1
|
Xiao T, Zhang L, Dong B, Xu Z. Effect of dissolved ozone flotation thickening process on coliform bacteria and antibiotics simultaneous abatement: A pilot-scale study. Sci Total Environ 2024; 912:169506. [PMID: 38123084 DOI: 10.1016/j.scitotenv.2023.169506] [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: 10/17/2023] [Revised: 12/16/2023] [Accepted: 12/17/2023] [Indexed: 12/23/2023]
Abstract
This study focused on the removal of the total coliforms, fecal coliforms and four target antibiotics in the dissolved ozone flotation (DOF) thickening sludge process. Additionally, the thickened effluent chromaticity and its effect on thickened sludge hydrolysis process were investigated. Ozonation in the DOF process could inactivate coliforms by oxidizing cellular components and destroying genetic material, as well as altering the chemical structure of antibiotics, leading to the degradation of antibiotics. At an O3 dosage of 16 mg/g TS, the concentration of total coliforms and fecal coliforms decreased by 2.2 log and 2.4 log, corresponding to an overall removal rate of 99.4 % and 99.7 %, respectively. The total degradation rate of four target antibiotics (tetracycline (TC), oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL)) were 66.5 %, 68.8 %, 53.3 % and 57.5 %, respectively. The chromaticity removal rate of the thickened effluent reached 95 %. Analysis of fluorescence spectra indicated alterations in the fluorescence properties of dissolved organic matter, resulting in a decrease in fluorescence intensity by ozonation. The thickened sludge had higher hydrolysis rates, resulting in a greater production of volatile fatty acids (VFAs). This was mainly attributed to the increased amount of soluble protein and carbohydrate in the substrate after DOF treatment, which was more conducive for the rapid conversion of hydrolysis into VFAs during the initial stage. These results provided new ideas for upgrading and transforming the thickening process of wastewater treatment plants (WWTPs).
Collapse
Affiliation(s)
- Tingting Xiao
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Lingjun Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Bin Dong
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; YANGTZE Eco-Environment Engineering Research Center, China Three Gorges Corporation, Beijing 100038, China.
| | - Zuxin Xu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| |
Collapse
|
2
|
Chen S, Chen J, Wang X, Li J, Dong B, Xu Z. Footprints of total coliforms, faecal coliforms and E. coli in a wastewater treatment plant and the probabilistic assessment and reduction of E. coli infection risks. Sci Total Environ 2023; 900:165845. [PMID: 37506894 DOI: 10.1016/j.scitotenv.2023.165845] [Citation(s) in RCA: 1] [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: 06/01/2023] [Revised: 07/17/2023] [Accepted: 07/25/2023] [Indexed: 07/30/2023]
Abstract
Wastewater contains various pathogenic microorganisms, and the disease of workers caused by exposure to wastewater at the wastewater treatment plants (WWTPs) is a growing concern. The footprints of total coliforms (TC), faecal coliforms (FC) and Escherichia coli (E. coli) in a conventional activated sludge WWTP during 12 consecutive months were clarified. It was found that TC, FC and E.coli in influent were significantly removed (log 4.71, log 4.43 and log 4.62, respectively) by WWTP with sand filtration playing a key role, and excess sludge was a major potential pathway for them flowing to the environment. Through quantitative microbial risk assessment (QMRA), hand-to-mouth ingestion of untreated wastewater and wastewater in secondary/efficient sedimentation tanks, as well as accidental ingestion of sludge in dewatering workshop presented the highest infection risks of pathogenic E.coli in the WWTP, considerably exceeded the U.S. EPA benchmark (≤1 × 10-4 pppy). PPE application and E.coli concentration reduction in wastewater or sludge were recommended to reduce the infection risks at these stages. Further, partial ozonation and dissolved ozone flotation thickening were investigated able to reduce the infection risks at the stages of secondary and tertiary treatment of wastewater or sludge treatment by 90- 98 %. The findings of this study would assist in selecting appropriate processes for the further sanitation of WWTPs.
Collapse
Affiliation(s)
- Sisi Chen
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China; School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Jiangfeng Chen
- School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, PR China
| | - Xiankai Wang
- YANGTZE Eco-Environment Engineering Research Center, China Three Gorges Corporation, Beijing 100038, PR China
| | - Ji Li
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Bin Dong
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China; YANGTZE Eco-Environment Engineering Research Center, China Three Gorges Corporation, Beijing 100038, PR China.
| | - Zuxin Xu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| |
Collapse
|
3
|
Li Y, Liu L, Li X, Xie J, Guan M, Wang E, Lu D, Dong T, Zhang X. Influence of alternating electric field on deep dewatering of municipal sludge and changes of extracellular polymeric substance during dewatering. Sci Total Environ 2022; 842:156839. [PMID: 35732236 DOI: 10.1016/j.scitotenv.2022.156839] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 04/07/2022] [Revised: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 06/15/2023]
Abstract
A self-prepared experimental device made of plexiglass with alternating power supply system was used to study the deep dewatering of municipal dewatered sludge. Considering the reduction rate of sludge water content (Wr) as the index, factors affecting enhanced electric settlement of sludge such as exchange electrode method, voltage gradient, sludge thickness, and mechanical pressure were studied, and the dewatering mechanism was elucidated. The single-factor experiment combined with the surface response method based on the Box-Behnken central experimental design was performed. With Wr as the response value, the voltage gradient conditions, time ratio, and sludge thickness were optimized. Pearson correlation analysis showed that the reduction of proteins/polysaccharides was beneficial to improving the sludge dewatering effect. Tightly bound extracellular polymeric substances (TB-EPSs) showed a significant influence on the sludge dewatering effect. Under the action of the external electric field, particles with negative charge moved toward the anode sludge, water with partial positive charge flowed to the cathode, and the sludge cellular structure was damaged. This resulted in the dissolution of a large number of EPSs and the release of bound water. The anode sludge cake got thickened due to the accumulation of the sludge particles, leading to the increase in resistance. The TB-EPS was deconstructed by the ohmic heating to improve the sludge dewatering effect and achieve deep dewatering. Scanning electron microscopy results showed that the drying problem of anode sludge was alleviated during the dewatering process.
