# Biofouling Resistance Improvement in Membrane-Based Secondary Effluent Treatment: A Focus on Membrane Surface Modification by Graft Polymerization with 3-Allyl-5, 5-Dimethyl Hydantoin

## TL;DR

This study improves membrane resistance to biofouling by grafting a chemical onto RO membranes, showing better performance against bacterial fouling.

## Contribution

The novel use of graft polymerization with ADMH to enhance biofouling resistance in RO membranes is presented.

## Key findings

- ADMH grafting improved E. coli and S. aureus mortality and reduced fouling deposition rates.
- Flux recovery ratios ranged from 69.2% to 96.9% after biofouling tests.
- Optimal fouling resistance was achieved at moderate ADMH concentrations despite increased hydrophilicity.

## Abstract

The implementation of wastewater management strategies and wastewater treatment techniques, such as reverse osmosis (RO), has been increasing to promote environmental sustainability and reduce freshwater consumption. Municipal secondary effluent is a promising source for reuse and reducing the strain on freshwater consumption. Still, its diverse foulant composition promotes the fouling of polyamide RO membranes, leading to performance decline. In this study, 3-allyl-5,5-dimethylhydantoin (ADMH) was grafted onto thin-film composite RO membranes at varying concentrations via graft polymerization. The membranes were tested against foulant solutions of E. coli and S. aureus, as well as organic and inorganic foulant solutions mimicking the fouling activity of municipal wastewater secondary effluent. Biofouling tests showed improved mortality ratios—58.9% against E. coli and 37.4% against S. aureus—along with fouling deposition rates of 3.7–8.9% and flux recovery ratios of 69.2–96.9%. Although surface hydrophilicity increased with ADMH concentration, fouling resistance was optimal at a moderate concentration. Resistance to organic and inorganic foulants did not show similar improvement, highlighting the importance of the foulant type in determining overall membrane performance.