Towards simultaneously removing nitrogen and sulfur by a novel process: Anammox and autotrophic desulfurization-denitrification (AADD)

The combined anammox (anaerobic ammonium oxidation) and autotrophic desulfurization-denitrification (AADD) process represents a promising innovative technology for biological nitrogen and sulfur removal. In this study, an up-flow anaerobic sludge blanket reactor, which was started with anammox and methanogenic granules, was operated for 245 days to evaluate the co-treatment of wastewater containing nitrogen and sulfur. The reactor demonstrated good performance in terms of nitrogen and sulfide removal and exhibited excellent behavior for removal of NH4+-N, NO2--N and S2--S exceeding 252, 333 and 330 mg L-1, respectively. The highest nitrogen removal rate and sulfide removal rate attained were 4.00 kgN m(-3) d(-1) and 2.39 kgS m(-3) d(-1), respectively, which were also the highest reported values for a coupling-system. The influent NH4+-N:S2--S and NO2--N:S2--S ratios set at 1.74 and 2.20-2.27 are suitable for maintaining system stability. The specific activities of anammox and autotrophic desulfurization-denitrification (SAA and SADD), extracellular polymeric substance (EPS), heme c (an important cofactor of some anammox bacterial enzymes) and the diversity of anammox and autotrophic desulfurization-denitrification (ADD) bacteria were investigated during the operation. The SAA and SADD are regarded as key factors for high efficiency. The granules contained many EPS (128.4-204.5 mg g(-1) VSS) and minor heme c content (1.17 mu mol g(-1) VSS). The dominant bacteria belonged to members of Brocadiaceae and Hydrogenophilaceae, a majority of which were anammox bacteria and ADD bacteria, respectively. These observations suggest a new removal process for ammonia, nitrite and sulfide utilizing an uncommon mechanism involving simultaneous anammox and ADD. (C) 2016 Elsevier B.V. All rights reserved.