Microbial biodegradation of organic wastes containing surfactants in a continuous-flow reactor

In a continuous flow bioreactor seeded with microbes from municipal activated sludge, complete organic carbon oxidation of simulated graywater (wastewater produced in human residences, excluding toilet wastes) was achieved at dilution rates up to 0.36 h-1 in the presence of 64.1 microM linear alkylbenzenesulfonate (LAS) L-1. At LAS concentrations of 187 microM, the system functioned only at dilution rates up to 0.23 h-1, and the biomass yield was two-fold lower. There were physiological changes in the microbial communities under different operating conditions, as measured by specific contents of ATP and extracellular hydrolases as well as the respiratory potential of the biomass. LAS inhibited the activity of LAS-degrading microbes at >150 microM LAS, and the activity of other microbes at >75 microM LAS. Chemical analysis of graywater indicated that samples consisted primarily of biological polymers (proteins and polysaccharides) and lower concentrations of surfactants. Biological remediation of graywater is possible, although treatment efficiency is influenced by the operating conditions and wastestream composition.