A novel process for simultaneous biological nutrient removal and waste activated sludge reduction in one-stage system without aeration

This study presented a novel process for simultaneous biological nutrient removal and waste activated sludge reduction in one-stage municipal wastewater treating system without aeration on the basis of endogenous partial denitrification, anammox and Candidatus Phosphoribacter dominated biological phosphate removal with sludge reduction (EPDA/PSR). The effluent total inorganic nitrogen and phosphate concentrations were 0.1 mg/L and lower than detection limit (0.1 mg/L), respectively, without dosing external carbon sources. Compared with partial denitrification-anammox process, the daily sludge production in EPDA/PSR process reduced by 50.8 %. The percentage of intact cells measured by flow cytometry reduced from 92.4 % to 77.3 % with the increase of aromatic protein, DNA content of supernatant, soluble microbial byproduct-like substance and decline of particle size. The sludge stabilization structure was destructed, and intracellular organics were released, which resulted in the reduction of sludge production. Microbial community structure at transcriptional level indicated that really working Candidatus Phosphoribacter (phosphorus accumulating organisms with fermentation capacity), Candidatus Competibacter (endogenous partial denitrification bacteria) and Candidatus Brocadia (anammox bacteria) reached 68.4 %, 9.84 % and 8.02 %, respectively, and Candidatus Kuenenia (anammox bacteria) did not play a role in EPDA/PSR system. The novel one-stage EPDA/PSR process realized high efficient biological nutrient removal, achieved waste activated sludge reduction and saved 100 % of aeration energy consumption cost and external carbon source dosage cost, which effectively developed internal carbon source and provided a new idea for wastewater treatment.