Importance of low-abundance microbial species in response to disturbances in wastewater bioreactors

Abstract

This study demonstrates the importance of low-abundance species in maintaining biosystem stability in response to a changing reactor operation condition. Initiation and termination of effluent recirculation were applied as the operational disturbance factors in two upflow anaerobic sludge blanket (UASB) reactors treating high-strength wastewater, respectively. The microbial growth rates during the community evolution were calculated based on the non-steady-state mass balance model. Community evolution studies showed that directly following the initiation/termination of effluent recirculation, the microbial communities reached the highest diversity. The net growth rates of individual microbes during community evolution illustrated that low-abundance species played a critical role in response to the disturbance induced by initiating or discontinuing effluent recirculation. This study highlights the importance of the response of low-abundance species in maintaining biosystem stability when a disturbance is applied to a wastewater bioreactor.