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Zhou XR, Wang R, Tang CC, Varrone C, He ZW, Li ZH, Wang XC. Advances, challenges, and prospects in microalgal-bacterial symbiosis system treating heavy metal wastewater. CHEMOSPHERE 2023; 345:140448. [PMID: 37839742 DOI: 10.1016/j.chemosphere.2023.140448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/29/2023] [Accepted: 10/12/2023] [Indexed: 10/17/2023]
Abstract
Heavy metal (HM) pollution, particularly in its ionic form in water bodies, is a chronic issue threatening environmental security and human health. The microalgal-bacterial symbiosis (MABS) system, as the basis of water ecosystems, has the potential to treat HM wastewater in a sustainable manner, with the advantages of environmental friendliness and carbon sequestration. However, the differences between laboratory studies and engineering practices, including the complexity of pollutant compositions and extreme environmental conditions, limit the applications of the MABS system. Additionally, the biomass from the MABS system containing HMs requires further disposal or recycling. This review summarized the recent advances of the MABS system treating HM wastewater, including key mechanisms, influence factors related to HM removal, and the tolerance threshold values of the MABS system to HM toxicity. Furthermore, the challenges and prospects of the MABS system in treating actual HM wastewater are analyzed and discussed, and suggestions for biochar preparation from the MABS biomass containing HMs are provided. This review provides a reference point for the MABS system treating HM wastewater and the corresponding challenges faced by future engineering practices.
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Affiliation(s)
- Xing-Rui Zhou
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Rong Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Cong-Cong Tang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
| | - Cristiano Varrone
- Department of Chemistry and BioScience, Aalborg University, Fredrik Bajers Vej 7H 9220, Aalborg Ø, Denmark
| | - Zhang-Wei He
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Zhi-Hua Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Xiaochang C Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an, 710055, China
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Nabi M, Liang H, Zhou Q, Cao J, Gao D. In-situ membrane fouling control and performance improvement by adding materials in anaerobic membrane bioreactor: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 865:161262. [PMID: 36586290 DOI: 10.1016/j.scitotenv.2022.161262] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/14/2022] [Accepted: 12/24/2022] [Indexed: 06/17/2023]
Abstract
Anaerobic membrane bioreactor (AnMBR) is a promising treatment technique for various types of wastewaters, and is preferred over other conventional aerobic and anaerobic methods. However, membrane fouling is considered a bottleneck in AnMBR system, which technically blocks membrane pores by numerous inorganics, organics, and other microbial substances. Various materials can be added in AnMBR to control membrane fouling and improve anaerobic digestion, and studies reporting the materials addition for this purpose are hereby systematically reviewed. The mechanism of membrane fouling control including compositional changes in extracellular polymeric substances (EPSs) and soluble microbial products (SMPs), materials properties, stimulation of antifouling microbes and alteration in substrate properties by material addition are thoroughly discussed. Nonetheless, this study opens up new research prospects to control membrane fouling of AnMBR, engineered by material, including compositional changes of microbial products (EPS and SMP), replacement of quorum quenching (QQ) by materials, and overall improvement of reactor performance. Regardless of the great research progress achieved previously in membrane fouling control, there is still a long way to go for material-mediated AnMBR applications to be undertaken, particularly for materials coupling, real scale application and molecular based studies on EPSs and SMPs, which were proposed for future researches.
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Affiliation(s)
- Mohammad Nabi
- Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development in Beijing, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Hong Liang
- Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development in Beijing, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Qixiang Zhou
- Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development in Beijing, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Jiashuo Cao
- Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development in Beijing, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Dawen Gao
- Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development in Beijing, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing 100044, China.
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Wan C, Fu L, Li Z, Liu X, Lin L, Wu C. Formation, application, and storage-reactivation of aerobic granular sludge: A review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 323:116302. [PMID: 36150350 DOI: 10.1016/j.jenvman.2022.116302] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/31/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
It was an important discovery in wastewater treatment that the microorganisms in the traditional activated sludge can form aerobic granular sludge (AGS) by self-aggregation under appropriate water quality and operation conditions. With a typical three-dimensional spherical structure, AGS has high sludge-water separation efficiency, great treatment capacity, and strong tolerance to toxic and harmful substances, so it has been considered to be one of the most promising wastewater treatment technologies. This paper comprehensively reviewed AGS from multiple perspectives over the past two decades, including the culture conditions, granulation mechanisms, metabolic and structural stability, storage, and its diverse applications. Some important issues, such as the reproducibility of culture conditions and the structural and functional stability during application and storage, were also summarized, and the research prospects were put forward. The aggregation behavior of microorganisms in AGS was explained from the perspectives of physiology and ecology of complex populations. The storage of AGS is considered to have large commercial potential value with the increase of large-scale applications. The purpose of this paper is to provide a reference for the systematic and in-depth study on the sludge aerobic granulation process.
