Using a high shear rotary membrane system to treat shipboard wastewaters: Experimental disc diameter, rotation and flux relationships

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 (Jss) was highly dependent on ω and D ranging from 10 to 433 L/m2 hr (LMH). For every 100 rpm increase in ω, Jss increased on average by 26 LMH. The outer membrane third provided ≥50% of the total flow, with the inner third providing about 15%. The Jss–γ relationship was extended to larger membranes (312 and 374 mm) and predicted that Jss increased by about 15% for each increase in size. Qss 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.