Abstract: The nutrients in biogas slurry was concentrated by membrane concentration technology and the concentrated liquid was used as organic fertilizer, which was a way of biogas slurry resource utilization. In view of the high content of suspended solids in the biogas slurry, which caused the membrane pores to block during the membrane concentration treatment, the “pretreatment + microfiltration membrane” process was used to treat the kitchen anaerobic biogas slurry. Experiment was carried out to study the removal effect of pretreatment process on suspended solids in biogas slurry, as well as the operating process parameters of microfiltration ceramic membrane, the contaminant removal effect, and the membrane cleaning effect. The results showed that under the optimal process parameters of natural settling for 24 h, aeration volume of 5 L/min, continuous aeration for 18 h, microfiltration ceramic membrane pore size of 400 nm, and operating pressure of 0.3 MPa, the membrane flux could reach 34 L/(m2?h) and the optimal concentration ratio of biogas slurry was 5~6 times. In addition, a better cleaning effect and 96% of the membrane permeate flux could be achieved by the combined cleaning way of sodium hypochlorite, sodium hydroxide and citric acid, or sodium hypochlorite, sodium hydroxide and nitric acid.

Key words: biogas slurry, suspended solids, pretreatment, microfiltration