Modeling of spiral wound ultrafiltration membrane forward flushing during secondary wastewater upgrading for unrestricted irrigation

Abstract

A two-stage membrane system comprising of an ultrafiltration (UF) stage followed by a reverse osmosis (RO) leg was employed for unrestricted irrigation. The UF stage served as a vital pretreatment step for the RO stage. To address the fouling phenomenon of the UF membrane, field experiments were meticulously conducted to thoroughly characterize the flow decline employing forward flushing. Forward flushing of the UF membrane was the preferred selected method although no other cleaning method was evaluated (besides once a week chemical cleaning). Optimal frequency of forward flushing and the associated costs per flush in the UF stage were carefully investigated.The spiral wound UF membranes was economically modeled to achieve most efficient filtration. Modeling considers a range of factors, including energy costs and clean water consumption per forward flush. General curves were obtained to describe the system's performance under diverse filtration conditions.Frequency of forward flushing, almost every 30 min, emerged as the recommended option. This approach proved to be effective in minimizing membrane fouling and sustaining filtration. Modeling of this strategy considered the costs associated with the frequent flushes, and it was found to be a justifiable investment given the considerable benefits in membrane performance and overall system efficiency.