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Zhang H, Liu WH, Gao YY, Sun P, Zeng YP, Ma LL, Wu JN, Zhou SG, Cui XQ, Zeng RJ, Wang HF. A novel approach for sludge deep-dewatering via flowing-out enhancement but not relying on cell lysis and bound water release. WATER RESEARCH 2024; 257:121743. [PMID: 38728775 DOI: 10.1016/j.watres.2024.121743] [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: 01/24/2024] [Revised: 04/14/2024] [Accepted: 05/05/2024] [Indexed: 05/12/2024]
Abstract
Effective deep-dewatering is crucial for wastewater sludge management. Currently, the dominant methods focus on promoting cell lysis to release intracellular water, but these techniques often lead to secondary pollution and require stringent conditions, limiting their practical use. This study explores an innovative method using a commercially available complex quaternary ammonium salt surfactant, known as G-agent. This agent remarkably reduces the sludge water content from 98.6 % to 56.8 % with a low dosage (50 mg/g DS) and under neutral pH conditions. This approach surpasses Fenton oxidation in terms of dewatering efficiency and avoids the necessity for cell lysis and bound water release, thereby reducing the risk of secondary pollution in the filtrate, including heavy metals, nitrogen, phosphorus, and other contaminants. The G-agent plays a significant role in destabilizing flocs and enhancing flocculation during the conditioning and initial dewatering stages, effectively reducing the solid-liquid interfacial affinity of the sludge. In the compression filtration stage, the agent's solidification effect is crucial in forming a robust skeleton that improves pore connectivity within the filter cake, leading to increased water permeability, drainage performance and water flow-out efficiency. This facilitates deep dewatering of sludge without cell lysis. The study reveals that the G-agent primarily improves water flow-out efficiency rather than water flowability, indicating that cell lysis and bound water release are not indispensable prerequisites for sludge deep-dewatering. Furthermore, it presents an encouraging prospect for overcoming the limitations associated with conventional sludge deep-dewatering processes.
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Affiliation(s)
- Hao Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wen-Hui Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yun-Yan Gao
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ping Sun
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuan-Ping Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lin-Lin Ma
- Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jiang-Nan Wu
- Fujian Haixia Environmental Protection Group Co.,Ltd, Fuzhou 350002, China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xi-Qin Cui
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Raymond Jianxiong Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Hou-Feng Wang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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Lv J, Zhao Q, Jiang J, Ding J, Wei L. Sludge dewaterability improvement with microbial fuel cell powered electro-Fenton system (MFCⓅEFs): Performance and mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171422. [PMID: 38432365 DOI: 10.1016/j.scitotenv.2024.171422] [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: 01/03/2024] [Revised: 02/15/2024] [Accepted: 02/29/2024] [Indexed: 03/05/2024]
Abstract
Throughout the entire process of sludge treatment and disposal, it is crucial to explore stable and efficient techniques to improve sludge dewaterability, which can facilitate subsequent resource utilization and space and cost savings. Traditional Fenton oxidation has been widely researched to enhance the performance of sludge dewaterability, which was limited by the additional energy input and the instabilities of Fe2+ and H2O2. To reduce the consumption of energy and chemicals and further break the rate-limiting step of the iron cycle, a novel and feasible method that constructed microbial fuel cell powered electro-Fenton systems (MFCⓅEFs) with ferrite and biochar electrode (MgFe2O4@BC/CF) was successfully demonstrated. The MFCⓅEFs with MgFe2O4@BC/CF electrode achieved specific resistance filtration and sludge cake water content of 2.52 × 1012 m/kg and 66.54 %. Cellular structure and extracellular polymeric substances (EPS) were disrupted, releasing partially bound water and destroying hydrophilic structures to facilitate sludge flocs aggregation, which was attributed to the oxidation of hydroxyl radicals. The consistent electron supply supplied by MFCⓅEFs and catalytically active sites on the surface of the multifunctional functional group electrode was responsible for producing more hydroxyl radicals and possessing a better oxidizing ability. The study provided an innovative process for sludge dewaterability improvement with high efficiency and low energy consumption, which presented new insights into the green treatment of sludge.
