The Effect of Concentration Staging on Performance of Produced Water treatment using Forward Osmosis

During oil and gas production, a large amount of produced water (PW) is generated, which would be harmful to the environment if not treated properly. Treatment of such wastewater requires multi-processing units and typically includes fouling prone pressure driven membranes. Forward osmosis (FO) seems promising due to its high salt rejection, high total dissolved solid removal, more reversible fouling type, does not require external pressure to operate and potentially can be used as a standalone unit with minimum pretreatment. However, FO still suffers from low permeate flux, high reverse solute flux (RSF) and membrane fouling, although not as severe as in pressure driven membrane. Since FO depends largely on osmotic pressure difference, the effect of concentration staging was investigated. It was found that multi-stage concentration was able to achieve up to 80% water recovery due to sufficient osmotic pressure.