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The permeate flux ( J ) and volume throughput ( Q ) dependence on rotation ( ω ), diameter ( D ), Reynolds Number (Re) and shear rate ( γ ) for a high shear rotary membrane system (HSR-MS) was investigated to determine if larger, slower rotated discs could lead to a smaller system weight and foot/cube-print which is needed for US Navy shipboard placement. The HSR-MS steady state flux ( J ss ) was highly dependent on ω and D ranging from 10 to 433 L/m 2 hr (LMH). For every 100 rpm increase in ω , J ss increased on average by 26 LMH. The outer membrane third provided ≥50% of the total flow, with the inner third providing about 15%. The J ss – γ relationship was extended to larger membranes (312 and 374 mm) and predicted that J ss increased by about 15% for each increase in size. Q ss was much more sensitive to increases in diameter and corresponding surface area – Q increased by 45% for D =267 mm→312 mm and 65% increased for D =312 mm→374 mm (≈1% increase in Q per mm increase in diameter). Collectively, the results show that larger discs, rotated at lower rotations, can produce similar or greater Q compared to smaller discs rotating faster.

Ferrate [Fe(VI)] and alkaline chlorination (AC) were investigated for the treatment of a maritime wastewater (CN, Cd, Cu, Ni, Pb, and Zn) in a seawater matrix. AC reduced CN concentrations but large dosages were required (0.018–0.056 mol CN consumed/mol HOCl). Metal removal occurred during the first stage (pH>10) but the amount of sludge produced was large due to Mg(OH)2(S) formation. Fe(VI) was effective in oxidizing CN and removing heavy metals to low levels without pH adjustment. Fe(VI) requirements [0.12 mol CN/mol Fe(VI)] were higher than those observed for other wastes but are considered more manageable compared with HOCl. Metal removal occurred by adsorption and coprecipitation with Fe(III) oxide, which results from the oxidation of Fe(VI). During staged treatment, metal removal and CN destruction increased [2× for Cd, 3× for Cu, 2.7× for Ni, 0.12 to 0.18 mol CN consumed/mol Fe(VI)]. Fe(III) oxide was relatively easy to separate using ultrafiltration tubular membranes and the amount of slu...

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...

Membrane filtration systems can handle varying wastewaters with simple and robust operation. However, current low permeate flux rates attributed to solids accumulation at the membrane surface limit more widespread technology use. This work seeks a better understanding of flux performance relative to solids concentration and transmembrane pressure coupled with potential flux enhancements. Enhancements revolve around disturbing solids accumulation at the membrane surface by physical cleaning or periodic flow reversal. Results indicate both rotary and tubular membranes produce consistent particle-free, low-turbidity permeate at varying levels of feed solids concentrations. Rotary membranes may produce only slightly greater permeate flux rates than tubular membranes at low feed solids concentration, but the difference increases drastically as feed solids concentration increases. Rotary membrane systems can concentrate wastewaters to greater than 40% solids, but the greater the feed solids, the less ad...

A laboratory investigation evaluated the effect of backpulsing (BP) and continuous surface cleaning (CSC) on high-shear rotary membrane system (HSR-MS) flux performance while treating three surrogate naval shipboard wastewaters (i.e., bilgewater, blackwater, and thermal destruction quench water) while also seeking to better understand the HSR-MS permeate flux-rotation-diameter (J-ω-D) relationship. J increased with ω, BP, and CSC. BP and CSC provided the most benefit at lower ω. Incorporating BP and CSC improved the inner area J. A volumetric flow rate analysis conveyed the importance of disc diameter—the outer membrane area produced the majority of the total flow. Collectively, the results indicate that BP and CSC enhanced the standard HSR-MS flux performance at low ω by replacing the loss of or augmenting the rotationally induced shear. This conclusion supports HSR-MS operation at lower ω, which allows the use of larger disc diameters, providing an increase in performance per disc and a reductio...

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.