Use of coagulation as a pretreatment to improve membrane filtration performance for high strength wastewater from municipal solid waste anaerobic digestion.

摘要

Effluents from the anaerobic digestion of municipal solid wastes contain a complex mixture of organic and inorganic components with significantly high contents of nitrogen and phosphorous. An experimental study was carried out to examine the feasibility of membrane filtration, coupled with coagulation, as a pretreatment for this high strength wastewater. Standard jar tests were conducted with alum as a coagulant at different pH values and coagulant doses. Both raw and coagulation-pretreated wastewaters were then filtered using a crossflow microfiltration and a submerged ultrafiltration apparatus respectively. The results showed that coagulation improved membrane filtration by greatly reducing the rates of membrane fouling. The submerged membrane system is found to be superior to a crossflow membrane process in filtering the high strength wastewater. The particle size analysis of feeds with crossflow membrane filtration showed that particles enlarged by coagulation were disaggregated into fine colloidals and particles.