Sodium hypochlorite perturbation of a graywater treatment

Abstract

A novel graywater treatment system consisting of an aerated batch reactor and biomass-retaining ultrafiltration unit was evaluated for treatment of shipboard wastes. The focus of this study was to determine the resilience of the biomass recycle reactor to perturbations of sodium hypochlorite, the major component of bleach. A bench-scale reactor was perturbed with 50, 190, and 1000 mg L-1 sodium hypochlorite and monitored for changes in respiration, substrate utilization, viable plate counts, fatty acid methyl ester profiles, and Biolog-GN patterns. Following the addition of hypochlorite, respiration and substrate utilization were not detected, and viable biomass decreased. Recovery times following perturbations were longer with higher concentrations of sodium hypochlorite. Community composition (determined by fatty acid methyl ester analysis) changed during the recovery from hypochlorite perturbations. However, more significant differences in community composition were noted between different perturbations and were a function of time. Irrespective of initial community composition, the reactor communities recovered from hypochlorite perturbations. Biolog patterns showed no notable change in the overall metabolic capacity of the community. The biomass recycle reactor's resistance to sodium hypochlorite perturbations contributes to its usefulness in treatment of shipboard wastes.