ANAMMOX-like performances for nitrogen removal from ammonium-sulfate-rich wastewater in an anaerobic sequencing batch reactor

ABSTRACTAmmonium removal by the ANaerobic AMonium OXidation (ANAMMOX) process was observed through the Sulfate-Reducing Ammonium Oxidation (SRAO) process. The same concentration of ammonium (100 mg N L−1) was applied to two anaerobic sequencing batch reactors (AnSBRs) that were inoculated with the same activated sludge from the Vermicelli wastewater treatment process, while nitrite was fed in ANAMMOX and sulfate in SRAO reactors. In SRAO-AnSBR, in substrates that were fed with a ratio of NH4+/SO42− at 1:0.4 ± 0.03, a hydraulic retention time (HRT) of 48 h and without sludge draining, the Ammonium Removal Rate (ARR) was 0.02 ± 0.01 kg N m−3.d−1. Adding specific ANAMMOX substrates to SRAO-AnSBR sludge in batch tests results in specific ammonium and nitrite removal rates of 0.198 and 0.139 g N g−1 VSS.d, respectively, indicating that the ANAMMOX activity contributes to the removal of ammonium in the SRAO process using the nitrite that is produced from SRAO. Nevertheless, the inability of ANAMMOX to utilize s...