Collapse
Affiliation(s)
- Yalin Li
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China; School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan 430068, PR China.
| | - Lei Liu
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| | - Xiaoran Li
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan 430068, PR China
| | - Junpu Xie
- School of Mathematics and Statistics, Carleton University, Ontario K1S 5B6, Canada
| | - Mingyue Guan
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| | - Enci Wang
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| | - Dongxue Lu
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| | - Tingting Dong
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| | - Xing Zhang
- School of College of Environmental and Biological Engineering, Henan University of Engineering, Zhengzhou 451191, PR China
| |
Collapse
|
4
|
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.
Collapse
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.
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Li M, Song G, Liu R, Huang X, Liu H. Inactivation and risk control of pathogenic microorganisms in municipal sludge treatment: A review. Front Environ Sci Eng 2022; 16:70. [PMID: 34608423 PMCID: PMC8482957 DOI: 10.1007/s11783-021-1504-5] [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: 03/23/2021] [Revised: 06/28/2021] [Accepted: 07/12/2021] [Indexed: 05/05/2023]
Abstract
The rapid global spread of coronavirus disease 2019 (COVID-19) has promoted concern over human pathogens and their significant threats to public health security. The monitoring and control of human pathogens in public sanitation and health facilities are of great importance. Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants (WWTPs). It is an important sink of different pollutants and pathogens, and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health. However, there is a lack of comprehensive analysis of the diversity, exposure risks, assessment methods and inactivation techniques of pathogenic microorganisms in sludge. Based on this consideration, this review summarizes the control performance of pathogenic microorganisms such as enterovirus, Salmonella spp., and Escherichia coli by different sludge treatment technologies, including composting, anaerobic digestion, aerobic digestion, and microwave irradiation, and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed. Additionally, this study reviews the diversity, detection methods, and exposure risks of pathogenic microorganisms in sludge. This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.
Collapse
Affiliation(s)
- Mengtian Li
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Ge Song
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Ruiping Liu
- Center for Water and Ecology, School of Environment, Tsinghua University, Beijing, 100084 China
| | - Xia Huang
- School of Environment, Tsinghua University, Beijing, 100084 China
| | - Huijuan Liu
- Center for Water and Ecology, School of Environment, Tsinghua University, Beijing, 100084 China
| |
Collapse
|
7
|
Ling X, Deng J, Ye C, Cai A, Ruan S, Chen M, Li X. Fe(II)-activated sodium percarbonate for improving sludge dewaterability: Experimental and theoretical investigation combined with the evaluation of subsequent utilization. Sci Total Environ 2021; 799:149382. [PMID: 34358742 DOI: 10.1016/j.scitotenv.2021.149382] [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] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/15/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
Fe(II)-activated sodium percarbonate (SPC) was an emerging technology for enhancing the dewaterability of waste activated sludge, and its operational parameters were systematically explored. The results showed that after the treatment by 1.20 mmol/g VSS SPC and 1.44 mmol/g VSS Fe(II) at initial pH 3.0, the water content and specific resistance to filtration remained at 76.05 ± 0.36% and 2.57 ± 0.08 × 1012 m·kg-1, respectively. The acid condition was instrumental in sludge dewatering, whereas overdosing Fe(II) or SPC imposed adverse effect. The conversion of EPS fractions was examined to elucidate the underlying mechanism, which indicated that a coexisting oxidation/flocculation process accounted for the improvement of sludge dewaterability. The stronger oxidative ·OH degraded the hydrophilic compounds (proteins and carbohydrates) of tightly-bound extracellular polymeric substance and the dissolved multivalence iron promoted solid-liquid separation. Additionally, the theoretical analysis (DFT calculation) demonstrated that the oxygen- and nitrogen-containing groups of EPS resulted in high-water holding capacity of sludge. The difficulty of destroying hydrophilic functional groups followed C=O > C-N > C-O during oxidation process. Moreover, Fe(II)/SPC treatment performed well in coliforms inactivation and phytotoxicity reduction compared with different ·OH-based advanced oxidation processes for sludge conditioning.
