Effect of membrane coupling technology on concentration and water purification of biogas slurry

Abstract

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.

Keywords

• membrane coupling technique
• concentration multiple
• water purification
• heavy metal removal
• membrane pollution