A novel control strategy for the partial nitrification and anammox process (PN/A) of immobilized particles: Using...

The impact of the addition of salinity on partial nitrification and anammox (PN/A) was investigated in this study. The sludge was immobilized by polyethylene glycol (PEG)-modified polyvinyl alcohol (PVA)-sodium alginate (SA) immobilization technology, and the effective diffusion coefficient (D_e) of the immobilized particles was measured to be 0.313 × 10^-9 m²·s^-1, indicating that the system has excellent mass transfer performance. An experiment was carried out by adding NaCl to create a salinity gradient. It was found that the initiation of partial nitrification was achieved at a concentration of 10 g·L^-1 NaCl and the nitrite accumulation rate (NAR) reached 81.03%, which could provide sufficient NO₂^--N for subsequent anammox. Additionally, an anammox reactor operating at the same salinity maintained a stable state after acclimation, and the removal rates of NH₄⁺-N and NO₂^--N reached 80%. The dominant population in the anammox system was Planctomycetes. Salinity is a feasible factor for controlling the PN/A process.