Experimental study of RO membrane organic fouling for wastewater reclamation

Abstract

Membrane fouling remains as a major technical hurdle that needs to be addressed to enhance the cost-effectiveness of reverse osmosis (RO) systems for wastewater reclamation. The residual organic matter in treated secondary effluent, known as effluent organic matter (EfOM), has been implicated as an important RO foulant. However, our current understanding of this category of foulant is still very limited towards its efficient control. This study first investigated the fouling behaviors (i.e., the rate and extent of flux decline and fouling reversibility) of wastewater reclamation RO membranes fed with ultrafiltration (UF) prefiltered secondary effluent from a tropical area wastewater reclamation plant at two operationally important permeate recovery levels. The associated fouling mechanisms were delineated with the aid of microscopic analysis of the fouling layer characteristics (i.e., composition, morphology and the fouled membrane surface properties). As EfOM is a mixture of structurally complex poorly-defined organic compounds, this study further investigated the interactions between fractional components of EfOM and RO membranes and attempted to identify the most influential fraction(s) or physical-chemical properties governing the fouling process.