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Affiliation(s)
- Chunli Wan
- Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China
| | - Liya Fu
- Research Center of Environmental Pollution Control Engineering Technology, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Zhengwen Li
- Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China
| | - Xiang Liu
- Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.
| | - Lin Lin
- Environmental Science and New Energy Technology Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen, 518055, China
| | - Changyong Wu
- Research Center of Environmental Pollution Control Engineering Technology, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
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Hydroxyapatite Precipitation and Accumulation in Granules and Its Effects on Activity and Stability of Partial Nitrifying Granules at Moderate and High Temperatures. Processes (Basel) 2021. [DOI: 10.3390/pr9101710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Precipitation and accumulation of calcium phosphate in granular sludge has attracted research attention recently for phosphate removal and recovery from wastewater. This study investigated calcium phosphate accumulation from granulation stage to steady state by forming heterotrophic granules at different COD/N ratios at 21 and 32 °C, respectively, followed by the transformation of heterotrophic granules to partial nitrifying granules. It was found that mature granules accumulated around 60–80% minerals in granules, much higher than young granules with only around 30% ash contents. In addition, high temperature promoted co-precipitation of hydroxyapatite and calcite in granules with more calcite than hydroxyapatite and only 4.1% P content, while mainly hydroxyapatite was accumulated at the moderate temperature with 7.7% P content. The accumulation of minerals in granules at the high temperature with 75–80% ash content also led to the disintegration and instability of granules. Specific ammonium oxidation rates were reduced, as well, from day 58 to day 121 at both temperatures due to increased mineral contents. These results are meaningful to control or manipulate granular sludge for phosphorus removal and recovery by forming and accumulating hydroxyapatite in granules, as well as for the maintenance of microbial activities of granules.
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Lin H, Wang Q, Zhou J, Wang D, Men Y, Bai Y, Qu J. Recovery trajectories and community resilience of biofilms in receiving rivers after wastewater treatment plant upgrade. ENVIRONMENTAL RESEARCH 2021; 199:111349. [PMID: 34019892 DOI: 10.1016/j.envres.2021.111349] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 06/12/2023]
Abstract
Wastewater treatment plant (WWTP) upgrades can reduce both nutrient and micropollutant emissions into receiving rivers, thus modifying the composition and function of biological communities. However, how microbial communities vary and whether they can be restored to levels found in less-polluted rivers remains uncertain. Aquatic biofilms are sensitive to environmental change and respond rapidly to bottom-up pressure. Thus, we used 12 flumes configured in three experimental treatments to mimic the dynamic processes of biofilm microbial communities occurring in a wastewater-receiving river following WWTP upgrade, with rivers containing two levels of nutrients and micropollutants used as references. We compared the biofilm microbial biomass, carbon source utilization, and community composition among the three "blocks". Results showed that the metabolic patterns of the carbon sources and composition of the biofilm bacterial communities in the flumes mimicking a receiving river with WWTP upgrade recovered over time to those mimicking a less-disturbed river. The restoration of potential carboxylic acid-consuming denitrifying bacteria (i.e., Zoogloea, Comamonas, Dechloromonas, and Acinetobacter) likely played a significant role in this process. Combining quantitative analysis of the denitrification genes nirS and nosZ, we confirmed that the denitrification function of the river biofilms recovered after WWTP upgrade, consistent with our previous field investigation.
