Application of nanofiltration to produce water for drinking and industrial needs of urban economy

Abstract

The issues associated with the operation of reverse osmosis plants at the water intake facilities (WIF) for the treatment of drinking water from groundwater sources are described. Ways of increasing reverse osmosis plants performance are considered. The technology of plants modernisation with the purpose of operational costs reduction and minimisation of concentrate discharges into sewerage system, consisting in replacement of reverse osmosis (RO) membranes with nanofiltration membranes, is provided. The use of nanofiltration membranes reduces the intensity of sedimentation and at the same time the concentrate flow without the sedimentation hazard. Also, nanofiltration membranes make it possible to reduce inhibitor dosage and operation costs respectively. Experimental studies on groundwater treatment and efficiency of the provided technology have been carried out. Rates of sedimentation in each device of the layout, as well as composition of water treated by each device depending on the volume reduction factor K (source water flow to the concentrate flow ratio) for the plant were determined. The feasibility comparative study considered the following parameters of the plant operation, without limitation: inhibitor dosage, membrane types, salt selectivity of membranes, source water volume reduction factor K.