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Zhang Q, Tang T, Cui G, Wang Z, Liu Y. Pressurized electro-osmotic dewatering treatment of sludge: focusing on the influences on nutrients for agricultural application. Environ Technol 2023:1-15. [PMID: 37970842 DOI: 10.1080/09593330.2023.2283090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 09/09/2023] [Indexed: 11/19/2023]
Abstract
Sewage sludge requires effective dewatering and high nutrients retention before disposal for agricultural application. Pressurized electro-osmotic dewatering (PEOD) process with low energy consumption can effectively remove water from sludge, but the influences of PEOD process on nutrients for agricultural application still lacks in-depth research. In this study, the influences of PEOD process on nutrients for agricultural application were investigated, including organic matter, nitrogen, phosphorus, potassium and silicon contents. Layered experiments were conducted to investigate the layered variation of nutrients in sludge and to understand the potential change mechanisms. The experimental results showed that PEOD process caused small losses (<10%) of organic matter and total phosphorus (TP) in sludge, but caused 11.2-18.4% loss of total nitrogen (TN). PEOD process also caused 18.6-27.0% loss of total potassium (TK) and over 80% loss of available potassium in sludge, and could weaken the potential salt damage during the agricultural application of sludge. Furthermore, the available phosphorus content of sludge in the anode area increased significantly after the PEOD process, indicating that PEOD process could enhance the phosphorus bioavailability of sludge in the anode area. Besides, PEOD process caused a slight loss of silicon components in sludge, but improved the long-term silicon dissolution and release ability of sludge. This work could expand the knowledge about the influences of PEOD process on sludge nutrients and provide scientific guidance for the agricultural application of PEOD sludge.
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Affiliation(s)
- Qiming Zhang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, People's Republic of China
| | - Tian Tang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, People's Republic of China
| | - Guodong Cui
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, People's Republic of China
| | - Zheng Wang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, People's Republic of China
| | - Yangsheng Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, People's Republic of China
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2
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Zhang Q, Cui G, He X, Wang Z, Tang T, Zhao Q, Liu Y. Effects of voltage and pressure on sludge electro-dewatering process and the dewatering mechanisms investigation. Environ Res 2022; 212:113490. [PMID: 35594958 DOI: 10.1016/j.envres.2022.113490] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/31/2022] [Accepted: 05/14/2022] [Indexed: 06/15/2023]
Abstract
Electro-dewatering technology shows a good application prospect because of its high efficiency in removing water from sludge and low energy consumption, but the potential mechanisms of sludge electro-dewatering have not been investigated in depth, which seriously limits the further development and application of electro-dewatering technology. In this study, the effects of voltage and pressure on sludge electro-dewatering performance, physicochemical characteristics and extracellular polymeric substances (EPS) compositions and distributions were investigated. The spatial distributions of EPS main components, including polysaccharide (PS) and protein (PN), were characterized by a confocal laser scanning microscopy (CLSM). The experimental results showed that under the conditions of a voltage of 40 V and a pressure of 90 kPa, the moisture content of sludge was reduced from 83.15% to 53.12%, and the bound water content of sludge in the anode layer, middle layer and cathode layer were decreased significantly from 1.16 g/g dry solid (DS) to 0.20, 0.47 and 0.35 g/g DS, respectively. The PN content of EPS in anode layer was significantly lower than that in cathode layer due to the electrochemical oxidation, while the variation of PS content showed the opposite trend, which agreed with the results visualized by CLSM. Pearson's correlation coefficient and hierarchical cluster analysis revealed that PN in TB-EPS was the major factor influencing the effect of sludge electro-dewatering. This work can be helpful to understand the potential mechanisms of electro-dewatering and provide theoretical support for the further popularization and application of electro-dewatering technology.
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Affiliation(s)
- Qiming Zhang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Guodong Cui
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Xiao He
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Zheng Wang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Tian Tang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Qing Zhao
- State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum, Beijing, 102249, China
| | - Yangsheng Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China.
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3
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Cai M, Qian Z, Xiong X, Dong C, Song Z, Shi Y, Wei Z, Jin M. Cationic polyacrylamide (CPAM) enhanced pressurized vertical electro-osmotic dewatering of activated sludge. Sci Total Environ 2022; 818:151787. [PMID: 34808190 DOI: 10.1016/j.scitotenv.2021.151787] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/10/2021] [Accepted: 11/14/2021] [Indexed: 06/13/2023]
Abstract
Pressurized vertical electro-osmotic dewatering (PVEOD) has been regarded as a feasible method to achieve sludge deep-dewatering, but the dewatering efficiency is still challenged by high electric resistance. This study employed cationic polyacrylamide (CPAM) as a skeleton builder to enhance electro-osmotic flow in PVEOD. The sludge dewatering efficiency and synergistic effect of CPAM and PVEOD were elucidated. The sludge morphology, surface property, extracellular polymeric substances (EPS) destruction and migration, spatial distributions of proteins and polysaccharides, and current changes were investigated. After the addition of optimal CPAM dose, the sludge formed a uniform and porous structure that provided water channels and enhanced electric transport, thus promoting EPS destruction. The sludge moisture content (MC) analysis indicated the more liberation of bound water due to EPS destruction. Besides, the re-flocculation of disintegrated sludge flocs improved the sludge filtration and thus dewaterability. Instantaneous energy consumption (Et,0.5) was optimized and two-step synergistic mechanism was thus proposed. These findings indicated that the combination of CPAM and PVEOD is a promising strategy to broaden the scope of industrial application of sludge deep-dewatering.
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Affiliation(s)
- Meiqiang Cai
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zhuohui Qian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Xingaoyuan Xiong
- Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Universitetsbyen 36, 8000 Aarhus C, Denmark
| | - Chunying Dong
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
| | - Zhijun Song
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Yuejing Shi
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zongsu Wei
- Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Universitetsbyen 36, 8000 Aarhus C, Denmark
| | - Micong Jin
- Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China; Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China
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4
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Wang HF, Qi HY, Lian ZH, Zhang YL, Li J, Zeng RJ. A unified operating procedure is crucial to evaluate sludge dewaterability, taking the setup of refrigerated storage time as an example. J Environ Manage 2022; 307:114528. [PMID: 35091248 DOI: 10.1016/j.jenvman.2022.114528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/08/2022] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Although extensive efforts have been carried out to study sludge dewatering mechanism, the lack of universal operating procedures makes it never be satisfactorily explained. This study evaluated the impact of a unified operating procedure on waste activated sludge (WAS) dewaterability by taking the setup of refrigerated storage time as an example. It was found that storage time played an important role in determining WAS dewaterability and sampled WAS should be refrigerated within 2 days. The results showed that after 2-d storage, sludge filterability was deteriorated significantly while the extent of dewatering efficiency had little change. Meanwhile, increasing storage time greatly increased the release of extracellular polymeric substances (EPS) and heavy metals, decreased sludge viscosity and weakened its network strength, but had little impact on the floc size and zeta potential of the sludge samples. It can hardly reveal the mechanism of storage time on sludge dewaterability due to the non-uniformity of operating procedures in literatures, which is normally ignored. This study emphasizes a unified operating procedure is crucial to evaluate WAS dewaterability. Therefore, more efforts shall be focused on establishing the uniform operating procedure while advancing applied research in the field of sludge dewatering.