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Affiliation(s)
- Hui Lin
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiaojuan Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jie Zhou
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Donglin Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yujie Men
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, United States
| | - Yaohui Bai
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
| | - Jiuhui Qu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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Sun M, Zhang Z, Liu G, Lv M, Feng Y. Enhancing methane production of synthetic brewery water with granular activated carbon modified with nanoscale zero-valent iron (NZVI) in anaerobic system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143933. [PMID: 33341639 DOI: 10.1016/j.scitotenv.2020.143933] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Anaerobic digestion is an effective treatment technology for wastewater. However, long HRT and low CH4 production limit the application of anaerobic treatment. Iron-based materials, carbon-based materials and Fe-C composite particles have been used in anaerobic processes. However, the strengthening effect of Fe-C composite particles on anaerobic systems requires further research. In this study, granular activated carbon (GAC) loaded with nanoscale zero-valent iron (NZVI) was prepared by a co-precipitation method and its morphology was characterized. Different concentrations of GAC-NZVI particles were used in the batch experiment to study the enhancing effect of the anaerobic biological treatment process. The water quality, sludge properties and microbial community were analyzed. The degradation rate of COD and total CH4 production increased by 9.38% and 14.29% with particles at a concentration of 1000 mg/L, respectively. The average methane yield was 169.86 mL CH4/g-COD removed, which was 9.39% higher than that of the control. The measurement results of extracellular polymeric substance (EPS), conductivity, cyclic voltammetry (CV) and Fe concentration indicated that the composite particles showed excellent electrical conductivity and promoted microorganism metabolism, which accelerated the use of substrates and methane generation. The 3-dimensional excitation (Ex) - emission (Em) matrix (3D-EEM) fluorescence spectroscopy of soluble microbial product (SMP) and EPS indicated that the particles could affect the endogenous respiration of microorganisms. Microbial community analysis revealed that the dominant genus Methanothrix (acetoclastic methanogens) increased by 13.32%, which could strengthen acetoclastic methanogenesis and lead to higher CH4 production. The abundance of hydrogenotrophic archaea decreased after the addition of GAC-NZVI. These results provide an alternate method for enhancing anaerobic wastewater treatment using conductive particles.
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Affiliation(s)
- Muchen Sun
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090, China
| | - Zhaohan Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090, China
| | - Guohong Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090, China
| | - Miao Lv
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090, China
| | - Yujie Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090, China.
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Wang S, Zhi L, Shan W, Lu H, Xu Q, Li J. Correlation of extracellular polymeric substances and microbial community structure in denitrification biofilm exposed to adverse conditions. Microb Biotechnol 2020; 13:1889-1903. [PMID: 32700468 PMCID: PMC7533329 DOI: 10.1111/1751-7915.13633] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 07/01/2020] [Indexed: 01/24/2023] Open
Abstract
Microbial community may respond to different adverse conditions and result in the variation of extracellular polymeric substances (EPS) in denitrification biofilm; this study discovered the role of EPS in accordance with the analysis of cyclic diguanylate (c-di-GMP) and electron equilibrium (EE) under low organic loading rate, shock organic loading rate and low temperature conditions. Good nitrate removal performance could be achieved under shock organic loading rate and low temperature conditions; however, owing to the low organic loading rate, the carbon source was preferentially utilized for biomass growth. Tightly bound EPS (TB-EPS) contents progressively increased and facilitated cell adhesion and biofilm formation. The stable TB protein (TB-PN) content in TB-EPS built a cross-linked network to maintain internal biofilm structure and led to the rapid biosynthesis of polysaccharides, which could further enhance microbial adhesion and improve nitrate removal. C-di-GMP played an important role in biomass retention and biofilm formation, based on the correlation analysis of c-di-GMP and EPS. TB polysaccharide (TB-PS) contents presented a significant positive correlation with c-di-GMP content, microbial adhesion and biofilm stabilization was further enhanced through c-di-GMP regulation. In addition, a remarkable negative correlation between electron deletion rate (EDR) and TB-PN and TB-PS was discovered, and TB-PS was required to serve as energy source to enhance denitrification according to EE analysis. Surprisingly, dynamic microbial community was observed due to the drastic community succession under low temperature conditions, and the discrepancy between the dominant species for denitrification was found under shock organic loading rate and low temperature conditions. The notable increase in bacterial strains Simlicispira, Pseudomonas and Chryseobacterium was conducive to biofilm formation and denitrification under shock organic loading rate, while Dechloromonas and Zoogloea dramatically enriched for nitrate removal under low temperature conditions. The high abundance of Dechloromonas improved the secretion of EPS through the downstream signal transduction, and the c-di-GMP conserved in Pseudomonas concurrently facilitated to enhance exopolysaccharide production to shock organic loading rate and low temperature conditions.
