Effect of Temperature on Anammox Processes under Mesophilic Conditions

Anaerobic ammonium oxidation (anammox) is one of the cost-effective ways to remove nitrogen from wastewater. In fact, full-scale anammox plants have been installed in many kinds of wastewater treatment all over the world. In some types of wastewater treatment systems, there is a possibility to operate anammox processes under high water temperatures due to high temperature of nitrogen wastewater. However, there are few reports on the effects of high temperature conditions on the anammox processes. In the present study, continuous feeding tests using 2 types of anammox carriers were operated under temperature control in the range of 36‒38°C. Consequently, nitrogen removal performances were deactivated when water temperature was set to 37°C on the all continuous feeding tests. It was revealed that the ratio of nitrate production (ΔNO₃⁻) against to ammonium removed (ΔNH₄⁺) were decreased when water temperature was increased to 37°C. The ratio of nitrite removed (ΔNO₂⁻) against to ΔNH₄⁺ was also decreased under high temperature inhibition. Microbial community analysis revealed that dominant anammox bacteria in the reactors were Candidatus Kuenenia stuttgartiensis.