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Affiliation(s)
- Hou-Feng Wang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Hui-Yun Qi
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Ze-Han Lian
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Ya-Li Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Jing Li
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 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, Fujian, 350002, China.
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5
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Sha L, Wu Z, Ling Z, Liu X, Yu X, Zhang S. Investigation on the improvement of activated sludge dewaterability using different iron forms (ZVI vs. Fe(II))/peroxydisulfate combined vertical electro-dewatering processes. Chemosphere 2022; 292:133416. [PMID: 34953873 DOI: 10.1016/j.chemosphere.2021.133416] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/08/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
The high moisture content (MC) of activated sludge dewatered by traditional vertical electro-dewatering (VED) is unable to meet the disposal requirements. Therefore, different iron forms (ZVI vs. Fe(II))/peroxydisulfate (PDS) combined VED (ZVI/PDS-VED and Fe(II)/PDS-VED) were employed to enhance the dewaterability of activated sludge. The dewatering behaviors of the two combined dewatering processes and the underlying mechanism related to the sludge characteristics were investigated and compared. Sludge was conditioned using ZVI/PDS and Fe(II)/PDS, respectively, and then dewatered by the VED in the experiment. Experimental results showed that with 0.3 g (g dry solids (DS))-1 of iron activators, 0.583 g (g DS) -1 of PDS, and 30 V of voltage, the MC of sludge after ZVI/PDS-VED and Fe(II)/PDS-VED reached the minimum values of 50.6 ± 1.2% and 32.1 ± 1.5%, respectively. ZVI/PDS and Fe(II)/PDS conditioning reduced the MC difference of sludge between the anode and the cathode during the VED, facilitating the water homogenization in the sludge cake. ZVI/PDS-VED and Fe(II)/PDS-VED could effectively reduce the bound water and the free water. Free water had high correlations with α-helix (r = 0.999, p < 0.05) and CO (r = 0.998, p < 0.05). Compared with the traditional VED and the ZVI/PDS-VED, the Fe(II)/PDS-VED had a greater improvement of sludge dewaterability due to the more efficient degradation of extracellular polymeric substances and the increase of sludge surface hydrophobicity. This study promoted the development of the new sludge deep-dewatering technology.
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Affiliation(s)
- Li Sha
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Zhangxiang Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Zichen Ling
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xingxin Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xiaoyan Yu
- School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, 030008, China
| | - Shuting Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China.
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6
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Navab-Daneshmand T, Guo B, Gehr R, Frigon D. Impact of pH and removed filtrate on E. coli regrowth and microbial community during storage of electro-dewatered biosolids. Sci Total Environ 2022; 814:152544. [PMID: 34952058 DOI: 10.1016/j.scitotenv.2021.152544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/15/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Residual biosolids can be land applied if they meet microbiological requirements at the time of application. Electro-dewatering technology is shown to reduce biosolids bacterial counts to detection limits with little potential for bacterial regrowth during incubations. Here, we investigated the impacts on Escherichia coli regrowth and microbial communities of biosolids pH, removed nutrients via the filtrate, and inhibitory compounds produced in electro-dewatered biosolids. Findings suggest pH as the primary mechanism impacting E. coli regrowth in electro-dewatered biosolids. Propidium monoazide treatments were effective at removing DNA from dead cells, based on the removal of obligate anaerobes observed after anaerobic incubation. Analyses of high throughput sequenced data showed lower alpha-diversities associated with electro-dewatering treatment and incubation time. Moreover, biosolids pH and incubation period were the main factors contributing to the variations in microbial community compositions after incubation. Results highlight the role of electro-dewatered biosolids' low pH on inhibiting the regrowth of culturable bacteria as well as reducing the microbial community variance.
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Affiliation(s)
- Tala Navab-Daneshmand
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, 105 SW 26th St., Corvallis, OR 97331, USA; Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke St. West, Montreal, Quebec H3A 0C3, Canada
| | - Bing Guo
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke St. West, Montreal, Quebec H3A 0C3, Canada; Centre for Environmental Health and Engineering, Department of Civil and Environmental Engineering, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Ronald Gehr
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke St. West, Montreal, Quebec H3A 0C3, Canada
| | - Dominic Frigon
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke St. West, Montreal, Quebec H3A 0C3, Canada.
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7
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Liu Y, Ptacek CJ, Beauchemin S, MacKinnon T, Blowes DW. Effect of composting and amendment with biochar and woodchips on the fate and leachability of pharmaceuticals in biosolids destined for land application. Sci Total Environ 2022; 810:151193. [PMID: 34699834 DOI: 10.1016/j.scitotenv.2021.151193] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Land application of biosolids can improve soil fertility and enhance crop production. However, the occurrence and persistence of pharmaceutical compounds in the biosolids may result in leaching of these contaminants to surface water and groundwater, causing environmental contamination. This study evaluated the effectiveness of two organic amendments [biochar (BC) and woodchips (WC)] for reducing the concentration and leachability (mobility) of four pharmaceuticals in biosolids derived from wastewater treatment plants in southern Ontario, Canada. The effect of 360-d composting on fate and leachabilities of target pharmaceuticals in biosolid mixtures was also investigated. Composting decreased total and leachable concentrations of pharmaceuticals in unamended and BC- and WC-amended biosolids to various degrees, from 10% up to 99% depending on the compound. Blending BC or WC into the biosolids greatly increased the removal rates of the target pharmaceuticals, while simultaneously decreasing their half-lives (t0.5), compared to unamended biosolids. The t0.5 of contaminants in this study followed the order: carbamazepine (304-3053 d) > gemfibrozil (42.3-92.4 d) > naproxen (15.3-104 d) > ibuprofen (12.5-19.0 d). Amendment with BC and(or) WC significantly reduced the leachability of carbamazepine, ibuprofen, and gemfibrozil to variable extents, but significantly enhanced the leachability of naproxen, compared to unamended biosolids (P < 0.05). Biochar and WC exhibited different (positive or negative) effects on the leachability of individual pharmaceuticals. Significantly lower concentrations of total and(or) leachable (mobile) pharmaceuticals were observed in amended biosolids than unamended biosolids (P < 0.05). Biochar and WC are effective amendments that can reduce the environmental impact of biosolid land applications with respect to pharmaceutical contamination.
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Affiliation(s)
- YingYing Liu
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
| | - Suzanne Beauchemin
- Natural Resources Canada, CanmetMINING, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada
| | - Ted MacKinnon
- Natural Resources Canada, CanmetMINING, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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8
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Zeng Q, Huang H, Tan Y, Chen G, Hao T. Emerging electrochemistry-based process for sludge treatment and resources recovery: A review. Water Res 2022; 209:117939. [PMID: 34929476 DOI: 10.1016/j.watres.2021.117939] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 11/17/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
The electrochemical process is gaining widespread interest as an emerging alternative for sludge treatment. Its potentials for sludge stabilization and resources recovery have been well proven to date. Despite the high effectiveness of the electrochemical process having been highlighted in several studies, concerns about the electrochemical sludge treatment, including energy consumption, scale-up feasibility, and electrode stability, have not yet been addressed. The present paper critically reviews the versatile uses of the electrochemical processes for sludge treatment and resource recovery, from the fundamentals to the practical applications. Particularly considered are the enhancement of the digestion of the anaerobic sludge and dewaterability, removal of pathogens and heavy metals, and control of sludge malodor. In addition, the opportunities and challenges of the sludge-based resource recovery (i.e., nitrogen, phosphorus, and volatile fatty acids) are discussed. Insights into the working mechanisms (e.g., electroporation, electrokinetics and electrooxidation) of electrochemical processes are reviewed, and perspectives and future research directions are proposed. This work is expected to provide an in-depth understanding and broaden the potential applications of electrochemical processes for sludge treatment and resource recovery.