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Affiliation(s)
- Shuo Wang
- Jiangsu Key Laboratory of Anaerobic BiotechnologySchool of Environment and Civil EngineeringJiangnan UniversityWuxi214122China
- Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction TechnologyJiangnan UniversityWuxi214122China
- Jiangsu College of Water Treatment Technology and Material Collaborative Innovation CenterSuzhou215009China
- Department of Civil EngineeringSchulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada
| | - Liling Zhi
- Jiangsu Key Laboratory of Anaerobic BiotechnologySchool of Environment and Civil EngineeringJiangnan UniversityWuxi214122China
| | - Wei Shan
- Jiangsu Key Laboratory of Anaerobic BiotechnologySchool of Environment and Civil EngineeringJiangnan UniversityWuxi214122China
| | - Hui Lu
- School of Environmental Science and EngineeringSun Yat‐sen UniversityGuangzhou510006China
| | - Qiao Xu
- Jiangsu Key Laboratory of Anaerobic BiotechnologySchool of Environment and Civil EngineeringJiangnan UniversityWuxi214122China
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic BiotechnologySchool of Environment and Civil EngineeringJiangnan UniversityWuxi214122China
- Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction TechnologyJiangnan UniversityWuxi214122China
- Jiangsu College of Water Treatment Technology and Material Collaborative Innovation CenterSuzhou215009China
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Wang S, Zou L, Li H, Zheng K, Wang Y, Zheng G, Li J. Full-scale membrane bioreactor process WWTPs in East Taihu basin: Wastewater characteristics, energy consumption and sustainability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 723:137983. [PMID: 32222501 DOI: 10.1016/j.scitotenv.2020.137983] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/12/2020] [Accepted: 03/15/2020] [Indexed: 06/10/2023]
Abstract
Based on the collection and analysis of essential data from wastewater treatment plants (WWTPs) in recent ten years, the work provides the wastewater characteristics and energy consumption performance in full-scale membrane bioreactor (MBR) process in East Taihu basin, China. High-quality effluent was achieved although the influent carbon source was not beneficial to total nitrogen and total phosphorus removal. The average specific energy consumption (SEC) was 0.52 kWh/m3, which was remarkably lower than that of full-scale MBR process in developed countries, however, the average SEC value was higher than that of conventional activated sludge (CAS) process in China. In addition, the SEC value was largely reduced in 2018, and the regulation of suction pump and aeration mode were considered as the main control methods. Energy consumption will increase along with the influent volume, while the elevation of COD and NH4+-N reduction will bring about relatively low energy consumption. Furthermore, sustainability index was established to comprehensively evaluate the performance of full-scale MBR process, meaning that with relatively low permeate ratio of effluent, full-scale MBR process presented to be inferior to CAS process in sustainability and not feasible to be applied in the upgradation and construction of WWTPs.
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Affiliation(s)
- Shuo Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou 215009, China; Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary T2N 1N4, Canada
| | - Luxi Zou
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Huaibo Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Kaikai Zheng
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Yan Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Guochen Zheng
- Songliao River Basin Administration of Water Resources Protection, Changchun 130021, China
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou 215009, China.
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Xu J, Pang H, He J, Nan J. The effect of supporting matrix on sludge granulation under low hydraulic shear force: Performance, microbial community dynamics and microorganisms migration. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 712:136562. [PMID: 32050387 DOI: 10.1016/j.scitotenv.2020.136562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/12/2019] [Accepted: 01/04/2020] [Indexed: 06/10/2023]
Abstract
Granular sludge usually takes extracellular polymers (EPS) as matrices for colonizing microorganisms and maintaining structural stability. However, the low strength of EPS threatens the disintegration of granules, especially under low hydraulic shear force. To accelerate the formation and enhance the stability of granules, micro-sized melamine (ME) sponges (RA) and polyurethane (PU) sponges (RB) were screened out as matrix substitutes for developing aerobic granular biofilm (AGB) in this study. The superficial gas velocity was 0.8 cm s-1. Both reactors achieved over 95% ammonium nitrogen removal efficiency within 10 days. During stabilization period, the chemical oxygen demand, total nitrogen and total phosphorus removal efficiencies were 90.5%, 70% and 95% in RA and 87.8%, 83% and 88% in RB, respectively. Confocal laser scanning microscopy (CLSM) detection revealed that β-polysaccharide was more concentrated in the outer layer in PU-AGB but uniformly dispersed in ME-AGB. The denitrifying phosphorus accumulating organisms (Flavobacterium) was dominant in RA, while the denitrifying glycogen accumulating organisms (Candidatus_Competibacter) was dominant in RB. Fluorescence in situ hybridization (FISH) analysis indicated that the microbial distribution in ME-AGB was relatively uniform, while there was a significant migration of functional microorganisms in PU-AGB. The super-hydrophilicity of ME and the high hydrophobicity of PU may be the main reasons for these differences. Overall, this study indicated that ME sponge is a more suitable material for supporting AGB than PU sponge.
