Investigation of the Influence of Organics Contained in Natural Water on the Performance of Reverse Osmosis Membranes

Abstract

Aspects of the interaction of organic pollutants of natural water with nanofiltration and reverse osmosis membranes have been considered on the basis of experimental results and summarized literature data. Experimental studies have been carried out to determine the rates of membrane fouling by various organic substances including humic acids (imparting the color) and low-molecular-weight organics (responsible for the oxygen demand) during the treatment of river water and pretreated water. The effect of membrane material on the rate of organic deposition on them has been studied. Relationships have been obtained for calculating the rates of buildup of organics on membranes depending on their concentration in the feed water, the nature and molecular weight of foulants, the membrane material, the flow rates in device channels, and the recovery. Experimental determination of the rates of adsorption of organic substances of various natures has made it possible to measure the sorption capacity of the membrane surface. It is likely that in the case of simultaneous fouling of the membrane with poorly soluble salts (calcium carbonate), colloidal and organic substances, iron compounds, etc., the effect of the set of foulants and scalants on the membranes surface may differ significantly from the results obtained in this study. Predicting the amount of organic foulants will help to correctly select the composition of solutions for chemical cleaning of membranes and eliminate the influence of organics on scale dissolution.