Abstract: “Indigenous microbial biomass, such as the municipal wastewater treatment activated sludge, needs a prolonged acclimation period before the sludge can degrade a xenobiotic organic compound. During acclimation, some of the sludge microorganisms are converted into degraders by acquiring specific genetic coding for metabolism of the xenobiotic organic. At activated sludge system start-up and during xenobiotic shocks, activated sludge microorganisms may not have been acclimated to the newly introduced xenobiotic and thus may fail to treat the influent xenobiotic. The purpose of this study was to investigate the benefits of bioaugmentation to activated sludge during the vulnerable times of xenobiotic treatment start-up and shock-loading. Laboratory activated sludge reactors fed biogenic organics were operated and start-up and shock-loading tests were performed with the steady state activated sludge. 2,4-dichlorophenoxyacetice acid (2,4-D) replaced biogenic influent in the start-up and shock-”

Keywords: Bioaugmentation, activated sludge, xenobiotic, start-up, xenobiotic shock