Sodium hypochlorite perturbation of a graywater treatment system

A novel graywater treatment system consisting of an aerated batch reactor a nd biomass-retaining ultrafiltration unit was evaluated for treatment of sh ipboard wastes, The focus of this study was to determine the resilience of the biomass recycle reactor to perturbations of sodium hypochlorite, the ma jor component of bleach. A bench-scale reactor was perturbed with 50, 190, and 1000 mg L-1 sodium hypochlorite and monitored for changes in respiratio n, substrate utilization, viable plate counts, fatty acid methyl ester prof iles, and Biolog-GN patterns. Following the addition of hypochlorite, respi ration and substrate utilization were not detected, and viable biomass decr eased. Recovery times following perturbations were longer with higher conce ntrations of sodium hypochlorite. Community composition (determined by fatt y acid methyl ester analysis) changed during the recovery from hypochlorite perturbations. However, more significant differences in community composit ion were noted between different perturbations and were a function of time. Irrespective of initial community composition, the reactor communities rec overed from hypochlorite perturbations. Biolog patterns showed no notable c hange in the overall metabolic capacity of the community. The biomass recyc le reactor's resistance to sodium hypochlorite perturbations contributes to its usefulness in treatment of shipboard wastes.