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Affiliation(s)
- Qian Zeng
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metals Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Hao Huang
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metals Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yunkai Tan
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Guanghao Chen
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metals Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Tianwei Hao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
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9
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Liu C, Zhou X, Zhou L, Wei Y, Liu J. Enhancement of sludge electro-dewatering by anthracite powder modification. Environ Res 2021; 201:111510. [PMID: 34147466 DOI: 10.1016/j.envres.2021.111510] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 06/12/2023]
Abstract
Electro-dewatering of sludge has received considerable attention due to its low energy consumption for sludge deep-dewatering. However, prior studies have shown the resistance of dried sludge near anode significantly hinders electro-dewatering. The dewatering performance may be improved by reducing the resistance with the addition of conductive material into sludge. We conditioned municipal sludge by anthracite powder, an inexpensive product, to increase solid conductivity, followed by electro-dewatering. After running for 20 min under a constant voltage of 30 V, when the anthracite powder mass was 10%-22% of raw sludge dry solids mass (DS), the final dry solids content of the mud cake after dehydration was 6.2%-12.9% higher than that from dehydration of unconditioned sludge. The average filtrate flow rate ranged from 0.0243 to 0.0285 g s-1. The lowest unit energy consumption, 0.19 kW h·kgwater-1, which was 14% lower than that of control, was reached when 18% DS of anthracite was added. Our theoretical analysis indicates that properly increasing solid conductivity of sludge can reduce the adverse effect caused by the high electrical resistance of sludge near anode. The experimental results, along with the theoretical analysis, show that using anthracite powder for sludge modification is an economical approach to improve sludge dewatering rate and reduce energy consumption.
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Affiliation(s)
- Changyuan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China
| | - Xingqiu Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, PR China.
| | - Lang Zhou
- Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin, 301 E. Dean Keeton Street, Austin, TX, 78712, United States
| | - Yijun Wei
- Shenzhen Water (Group) CO., LTD, Futian Branch Company, Shenzhen, 518000, PR China
| | - Jiangyan Liu
- Shenzhen Shenshui Ecological & Environmental Technology CO., LTD., Shenzhen, 518000, PR China
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10
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Lv H, Xiong Q, Liu D, Wu X. Coupling electro-dewatering and low-temperature air-drying for efficient dewatering of sludge. Sci Rep 2021; 11:19167. [PMID: 34580359 DOI: 10.1038/s41598-021-98477-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 09/08/2021] [Indexed: 12/05/2022] Open
Abstract
This study investigated the effects of electro-dewatering on subsequent low-temperature drying at various potentials and the characteristics of low-temperature air-drying sludge were explored through experiments and multi-physical modeling. Experimental results showed that the extracellular polymeric substance (EPS) content in the sludge was reduced during electro-dewatering process, even the species of organic matter was changed, as well as the dewatered cake tend to form many seepage channels, crack and a certain number of holes. These changes in the properties and structure were conducive to the subsequent low-temperature drying process. For air-drying process, the mass of the sludge cake variation was simulated and results were consistent with the experimental phenomenon. Firstly, the weight of the sludge cake was decreased approximately linearly with time, then tended to stable and reached the dewatering limitation finally. The applied higher electric field intensity (25 V cm−1) in the front-end electro-dewatering were conducive to promote water vapor diffusion activity in air-drying stage. Energy consumption and yield analysis results indicated that the combined technology has lower energy consumption and higher yield than that of directly low-temperature drying.
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11
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Sha L, Yu X, Wu Z, Liu X, Wang H, Jiang Q, Zhang S. Study of the variations in apparent electrical resistivity of activated sludge during the electro-dewatering process. Environ Res 2021; 198:110453. [PMID: 33188765 DOI: 10.1016/j.envres.2020.110453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/15/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
The high energy consumption of high apparent electrical resistivity (AER) in sludge during the later stages of the electro-dewatering (EDW) process is a difficult problem; however, analysis of sludge AER may contribute to a reduction in energy consumption. In this study, the variations in the AER of activated sludge and potential mechanisms related to sludge properties were systematically examined. First, a sludge cake was divided into four horizontal layers, in order to investigate the sludge AER in each layer. Then, the effects of variations in water distribution, oxidation-reduction potential (ORP), pH, metal ions, sludge conductivity, zeta potential, temperature, and sludge microstructure on the AER in each layer were explored. The results showed that the sludge AER began to increase from the bottom layers to the top layers when the moisture content (MC) was decreased to 60%. The formation of nonionic chemical systems and the gas barrier layer could increase the AER in the top layers, and the increase in sludge AER in the bottom layers was due to the decrease in MC and sludge conductivity. In addition, electrolyte release and electromigration had a significant effect on the sludge AER. This work identifies potential causes for the increase in AER, and provides a reference for solving problems related to high AER in sludge during the later stages of the EDW process.
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Affiliation(s)
- Li Sha
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xiaoyan Yu
- School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, 030008, China
| | - Zhangxiang Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xingxin Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Haozhe Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Qingqing Jiang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Shuting Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China.
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12
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Sha L, Yu X, Wu Z, Liu X, Zhang S. Effects of sludge characteristics on electrical resistance and energy consumption during electro-dewatering process. J Environ Sci (China) 2021; 101:339-350. [PMID: 33334528 DOI: 10.1016/j.jes.2020.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 08/19/2020] [Accepted: 09/01/2020] [Indexed: 06/12/2023]
Abstract
The increase of electrical resistance (ER) and energy consumption (EC) during the later stage of dewatering is a major problem hindering the development of electro-dewatering (EDW) technology. As the variations of sludge characteristics are significant during the EDW process, the relationships between sludge characteristics and ER and EC during EDW remain unclear. In this study, the effects of moisture content (MC), thickness, pH, conductivity, zeta potential, temperature, and gas volume on the ER and EC during the EDW process were statistically investigated using correlation and multiple linear regression analyses. Herein, the results showed that the ER of the sludge near the anode was primarily affected by pH, whereas the sludge near the cathode was primarily affected by the MC and conductivity. Further, sludge temperature and conductivity were the most reliable indicators to predict the EC near the anode and cathode, respectively. The results of this study provide theoretical guidance useful for solving the increase of ER and EC during the later stage of the EDW process.
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Affiliation(s)
- Li Sha
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China
| | - Xiaoyan Yu
- School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan 030008, China
| | - Zhangxiang Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China
| | - Xingxin Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China
| | - Shuting Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China.