Collapse
Affiliation(s)
- Xiao Ling
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Jing Deng
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China.
| | - Cheng Ye
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Anhong Cai
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Shuyu Ruan
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Minjie Chen
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Xueyan Li
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
| |
Collapse
|
8
|
Wu SL, Wei W, Ni BJ. Enhanced methane production from anaerobic digestion of waste activated sludge through preliminary pretreatment using calcium hypochlorite. J Environ Manage 2021; 295:113346. [PMID: 34348434 DOI: 10.1016/j.jenvman.2021.113346] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 03/21/2021] [Revised: 07/18/2021] [Accepted: 07/18/2021] [Indexed: 06/13/2023]
Abstract
Methane recovery from waste activated sludge (WAS) through anaerobic digestion is generally restricted by the poor degradability of WAS. Herein, a novel sludge pretreatment technology by using the calcium hypochlorite (Ca(ClO)2) in enhancing the methane production from WAS anaerobic digestion was reported. The solubilization of WAS was significantly increased after 10-240 mg Ca(ClO)2/g VS (VS: volatile solids) pretreatment for 48 h, under which the solubilization was 1.7-3.4 folds (i.e., 0.17-0.34 mg SCOD/mg VS; SCOD: soluble chemical oxygen demand) higher than that without Ca(ClO)2 pretreatment (i.e., 0.1 mg SCOD/mg VS). Correspondingly, the methane production was increased from 250.0 ± 5.3 mL/g VS to 385.1 ± 3.3 mL/g VS with the doses of Ca(ClO)2 increasing from 10 mg/g VS to 240 mg/g VS, resulted in an increasing methane production of 3.6%-59.7% than that without Ca(ClO)2 pretreatment. The microbial community composition results exhibited that the populations of key acidogens (e.g., Longilinea sp.) and methanogens (e.g., Methanosaeta sp.) were both reduced significantly. Moreover, Ca(ClO)2 decreased the cells viability, leading to a 76.2% reduction of living cells fraction. Accordingly, it was further confirmed that high dosage of Ca(ClO)2 could inhibit three microbial-related processes relevant to methane production, i.e., acidification, hydrolysis and methanogenesis.
Collapse
Affiliation(s)
- Shu-Lin Wu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Bing-Jie Ni
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
| |
Collapse
|
9
|
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.
Collapse
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.
| |
Collapse
|
10
|
Li Y, Yu X, Zhang S, Zhang Y. Influences of K +, Ca 2+, and Al 3+ on electrokinetic process and conductive mechanism of sludge electro-dewatering. Environ Res 2021; 198:111222. [PMID: 33933492 DOI: 10.1016/j.envres.2021.111222] [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] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
In the process of sludge electro-dewatering (EDW), ions migration accompanied has significant influences on the dewatering efficiency. However, the effects of ions on sludge electrochemical properties and the roles in EDW are still not well understood. In this paper, influences of K+, Ca2+, and Al3+ on the mechanical dewatering and EDW process were investigated, and the mechanisms of EDW were analyzed from electrokinetic phenomena and electric conduction model. The results showed that the increase of cationic valence improved sludge mechanical dewatering but deteriorated EDW performance. The spatially distributed voltage used for ionic electromigration indicated that the lagged migration of divalent cation Ca2+ consumed more energy and reduced the dewatering rate in the later stage of EDW compared to that of monovalent cation K+. And trivalent cation Al3+ migrated less and took less water out, while it made the electrochemical reaction of EDW system easier to carry out. The decrease of the absolute zeta potential value of K+, Ca2+, and Al3+ also revealed the degeneration of dewaterability limit. An electric conduction model of partially water-saturated state porous media related to geometric factors was used and clarified the weight variation of continuous phase conductivity and surface conductivity during EDW. The results showed that the conductivity of Al-sludge was more affected by geometric factors and resulted in worse dewatering performance. This study provided a theoretical guidance for understanding the ions behavior affecting the dewatering efficiency and energy consumption of EDW.
Collapse
Affiliation(s)
- Yingte Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xiaoyan Yu
- Department 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
| | - Yuxin Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| |
Collapse
|
11
|
Sun X, Ma D, Lin S, Wang Y, Liu Q. Research on push-type sludge electro-dewatering equipment with fixed-plate electrodes. Sep Purif Technol 2021; 267:118612. [DOI: 10.1016/j.seppur.2021.118612] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
12
|
Wang M, Chen H, Liu S, Xiao L. Removal of pathogen and antibiotic resistance genes from waste activated sludge by different pre-treatment approaches. Sci Total Environ 2021; 763:143014. [PMID: 33190880 DOI: 10.1016/j.scitotenv.2020.143014] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [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: 07/02/2020] [Revised: 09/12/2020] [Accepted: 10/07/2020] [Indexed: 05/13/2023]
Abstract
In wastewater treatment plants, most of the pathogens and antibiotic resistant genes (ARGs) transferred into and concentrated in waste activated sludge (WAS), which would cause severe public health risks. In this study, the capabilities of several WAS pre-treatment approaches to inactivate coliforms/E. coli and ARGs, as well as the subsequent regrowth of coliforms/E. coli and ARGs/intI1 in treated sludge were investigated. The results showed that electro-Fenton (EF), with continuous hydroxyl radical generation, could efficiently inactivate coliforms/E. coli in 60 min (about 4 log units), followed by methanol (MT), anode oxidization (AO), and acidification (AT). Kinetic analysis showed that the inactivation mainly occurred in the first 10 min. However, the efficiencies of all studied pre-treatment approaches on inactivating ARGs/intI1 (<2 log units) were lower than coliforms/E. coli, whilst EF still had the highest efficiency of ARGs/intI1 reduction. Mechanical ultrasound treatment (ULS) could not inactivate coliforms/E. coli in WAS, but it could efficiently reduce ARGs/intI1. High regrowth rates of coliforms/E. coli were observed in the treated WAS in 10 days, but the abundances of ARGs/intI1 continuously reduced during the after-treatment incubation. Our study showed that EF could efficiently disinfect potential pathogens, however, the reduction of ARGs/intI1 in WAS need further investigation.
