Towards low carbon demand and highly efficient nutrient removal: Establishing denitrifying phosphorus removal in a biofilm-based system

• Published in: Bioresource technology Vol. 372; p. 128658
• Main Authors: Dong, Kaiyue, Qiu, Yanling, Wang, Xiaoxia, Yu, Deshuang, Yu, Zhengda, Feng, Juan, Wang, Jimiao, Gu, Ruihuan, Zhao, Ji
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-03-2023
• Subjects: Biofilms; Bioreactors; Carbon; Denitrification; Denitrifying phosphorus removal; Glycogen accumulating organisms (GAOs); Integrated fixed-biofilm activated sludge (IFAS); Metagenomics; Nitrates; Nitrogen; Nutrients; Organic Chemicals; Phosphate accumulating organisms (PAOs); Phosphates; Phosphorus; Sequencing batch biofilm reactor (SBBR); Sewage; Waste Disposal, Fluid - methods; Metagenomics; Sequencing batch biofilm reactor (SBBR); Denitrifying phosphorus removal; Phosphate accumulating organisms (PAOs); Glycogen accumulating organisms (GAOs); Integrated fixed-biofilm activated sludge (IFAS)
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2023.128658

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•Unable to discharge suspended sludge led to decreased PRE in the DPR-SBBR.•PUAax and PUAo were 51 and 40 mg, indicating the necessity of the aerobic stage.•Pseudomonas and Thiothrix might play roles in DPR.•Ca. Competibacter might act as pioneers for biofilm formation by secreting EPS.•The success of the DPR-Anammox process relies on the stable operation of DPR-SBBR.
The combined denitrifying phosphorus removal (DPR) and Anammox process is expected to achieve advanced nutrient removal with low carbon consumption. However, exchanging ammonia/nitrate between them is one limitation. This study investigated the feasibility of conducting DPR in a biofilm reactor to solve that problem. After 46-day anaerobic/aerobic operation, high phosphorus removal efficiency (PRE, 83.15 %) was obtained in the activated sludge (AS) and biofilm co-existed system, in which the AS performed better. Phosphate-accumulating organisms might quickly adapt to the anoxic introduced nitrate, but the following aerobic stage ensured a low effluent orthophosphate (<1.03 mg/L). Because of waste sludge discharging and AS transforming to biofilm, the suspended solids dropped below 60 mg/L on Day 100, resulting in PRE decline (17.17 %) and effluent orthophosphate rise (4.23 mg/L). Metagenomes analysis revealed that Pseudomonas and Thiothrix had genes for denitrification and encoding Pit phosphate transporter, and Candidatus_Competibacter was necessary for biofilm formation.