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13
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Xue ZJ, Yan CG, Li WG. Coupling of electrochemical-temperature-mechanical processes in marine clay during electro-osmotic consolidation. Sci Rep 2020; 10:13961. [PMID: 32811846 DOI: 10.1038/s41598-020-70700-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/26/2020] [Indexed: 11/09/2022] Open
Abstract
Electro-osmotic consolidation has been applied in several geotechnical engineering applications that contain a series of complex processes, including electrochemical processes, temperature changes, and mechanical evolution. To explore the combination of electrochemical–temperature–mechanical processes in marine clay, electro-osmotic consolidation experiments were conducted using a self-made electro-osmotic consolidation system under various durations and voltages. The following findings was obtained: (1) the change in the pH value increased during electro-osmotic consolidation and as the voltage rise; (2) the temperature increased with a rise in voltage in the initial stage of the experiments, which was induced by Joule heating; (3) the temperature rise promoted the electro-osmotic consolidation process, which included a rise in the coefficient of consolidation and a reduction in water content; (4) horizontal shrinkage occurred when the horizontal stress increment was greater than the critical stress condition. In addition, the volume difference reached a constant value, and was proportional to the voltage rise. After the discussion, a coupling analysis was conducted, which can help to better understand the mechanism of electro-osmotic consolidation and can provide reference for engineering applications.
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14
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Wei Y, Zhou X, Zhou L, Liu C, Liu J. Electro-dewatering of sewage sludge: Effect of near-anode sludge modification with different dosages of calcium oxide. Environ Res 2020; 186:109487. [PMID: 32334167 DOI: 10.1016/j.envres.2020.109487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/23/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
The efficiency of common sludge electro-dewatering (EDW) is restrained by the following issues: 1, the near-anode sludge dries out quickly, causing a rapid increase in electrical resistance; 2, the pH at anode decreases by the accumulation of H+ from the electrolysis of moisture, resulting in a decrease in Zeta potential (ζ). Alleviating the negative impact of these problems is the key to improving the dewatering efficiency of EDW. Therefore, in this study, calcium oxide (CaO) was used for near-anode sludge modification to increase its pH and electrical conductivity. With increasing CaO dosage, pH rose from 6.0 to 12.2, electrical conductivity increased from 368 ± 16 μS/cm to 6285 ± 21 μS/cm and the ζ declined from -15.3 ± 0.6 mV to -8.8 ± 0.4 mV. The EDW tests were conducted at 30 V and 25.5 kPa. The results indicate near-anode sludge modification with CaO weighing 3%-5% mass of raw sludge (mu(RS)) improved the EDW effect, while the energy consumption increased slightly. When 3%-5% mu(RS) of CaO was added, the final moisture content of sludge was 54.5%-44.3%, below that of the blank group (no CaO added), which was 57.9%; the time to obtain target moisture content (60%) was 910 s-590 s, lower than the blank group's 1060 s; and the energy consumption to obtain target moisture content was 0.233 kW h/kg H2O-0.271 kW h/kg H2O, higher than the blank group's 0.157 kW h/kg H2O. A quantitative criterion (KsiEDW) was adopted to assess the feasibility of EDW. Economically and energetically, the experiment with 4% mu(RS) of CaO added for near-anode modification was the optimal condition in this research, due to its second smallest KsiEDW, the best sludge reduction effect (67.2%), lower final moisture content (46.2%) and less time (640 s) to obtain target moisture content. The results show some mechanisms of EDW and provide experience for practical application.
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Affiliation(s)
- Yijun Wei
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China
| | - Xingqiu Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, PR China.
| | - Lang Zhou
- Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin, 301 E. Dean Keeton Street, Austin, TX, 78712, United States
| | - Changyuan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China
| | - Jiangyan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China
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15
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Wu P, Pi K, Shi Y, Li P, Wang Z, Zhang H, Liu D, Gerson AR. Dewaterability and energy consumption model construction by comparison of electro-dewatering for industry sludges and river sediments. Environ Res 2020; 184:109335. [PMID: 32169737 DOI: 10.1016/j.envres.2020.109335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
Electro-dewatering (EDW) is an emerging technology for improved sludge/sediment dewatering enabling subsequent cost effective treatment for toxicity and pathogenic reduction if required and/or disposal, but the effects of sediment/sludge properties on the efficacy of EDW remain unclear. Here we investigate EDW in the absence of chemical conditioning which can result in secondary pollution. The influence of sediment/sludge volatile solids content (VS), electrical conductivity (EC), pH and zeta potential (ζ), on mechanical and electrical behaviors determining dewaterability and energy consumption (PE) was investigated. Optimization of EDW parameters increased the final solids content (DSf) from 40 wt% to more than 55 wt% for river sediment, while the solids content in municipal sludge was only increased from 10 wt% to 15-20 wt%. Multiple linear regression and statistical analysis showed that electro-dewatering performance is primarily affected by VS and PE is mainly affected by EC. A theoretical basis for engineering design and selection of operational parameters for sludge/sediment electro-dewatering is provided by this study.
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Affiliation(s)
- Pan Wu
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China; Future Industries Institute, Mawson Lakes Campus, University of South Australia (UniSA), South Australia, Adelaide, Australia
| | - Kewu Pi
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China.
| | - Yafei Shi
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Pian Li
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Zheng Wang
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Huiqin Zhang
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Defu Liu
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Andrea R Gerson
- Blue Minerals Consultancy, Wattle Grove, Tasmania, 7109, Australia
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16
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Deng W, Lai Z, Hu M, Han X, Su Y. Effects of frequency and duty cycle of pulsating direct current on the electro-dewatering performance of sewage sludge. Chemosphere 2020; 243:125372. [PMID: 31759206 DOI: 10.1016/j.chemosphere.2019.125372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 10/28/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
Electro-dewatering of sewage sludge with pulsating direct current (PDC-dewatering) was conducted to investigate the effects of pulsating frequency (0.01-60 Hz) and duty cycle (DTC) (20-100%) on sludge dewatering. The results indicated that both the frequency and DTC showed marked influences on electro-dewatering. Compared with the condition under the stable direct current (SDC-dewatering) of 30 V, the filtrate discharged from PDC-dewatering (at DTC of 40-60% and frequency of 30 Hz) was about 8% higher than that from SDC-dewatering. At DTC of 40%, the sludge electro-dewatering performance was promoted when the frequency increased from 0.01 Hz to 30 Hz. Compared with SDC-dewatering, PDC-dewatering can effectively mitigate ohmic heating. Layered tests were also conducted to investigate the differences of SDC- and PDC-dewatering in the distributions of water, pH, organic matters, zeta potential and conductivity in the upper, middle and lower layer of sludge cake. The results indicated that the variation tendencies of these parameters were similar between SDC- and PDC-dewatering, but the water, organic matters and charged ions in sludge cake were more homogeneously distributed during PDC-dewatering than SDC-dewatering. In addition, the anodic pH of PDC-dewatering was higher than that of SDC-dewatering, suggesting the potential of mitigating anodic corrosion during PDC-dewatering. Finally, energy consumptions of PDC- and SDC-dewatering were calculated and compared. The effects of frequency and DTC on energy consumption were investigated. PDC-dewatering was found to be more energy efficient than that of SDC-dewatering, making PDC-dewatering a promising electro-dewatering technology in future.