Collapse
Affiliation(s)
- Min Wang
- State Key laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Huiping Chen
- State Key laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Shulei Liu
- State Key laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Lin Xiao
- State Key laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
| |
Collapse
|
13
|
Hu S, Hu J, Sun Y, Zhu Q, Wu L, Liu B, Xiao K, Liang S, Yang J, Hou H. Simultaneous heavy metal removal and sludge deep dewatering with Fe(II) assisted electrooxidation technology. J Hazard Mater 2021; 405:124072. [PMID: 33535356 DOI: 10.1016/j.jhazmat.2020.124072] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 04/17/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 05/21/2023]
Abstract
A hybrid sludge conditioning strategy with electrooxidation and Fe(II) addition was used for heavy metal removal from sewage sludge and industrial sludge, with simultaneous sludge dewatering and stabilization. With the addition of 82 mg/g DS Fe(II) and treatment time of 4.5 h, heavy metal removals of 72.95% and 78.49% for Cu, 66.29% and 84.26% for Zn, and 36.52% and 36.99% for Pb were achieved from sewage sludge and industrial sludge samples respectively. The system pH decreased to 2.33 and 2.98 and the oxidation-reduction potential (ORP) values increased to 435.90 mV and 480.60 mV in sewage sludge and industrial sludge samples, respectively, which was conducive to the desorption and dissolution of heavy metals from sludge structures and the degradation of the organic compounds that complexed with heavy metals. In addition, the hybrid conditioning process demonstrated excellent dewatering performance due to the efficient electrochemical disintegration of sludge flocs together with the coagulation of sludge particles by Fe(III) generated via electrooxidation. The strong acidic and oxidative environment produced by the enhanced electrooxidation process was also responsible for pathogen inactivation.
Collapse
Affiliation(s)
- Shaogang Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Jingping Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Yingfei Sun
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Qian Zhu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Longsheng Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Bingchuan Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Sha Liang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Huijie Hou
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China.
| |
Collapse
|
14
|
Ai J, Wang Z, Dionysiou DD, Liu M, Deng Y, Tang M, Liao G, Hu A, Zhang W. Understanding synergistic mechanisms of ferrous iron activated sulfite oxidation and organic polymer flocculation for enhancing wastewater sludge dewaterability. Water Res 2021; 189:116652. [PMID: 33278721 DOI: 10.1016/j.watres.2020.116652] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 09/20/2020] [Revised: 11/01/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
The bound water in waste activated sludge (WAS) is trapped in extracellular polymeric substances (EPS) in the form of gel-like structure, leading to a great challenge in the sludge deep dewatering. Traditional flocculation conditioning is unable to destroy EPS and ineffective to remove the bound water in WAS. In this study, we employed integration of Fe(II)-sulfite oxidation and polyacrylamide flocculation (F/S-PAM) treatment for removing the bound water and improving sludge dewaterability under aerobic conditions. Meanwhile, the floc microstructure and EPS properties were examined to understand the mechanisms of F/S-PAM conditioning. F/S produced SO3·- radicals which could decompose the EPS in sludge, releasing bound water into free water. In addition, the formed Fe(III) from F/S led to re-coagulation of decomposed EPS, and C=O groups of tryptophan played the leading role in Fe-EPS association binding, causing transformation of the secondary structure of proteins (especially β-sheets and α-helices). Then, the introduction of PAM caused re-flocculation of disintegrated sludge flocs, enhancing the sludge filterability. This work provides a novel and cost-effective method for efficient removal of bound water in sludge, and subsequence improvement in sludge dewaterability.
Collapse
Affiliation(s)
- Jing Ai
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China; Environmental Engineering and Science Program, Department of Chemical and Environmental Engineering (ChEE), University of Cincinnati, Cincinnati, OH 45221-0012, USA
| | - Zhiyue Wang
- The Biotechnology Institute, University of Minnesota, St. Paul, MN 55108-6106, USA
| | - Dionysios D Dionysiou
- Environmental Engineering and Science Program, Department of Chemical and Environmental Engineering (ChEE), University of Cincinnati, Cincinnati, OH 45221-0012, USA.
| | - Ming Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Yun Deng
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Mingyue Tang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Guiying Liao
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Aibin Hu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Weijun Zhang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China.
