Nitrogen-removal granular sludge (NRGS) is a promising technology in wastewater treatment, with advantages of efficient nitrogen removal, less footprint, lower sludge production and energy consumption, and is a way for wastewater treatment plants to achieve carbon-neutrality. Aerobic granular sludge (AGS) and anammox granular sludge (AnGS) are two typical NRGS technologies that have attracted extensive attention. Mounting evidence has shown strong associations between NRGS properties and the status of NRGS systems; however, a holistic view is still missing. The aim of this article is to provide an overview of NRGS with an emphasis on characterization. Specifically, the integrated nitrogen transformation pathways inside NRGS and the performance of NRGS treating various wastewaters are discussed. NRGS properties are categorized as physical-, chemical-, biological- and systematical ones, presenting current advances and corresponding characterization technologies. Finally, the future prospects for furthering the mechanistic understanding and engineering application of NRGS are proposed. Overall, the technological advancements in characterization have greatly contributed to understanding NRGS properties, which are potential factors for optimizing the performance and evaluating the working status of NRGS. This review will provide guidance in characterizing NRGS properties and boost the introduction of novel characterization technologies.
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http://dx.doi.org/10.1016/j.watres.2022.118214 | DOI Listing |
Bioresour Technol
January 2025
School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China.
Ammonia-oxidizing bacteria (AOB) sourced from an aerobic granular sludge (AGS) process were rapidly enriched by progressively increasing ammonia nitrogen (NH-N) loads, achieving a Nitrosomonas abundance of 20.7 % and a nitrite accumulation rate exceeding 80 %. Mycelial pellets formed by Cladosporium, isolated from the same AGS system, provided a porous surface structure for the immobilization of the enriched AOB, creating mycelial pellet/AOB composites.
View Article and Find Full Text PDFWater Res
December 2024
Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland. Electronic address:
Aerobic granular sludge (AGS) is usually considered to be a biofilm system consisting of granules only, although practical experience suggests that flocs and granules of various sizes co-exist. This study thus focused on understanding the contribution of flocs and granules of various sizes to nitrification in a full-scale AGS-based wastewater treatment plant (WWTP) operated as a sequencing batch reactor (SBR). The size distribution in terms of total suspended solids (TSS) and the distribution of the nitrifying communities and activities were monitored over 14 months.
View Article and Find Full Text PDFBioresour Technol
January 2025
National and Local Joint Engineering Laboratory of Municipal Sewage Resource Utilization Technology, Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, PR China. Electronic address:
There is limited understanding of the granular partial denitrification/anammox (PD/A) microbiota and metabolic hierarchy specific to municipal wastewater treatment, particularly concerning the multi-mechanisms of functional differentiation and granulation tendencies under high-loading shocks. Therefore, this study utilized fragmented mature biofilm as the exclusive inoculum to rapidly establish a granular PD/A system. Following long-term feeding with municipal wastewater, PD/A process reached a total nitrogen removal efficiency of 97.
View Article and Find Full Text PDFBioresour Technol
January 2025
School of Environmental Engineering, Henan University of Technology, Zhengzhou 450001, China; Zhengzhou International Cooperation Base for Science and Technology on Carbon Neutrality of Organic Solid Waste Conversion, Zhengzhou 450001, PR China; Henan International Joint Laboratory of Environmental Pollution Remediation and Grain Quality Security, Zhengzhou 450001, China.
This study integrates partial denitrification/Anammox (PD/A) with hydroxyapatite (HAP) crystallization in a single reactor, achieving simultaneous nitrogen and phosphorus removal along with phosphorus recovery. By adjusting pH, sludge concentration, low COD/TN ratio, and applying moderate dissolved oxygen stress, the system operated stably and promoted the synergistic growth of HAP and biomass. Results showed a nitrogen removal efficiency (NRE) of 94.
View Article and Find Full Text PDFEnviron Res
January 2025
School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China.
Iron-loaded diatomite (Fe-DE) was developed as the innovative material to enhance anammox granular sludge (AnGS) and mainstream anammox performance. By adding Fe-DE with the Fe:DE ratio of 1:20 and the dosage of 3 g/L, the start-up period of mainstream anammox process was shortened from 29 d to 17 d and its nitrogen removal rate was increased from 0.234 kg N/(m·d) to 0.
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