Enhancing energy and nitrogen removal efficiency through automatic split injection and innovative aeration device: A study of low C/N ratio environments

Abstract

A new aeration device based on Bernoulli's principle, Jetventrumixer (JVM), was introduced into an aeration tank in denitrification process, which involved an automatic split injection system (ASIS) into two denitrification tanks every 10 minutes. Real-time monitoring of influent water allowed the calculation of the C/N ratio, enhancing the utilization efficiency of internal carbon sources while reducing the need for external carbon. The comparison of the JVM with the conventional air diffuser for 100 days operation showed that the removal efficiency for NH4+-N in both systems was approximately 98 %, but the nitrification efficiencies were 84 % and 80 %, respectively. This indicates that the JVM achieves an high enough removal efficiency and nitrification efficiency compared with conventional air diffuser system with dramatic reduction in energy consumption by 52.1 %. When the influent wastewater was split and injected into duplicate denitrification tanks at ratios of 3:7, 5:5, and 7:3, the total nitrogen (TN) removal efficiencies were 77 %, 73 %, and 72 %, respectively. In contrast, with the implementation of the ASIS, the TN removal efficiency increased up to 82 %. The increase in TN removal indicates that real-time monitoring could stably track changes chemical composition in wastewater influent over 24 h and introducing ASIS facilitate the efficient utilization of internal carbon sources, thereby enhancing denitrification efficiency and improving TN removal efficiency. Finally, the greenhouse gas (GHG) emissions from the JVM and air diffuser were 9.39401 and 19.60488 tCO(2)eq year(-1), respectively, representing a 52% reduction. Therefore, JVM and ASIS successfully reduced energy consumption and enhanced both nitrification and denitrification efficiencies.