Establishment of the Anammox Wastewater Treatment Process in a Lab-Scale Expanded Bed Biofilm Reactor with ABDite^®

The anaerobic ammonia oxidation (Anammox), a biological wastewater treatment (WWT) process, has the benefit of converting wastewater ammonia and nitrite to nitrogen gas. While Anammox has been conducted in various bioreactors that use various biomass support medium, this process has not been investigated with the expanded bed biofilm reactor (EBBR) that has been used successfully for total nitrification. This research investigated the ability of the lab-scale EBBR and the ABDite^® growth support medium originally designed to grow aerobic ammonia-oxidizing bacteria (AOB) to be adapted for the Anammox WWT process. Experiments conducted included chemical analysis to determine ammonia and nitrite concentrations removed from the EBBR, scanning electron microscope (SEM) examination of biofilms formed on the ABDite medium, molecular biology analysis (DNA extraction, Sanger sequencing and BLAST, and next-generation sequencing (NGS) to identify key bacterial groups. Results obtained from physical observation, chemical, SEM, and molecular biology investigations revealed that (i) the Anammox WWT process was established in the EBBR and the ABDite^® medium supported the development of Anammox bacterial biofilm for the first time. (ii) The EBBR-Anammox process achieved a nitrogen removal rate of 6.1 KgN m⁻³ d⁻¹ from a loading rate of 9.8 KgN m⁻³ d⁻¹ with 80–100% nitrogen removal efficiency. (iii) SEM analysis detected the cauliflower-like structure characteristic of Anammox bacteria biofilm. (iv) Anammox bacteria genera (Candidatus Brocadia, Kuenenia, and Jettenia), AOB (e.g., Nitrosomonas), and other bacterial communities were identified with molecular biology techniques.