Evaluation of a bench-scale membrane fouling protocol to determine fouling propensities of membranes during full-scale water reuse applications

Abstract

There is increasing interest in recycling wastewater effluents for augmentation of existing water supplies. The treatment of wastewater effluents by an integrated membrane system, such as microfiltration pre-treatment followed by reverse osmosis, is the industry standard for groundwater recharge or reservoir augmentation projects. Membrane fouling, especially effluent organic matter fouling, is a major challenge for water reuse applications employing high-pressure membranes. While fouling control through pre-treatment is an important aspect in membrane system design and operation, selecting low fouling membranes is an equally important aspect. Although recent research has begun to elucidate fouling mechanisms, little work has been performed to develop methods to pre-determine the effluent organic matter fouling propensities of high-pressure membranes so that low-fouling membranes can be pre-selected for reuse applications. The purpose of this study was to utilize a bench-scale testing protocol to test the relative effluent organic matter fouling propensities of commercially available NF and RO membranes when treating wastewater effluents. Bench-scale fouling test results were then compared to operational data generated during pilot- and full-scale membrane testing. Pilot- and full-scale testing using recycled water demonstrated that membranes foul at significantly different rates and that the extent of fouling could be estimated utilizing the proposed bench-scale testing protocol.