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Affiliation(s)
- Wenyi Deng
- School of Environmental Science and Engineering, Donghua University. 2999 North Renmin Road, Songjiang Dist., Shanghai, 201620, PR China.
| | - Zhicheng Lai
- School of Environmental Science and Engineering, Donghua University. 2999 North Renmin Road, Songjiang Dist., Shanghai, 201620, PR China
| | - Menghao Hu
- School of Environmental Science and Engineering, Donghua University. 2999 North Renmin Road, Songjiang Dist., Shanghai, 201620, PR China
| | - Xiaoran Han
- School of Environmental Science and Engineering, Donghua University. 2999 North Renmin Road, Songjiang Dist., Shanghai, 201620, PR China
| | - Yaxin Su
- School of Environmental Science and Engineering, Donghua University. 2999 North Renmin Road, Songjiang Dist., Shanghai, 201620, PR China
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17
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Lv H, Xing S, Liu D, Wang F, Zhang W, Sun G, Wu X. Soluble metal ions migration and distribution in sludge electro-dewatering. Environ Res 2020; 180:108862. [PMID: 31706597 DOI: 10.1016/j.envres.2019.108862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/12/2019] [Accepted: 10/25/2019] [Indexed: 06/10/2023]
Abstract
In this study, the effects of electro-dewatering technology applied to high-salt industrial sludge dewatering performance were investigated, in terms of ions migrations and distributions by model simulation and layered tests. The simulation results of Na+ and K+ migrations were consistent with layered experiments during electro-dewatering, where Na+ ions migrated faster than K+ ions. More than 80% Na+ ions were removed by electromigration, which would be useful in subsequent sludge utilization. The mass specific energy consumption was reduced from 350.08 to 295.88 kWh per ton sludge by means of piecewise voltage electro-dewatering method. This study provided insights into the soluble ions migration and distribution mechanism in electro-dewatering process, and a method to improve commercial application performance of high-salt industrial sludge electro-dewatering.
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Affiliation(s)
- Hang Lv
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Siqi Xing
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Daoguang Liu
- Shanghai Techase Environment Protection Co., Ltd, 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China; College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Fang Wang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Wenbiao Zhang
- Shanghai Techase Environment Protection Co., Ltd, 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China
| | - Gangfan Sun
- Shanghai Techase Environment Protection Co., Ltd, 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China
| | - Xu Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China.
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18
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Li Y, Liu Y, Yu X, Li Q, Zhang R, Zhang S. Enhancement of sludge electro-dewaterability during biological conditioning. RSC Adv 2020; 10:3153-3165. [PMID: 35497773 PMCID: PMC9048689 DOI: 10.1039/c9ra09126b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/31/2019] [Indexed: 11/24/2022] Open
Abstract
Electro-dewatering (EDW) is considered as one of the most promising dewatering technologies due to saving power consumption. In this study, the potential effects of anaerobic biological conditioning (BC) on sludge EDW treatments was investigated. The results showed that without any additives BC pretreatment of sludge enhanced EDW dewaterability and energy efficiency. At 35 °C BC for 3 days, the dry solids (DS) of sludge dewaterability limit could increase up to 49%, which corresponded to an increase of 13% of DS in dewatered sludge cake without BC pretreatment, and the dewatering time was shortened by 22%. There was an economic advantage saving in energy consumption of around 49.5% in the case of BC-EDW when the DS of sludge was up to 38%. Then, the mechanism of BC to improve EDW performance was studied. The principal component regression (PCR) analysis showed that the DS content of dewaterability limit mainly depended on the degradation of organic matter and the change of conductivity in sludge. Fourier transform infrared spectroscopy (FTIR), zeta potential and bound water in sludge were also determined in an attempt to explain the observed changes in sludge BC-EDW. It was indicated that the increase of negatively charged hydroxyl groups on the surface of sludge particles resulted in an increase of the absolute value of the zeta potential and significantly promoted EDW. The tightly bound EPS (TB-EPS) decreased and it loosened the bond between water or metal cations and sludge particles, and the bound water was also found to be released into free water in sludge during BC. An effective deep dewatering process of coupling biological conditioning and electro-dewatering was proposed and analyzed.![]()
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Affiliation(s)
- Yingte Li
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Yong Liu
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Xiaoyan Yu
- School of Energy and Chemical Engineering
- Liaoning Technical University
- Huludao 125105
- China
| | - Qian Li
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Rui Zhang
- School of Energy and Safety Engineering
- Tianjin Chengjian University
- Tianjin 300384
- China
| | - Shuting Zhang
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
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19
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Lv H, Liu D, Xing S, Wu D, Wang F, Yang J, Wu X, Zhang W, Dai X. The effects of aging for improving wastewater sludge electro-dewatering performances. J IND ENG CHEM 2019. [DOI: 10.1016/j.jiec.2019.08.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Bai H, Zhu R, An H, Zhou G, Huang H, Ren H, Zhang Y. Influence of wastewater sludge properties on the performance of electro-osmosis dewatering. Environ Technol 2019; 40:2853-2863. [PMID: 29557729 DOI: 10.1080/09593330.2018.1455744] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 03/14/2018] [Indexed: 06/08/2023]
Abstract
Although the properties of municipal wastewater sludge play key roles in the electro-osmosis dewatering process, it is still controversial which properties have the greatest effect on the dewatering performance. In this study, multiple regression models with the Group Lasso method were used to investigate the relationship between the final moisture content and the sludge properties, including pH, electrical conductivity (EC), volatile solids content, zeta potential (ζ), initial moisture content, extracellular polymeric substances (EPS), proteins of EPS (EPSPr), polysaccharides of EPS (EPSPo) and the ratio of EPSPr and EPSPo (EPSR). Under the optimal conditions (pressure = 100 kPa, voltage = 50 V and cake thickness = 15 mm), EPS, EC and ζ were significantly related to sludge dewaterability and EPS was the most important factor. Furthermore, the coefficient estimate of EPSPo was greater than that of EPSPr and the coefficient of EPSR was negative, indicating that EPSPo plays more important roles in electro-osmosis dewatering than EPSPr. Thus, reducing the EPS content of sludge, especially the EPSPo content, is necessary to improve the performance of electro-osmosis dewatering.
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Affiliation(s)
- Hao Bai
- a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing , People's Republic of China
| | - Rong Zhu
- b Academy of Mathematics and Systems Science, Chinese Academy of Sciences , Beijing , People's Republic of China
| | - Hao An
- a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing , People's Republic of China
| | - Guoya Zhou
- c Peng Yao Environmental Protection Institute , Yixing , People's Republic of China
| | - Hui Huang
- a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing , People's Republic of China
| | - Hongqiang Ren
- a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing , People's Republic of China
| | - Yan Zhang
- a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing , People's Republic of China
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21
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Qian X, Zhou X, Wu J, Liu C, Wei Y, Liu J. Electro-dewatering of sewage sludge: Influence of combined action of constant current and constant voltage on performance and energy consumption. Sci Total Environ 2019; 667:751-760. [PMID: 30851608 DOI: 10.1016/j.scitotenv.2019.02.329] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
In this study, mechanically-dewatered sludge was used to investigate the effect of electro-dewatering (EDW) under two electrical modes, which are constant current mode followed by constant voltage mode (CV-EDW), and constant voltage mode followed by constant current mode (VC-EDW). The effect of current and voltage changes on dewatering efficiency and energy consumption of sludge electroosmosis under CV-EDW and VC-EDWs was evaluated The results show that compared with constant current mode (C-EDW), CV-EDW can improve the final dry solids content and reduce the heating rate, and the final dry solids content and unit energy consumption increase with the decrease of current and the increase of voltage. Under CV-EDW, when the dry solids content is 32%, the energy consumption can be reduced by changing to the constant voltage stage, and the energy consumption is 0.093-0.113 kWh/kgwater. Compared with constant voltage mode (V-EDW), VC-EDW significantly improves sludge dewatering rate. Under VC-EDW, the final dry solids content of sludge increases with the decrease of current and voltage. When the voltage is decreased by 10 V, the unit energy consumption is reduced by 27.15 ± 1.77% on average, and the energy consumption is 0.132-0.163 kWh/kgwater. Compared with CV-EDW, the dehydration rate of VC-EDW is increased by 72.9% on average. However, the unit energy consumption required for dehydration increases by 43.09% when the dry solids content is less than 45%.