| |
Collapse
|
15
|
Hu S, Zhao W, Hu J, Liu B, Wang D, Zhu Q, Yang J, Hou H. Integration of electrochemical and calcium hypochlorite oxidation for simultaneous sludge deep dewatering, stabilization and phosphorus fixation. Sci Total Environ 2021; 750:141408. [PMID: 32858289 DOI: 10.1016/j.scitotenv.2020.141408] [Citation(s) in RCA: 3] [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: 04/27/2020] [Revised: 06/23/2020] [Accepted: 07/30/2020] [Indexed: 05/15/2023]
Abstract
A hybrid electrochemical process with Ca(ClO)2 addition for simultaneous sludge dewaterability, stabilization and phosphorus fixation was proposed. Under optimal conditions (150 mg/g VS Ca(ClO)2, 15 V), the capillary suction time (CST) and specific resistance to filtration (SRF) were decreased by 88% and 92%, respectively. Efficient sludge stabilization with E. coli colonies of less than 1000 MPN/g TS was achieved. Phosphorus of 99% was removed from the filtrate and successfully fixed in the sludge cake and on the electrode surface. The integration of electrochemical and hypochlorite oxidation could effectively degrade the tightly bound extracellular polymeric substances (TB-EPS) structure with a total organic carbon (TOC) reduction of 52%. Besides, the disintegration of microbial cell envelopes was also achieved, with a reduction of living cell fraction of 98%. Furthermore, system pH could be maintained at near neutral (7.45) and the conversion of Fe(II) to Fe(III) was also facilitated with the addition of Ca(ClO)2, resulting in improved electrocoagulation process for enhanced sludge dewatering and phosphorus fixation. The multifunctional effects were achieved with the cooperated extracellular electrooxidation for EPS destruction and the active chlorine for intracellular microbial cell disintegration. This research provides a promising strategy for integrated sludge treatment and recycling for possible land utilization.
Collapse
Affiliation(s)
- Shaogang Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China
| | - Wenjin Zhao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China
| | - Jingping Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Bingchuan Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China
| | - Dongliang Wang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China
| | - Qian Zhu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Huijie Hou
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China.
| |
Collapse
|
16
|
|
17
|
Kim HJ, Chon K, Lee YG, Kim YK, Jang A. Enhanced mechanical deep dewatering of dewatered sludge by a thermal hydrolysis pre-treatment: Effects of temperature and retention time. Environ Res 2020; 188:109746. [PMID: 32540570 DOI: 10.1016/j.envres.2020.109746] [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: 11/11/2019] [Revised: 01/27/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
This study investigated effects of the thermal hydrolysis pre-treatment on mechanical deep dewaterability of dewatered sludge to extend understanding of dewatering characteristics of thermally hydrolyzed sludge. Floc sizes of dewatered sludge were gradually reduced during the thermal hydrolysis pre-treatment at 170 °C and 185 °C with increasing retention time whereas longer retention time (>60 min) increased floc sizes of thermally hydrolyzed sludges at 200 °C due to formation of undesired refractory organic materials (ROMs), which might hinder the disintegration of dewatered sludge flocs. Similar trends were found for thermal hydrolytic solubilization of dewatered sludge. This demonstrated that the efficiency of the thermal hydrolysis pre-treatment at a higher temperature (200 °C) with longer retention time (≥60 min) could be strongly influenced by the formation of ROMs associated with changes of solid fractions and some free amino acids (i.e., β-aminobutyric acid, 4-hydroxyproline, and cysteine). Since the trade-off between the degradation of dewatered sludge and the formation of ROMs determined mechanical deep dewaterability of thermally hydrolyzed sludge, the lowest residual weight and moisture content were observed for thermally hydrolyzed sludges at 200 °C with retention time range of 60 min (residual weight = 0.165; moisture content = 55.38%) to 90 min (residual weight = 0.160; moisture content = 59.87%). These observations were intimately correlated to variations of extracellular polymeric substances during the thermal hydrolysis pre-treatment, but not in accordance with the change pattern of capillary suction time (CST) values. This is evident that the CST value was inadequate to estimate mechanical deep dewaterability of thermally hydrolyzed sludge.
Collapse
Affiliation(s)
- Hee-Joong Kim
- Hansu Technical Service Research Center, 145 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea; Graduate School of Water Resources, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Kangmin Chon
- Department of Environmental Engineering, College of Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do, Republic of Korea.
| | - Yong-Gu Lee
- Department of Environmental Engineering, College of Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do, Republic of Korea
| | - Youn-Kwon Kim
- K-water Institute, Yuseong-daero, 1689 Beon-gil, Yuseong-gu, Daejeon, Republic of Korea
| | - Am Jang
- Graduate School of Water Resources, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea.
| |
Collapse
|
18
|
Rumky J, Visigalli S, Turolla A, Gelmi E, Necibi C, Gronchi P, Sillanpää M, Canziani R. Electro-dewatering treatment of sludge: Assessment of the influence on relevant indicators for disposal in agriculture. J Environ Manage 2020; 268:110689. [PMID: 32383657 DOI: 10.1016/j.jenvman.2020.110689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 01/10/2020] [Revised: 04/22/2020] [Accepted: 04/30/2020] [Indexed: 05/15/2023]
Abstract
Waste activated sludge requires effective dewatering, high biological stability and retention of nutrients prior to disposal for agricultural application. The study was conducted to evaluate the impact of pressure-driven electro-dewatering (EDW) on improving sludge characteristics related to disposal in agriculture, including biological stability, pathogen availability, heavy metals concentrations and nutrients content. Thickened conditioned and mechanically dewatered sludge samples were collected from two wastewater treatment plants (WWTPs), characterized by different stabilization processes, and treated by a lab-scale device at 5, 15 and 25 V. EDW increased significantly the dry solid (DS) content, up to 43-45%, starting from 2 to 3% of raw sludge. The endogenous value of specific oxygen uptake rate (SOUR), monitored as indicator of biological stability, increased up to 56% and 39% after EDW tests for sludge from two WWTPs. On the other hand, the exogenous SOUR decreased, indicating a significant drop in the active bacterial population. Likewise, a 1-2 log unit reduction was observed for E. coli after EDW tests at 15 and 25 V. However, no remarkable removal of heavy metals, namely chromium, nickel, lead, copper and zinc, was achieved. Finally, the concentration of nutrients for soil, such as carbon, nitrogen, phosphorus and sulfur, was not affected by the EDW process. In conclusion, EDW exerts considerable effects on the biological characteristics of sludge, which should be considered in a proper design of sludge management to ensure safe and sustainable resource recovery.
