Disinfection of Water by N-Halamine Biocidal Polymers

Abstract

Two novel polymers have been tested in a filter application for biocidal efficacy for flowing aqueous solutions of microorganisms. A laboratory water pump was employed in the experiments to provide contact times on the order of 1-2 s/mL. The two polymers are N-chlorinated and N-brominated derivatives of a polystyrene hydantoin. The variables of pH, temperature, flow rate, and dilution with inert sand have been examined. The N-bromamine polymer (Poly-IB) was generally more effective than the N-chloramine polymer (Poly-I), probably because N-bromamines and free bromine are more biocidal under a given set of conditions than are their N-chloramine and free chlorine analogs. Once the biocidal efficacies of the polymers were exhausted due to chemical reaction with microorganisms or organic load, they could be regenerated by exposure to circulated free chlorine or bromine. This demonstrated that the polymer materials were not permanently damaged by the exhaustion process.