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Ultrafiltration and nanofiltration membrane coupling technology was used to investigate the effects of membrane coupling technology on the concentration effect of biogas slurry and wastewater purification capacity under pH 5-9. The results showed that under the condition of VRF as 5 and 10 times, the concentration and nutrient removal effects under pH of 5-7 were better than those under alkaline condition. With pH of 7 and VRF of 10 times,the concentrations of TN,TP and TK in concentrated liquid were 1 760 mg/L, 435 mg/L and 2 100 mg/L, respectively,and the concentration times were 8.8, 7.63 and 6.34 times, which showed the best salt removal effect and concentration effect. The removal rates of NH4+-N, TN, TP and COD in the filtrate reached 89.71%, 81%, 99.82% and 95.77%, respectively. The effluent quality reached the secondary standards of Pollutant Discharge Standards for Urban Sewage Treatment Plants(GB18918—2002). According to the analysis of scanning electron microscope(SEM) and X-ray energy analyzer(EDX), the membrane pollution included organic-inorganic co-pollution. The removal of pollutants on the membrane surface could be partially achieved by acid and alkali washing.