Low carbon-to-nitrogen ratio digestate from high-rate anaerobic baffled reactor facilitates heterotrophic/autotrophic nitrifiers involved in nitrogen removal
2022
Zhou, Xiangtong | Arslan, Muhammad | Liu, Zhigang | Li, Da | Xi, Haipeng | Feng, Yujie | Li, Shanwei | Wei, Jing | Rong, Xinshan | Liang, Zhishui | Wang, Xiaochun | Wu, Zhiren | Gamal El-Din, Mohamed
In this study, baffled anaerobic–aerobic reactors (AOBRs) with modified basalt fiber (MBF) carriers and felt were used to treat domestic wastewater (DWW). The influent was first treated in anaerobic compartments, with the NH₄⁺-N containing digestate refluxed into aerobic compartment for nitrification. The nitrified liquid was channeled to the anaerobic compartments for further denitrification. Under optimal conditions, AOBR with MBF carriers could remove 91% chemical oxygen demand (COD) and 81% total nitrogen (TN), with biomass production increased by 7.6%, 4.5% and 8.7% in three successive anaerobic compartments compared to the control. Biological viability analysis showed that live cells outnumbered dead cells in bio-nests. Metagenomics analysis showed that multiple metabolic pathways accounted for nitrogen conversion in anaerobic and aerobic compartments. More importantly, low COD/TN ratio digestate facilitated heterotrophic nitrification-aerobic denitrification (HN-AD) species growth in aerobic compartment. This study provides a promising strategy to source treatment of DWW from urban communities.
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