Collapse
Affiliation(s)
- Jannatul Rumky
- Department of Green Chemistry, LUT University, Sammonkatu 12, 50130 Mikkeli, Finland
| | - Simone Visigalli
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Andrea Turolla
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Enrico Gelmi
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Chaker Necibi
- International Water Research Institute, Mohammed VI Polytechnic University, 43150, Green City Benguerir, Morocco
| | - Paolo Gronchi
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Mika Sillanpää
- Institute of Research and Development, Duy Tan University, 550000, Da Nang, Viet Nam; Faculty of Environment and Chemical Engineering, Duy Tan University, 550000, Da Nang, Viet Nam; School of Civil Engineering and Surveying, Faculty of Health, Engineering and Sciences, University of Southern Queensland, West Street, Toowoomba, 4350, QLD, Australia
| | - Roberto Canziani
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| |
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
Fan X, Wang Y, Zhang D, Guo Y, Gao S, Li E, Zheng H. Effects of acid, acid-ZVI/PMS, Fe(II)/PMS and ZVI/PMS conditioning on the wastewater activated sludge (WAS) dewaterability and extracellular polymeric substances (EPS). J Environ Sci (China) 2020; 91:73-84. [PMID: 32172984 DOI: 10.1016/j.jes.2020.01.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [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: 10/21/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 06/10/2023]
Abstract
The effects of four conditioning approaches: Acid, Acid-zero-valent iron (ZVI)/peroxydisulfate (PMS), Fe(II)/PMS and ZVI/PMS, on wastewater activated sludge (WAS) dewatering and organics distribution in supernatant and extracellular polymeric substances (EPS) layers were investigated. The highest reduction in bound water and the most WAS destruction was achieved by Acid-ZVI/PMS, and the optimum conditions were pH 3, ZVI dosage 0.15 g/g dry solid (DS), oxone dosage 0.07 g/g DS and reaction time 10.6 min with the reductions in capillary suction time (CST) and water content (Wc) as 19.67% and 8.49%, respectively. Four conditioning approaches could result in TOC increase in EPS layers and supernatant, and protein (PN) content in tightly bound EPS (TB-EPS). After conditioning, organics in EPS layers could migrate to supernatant. Polysaccharide (PS) was easier to migrate to supernatant than PN. In addition, Acid, Acid-ZVI/PMS or Fe(II)/PMS conditioning promoted the release of some polysaccharides containing ring vibrations v PO, v C-O-C, v C-O-P functional groups from TB-EPS. ESR spectra proved that both radicals of SO4-· and ·OH contributed to dewatering and organics transformation and migration. CST value of WAS positively correlated with the ratios of PN/PS in LB-EPS and total EPS, while it negatively correlated with TOC, PN content and PS content in TB-EPS, as well as PS content in supernatant and LB-EPS. BWC negatively correlated to zeta potential and TOC value, PN content, and HA content in supernatant.
Collapse
Affiliation(s)
- Xiaoyang Fan
- 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; Jinyun Forest Ecosystem Research Station, Beijing Forestry University, Beijing 100083, China.
| | - Daxin Zhang
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Yajie Guo
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Shihui Gao
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Enrui Li
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Huaili Zheng
- Key Laboratory of the Three Gorges Reservoir Regions Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China
| |
Collapse
|
21
|
Zhang Q, Wu Y, Luo J, Cao J, Kang C, Wang S, Li K, Zhao J, Aleem M, Wang D. Enhanced volatile fatty acids production from waste activated sludge with synchronous phosphorus fixation and pathogens inactivation by calcium hypochlorite stimulation. Sci Total Environ 2020; 712:136500. [PMID: 31931205 DOI: 10.1016/j.scitotenv.2020.136500] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 11/15/2019] [Revised: 12/10/2019] [Accepted: 01/01/2020] [Indexed: 06/10/2023]
Abstract
An efficient approach for synchronous volatile fatty acids (VFAs) promotion, phosphorus fixation and pathogens inactivation during waste activated sludge (WAS) anaerobic fermentation was achieved with optimal calcium hypochlorite (Ca(ClO)2) stimulation. The maximal VFAs were 3.6 folds of control in reactors with 0.01 g Ca(ClO)2/g TSS addition. The low dosage of Ca(ClO)2 enhanced WAS solubilization and hydrolysis by disrupting the extracellular polymeric substance (EPS) effectively. Sufficient substrates for fermentative bacteria were thereby provided with the maintenance of acceptable microbial activity and viability. However, high dosage of Ca(ClO)2 deteriorated the performance of anaerobic fermentation due to its strong oxidative ability, resulting in cell lysis greatly. Moreover, the largely released phosphorus during WAS fermentation was effectively precipitated and removed by the combination of Ca2+ at 0.01 g Ca(ClO)2/g TSS dosage. In addition, Ca(ClO)2 had distinguished effects on pathogens inactivation. The simultaneous phosphorus fixation and pathogens reduction during VFAs production increased the utilization value of fermentation liquid and benefitted the further disposal of fermented sludge.
