Implementation of a demand-side approach to reduce aeration requirements of activated sludge systems: Directed acclimation of biomass and its effect at the process level

Abstract

Conventionally, increased oxygen requirements of biological wastewater treatment systems have been addressed through supply-side approaches that focus on upgrading the oxygen mass transfer capabilities of aeration devices. Such approaches entail high aeration energy penalties for relatively low performance improvements, as well as causing decreased oxygen mass transfer efficiencies. In this study, a nitrifying community acclimated to low dissolved oxygen (DO) conditions has been demonstrated to yield similar treatment performance as a conventional nitrifying process with 20% less aeration requirements and 20% improvement in mass transfer efficiency. Such a demand-side approach has been shown to be successful due to an improvement of the half saturation constant of the acclimated biomass that has, in turn, been linked to the expression of hemoglobin proteins. Directed acclimation of nitrifying communities could help address the operational requirement to carry out ammonia oxidation at consistently low DO conditions in the mainstream anammox and simultaneous nitrification–denitrification processes.