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Affiliation(s)
- Jie Xu
- School of Environment, Harbin Institute of Technology (HIT), Harbin 150090, China
| | - Heliang Pang
- School of Environment, Harbin Institute of Technology (HIT), Harbin 150090, China.
| | - Junguo He
- Guangzhou University, Guangzhou 510006, China
| | - Jun Nan
- School of Environment, Harbin Institute of Technology (HIT), Harbin 150090, China
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10
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Wang S, Ma C, Zhu Y, Yang Y, Du G, Li J. Deep dewatering process of sludge by chemical conditioning and its potential influence on wastewater treatment plants. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:33838-33846. [PMID: 29905896 DOI: 10.1007/s11356-018-2351-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
FeCl3, quick lime, and cationic polyacrylamide (CPAM) were used for excess sludge conditioning from wastewater treatment plant (WWTP) and the dewatering performance by different chemical conditioners was investigated. Experimental results showed that FeCl3 could make small and concentrated sludge particles. Furthermore, new mineral phase structures for building a dewatering framework were obtained by the addition of quick lime, and the coagulation capacity was enhanced by the formation of colloid hydroxyl polymer, which was induced due to the alkaline environment. In addition, the floc particle size significantly increased after the CPAM dosage. The bound water could be released with the stripping of tightly bound extracellular polymeric substance (EPS). Therefore, the dewatering performance and efficiencies were improved and subsequently the hypothetical sludge deep dewatering process was depicted in accordance with the variation of EPS. However, high-strength refractory organics in sludge filtrates caused by quick lime pyrolysis could lead to the unstable operation of the WWTP, because the relatively high concentrations of organic compounds with benzene were dominant in sludge dewatering filtrates.
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Affiliation(s)
- Shuo Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
- Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China
| | - Cong Ma
- State Key Laboratory of Separation Membranes and Membrane Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin, 300387, China.
| | - Yin Zhu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Yangkun Yang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Guocheng Du
- Ministry Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China.
- Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China.
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Liu Z, Li N, Gao M, Wang J, Zhang A, Liu Y. Synergistic strengthening mechanism of hydraulic selection pressure and poly aluminum chloride (PAC) regulation on the aerobic sludge granulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 650:941-950. [PMID: 30308868 DOI: 10.1016/j.scitotenv.2018.08.389] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/26/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
This study aimed to enhance aerobic granulation by the integration of hydraulic selection pressure (HSP) and poly aluminum chloride (PAC) regulation. Based on an investigation of sludge characteristics, microbial aggregation and extracellular polymeric substances (EPS) secretion, the synergistic mechanisms of HSP and PAC regulation were revealed. For granule formation, HSP primarily improved the cell hydrophobicity and extracellular protein production, while PAC regulation markedly neutralized the surface charge of cells and reduced the interaction energy between them. In addition, biomass retention was also facilitated by the PAC dosing. Notably, the results of total interaction energy and flocculating ability imply that prior HSP screening could significantly promote PAC regulation on microbial aggregation. To optimize the balance between granule formation and reactor performances, five kinds of integrated strategies for HSP and PAC regulation were conducted in batch test. According to the results, 4.3 g/L initial mixed liquor volatile suspended solids (MLVSS) was preferred before the addition of PAC.
