Improving Nitrogen Removal Efficiency in SBR Reactors by Controlling Operational Phases

Abstract

Wastewater treatment facilities using the activated sludge process are the most widely used solutions worldwide, regardless of the region. According to statistics, the most common option for Vietnam’s conditions is the sequenced batch reactor, which is used at a third of wastewater treatment plants (WWTP). Thus, studies of treatment processes in SBRs that seek high-quality treatment may have a wide range of further applications in practice. Another reason is that wastewater treated to meet Vietnamese standards has a significant negative impact on water resources. The research was carried out in relation to Hoaxuan wastewater treatment plants, where pilot models were installed that worked on influent wastewater. Studies of the nitrification process in SBRs (cycle duration 4 h) have shown that the highest efficiency of removal of pollutants (organic pollution by 90%, ammonium nitrogen by 80%) is achieved at a pH value close to 8.0. The increase in pH also had a positive effect on the increase in the specific rate of nitrification. At the second stage of the research, the process of denitrification in SBRs (cycle duration of 6.5 h) was considered. The results demonstrated that treatment quality corresponded to the standards for the Russian Federation, which are stricter than Vietnamese standards (3.0 mg/L vs. 30 mg/L of biochemical oxygen demand; 0.4 mg/L vs. 5 mg/L of ammonium nitrogen). For the second part of the study, a specific denitrification rate was determined in order to establish its dependence on the main parameters of the SBR model performance.