Journal Article

Effects of external recirculation on a two-stage mainstream anaerobic-anammox treatment system

He, Zhen, Li, Xiaojin

2019

Overview

Nitritation-anammox treatment can be a potentially energy-and resource-efficient technology for treating mainstream wastewater. However, the issue of nitrate residue from anammox treatment remains to be addressed. Herein, external recirculation of the anammox effluent to a hybrid anaerobic reactor (HAR), which was also to provide a continuous flow with low COD/N for the nitritation-anammox reactor, was employed to decrease the residue compounds. The recirculation ratio of 50% was observed to be the optimal to achieve the best overall performance with potential savings in energy demand. Specifically, in the operation scenario of R = 50%, the highest COD removal of ~90% by the HAR was achieved. Meanwhile, the lowest COD/NH₄⁺-N ratio of ~2.0 in the HAR effluent ensured the lowest observed NO₃⁻-N/ NH₄⁺-N ratio of ~14% in the nitritation-anammox reactor. These results have demonstrated the feasibility of applying external recirculation for nitrate residue removal via denitrification in the anaerobic pretreatment stage.

• Publisher: John Wiley and Sons, Inc,Blackwell Publishing Ltd
• Subject: Ammonium Compounds - isolation & purification / Ammonium Compounds - metabolism / anaerobic ammonium oxidation / anaerobic digesters / anaerobic pretreatment / Anaerobic treatment / Anaerobiosis / Biological Oxygen Demand Analysis / Bioreactors / chemical oxygen demand / COD/NH4+‐N ratio / Continuous flow / Denitrification / effluent recirculation / Effluents / energy / Energy conservation / Energy demand / environment / Feasibility studies / mainstream treatment / Nitrates / nitritation‐anammox / Nitrogen / observed NO3‐‐N/NH4+‐N ratio / Pretreatment / Reactors / Removal / Residues / SHORT COMMUNICATION / total nitrogen / Waste Water - chemistry / wastewater / Wastewater treatment / water / Water Purification - methods