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Affiliation(s)
- Zhe Liu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road, No.13, Xi'an 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ning Li
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road, No.13, Xi'an 710055, China
| | - Min Gao
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road, No.13, Xi'an 710055, China
| | - Jiaxuan Wang
- School of Architecture and Civil Engineering, Xi'an University of Science and Technology, Yan Ta Road, No.58, Xi'an 710054, China
| | - Aining Zhang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road, No.13, Xi'an 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yongjun Liu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road, No.13, Xi'an 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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12
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Wang S, Qian K, Zhu Y, Yi X, Zhang G, Du G, Tay JH, Li J. Reactivation and pilot-scale application of long-term storage denitrification biofilm based on flow cytometry. WATER RESEARCH 2019; 148:368-377. [PMID: 30396102 DOI: 10.1016/j.watres.2018.10.072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/16/2018] [Accepted: 10/25/2018] [Indexed: 06/08/2023]
Abstract
The work provides a method on the basis of flow cytometry to evaluate the performance of denitrification biofilm during the preservation, reactivation and pilot-scale operation process. The viable cell ratio of denitrification biofilm significantly reduced and further led to the decrease of denitrification capacity after long-term preservation for 5 months. Protein component in tightly bound extracellular polymeric substances (TB-EPS) could serve to enhance microbial adhesion and promote denitrification biofilm formation. With the significant correlation of viable cell ratio and microbial characteristics, 4 °C was more appropriate for preserving denitrification biofilm and conducive to maintain the relatively high denitrification capacity. A maximum denitrification rate of 5.80 gNO3--N/m2·d was obtained in pilot-scale anoxic-oxic (AO) process and Dechloromonas became greater prevalence in denitrification suspended carriers. Furthermore, the enrichment of Pseudomonas, Parcubacteria, Acidovorax, Aquabacterium and Unclassified_Flavobacteriaceae enhanced biofilm formation and nutrient conservation. The significantly positive correlation between viable cell ratio and the ratio of nitrate reduction to COD consumption was discovered, and the indices of Chao, ACE, Shannon and Simpson of denitrification biofilm were positively correlated with viable cell ratio, meaning that flow cytometry analysis was reasonable and suitable to evaluate the performances of denitrification biofilm.
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Affiliation(s)
- Shuo Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China; Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, T2N 1N4, Canada
| | - Kai Qian
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Yin Zhu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Xuesong Yi
- School of Environmental Science and Engineering, Hainan University, Haikou, 570028, China
| | - Guangsheng Zhang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China
| | - Guocheng Du
- Ministry Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Joo-Hwa Tay
- Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, T2N 1N4, Canada
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China.
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13
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Xu J, He J, Wang M, Li L. Cultivation and stable operation of aerobic granular sludge at low temperature by sieving out the batt-like sludge. CHEMOSPHERE 2018; 211:1219-1227. [PMID: 30223338 DOI: 10.1016/j.chemosphere.2018.08.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/03/2018] [Accepted: 08/04/2018] [Indexed: 06/08/2023]
Abstract
Aerobic granules were successfully cultivated at 10 °C with relatively low strength substrate. Stable granules coexisted with the batt-like sludge (BLS) were obtained in 60 days. After removing the BLS, nutrient removal performance was greatly improved and stable removal efficiencies of 99% phosphorous, 98% ammonia and 60% TN were achieved. The bacterial community structure revealed that it was an unclassified-Comamonadaceae genus dominant in the BLS, which represented for low relative abundance in mature granules. Overgrowth of unclassified-Comamonadaceae genus was considered to be the key factor for inhibiting the performance of granules. The final configuration of granules was dominated by DPAO genus Flavobacterium and polysaccharide nutritional genus Chryseolinea. This study showed that stable aerobic granules with superior performance under low temperature could be successfully cultivated by sieving out the BLS.
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Affiliation(s)
- Jie Xu
- School of Environment, Harbin Institute of Technology (HIT), Harbin, 150090, China
| | - Junguo He
- School of Environment, Harbin Institute of Technology (HIT), Harbin, 150090, China.