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Affiliation(s)
- Xu Qian
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Xingqiu Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, Guangdong 510006, PR China.
| | - Jiandong Wu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, Guangdong 510006, PR China
| | - Changyuan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Yijun Wei
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Jiangyan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
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22
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Cao B, Wang R, Zhang W, Wu H, Wang D. Carbon-based materials reinforced waste activated sludge electro-dewatering for synchronous fuel treatment. Water Res 2019; 149:533-542. [PMID: 30502739 DOI: 10.1016/j.watres.2018.10.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/25/2018] [Accepted: 10/28/2018] [Indexed: 06/09/2023]
Abstract
Sludge treatment and disposal have become critical environmental issues in China. Electro-dewatering (ED) is an attractive technology for enhancing dewaterability and improving the sustainability of waste activated sludge (WAS) handling. However, electrically assisted mechanical dewatering processes consume more energy and the extracellular polymeric substance (EPS) dissolution caused by electrochemical reactions can lead to clogging of the filter cloth. Carbon-based materials (CBMs) such as activated carbon and graphite have electrical conductivity and well-developed pore structures which can adsorb the biopolymers. Therefore, addition of CBMs is expected to improve WAS electro-dewatering performance for fuel treatment by enhancing sludge conductivity and filterability. In this study, we evaluated the effects of the three carbon materials (AC-0, AC-5, and graphite) on sludge electro-dewatering behavior and the flammability of sludge cakes. The results showed that CBMs promote the performance of WAS electro-dewatering, and the promoting effect of the carbon materials on the sludge electro-dewatering is proportional to the electrical conductivity of the carbon material, and carbon materials can increase the electrophoretic mobility of sludge flocs and the electro-osmotic effect. Moreover, CBMs can adsorb the dissolved EPS, thus alleviate the plugging and filtration resistance of the filter medium. The addition of CBMs also decreases the energy consumption for water removal during the electro-dewatering process and improves the calorific value and sustainable combustion time of the sludge cake. Our approach can facilitate the resource utilization of the dewatered sludge cake in electro-dewatering processes.
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Affiliation(s)
- Bingdi Cao
- University of Chinese Academy of Science, Beijing, 100085, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Ruilu Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Weijun Zhang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, Hubei, China.
| | - Hanjun Wu
- School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, 430074, Hubei, China
| | - Dongsheng Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430074, Hubei, China
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23
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Wu P, Shi Y, Wang Z, Xiong Z, Liu D, Gerson AR, Pi K. Effect of electric field strength on electro-dewatering efficiency for river sediments by horizontal electric field. Sci Total Environ 2019; 647:1333-1343. [PMID: 30180340 DOI: 10.1016/j.scitotenv.2018.07.464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/31/2018] [Accepted: 07/31/2018] [Indexed: 06/08/2023]
Abstract
A series of electro-dewatering experiments were conducted to explore the effect of sediment cake thickness (1-5 cm) and electric field strength (2-50 V cm-1). The final dry solids content, energy consumption and dewatering productivity were modeled and the validity of the model was tested. It was demonstrated that the electric field strength determines final dry solids content and the power utilization is an exponential function of electric field strength. It was also found that a relatively low electric field strength (<10 V cm-1) significantly decreased energy consumption while maintaining an acceptable dry solids content. These findings are beneficial to practical applications of electro-dewatering.
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Affiliation(s)
- Pan Wu
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Yafei Shi
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Zheng Wang
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Ziming Xiong
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Defu Liu
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China; Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Wuhan, Hubei, 430068, China
| | - Andrea R Gerson
- Blue Minerals Consultancy, Wattle Grove, Tasmania, 7109, Australia
| | - Kewu Pi
- School of Resource and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China; Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Wuhan, Hubei, 430068, China; Blue Minerals Consultancy, Wattle Grove, Tasmania, 7109, Australia.
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24
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Yang Z, Lu X, Zhang S, Zhang K, Zhi S, Guo H, Li Q, Yu X. Pressurized electro-dewatering of activated sludge: Analysis of electrode configurations (anode). Waste Manag 2018; 81:157-167. [PMID: 30527032 DOI: 10.1016/j.wasman.2018.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 09/30/2018] [Accepted: 10/01/2018] [Indexed: 06/09/2023]
Abstract
An electric field and mechanical pressure combined are considered an effective electro-dewatering (PED) technology for activated sludge. Here, the curved surface anodes were used for electro-dewatering to improve the effective anode area, and the PED characteristics were investigated for three anode types (flat plate, sawtooth plate and wave plate). First, evaluation methodology of the modified energy consumption ( [Formula: see text] ) and the modified processing capacity ( [Formula: see text] ) were established, with electro-dewatering factor (ξED), to evaluate the PED efficiency of different anode configurations under three raw sludge processing capacity modes. Second, the solid content distribution was analyzed by the layered method, and the electric field and current density distribution were analyzed by the finite element method. Finally, the gas emission mechanism of the curved surface anodes was discussed. When the raw sludge processing capacity and dewatering time (10 min) were the same, nearly the same extent of dewatering was achieved for the wave plate anode as for the flat plate anode. The total filtrate amount was 69.5 g and 59.0 g for the wave plate and flat plate anodes, respectively, and [Formula: see text] increased by 17.8% for the former. Under the same raw sludge thickness, the dewatering percentages in area A of the sawtooth plate and wave plate anodes were 10% and 11%, respectively, higher than that of the flat plate anode. However, according to numeric simulation results, the current density at the tips of the sawtooth plate anode can reach 740-770 A/m2, which can reduce its service life as compared to flat plate anode. In area D, gas was more easily emitted from the wave plate anode than from the flat plate anode, reducing the influence of the gas barrier layer on the electrical contact between the sludge cake and the anode.
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Affiliation(s)
- Zengjun Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xuebin Lu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; Department of Chemistry and Environmental Science, School of Science, Tibet University, Lhasa 850000, China.
| | - Shuting Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Keqiang Zhang
- Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
| | - Suli Zhi
- Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
| | - Haigang Guo
- Achievement Transformation Center, Hebei University of Engineering, Handan 056038, China
| | - Qian Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xiaoyan Yu
- School of Energy and Chemical Engineering, Liaoning Technical University, Hu Ludao 125105, China
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25
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Masihi H, Badalians Gholikandi G. Employing Electrochemical-Fenton process for conditioning and dewatering of anaerobically digested sludge: A novel approach. Water Res 2018; 144:373-382. [PMID: 30055427 DOI: 10.1016/j.watres.2018.07.054] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/21/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
In this study, for the first time, the occurrence mechanism of anaerobically digested sludge conditioning for dewatering process based on Electrochemical-Fenton technology was investigated and the optimum condition has been determined to employ a lab-scale reactor. Due to the results of current studies using electrochemical and Fenton methods, a comparative economic-technical investigation has been provided accordingly. The results showed that under optimum operational condition by utilizing Electrochemical-Fenton process e.g. H2O2 = 25 mg/g DS (dry solid), Fe2+ = 15 mg/g DS, retention time = 20 min, electrolysis voltage = 11 V, the specific resistance to filterability (SRF) and time to filter (TTF) parameters reduction equal to 93.8% and 75.9% respectively. The occurrence mechanism of the sludge conditioning was determined by evaluation of extracellular polymeric substances (EPS), particle size distribution, zeta potential and bound water tests. The dry solids concentration of the conditioned sludge by Electrochemical-Fenton process was increased from 2.3% to 41% by dewatering employing filter press system. Furthermore, the estimated cost of conditioning using this method is 41.82 USD$/t DS, which is less than other investigated methods e.g. traditional Fenton process. It can be concluded that the results reached in this comprehensive and comparative study could be a suitable basis for further investigations regarding utilization of novel electrochemical advanced oxidation technologies for efficient sludge conditioning and dewatering purposes.