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Affiliation(s)
- Jiaqi Lv
- State Key Laboratory of Urban Water Resources and Environments (SKLURE), School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Qingliang Zhao
- State Key Laboratory of Urban Water Resources and Environments (SKLURE), School of Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Junqiu Jiang
- State Key Laboratory of Urban Water Resources and Environments (SKLURE), School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jing Ding
- State Key Laboratory of Urban Water Resources and Environments (SKLURE), School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Liangliang Wei
- State Key Laboratory of Urban Water Resources and Environments (SKLURE), School of Environment, Harbin Institute of Technology, Harbin 150090, China
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Chen Y, He X, Zhang Y, Cao M, Lin S, Huang W, Pan X, Zhou J. Response of nutrients removal efficiency, enzyme activities and microbial community to current and voltage in a bio-electrical anammox system. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 354:120322. [PMID: 38350279 DOI: 10.1016/j.jenvman.2024.120322] [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: 11/28/2023] [Revised: 01/21/2024] [Accepted: 02/08/2024] [Indexed: 02/15/2024]
Abstract
The effects of different current intensities and voltage levels on nutrient removal performance and microbial community evolution in a Bio-Electrical Anammox (BEA) membrane bioreactor (MBR) were evaluated. The nitrogen removal efficiency increased with the current intensity within the range of 64-83 mA, but this improvement was limited at the current further increased. The phosphorus removal in the BEA MBR was attributed to the release of Fe2+, which was closely associated with the applied current to the electrodes. Heme c concentration, enzyme activities, and specific anammox activity exhibited a decreasing trend, while the functional denitrification genes showed a positive correlation with rising voltage. The nitrogen removal efficiency of the BEA system initially increased and then decreased with the voltage rose from 1.5V to 3.5V, peaking at 2.0V of 94.02% ± 1.19%. Transmission electron microscopy and flow cytometry results indicated that accelerated cell apoptosis/lysis led to an irreversible collapse of the biological nitrogen removal system at 3.5V. Candidatus Brocadia was the predominant anammox bacteria in the BEA system. In contrast, closely related Candidatus Kuenenia and Chloroflexi bacteria were gradually eliminated in electrolytic environment. The abundances of Proteobacteria-affiliated denitrifiers were increased with the voltage rising since the organic matter released by the cell apoptosis/lysis was accelerated at a high voltage level.
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Affiliation(s)
- Yihong Chen
- Power Construction Corporation of China Guiyang Engineering Corporation Limited, Guiyang, 550081, China
| | - Xuejie He
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China
| | - Ying Zhang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China
| | - Meng Cao
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China
| | - Shuxuan Lin
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China
| | - Wei Huang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China
| | - Xinglin Pan
- Power Construction Corporation of China Guiyang Engineering Corporation Limited, Guiyang, 550081, China
| | - Jian Zhou
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
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Ning Z, Ma C, Zhong W, Liu C, Niu J, Wang C, Wang Z. Compound mutation by ultraviolet and diethyl sulfate of protease producing thermophilic bacteria to hydrolyze excess sludge. BIORESOURCE TECHNOLOGY 2024; 395:130330. [PMID: 38224788 DOI: 10.1016/j.biortech.2024.130330] [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: 09/15/2023] [Revised: 01/07/2024] [Accepted: 01/12/2024] [Indexed: 01/17/2024]
Abstract
Excess sludge (ES), a resource-rich organic waste, can be solubilized by thermophilic enzymes to extract proteins for sludge reduction and resources recovery. To solve the problems of low hydrolysis effect of ES and low enzyme producing ability of wild thermophilic bacteria, ultraviolet and diethyl sulfate (UV-DES) were adopted to mutate thermophilic bacteria in this study. Mutation sites were detected and annotated by whole genome sequencing analysis. The results showed that UV-DES mutagenesis could effectively improve enzyme-producing capacity of thermophilic bacteria and promote the hydrolysis of ES. The protease activity of the mutant strain KT16 was 46.7 % higher than that of the original strain DC8. The protein extraction rate with enzyme produced by KT16 reached 83.3 %. The total content of proteins recycled through KT16 enzyme solution was 3539.6 mg·L-1, 18.4 % higher than that of DC8. This work provided a theoretical idea and technical guidance for the protein recovery from ES.