Collapse
Affiliation(s)
- Qin Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Yang Wu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Jingyang Luo
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; Guohe Environmental Research Institute (Nanjing) Co., Ltd, Nanjing 211599, PR China.
| | - Jiashun Cao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; Guohe Environmental Research Institute (Nanjing) Co., Ltd, Nanjing 211599, PR China
| | - Chaojie Kang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Suna Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Keyan Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Jianan Zhao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Muhammad Aleem
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, PR China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China
| |
Collapse
|
22
|
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.![]()
Collapse
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
| |
Collapse
|
23
|
Zeng Q, Zan F, Hao T, Biswal BK, Lin S, van Loosdrecht MCM, Chen G. Electrochemical pretreatment for stabilization of waste activated sludge: Simultaneously enhancing dewaterability, inactivating pathogens and mitigating hydrogen sulfide. Water Res 2019; 166:115035. [PMID: 31494488 DOI: 10.1016/j.watres.2019.115035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 02/23/2019] [Revised: 08/27/2019] [Accepted: 08/30/2019] [Indexed: 05/15/2023]
Abstract
Stabilization of waste activated sludge (WAS) is an essential step for the disposal or reuse. In this study, WAS stabilization via electrochemical pretreatment (EPT) at 0-15V was evaluated for simultaneous dewaterability enhancement, pathogen removal and H2S mitigation. The mechanism underlying EPT was investigated and discussed based on the changes in the physicochemical (e.g., particle size, zeta potential, hydrophobicity and extracellular polymeric substances) and biological characteristics (i.e. cell morphology, and distribution and percentages of live/dead cells) of WAS with different EPT voltages. The results revealed that EPT disintegrated WAS flocs and disrupted the cell walls leading to a reduction in particle size (by up to 50%), increased release of extracellular and intracellular substances (by up to 4 times) to facilitate WAS stabilization. With EPT at 15V, the capillary suction time of WAS decreased by 42%, and the concentrations of E. coli and indicator pathogens (Salmonella spp. and Streptococcus faecalis) fell by nearly 5 log10 reaching U.S. EPA hygienization levels. Furthermore, EPT at 12V or higher suppressed the amounts of dissolved sulfide and H2S(g) produced from the WAS under anaerobic conditions by over 99%. This study demonstrates the feasibility of EPT for simultaneous WAS dewaterability enhancement, pathogen inactivation and H2S mitigation, providing a one-step alternative for sludge stabilization.
Collapse
Affiliation(s)
- Qian Zeng
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Feixiang Zan
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Tianwei Hao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
| | - Basanta Kumar Biswal
- Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Sen Lin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | | | - Guanghao Chen
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Wastewater Treatment Laboratory, FYT Graduate School, The Hong Kong University of Science and Technology, Guangzhou, China
| |
Collapse
|
24
|
Zhao Q, Liu Y. Is anaerobic digestion a reliable barrier for deactivation of pathogens in biosludge? Sci Total Environ 2019; 668:893-902. [PMID: 30870755 PMCID: PMC7112049 DOI: 10.1016/j.scitotenv.2019.03.063] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [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: 01/29/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 04/14/2023]
Abstract
As World Health Organization advocates, the global burden of sanitation related disease and access to safely managed sanitation and safely treated wastewater should be monitored strictly. However, the spread of pathogens through various agricultural applications or direct discharge of sewage sludge generated in municipal wastewater treatment plants poses a serious challenge on the environment and public health. Anaerobic digestion (AD), the principal method of stabilizing biosolids, can efficiently and largely deactivate viable pathogens, including parasite, virus, and the pathogens harboring antibiotic resistance genes. This review aims to provide a critical overview regarding the deactivation of sludge-associated pathogens by AD, through which a serious concern on the effectiveness and rationality of AD towards sludge pathogens control was raised. Meanwhile, the underlying deactivation mechanisms and affecting factors were all discussed, with the focus on pathogen-associated modeling, engineering design and technological aspects of AD. Lastly, a matric method incorporating the operating strategy of AD with the risk assessment was proposed for evaluating the reliability of AD-based pathogen deactivation, while the research agenda forward was also outlined.
Collapse
Affiliation(s)
- Qian Zhao
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, 1000 Fengming Road, Jinan 250101, China; Shandong Province Co-Innovation Center of Green Building, Jinan 250101, China; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
| | - Yu Liu
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141, Singapore.
| |
Collapse
|
25
|
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%.
Collapse
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
| |
Collapse
|
26
|
Chen Y, Chen H, Li J, Xiao L. Rapid and efficient activated sludge treatment by electro-Fenton oxidation. Water Res 2019; 152:181-190. [PMID: 30669040 DOI: 10.1016/j.watres.2018.12.035] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [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: 09/03/2018] [Revised: 11/23/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
Advanced oxidation process is one of the important process to improve the efficiency of activated sludge dewatering and digestion. In this study, electro-Fenton (EF) was investigated as a pretreatment method for improving activated sludge dewatering and disintegration in terms of specific resistance to filtration, volatile suspended solids removal and release of soluble organics. The morphology of sludge flocs and properties of extracellular polymeric substance (EPS) were investigated to understand the involved mechanisms. The results showed that EF could increase the dewaterability of activated sludge effectively in 40-60 min. The size of sludge flocs decreased after EF treatment, but zeta potential was elevated to near zero and floc structure became coarser with bigger holes. EF could enhance the sludge floc disintegration, released protein and polysaccharide to soluble EPS fraction, and promote the humification process. The kinetic analysis further indicated that EF increased the pseudo first-order EPS solubilization rate. EF had high operational stability by retaining over 90% initial activity even after five repeated use of dewatering filtrate. This study provides a rapid and efficient solution for improving sludge dewaterability by electro-Fenton.
