separation, is a new technology for wastewater treatment and reuse. MBR has the specified research foreground being used for treating the organic wastewater of high concentration and slow-biodegradable nature. Its removal effect of contamination, characteristics of sludge and soluble microbial products (SMP) and mechanism of membrane fouling were investigated to treat the leachate from JiangCungou municipal solid waste landfill site in Xi'an in this dissertation. Experimental results show:MBR has good effect in contamination removal, When volume loading rates of chemical oxygen demand (COD) and NH3-N were between 0.32~2.22kgCOD/m3.d and 0.14~0.50kgNH3-N/m3.d respectively, the MBR had removal efficiencies of COD and NH3-N ranging between 81.2-88.2% and over 99% respectively at hydraulic retention time (HRT) between 25~112h; When C/N and circumfluence rate of mixed liquor were 5.2 and 300% respectively, the system had removal rates of total nitrogen ranging between 75.2~82.2%.In experimental research of the characteristics of sludge and SMP, sludge concentration in stable stage increased with the enlargement of volumetric loading and was above 10.4g/L in process of the experiment; The slow-biodegradable substance such as SMP and extracellular polymers (ECP) were accumulated in the MBR with the extension of running time, which caused sludge settleability to become worse sludge activity to decrease the size of sludge particle to reduce and microbial variation to be bad, as well as contributing to the poor membrane permeability of the mixed liquor.In experimental research of the decline regularity of membrane flux and mechanism of membranefouling, HRT had the greater effect to the decline rate of membrane flux in actual running process, the decline rate of membrane flux was the largest when HRT act as 25~40h; The mixed liquor in the MBR was divided into centrifugal supematant cell liquid and soluble part, the tiny colloid in centrifugal supernatant was ascertained the main reason that created membrane fouling resistance by the filtration tests with a mini-membrane module; The conclusion was obtained that the membrane fouling resistance was mainly completed of polarization layer resistance and external fouling resistance with the distribution tests of resistance, and the sums of two took over 95% of total fouling resistance-, With the extension of experiment running time, a great deal of tiny colloid and soluble substances were accumulated among the MBR, that thereby leaded the total fouling resistance to increacing and the membrane permeability of the mixed liquor to becoming bad.
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