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Affiliation(s)
- Zhifang Ning
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; Pollution Prevention Biotechnology Laboratory of Hebei Province, Shijiazhuang 050018, China
| | - Caiyun Ma
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; Pollution Prevention Biotechnology Laboratory of Hebei Province, Shijiazhuang 050018, China
| | - Weizhang Zhong
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; Pollution Prevention Biotechnology Laboratory of Hebei Province, Shijiazhuang 050018, China.
| | - Chun Liu
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; Pollution Prevention Biotechnology Laboratory of Hebei Province, Shijiazhuang 050018, China
| | - Jianrui Niu
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; Pollution Prevention Biotechnology Laboratory of Hebei Province, Shijiazhuang 050018, China
| | - Changwei Wang
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China
| | - Zhaoyang Wang
- College of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China
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Wei Z, Niu S, Wei Y, Liu Y, Xu Y, Yang Y, Zhang P, Zhou Q, Wang JJ. The role of extracellular polymeric substances (EPS) in chemical-degradation of persistent organic pollutants in soil: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168877. [PMID: 38013104 DOI: 10.1016/j.scitotenv.2023.168877] [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: 09/18/2023] [Revised: 11/16/2023] [Accepted: 11/23/2023] [Indexed: 11/29/2023]
Abstract
Persistent organic pollutants (POPs) in soil show high environmental risk due to their high toxicity and low biodegradability. Studies have demonstrated the degradation function of microbial extracellular polymeric substances (EPS) on POPs in various matrices. However, the degradation mechanisms and the factors that influence the process in soil have not been clearly illustrated. In this review, the characteristics of EPS were introduced and the possible mechanisms of EPS on degradation of organic pollutants (e.g., external electron transfer, photodegradation, and enzyme catalysis) were comprehensively discussed. In addition, the environmental conditions (e.g., UV, nutrients, and redox potential) that could influence the production and degradation-related active components of EPS were addressed. Moreover, the current approaches on the application of EPS in biotechnology were summarized. Further, the future perspectives of enhancement on degradation of POPs by regulating EPS were discussed. Overall, this review could provide a new thought on remediation of POPs by widely-existing EPS in soil with low-cost and minimized eco-disturbance.
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Affiliation(s)
- Zhuo Wei
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Shuai Niu
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Yi Wei
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Yang Liu
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China.
| | - Yaxi Xu
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Yaheng Yang
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Peng Zhang
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Qingqiu Zhou
- Faculty of Environmental Science and Engineering, Kumming University of Science and Technology, Kumming 650500, Yunnan, China
| | - Jim J Wang
- School of Plant, Environment and Soil Sciences, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA
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Hou J, Hong C, Ling W, Hu J, Feng W, Xing Y, Wang Y, Zhao C, Feng L. Research progress in improving sludge dewaterability: sludge characteristics, chemical conditioning and influencing factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119863. [PMID: 38141343 DOI: 10.1016/j.jenvman.2023.119863] [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: 09/11/2023] [Revised: 11/29/2023] [Accepted: 12/12/2023] [Indexed: 12/25/2023]
Abstract
Sludge from wastewater treatment processes with high water content and large volume has become an inevitable issue in environmental management. Due to the challenging dewatering properties of sludge, current mechanical dewatering methods are no longer sufficient to meet the escalating water content standards of sludge. This paper summarizes the characteristics of various sludge and raises reasons for the their dewaterability differences. Affected by extracellular polymeric substances, biological sludge is hydrophilic and negatively charged, which limits the dewatering degree. The rheological properties, flocs, ionic composition, and solid phase concentration of the sludge also influence the dewatering to some extent. For these factors, the chemical conditioning measures with simple operation and excellent effect improve its dewaterability, which mainly include flocculation/coagulation, acid/alkali treatment, advanced oxidation, surfactant treatment and combined treatment. There is a growing necessity to explore the development of new chemical conditioning agents, even though traditional agents continue to remain widely used. However, the development of these new agents should prioritize finding a balance between various factors such as efficiency, effectiveness, ease of operation, environmental safety, and cost-effectiveness. Electrochemical dewatering enhances solid-liquid separation, and its coupling with chemical conditioning is also an excellent means to further reduce water content. In addition, the improvement of press filter is an effective way, which is influenced by pressure, processing time, sludge cake thickness and pore structure, filter media etc. In general, it is essential to develop new conditioning agents and enhance mechanical filtration press technology based on a thorough understanding of various sludge properties. Concurrently, an in-depth study of the principles of mechanical pressure filtration will contribute to establishing a theoretical foundation for effective deep sludge dewatering and propel further advancements in this field.
