Sulphate reduction, Autotrophic denitrification, NItrification, and Anammox (SANIA) integrated process for next-generation biological wastewater treatment

This study proposes the Sulphate reduction, mixed sulphide- and thiosulphate-driven Autotrophic denitrification, Nitrification, and Anammox integrated (SANIA) process for sustainable treatment of mainstream wastewater after organics capture. Three moving-bed biofilm reactors (MBBRs) were applied for developing sulphate reduction (SR), mixed sulphide- and thiosulphate-driven partial denitrification and anammox (MSPDA), and nitrification (N), respectively. Typical mainstream wastewater after organics capture (e.g., chemically enhanced primary treatment, CEPT) was synthesized with chemical oxygen demand (COD) of 110 mg/L, sulphate of 50 mg S/L, ammonium of 30 mgN/L. The feasibility of SANIA was investigated with mimic nitrifying effluent supplied in MSPDA-MBBR (Period I), followed by the examination of the applicability of SANIA process with N-MBBR integrated (Period II), under moderate temperatures (25–27 ℃). In Period I, SANIA process was established with both SR- and MSPDA-MBBR continuously operated for over 300 days (no anammox biomass inoculation). Specifically, in MSPDA-MBBR, high rates of denitratation (2.7 gN/(m²·d)) and anammox (2.8 gN/(m²·d)) were achieved with anammox contributing to 81% of the total inorganic nitrogen removal. In Period II, the integrated SANIA system was continuously operated for over 130 days, achieving up to 90% of COD, 93% of ammonium, and 61% of total inorganic nitrogen (TIN) removal, with effluent concentrations lower than 10 mg COD/L, 3 mg NH₄⁺-N/L, and 13 mg TIN-N/L. The implementation of SANIA can ultimately reduce 75% and 40% of organics and aeration energy for biological nitrogen removal. Considering the combination of SANIA with CEPT for carbon capture and sludge digestion/incineration for energy recovery, the new integrated wastewater technology can be a promising strategy for sustainable wastewater treatment.