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secondary clarifiers for both the suspended growth process and the attached growth system. <br /> Each DAF unit consists of one floatation tank, one air dissolving pump, and one static mixer. <br /> The dimensions of each DAF are 42 inches long, 42 inches wide and 7 feet tall. The maximum <br /> design flow capacity of each DAF is 205 gpm. The wasted sludge is discharged to the aerobic <br /> sludge digester for further stabilization before final disposal. <br /> 3.4 OF MEMBRANES <br /> The effluent of the DAF enters into the OF membranes for further polishing to ensure an <br /> effluent turbidity of 2 NTU. The advantages of using the OF membrane after the DAF, instead of <br /> the membrane biological reactor (MBR), is to reduce daily operation and maintenance <br /> headaches caused by membrane fouling and cleanings. <br /> The OF membrane is a PVC cartridge with a central permeate tube, containing membrane <br /> capillaries which are made from a blend of polyethersulphone and polyvinylpyrrolidone. The <br /> membrane capillaries fixated in the PVC-housing with only 2-3 cm epoxy resin, are fed to the <br /> inside with feed water. Particles larger than the membrane pore size will be rejected from the <br /> membrane surface, keeping it within ehWillaprlliquid <br /> the membranegonly(permlons and eate) and will particles <br /> be <br /> smaller than the membrane porepassthrough <br /> collected in the central permeate tube. <br /> Feed Feed <br /> Permeate <br /> Permeate — <br /> _ Feed <br /> Feed . �— <br /> ermeate ���.. Permeate <br /> Feed • . Retentate •. • • • <br /> • • • • <br /> Permeate <br /> Permeate <br /> Filtration mode Backwash mode <br /> Schematic view on waterflow in XIGA"" —Concept <br /> Filtration is enabled by a pressure difference between the feed side (in the capillaries) and the <br /> permeate side (out of the capillaries), also called "trans membrane pressure" or TMP. The TMP <br /> in a module is very low, most of the time < 0.5 bar. It is important to keep this TMP level low <br /> although the level increases during operation. The maximum TMP during the filtration mode is 1 <br /> bar. A TMP above 1 bar will cause an irreversible fouling on the membrane surface. A periodical <br /> backwash is required. <br /> During the backwash, the water flow will be reversed. Clean permeate water will be forced from <br /> the outside of the capillaries to the inside, and will transport the foulant out of the capillaries. <br /> Wine Cup Motor Coach Resort WWTP Page 7 of 10 8/22/2007 <br /> Preliminary Design Report <br />