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Affiliation(s)
- Jiachen Hou
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chen Hong
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Wei Ling
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jiashuo Hu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Weibo Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yi Xing
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yijie Wang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chengwang Zhao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Lihui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
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Zeng H, Tang H, Sun W, Wang L. Deep dewatering of bauxite residue via the synergy of surfactant, coagulant, and flocculant: Effect of surfactants on dewatering and settling properties. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Lu Q, Liu Q, Liu X, Li Y, Yin Z, Wang D. Enhanced dewaterability of anaerobically fermented sludge through acid-driven indigenous enzymatic hydrolysis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 323:116212. [PMID: 36261978 DOI: 10.1016/j.jenvman.2022.116212] [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: 03/05/2022] [Revised: 08/05/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
The poor dewaterability of fermented sludge is an important factor limiting the development of anaerobic fermentation applications. Herein we reported an efficient strategy, i.e., using acidic regulation to stimulate the release of indigenous enzymes, to enhance the hydrolysis and dewatering of fermented sludge. The results showed that after acidic regulation at pH 4.0 for 1 day, the activity of protease and α-glucosidase were improved by 131.4% and 146.0%, while the capillary suction time and specific resistance to filtration were decreased by 93.8% and 69.5%, respectively. Mechanism study revealed that the method firstly destroyed the slime and bound EPS and cells of fermented sludge, causing the release of indigenous enzymes (i.e., protease and α-glucosidase) contained in. Then, the released enzymes directly accelerated the hydrolysis and acidification of fragmentized extracellular polymeric substances, thereby benefited the release of bound water in sludge particles. Finally, such acidic condition decreased the electrostatic repulsive interactions between destroyed sludge particles, further improving their flocculation. The findings not only deepen the understanding of indigenous enzymes contained in fermented sludge affecting sludge dewatering, but also might guide engineers to develop promising strategies to facilitate fermented sludge dewatering and fermentation liquid recovery in the future.
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Affiliation(s)
- Qi Lu
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China.
| | - Qiang Liu
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China.
| | - Xuran Liu
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China
| | - Yifu Li
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China
| | - Zhuo Yin
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China.
| | - Dongbo Wang
- Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China.
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9
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Liu X, Zhai Y, Xu Z, Zhu Y, Zhou Y, Wang Z, Liu L, Ren W, Xie Y, Li C, Xu M. The novel application of type II deep eutectic solvents (DES) for sludge dewatering. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Yuan L, Liu H, Lu Y, Lu Y, Wang D. Enhancing the dewaterability of waste activated sludge by the combined ascorbic acid and zero-valent iron/persulfate system. CHEMOSPHERE 2022; 303:135104. [PMID: 35623430 DOI: 10.1016/j.chemosphere.2022.135104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/15/2022] [Accepted: 05/22/2022] [Indexed: 06/15/2023]
Abstract
In this work, a reducing/chelating agent, ascorbic acid (H2A) was introduced to the traditional zero-valent iron (Fe0)/persulfate (PS) process for waste activated sludge dewatering. The experimental data indicated that H2A-Fe0/PS process significantly enhanced the dewatering performance of sludge and enhanced the oxidation efficiency of Fe0-PS treatment. Under optimal conditions, the capillary suction time ratio before and after treatment (CST0/CST) of H2A-Fe0/PS treated sludge increased by 118% and 31.3% compared with untreated sludge and Fe0-PS treated sludge, respectively. The mechanism investigations revealed that the H2A-Fe0/PS induced excellent enhancement for sludge dewaterability could be credited to the reduction and chelating capacity of ascorbic acid. Free radicals including SO4•-, O2•- and •OH produced in the H2A-Fe0/PS process destroyed proteinaceous components and humic substances in sludge extracellular polymeric substances (EPS), thus reducing the negative charge and water holding capacity of sludge, improving the sludge rheological properties. As a result, the dewatering performance of sludge has been significantly improved.
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Affiliation(s)
- Longhu Yuan
- State Key Laboratory of Hydrology, Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China.
| | - Huaixiang Liu
- State Key Laboratory of Hydrology, Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China.
| | - Yongjun Lu
- State Key Laboratory of Hydrology, Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China.
| | - Yan Lu
- State Key Laboratory of Hydrology, Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
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