Quds University Small Scale Waste Water Treatment Plants in West ...

emove total nutrient must have an aerobic zone for nitrification and an anoxic zone for
denitrification, and systems designed to remove total phophorus must have an
anaerobic zone free of dissolved oxygen and nitrate. Often, sand or other media
filtration is used as a polishing step to remove particulate matter when low total nitrogen
or total phophorus effluent concentrations are required. Sand filtration can also be
combined with attached growth denitrification filters to further reduce soluble nitrates
and effluent total nitrogen levels (Crittenden, 2005).
3- Ions removal by reverse osmosis
Reverse osmosis systems invert the principle of osmosis. High pressure is applied to the
feed side of the reverse osmosis membrane (Fig.1). The pressure forces water through the
semi-permeable RO membrane, this water becomes the permeate flow and is returned for
process use. Particles and dissolved salts are unable to pass through the membrane and
instead flow past into what becomes the concentrate flow to drain. (Nuhoglu, 2004)
Figure.1 Reverse osmosis membrane (Elias, 1979)
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