| | - Mengfei Wang
- School of Environment, Harbin Institute of Technology (HIT), Harbin, 150090, China
| | - Lin Li
- School of Environment, Harbin Institute of Technology (HIT), Harbin, 150090, China
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14
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Gonzalez-Martinez A, Muñoz-Palazon B, Rodriguez-Sanchez A, Maza-Márquez P, Mikola A, Gonzalez-Lopez J, Vahala R. Start-up and operation of an aerobic granular sludge system under low working temperature inoculated with cold-adapted activated sludge from Finland. BIORESOURCE TECHNOLOGY 2017; 239:180-189. [PMID: 28521227 DOI: 10.1016/j.biortech.2017.05.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/04/2017] [Accepted: 05/07/2017] [Indexed: 06/07/2023]
Abstract
An aerobic granular sludge system has been started-up and operated at 7°C temperature using cold-adapted activated sludge as inoculum. The system could form granular biomass due to batch operation allowing for just 5-3min of biomass sedimentation. Scanning electron microscopy showed that fungi helped in the granular biomass formation in the early stages of the granule formation. The removal performance of the system was of 92-95% in BOD5, 75-80% in COD, 70-76% in total nitrogen and 50-60% in total phosphorous. The bacterial community structure from cold-adapted activated sludge changed during the operational time, leading to a final configuration dominated by Microbacteriaceae members Microbacterium and Leucobacter, which were strongly correlated to biomass settling velocity and bioreactor performance, as suggested by multivariate redundancy analyses. This experiment showed that aerobic granular sludge systems could be successfully started-up and operated, with high performance, under low operational temperatures when using cold-adapted biomass as inoculum.
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Affiliation(s)
| | - Barbara Muñoz-Palazon
- Institute of Water Research, University of Granada, C/Ramon y Cajal, 4, 18071 Granada, Spain
| | | | - Paula Maza-Márquez
- Institute of Water Research, University of Granada, C/Ramon y Cajal, 4, 18071 Granada, Spain
| | - Anna Mikola
- Department of Built Environment, University of Aalto, P.O. Box 15200, Aalto, FI-00076 Espoo, Finland
| | - Jesus Gonzalez-Lopez
- Institute of Water Research, University of Granada, C/Ramon y Cajal, 4, 18071 Granada, Spain
| | - Riku Vahala
- Department of Built Environment, University of Aalto, P.O. Box 15200, Aalto, FI-00076 Espoo, Finland
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15
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Wang D, Ma W, Han H, Li K, Xu H, Fang F, Hou B, Jia S. Enhanced anaerobic degradation of Fischer-Tropsch wastewater by integrated UASB system with Fe-C micro-electrolysis assisted. CHEMOSPHERE 2016; 164:14-24. [PMID: 27573211 DOI: 10.1016/j.chemosphere.2016.08.074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 08/06/2016] [Accepted: 08/16/2016] [Indexed: 06/06/2023]
Abstract
Coupling of the Fe-C micro-electrolysis (IC-ME) into the up-flow anaerobic sludge blanket (UASB) was developed for enhanced Fischer-Tropsch wastewater treatment. The COD removal efficiency and methane production in R3 with IC-ME assisted both reached up to 80.6 ± 1.7% and 1.38 ± 0.11 L/L·d that higher than those values in R1 with GAC addition (63.0 ± 3.4% and 0.95 ± 0.09 L/L·d) and R2 with ZVI addition (74.5 ± 2.8% and 1.21 ± 0.09 L/L·d) under the optimum HRT (5 d). The Fe corrosion as electron donor reduced the ORP values and stimulated the activities of hydrogenotrophic methanogens to lower H2 partial pressure in R2 and R3. Additionally, Fe2+ as by-product of iron corrosion, its presence could effectively increase the percentage of protein content in tightly bound extracellular polymeric substances (TB-EPS) to promote better bioflocculation, increasing to 90.5 mg protein/g·VSS (R2) and 106.3 mg protein/g·VSS (R3) while this value in R1 was simply 56.6 mg protein/g·VSS. More importantly, compared with R1, the excess accumulation of propionic acid and butyric acid in system was avoided. The macroscopic galvanic cells around Fe-C micro-electrolysis carriers in R3, that larger than microscopic galvanic cells in R2, further accelerate to transfer the electrons from anodic Fe to cathodic carbon that enhance interspecies hydrogen transfer, making the decomposition of propionic acid and butyric acid more thermodynamically feasible, finally facilitate more methane production.
