Can anammox process be adopted for treating wastewater with high salinity exposure risk?

Anammox was a promising technology for nitrogen removal, and has been applied for treating many kinds of nitrogenous wastewaters. Considering the risk in high salinity of the municipal sewage in coastal city, the feasibility of Anammox process for treating low ammonia wastewater (around 50 mg L^-1) with increasing salinity was investigated in this study. The results showed that the salinity in low concentrations (1-5 g L^-1) had slight impact on the nitrogen removal and activity of Anammox bacteria but significantly improved its growth. The moderate salinity (10-40 g L^-1) decreased the specific Anammox activity (SAA) to 8.11 from the initial 13.15 mg N g^-1 SS h^-1, but increased the abundance to 52.3% from 30.1% (Candidatus Kuenenia). High salinity (50-60 g L^-1) performed severe inhibition on activity and abundance both, with the SAA decreased to 0 and abundance to 11.9%. The self-recovery performance was unsatisfactory when salinity was unavailable. A quadratic curve between the SAA and salinity concentration was fitted, and the IC₅₀ was calculated as 42.1 g L^-1 (NaCl). Anammox process could be directly adopted for treating low ammonia sewage with low salinity, whereas activity enhancement or adaption improvement should be pre-presented for treating sewage with moderate or high salinity.