Applying a microbial electrolysis cell to promote imidacloprid removal in the adsorption biological coupling system at low temperature via accelerating coke regeneration and bioaugmentation

Abstract

In this study, imidacloprid (IMI) wastewater was treated by adsorption biological coupling (ABC) and microbial electrolysis cell (MEC)-ABC technologies at low temperature (15 °C). Meanwhile, the degradation mechanism of IMI and the expression of functional genes were revealed. Results showed that under MEC enhanced treatment, the removal efficiency of COD, NH3-N, total-phosphorous (TP), and IMI reached 90.37 %, 92.03 %, 77.12 %, and 100 %, respectively, which were 9.71 %, 6.30 %, 9.48 % and 30.40 % higher than those of ABC treatment, respectively. Aestuariivirga sp. YIM B02566 became the dominant bacterium in ABC and MEC-ABC reactors under low-temperature conditions. MEC increased the relative abundance of Sphingomonadales, Hyphomicrobiales, and Aestuariivirga sp. YIM B02566 by 8.87 %, 16.15 %, and 5.29 %, respectively. Moreover, it up-regulated the abundance of key genes related to carbon and phosphorus metabolism, such as PGK (10.91 %), ENO (15.61 %), pstS (2.40 %), phnP (0.45 %) and phoD (0.97 %). Finally, MEC facilitated the conversion of C9H9ClN4 (m/z 209.0581), C9H11ClN4 (m/z 211.0729), C9H10ClN3O (m/z 212.0584), C9H11N5O2 (m/z 222.0964), C9H11ClN4O (m/z 227.0685) to C9H10ClN3O (m/z 212.0600), C9H11N5O2 (m/z 222.0964). The stability of MEC-ABC reactor operation at low temperature not only minimized the formation of IMI degradation products, but also provided an theoretical foundation for expanding the practical application of MEC-ABC technology in the treatment of IMI neonicotinoid insecticide wastewater.