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Affiliation(s)
- Dexin Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Wencheng Ma
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Hongjun Han
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Kun Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Hao Xu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Fang Fang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Baolin Hou
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Shengyong Jia
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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16
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Liu YQ, Tay JH. Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate. WATER RESEARCH 2015; 80:256-266. [PMID: 26005786 DOI: 10.1016/j.watres.2015.05.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 04/01/2015] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
The combined strong hydraulic selection pressure (HSP) with overstressed organic loading rate (OLR) as a fast granulation strategy was used to enhance aerobic granulation. To investigate the wide applicability of this strategy to different scenarios and its relevant mechanism, different settling times, different inoculums, different exchange ratios, different reactor configurations, and different shear force were used in this study. It was found that clear granules were formed within 24 h and steady state reached within three days when the fast granulation strategy was used in a lab-scale reactor seeded with well settled activated sludge (Reactor 2). However, granules appeared after 2-week operation and reached steady state after one month at the traditional step-wise decreased settling time from 20 to 2 min with OLR of 6 g COD/L·d (Reactor 1). With the fast granulation strategy, granules appeared within 24 h even with bulking sludge as seed to start up Reactor 3, but 6-day lag phase was observed compared with Reactor 2. Both Reactor 2 and Reactor 3 experienced sigmoidal growth curve in terms of biomass accumulation and granule size increase after granulation. In addition, the reproducible results in pilot-scale reactors (Reactor 5 and Reactor 6) with diameter of 20 cm and height/diameter ratio (H/D) of 4 further proved that reactor configuration and fluid flow pattern had no effect on the aerobic granulation when the fast granulation strategy was employed, but biomass accumulation experienced a short lag phase too in Reactor 5 and Reactor 6. Although overstressed OLR was favorable for fast granulation, it also led to the fluffy granules after around two-week operation. However, the stable 6-month operation of Reactor 3 demonstrated that the rapidly formed granules were able to maintain long-term stability by reducing OLR from 12 g COD/L·d to 6 g COD/L·d. A mechanism of fast granulation with the strategy of combined strong HSP and OLR was proposed to explain results and guide the operation with this fast strategy.
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Affiliation(s)
- Yong-Qiang Liu
- Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
| | - Joo-Hwa Tay
- Schulich School of Engine, University of Calgary, 2500 University Dr NW, Calgary, Alberta, T2N 1N4, Canada
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17
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Influence of calcium, magnesium, and iron ions on aerobic granulation. Appl Biochem Biotechnol 2014; 174:2910-8. [PMID: 25240847 PMCID: PMC4237934 DOI: 10.1007/s12010-014-1236-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 09/10/2014] [Indexed: 11/06/2022]
Abstract
In this study, we investigated the effect of different multivalent cations on granule formation. Previous experiments showed that formation of matrix EPS and their structure depend of the presence of divalent cations. This study indicates that trivalent cations are also playing an important role. However, the more compact granules were formed in the presence of all cations. The authors tried also to determine changes in proteomic profile of slime and tightly bound EPS. These results showed that matrix EPS is composed of a variety of large and complex proteins, but there are also small proteins, like for example, lectins. These small proteins have a role in the interaction between cells and exopolysaccharides and in granules formation.
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18
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Recovery of stored aerobic granular sludge and its contaminants removal efficiency under different operation conditions. BIOMED RESEARCH INTERNATIONAL 2013; 2013:168581. [PMID: 24106695 PMCID: PMC3784152 DOI: 10.1155/2013/168581] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 06/27/2013] [Indexed: 11/18/2022]
Abstract
The quick recovery process of contaminants removal of aerobic granular sludge (AGS) is complex, and the influencing factors are still not clear. The effects of dissolved oxygen (DO, air intensive aeration rate), organic loading rate (OLR), and C/N on contaminants removal characteristics of AGS and subsequently long-term operation of AGS bioreactor were investigated in this study. DO had a major impact on the recovery of AGS. The granules reactivated at air intensive aeration rate of 100 L/h achieved better settling property and contaminants removal efficiency. Moreover, protein content in extracellular polymeric substance (EPS) was almost unchanged, which demonstrated that an aeration rate of 100 L/h was more suitable for maintaining the biomass and the structure of AGS. Higher OLR caused polysaccharides content increase in EPS, and unstable C/N resulted in the overgrowth of filamentous bacteria, which presented worse NH4+-N and PO43−-P removal. Correspondingly, quick recovery of contaminants removal was accomplished in 12 days at the optimized operation conditions of aeration rate 100 L/h, OLR 4 g/L·d, and C/N 100 : 10, with COD, NH4+-N, and PO43−-P removal efficiencies of 87.2%, 86.9%, and 86.5%, respectively. The renovation of AGS could be successfully utilized as the seed sludge for the rapid start-up of AGS bioreactor.
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