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A pilot scale investigation was undertaken at the Allegheny County Sanitary Authority (ALCOSAN) for approximately 12 months to evaluate the feasibility of using cross-flow microfiltration for the treatment of primary sewage effluent simulating combined and sanitary sewer overflows. Ceramic membranes of various pores sizes (0.05–1.4 μm) were tested to understand the impact of cross-flow velocity, transmembrane pressure, and feed suspended solids on permeate water quality and permeate flux rate. A 0.2 μm membrane operated with a 1.8 m∕s cross-flow velocity, a transmembrane pressure below 2.1 bar and a backpulse frequency of 60 s showed the best performance among the conditions evaluated in this study. The 0.2 μm membrane consistently met water quality objectives for fecal coliforms, E Coli, enterococci, BOD5 , and suspended solids independent of the feed concentration, suggesting that direct discharge to surface water may be feasible. Feed suspended solids concentration and temperature influenced membrane p...

Primary-effluent wastewater from the Allegheny County Sanitary Authority (Pennsylvania) was used as a surrogate for combined- sewer-overflow waters contained in the sewershed. Pathogens contained in combined-primary-effluent wastewaters or combined-sewer overflows (CSOs) may pose a human-health threat to those coming in contact with such receiving waters. Polymeric ultra- and nano-membranes can be used to capture these microorganisms from CSOs. This research investigates the ability of polymeric hydrophobic and hydrophilic membranes, ranging in pore size from 0.2 to 0.8 lm, to remove pathogen-indicator organisms (Escherichia coli, enterococcus, and fecal coliforms). Membranes, with pore size 0.45 lm and smaller, were able to reduce the bacteria levels to nondetectable levels, with the sole exception of one membrane with pore size 0.3 lm. Water Environ. Res., 78, 557 (2006).

A pilot scale investigation was undertaken at the Allegheny County Sanitary Authority (ALCOSAN) for approximately 14 months to evaluate the feasibili ty of cross-flow ceramic membrane microfiltration for the treatment of primary sewage effluent simulating combined and sanitary sewer overflows. Ceramic membranes of various pores sizes (0.05 - 1.4 microns) were tested to understand the impact of cross flow velocity, transmembrane pressures, and inlet suspended solids on permeate water quality and flux rate. A 0.2 micron membrane operated with a 1.8 m/s cross flow velocity, a transmembrane pressure less than 2.1 bar and a backpulse frequency of 60 seconds was selected as the preferred operating conditions. Permeate from this membrane had virtually undetectable levels of fecal coliforms, e-Coli, enterococci, and levels of BOD5 and SS commensurate with secondary treatment expectations. Elevated membrane-feed suspended solids concentration reduces steady state flux rates; a quantification of t he influence of feed suspended solids is for the design of multi-stage membrane systems.