Low carbon-to-nitrogen ratio digestate from high-rate anaerobic baffled reactor facilitates heterotrophic/autotrophic nitrifiers involved in nitrogen removal

• DOI: 10.1016/j.biortech.2022.127346
• Publication Date: 2022-05-21T04:47:11Z
• Authors: Xiangtong Zhou; Muhammad Arslan; Zhigang Liu; Da Li; Haipeng Xi; Yujie Feng; Shanwei Li; Jing Wei; Xinshan Rong; Zhishui Liang; Xiaochun Wang; Zhiren Wu; Mohamed Gamal El-Din
• Keywords: 0301 basic medicine; 03 medical and health sciences; Bioreactors; Nitrogen; Denitrification; Heterotrophic Processes; Anaerobiosis; Wastewater; Nitrification; Carbon; 6. Clean water

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.