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Affiliation(s)
- Hamidreza Masihi
- Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, A.C, Tehran, Iran.
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26
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Lv H, Wang F, Liu D, Zhang Y, Gu Y, Yuan D, Xing S, Wu X, Yang J, Zhang W, Scott K. Effects of Piecewise Electric Field Operation on Sludge Dewatering: Phenomena and Mathematical Model. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b01019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hang Lv
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Fang Wang
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Daoguang Liu
- Shanghai Techase
Environment Protection Co., Ltd. 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China
| | - Yanlin Zhang
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Yueyuan Gu
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Du Yuan
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Siqi Xing
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Xu Wu
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Wenbiao Zhang
- Shanghai Techase
Environment Protection Co., Ltd. 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China
| | - Keith Scott
- School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
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27
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Yin Z, Hoffmann M, Jiang S. Sludge disinfection using electrical thermal treatment: The role of ohmic heating. Sci Total Environ 2018; 615:262-271. [PMID: 28972902 PMCID: PMC5711000 DOI: 10.1016/j.scitotenv.2017.09.175] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/17/2017] [Accepted: 09/17/2017] [Indexed: 05/04/2023]
Abstract
Electrical heating has been proposed as a potential method for pathogen inactivation in human waste sludge, especially in decentralized wastewater treatment systems. In this study, we investigated the heat production and E. coli inactivation in wastewater sludge using electrical thermal treatment. Various concentrations of NaCl and NH4Cl were tested as electrolyte to enhance conductivity in sludge mixtures. At same voltage input (18V), sludge treated with direct current (DC) exhibited slower ascent of temperature and lower energy efficiencies for heat production comparing to that using alternate current (AC). However, DC power showed better performance in E. coli inactivation due to electrochemical inactivation in addition to thermal inactivation. Greater than 6log10 removal of E. coli was demonstrated within 2h using 0.15M of NaCl as electrolyte by AC or DC power. The heat production in sludge was modeled using Maxwell-Eucken and effective medium theory based on the effective electrical conductivity in the two-phase (liquid and solid) sludge mixtures. The results showed that the water and heat loss is a critical consideration in modeling of sludge temperature using ohmic heating. The experimental data also suggested that the models are less applicable to DC power because the electrochemical reactions triggered by DC reduce the concentration of NH4+ and other ions that serve as electrolyte. The results of this study contribute to the development of engineering strategies for human waste sludge management.
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Affiliation(s)
- Ziqiang Yin
- Department of Civil and Environmental Engineering, University of California, Irvine, Irvine 92617, CA, United States
| | - Michael Hoffmann
- Division of Engineering and Applied Science, California Institution of Technology, Pasadena 91125, CA, United States
| | - Sunny Jiang
- Department of Civil and Environmental Engineering, University of California, Irvine, Irvine 92617, CA, United States.
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28
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Mahmoud A, Hoadley AFA, Citeau M, Sorbet JM, Olivier G, Vaxelaire J, Olivier J. A comparative study of electro-dewatering process performance for activated and digested wastewater sludge. Water Res 2018; 129:66-82. [PMID: 29132123 DOI: 10.1016/j.watres.2017.10.063] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/23/2017] [Accepted: 10/28/2017] [Indexed: 06/07/2023]
Abstract
Electro-dewatering (EDW) is an alternative emerging and energy-efficient technology that provides improved liquid/solids separations in the dewatering of wastewater sludge. The EDW technology is not only an innovative dewatering method for significantly reducing the volume of wastewater sludge before re-utilization or disposal, but is also a promising emerging method which may potentially be used for decontamination purposes. In this study, the influence of the sludge properties (e.g. electrical conductivity, zeta potential, specific cake resistance, among others) on their mechanical and electrical behaviour in terms of dewaterability and electro-dewaterability, the applied current (current density from 20 to 80 A/m2), and filter cloth position relative to the electrode was investigated. A two-sided filter press at lab-scale with moving anode was used, and the treatment performance of the EDW process on two different types of wastewater sludge (activated and digested) was thoroughly assessed from both an electrochemical viewpoint and in terms of the dewatering rate. The results showed that the conditioned digested sludge was more easily dewatered by mechanical dewatering (MDW) with 34-35% (w%) of dry solids content compared to 19-20% (w%) for the activated sludge, thanks to the lower content of both the microbial extracellular polymeric substances (EPS) and the volatile suspended solids fraction. For the EDW results, the electrical conductivity of the sludge was pivotal to the dryness of the final solids and therefore also to the dewatering kinetics. The results demonstrated that the activated sludge arrived at an equilibrium much faster (after approximately 3600 s) compared with digested sludge, thanks to its lower electrical conductivity (0.8 mS/cm) providing a greater voltage drop across the cathode and therefore more repulsion of the solids from the cathode leading to continuously high filtrate flowrate. Also the EDW performance was analysed by comparing the ratio of the filtrate volume collected at the anode to the volume collected at the cathode side. For digested sludge at 5 bar, 40 A/m2 different positions of the filter cloth were tested but these configurations barely impacted the EDW performance, despite having a significant impact on the energy requirements. At industrial scale, it would be useful to position the filter cloths at some distance from the electrodes, but this study shows that this benefit may be quickly outweighed by the loss in EDW energy efficiency.
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Affiliation(s)
- Akrama Mahmoud
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075 Pau Cedex, France.
| | - Andrew F A Hoadley
- Department of Chemical Engineering, Building 35, Clayton Campus, Monash University, Victoria 3800, Australia
| | - Morgane Citeau
- OLEAD - 11 rue Monge, Parc Industriel Bersol 2, 33600 Pessac, France
| | - Jean Michel Sorbet
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075 Pau Cedex, France
| | - Gelade Olivier
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075 Pau Cedex, France
| | - Jean Vaxelaire
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075 Pau Cedex, France
| | - Jérémy Olivier
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075 Pau Cedex, France
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29
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Xiao J, Wu X, Yu W, Liang S, Yu J, Gu Y, Deng H, Hu J, Xiao K, Yang J. Migration and distribution of sodium ions and organic matters during electro-dewatering of waste activated sludge at different dosages of sodium sulfate. Chemosphere 2017; 189:67-75. [PMID: 28926790 DOI: 10.1016/j.chemosphere.2017.09.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
In this study, the influence of Na2SO4 on electro-dewatering (EDW) of waste activated sludge (WAS) was investigated. The highest water removal efficiency of 42.5% was achieved at the optimum Na2SO4 dosage of 12.5 g kg-1 DS during EDW process at a constant voltage of 20 V. The migration and distribution of water, organic matters and Na+ at different Na2SO4 dosages were investigated through layered experiments. The results indicated the entire EDW process followed the S curve model, and it can be divided into three stages: (1) initial desalination stage: at the initial few min of EDW process, the rate of electroosmosis was extremely slow while electromigration of ions like Na+ was intense, and the electromigration was more obvious with increased Na2SO4 dosage; (2) dewatering stage: the dewatering efficiency increased dramatically via electroosmosis; (3) the dewaterability limit stage: the maximum value of dewatering efficiency has been achieved, while the water removal efficiency and dry solids content remained constant. During the EDW process, the possible electrolysis resulted in a pH gradient in the sludge cake. With the addition of Na2SO4 in the EDW, the pH gradient was intensified, and the migration rate of organic matters moving from cathode to anode increased while compared with the raw WAS. This study provided insights into the mechanism of EDW process at different dosages of Na2SO4.
