The effect of sulfide inhibition on the ANAMMOX process

The feasibility of anaerobic ammonium oxidation (ANAMMOX) process to treat wastewaters containing sulfide was studied in this work. Serum bottles were used as experimental containers in batch tests to analyze the short-term response of the ANAMMOX process under sulfide stress. The IC50 of sulfide-S for ANAMMOX biomass was substrates-dependent and was calculated to be 264 mg L−1 at an initial total nitrogen level of 200 mg L−1 (molar ratio of ammonium and nitrite was 1:1). The long-term effects and the performance recovery under sulfide stress were continuously monitored and evaluated in an upflow anaerobic sludge blanket reactor. The performance of the ANAMMOX system was halved at an sulfide-S level of 32 mg L−1 within 13 days; however, the nitrogen removal rate (NRR) decreased by only 17.2% within 18 days at an sulfide-S concentration of 40 mg L−1 after long-time acclimatization of sludge in the presence of sulfide. The ANAMMOX performance recovered under sulfide-S level of 8 mg L−1 with a steady NRR increasing speed, linear relationship between the NRR and operation time. The synchronic reduce in the specific ANAMMOX activity and the biomass extended the apparent doubling time of the nitrogen removal capacity and decreased biomass growth rate. ► The short- and long-term effects of sulfide on ANAMMOX were distinctive. ► The changes in the properties of granule after sulfide inhibition were determined. ► The modified non-competitive inhibition model fit the batch-test data well. ► The qualitative and quantitative indicators were proposed to describe the ANAMMOX.