Microfiltration of municipal wastewater for disinfection and advanced phosphorus removal: Results from trials with different small-scale pilot plants

The Berliner Wasserbetriebe have been conducting a research project on microfiltration of municipal wastewater for disinfection and advanced phosphorus removal since 1992. The goal of this project is to examine whether microfiltration (MF) is a technically feasible and economically competitive process for disinfection and advanced phosphorus removal for secondary effluent. Different small-scale MF systems under investigation performed well. Microfiltration is suitable for reaching low target concentrations of total coliforms (< 100/100 mL) and total phosphorus (< 50 mug/L). Significant virus removal was also noted, which was unexpected when the trials commenced. This report summarizes a survey of dead-end MF systems using different membranes and modules. The competitive trial period, with the most suitable polymeric dead-end MF unit used in parallel with a ceramic dead-end MF unit showed no advantage over an inorganic membrane. Based on the MF data for operational costs presented and an estimation for capital costs, total costs were estimated to range between U.S. $0.27-0.54/m(3) filtrate. A final evaluation as to which MF system is the most suitable for municipal wastewater treatment will be provided following the conclusion of current large-scale trials.