Enhanced nitritation/denitritation and potential mechanism in an electrochemically assisted sequencing batch biofilm reactor treating sludge digester liquor with extremely low C/N ratios. (November 2022)

• Record Type: Journal Article
• Authors: Shi, Shuohui; Fan, Xing; He, Xuejie; He, Lei; Cao, Meng; Wang, Hai; Zhou, Jian
• Is Part Of: Bioresource technology. Volume 363(2022)
• Publication Date: 2022-11
• Subjects: Nitritation -- Denitritation -- Electrolysis -- Low C/N ratio -- Sludge digester liquor; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2022.127936
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: A novel electrochemically assisted sequencing batch biofilm reactor was established. High-strength FA magnified by electrolysis contributed to stable nitritation. Over 70 % TN removal was obtained even at extremely low C/N ratios (<0.5). Heterotrophic rather than autotrophic denitritation dominated in the TN removal. Cell lysis stimulated by electrolysis and FA provided carbon supplementation. Abstract: Nitritation/denitritation is a promising strategy to treat sludge digester liquor but would be unstable and inefficient at extremely low C/N ratios. Here, a novel electrochemically assisted sequencing batch biofilm reactor (E-SBBR) was established to treat synthetic/real sludge digester liquor with decreasing C/N ratios. The results showed that the E-SBBR achieved stable nitritation and appreciable TN removal (>70 %) even at C/N < 0.5. The high-strength free ammonium (FA) (91.1–132.8 mg NH3 -N/L) and long inhibition time (>9h) magnified by electrolysis promoted the robustness of nitritation through efficient nitrite-oxidizing bacteria elimination. Meanwhile, mass balance denoted that heterotrophic denitritation dominated in the enhanced TN removal and relied on carbon supplementation from cell apoptosis/lysis stimulated by electrolysis and high-strength FA, further supported by the recovery of heterotrophic denitrifiers, fermentation bacteria, and relevant functional genes at extremely low C/N ratios. This study provides a novel nitrogen removal approach for the sludge digester liquor treatment.