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Affiliation(s)
- Jun Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Xu Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Sha Liang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Jiangwei Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Yueyuan Gu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Huali Deng
- Dongjiang Environment Company, Shenzhen, Guangdong, 518000, PR China
| | - Jiukun Hu
- Dongjiang Environment Company, Shenzhen, Guangdong, 518000, PR China
| | - Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
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30
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Guo X, Wang Y, Wang D. Permanganate/bisulfite (PM/BS) conditioning-horizontal electro-dewatering (HED) of activated sludge: Effect of reactive Mn(III) species. Water Res 2017; 124:584-594. [PMID: 28820989 DOI: 10.1016/j.watres.2017.08.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/07/2017] [Accepted: 08/10/2017] [Indexed: 06/07/2023]
Abstract
A novel activated sludge (AS) conditioning method through permanganate/bisulfate (PM/BS) process was proposed. The method involved a new conditioner of reactive Mn(III) intermediate. Moreover, a Mn(III) conditioning-horizontal electro-dewatering (Mn(III) C-HED) process was established to improve AS dewatering performance. Underlying mechanisms were unraveled by investigating changes in physicochemical characteristics, scanning electron microscope (SEM) morphology, and transformation of water and organic matters. The optimum dewatering conditions for Mn(III) C-HED process with the final water content of 86.94% were determined as the combination of KMnO4 0.01 mol/L AS and NaHSO3 0.05 mol/L AS at 20 V for 120 min. Results showed that Mn(III) C-HED process effectively reduced free water and bound water with the corresponding removal ratios of 51.68% and 87.62% at the anode-side as well as 36.55% and 85.08% at the cathode-side, respectively. During the PM/BS process, the produced Mn(III), Mn2+, and MnO2 exerted chemical and physical effects on AS conditioning and dewatering. Mn(III) disintegrated extracellular polymeric substances (EPS) fractions and cells in AS, as well as induced partial bound water release. Additionally, flocculation effect induced by Mn2+ and MnO2 skeleton building also benefited AS dewatering. AS cells were further disrupted under the effect of a horizontal electric field. Accordingly, EPS within the AS matrix was solubilized, tightly bound (TB)-EPS or loosely bound (LB)-EPS was converted to their corresponding outer EPS fractions, and AS dewaterability improved. Additionally, changes in pH and temperature at HED stage damaged the AS cells and changed the floc properties, thereby leading to easy separation of liquid and AS particles.
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Affiliation(s)
- Xinxin Guo
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Yili Wang
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China.
| | - Dongsheng Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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31
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Zhang S, Yang Z, Lv X, Zhi S, Wang Y, Li Q, Zhang K. Novel electro-dewatering system for activated sludge biosolids in bench-scale, pilot-scale and industrial-scale applications. Chem Eng Res Des 2017; 121:44-56. [DOI: 10.1016/j.cherd.2017.02.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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32
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Mahmoud A, Hoadley AFA, Conrardy JB, Olivier J, Vaxelaire J. Influence of process operating parameters on dryness level and energy saving during wastewater sludge electro-dewatering. Water Res 2016; 103:109-123. [PMID: 27448036 DOI: 10.1016/j.watres.2016.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/06/2016] [Accepted: 07/09/2016] [Indexed: 06/06/2023]
Abstract
Electrically assisted mechanical dewatering, known as electro-dewatering (EDW), is an alternative emerging technology for energy-efficient liquid/solids separation in the dewatering of wastewater sludge. In this study, the performance of the electro-dewatering (EDW) process for activated wastewater sludge was investigated. The influence of the operating modes; being the timing of voltage (U-EDW) or current (I-EDW) application to either or both the filtration and compression stages, and the influence of the applied pressure (in successive 30 min pressure steps) were studied. The results showed that by delaying the application of the electric field to the filter cake compression stage, there was a potential saving in power consumption of around 10-12% in the case of U-EDW and about 30-46% in the case of I-EDW. The increase of the applied pressure from 0.5 to 12 bar during the filter cake compression stage leads to an increase in electro-dewatering kinetics. The results also reveal that at a low electric field level the increase of the processing pressure has a relatively pronounced effect on the dewatering process. At high levels of the electric field, a minimum processing pressure (4-6 bar) is required to improve the electrical contact between the electrode and the sludge and thus lower the energy consumption.
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Affiliation(s)
- Akrama Mahmoud
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075, Pau Cedex, France.
| | - Andrew F A Hoadley
- Department of Chemical Engineering, Building 35, Clayton Campus, Monash University, Victoria, 3800, Australia
| | - Jean-Baptiste Conrardy
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075, Pau Cedex, France
| | - Jérémy Olivier
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075, Pau Cedex, France
| | - Jean Vaxelaire
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, BP 7511, 64075, Pau Cedex, France
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33
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Conrardy JB, Vaxelaire J, Olivier J. Electro-dewatering of activated sludge: Electrical resistance analysis. Water Res 2016; 100:194-200. [PMID: 27192354 DOI: 10.1016/j.watres.2016.05.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 06/05/2023]
Abstract
The significant risk of ohmic heating and the high electric energy consumption at terminal stages of the dewatering are two problems that hamper the development of the electro-dewatering (EDW) technology. In the future prospect of studying these two issues, it is important to provide and analyse quantitative data relative to the behavior of the electric resistance in EDW. It was the main goal of this study. It showed that the electric resistance of the complete system (cake + filter cloth) depended on the cake dryness. It increased sharply when the solids content exceeded around 45%.The solids loading also influenced the apparent resistance at the beginning of the process. The electric resistance of the filter cloth represented about 20% of the total resistance. It remained relatively constant over the process except at the terminal stage where it generally increased sharply. The use of conductive filter, such as metallic cloth, enabled to decrease the electric resistance and reduce the energy consumption of the process. The electric resistance decreased across the cake from the anode to the cathode. This behavior may be explained by several phenomena such as the ions migration and their interaction with the solid, the decrease of dry solids content from the anode to the cathode and the gas presence at the anode (due to electrolysis reaction).
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Affiliation(s)
- Jean-Baptiste Conrardy
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, rue Jules Ferry, BP 7511, 75075 Pau Cedex, France
| | - Jean Vaxelaire
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, rue Jules Ferry, BP 7511, 75075 Pau Cedex, France.
| | - Jérémy Olivier
- Laboratoire de Thermique Energétique et Procédés (EAD 1932), UPPA, ENSGTI, rue Jules Ferry, BP 7511, 75075 Pau Cedex, France
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