An efficient way to enhance the total nitrogen removal efficiency of the Anammox process by S0-based short-cut autotrophic denitrification

Abstract

In order to reduce the amount of NO3−–N generated by the Anammox process, and alleviate the competition between denitrification and Anammox for NO2−–N in a single reactor, the preference of S0 for reacting with coexisting NO2−–N and NO3−–N in the sulfur autotrophic denitrifying (SADN) process and the coupling effect of short-cut SADN and the Anammox process were studied. The results showed that S0 preferentially reacted with NO3− to produce NO2−–N, and then reacted with NO2−–N when NO3−–N was insufficient, which could effectively alleviate the competition between SADN bacteria (SADNB) and Anammox bacteria (AnAOB) for NO2−–N. After 170 days of operation, coupling between short-cut S0-SADN and the Anammox process was first successfully achieved. SADNB converted the NO3−–N generated by the Anammox process into NO2−–N, which was once again available to AnAOB. The total nitrogen removal efficiency eventually stabilized at over 95%, and the effluent NO3−–N was controlled within 10 mg/L, when high NH4+–N wastewater was treated by the Anammox process. Microbial community analysis further showed that Candidatus Brocadia and Thiobacillus were the functional microorganisms for AnAOB and SADNB.