Membrane Microfiltration of Secondary Wastewater Effluent

This pilot study was designed to evaluate the efficacy of membrane microfiltration in treating secondary wastewater effluent. An 8 liter per minute pilot was operated at the City of Houston’s Southwest Wastewater Treatment Plant. Membrane permeates were of similar or better quality than filtrates from the plant’s conventional sand filters. Good removal of particulate contaminants, including coliform bacteria, was observed. In comparison with the plant’s filtrate, permeate quality was also much less variable. Operating the pilot in a crossflow configuration did not improve the permeate quality and did not retard the increase in transmembrane pressure in comparison with dead-end operation. Chemical cleaning of the membrane with caustic solution was required approximately once every 5 days. Preliminary results indicate that coagulation pretreatment in conjunction with membrane microfiltration can also be used to remove phosphorus from wastewater.