Collapse
Affiliation(s)
- Yasong Chen
- State Key Laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Huiping Chen
- State Key Laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Jie Li
- State Key Laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Lin Xiao
- State Key Laboratory of Pollution Control & Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China.
| |
Collapse
|
27
|
Sha L, Yu X, Liu X, Yan X, Duan J, Li Y, Zhang S. Electro-dewatering pretreatment of sludge to improve the bio-drying process. RSC Adv 2019; 9:27190-27198. [PMID: 35529198 PMCID: PMC9070639 DOI: 10.1039/c9ra02920f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [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: 04/18/2019] [Accepted: 08/05/2019] [Indexed: 11/21/2022] Open
Abstract
In this study, the feasibility of electro-dewatering (EDW) as a pretreatment of the subsequent bio-drying process (EB process) was investigated from the point of view of the influence of EDW on the microbial biodegradability of sludge. The results showed that suitable EDW pretreatment was beneficial for microbial growth in the sludge cake, and in the subsequent bio-drying process it increased the metabolic activity of microorganisms. However, electric field strength impacted microbial activity and soluble chemical oxygen demand (SCOD) of the sludge. As the applied electric field strength increased from 20 to 60 V cm−1, the microbial activity of sludge decreased gradually but SCOD of sludge increased. The specific oxygen uptake rate (SOUR) at electric field strength of 20 V cm−1 was 8.7% higher than that of raw sludge. EDW pretreatment accelerated the drying rate of bio-drying process, and the final water content of sludge (44%) was 6.3% lower than that of non-pretreated sludge. It was observed that in the bio-drying process with an EDW pretreatment, the first peak temperature of the sludge pile was 58.7 °C at 36 h and the second peak temperature was 48.7 °C at 56 h, whereas that of the non-pretreated sludge was only 46.5 °C at 42 h and 40.3 °C at 62 h, respectively. The EDW sludge incorporating straw as a bulking agent showed promising results during bio-drying. In addition, EDW pretreatment of sludge to improve the bio-drying process showed lower energy consumption and cost. The feasibility of electro-dewatering (EDW) as a pretreatment of the subsequent bio-drying process was investigated in this study.![]()
Collapse
Affiliation(s)
- Li Sha
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Xiaoyan Yu
- School of Energy and Chemical Engineering
- Liaoning Technical University
- Huludao 125105
- China
| | - Xingxin Liu
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Xiaotong Yan
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Jingxiao Duan
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Yingte Li
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Shuting Zhang
- School of Environment Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| |
Collapse
|
28
|
Yu W, Wen Q, Yang J, Xiao K, Zhu Y, Tao S, Lv Y, Liang S, Fan W, Zhu S, Liu B, Hou H, Hu J. Unraveling oxidation behaviors for intracellular and extracellular from different oxidants (HOCl vs. H 2O 2) catalyzed by ferrous iron in waste activated sludge dewatering. Water Res 2019; 148:60-69. [PMID: 30347276 DOI: 10.1016/j.watres.2018.10.033] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [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: 08/01/2018] [Revised: 09/26/2018] [Accepted: 10/11/2018] [Indexed: 05/15/2023]
Abstract
Cell lysis in sludge pretreatment by advanced oxidation process (AOP) has a great effect on sludge dewaterability. Cell lysis caused by reactive radicals (e.g. hydroxyl radical) was dependent on the reaction site of AOP. However, little is known about the accurate radical generation site of AOP in sludge pretreatment. In this study, two kinds of oxidation behaviors from different oxidants (HOCl vs. H2O2) catalyzed by ferrous iron were comparatively investigated. Higher amount of living cells (84.3%) and hydroxyl radicals (9.86 × 10-5 M), and more fragmentized sludge flocs (particle sizes of D50 was 50.1 vs. 57.3 μm of RS) were detected in sludge conditioned by Fe2+/H2O2, which implied that Fenton reaction mainly happened at surface and outside of sludge flocs (such as EPS layer and liquid phase). Thus, it could be regarded as "extracellular oxidation". Fewer living cells (undetectable), fewer amount of hydroxyl radicals (undetectable in sludge), and more integrated sludge flocs (particle size of D50 was 56.1 vs. 57.3 μm of RS) were determined in sludge conditioned by Fe2+/Ca(ClO)2. Hence, it could be regarded as "Intracellular oxidation". In addition, sludge pretreatment based on Fe2+/Ca(ClO)2 could achieve simultaneous deep-dewatering performance and total coliforms inactivation. Based on response surface methodology, the optimal dosages of Fe2+ and Ca(ClO)2 were proposed as 106.1 and 234.5 mg/g volatile solids respectively, without any acidification of sludge. Under these optimal dosages, the water content of dewatered sludge cake was 51.9 ± 0.1 wt% and the pH of the final filtrate was 5.8 ± 0.2. Total coliforms of sludge could be inactivated in 10 s after Fe2+/Ca(ClO)2 addition.
Collapse
Affiliation(s)
- Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Qianqian Wen
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
| | - Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Yuwei Zhu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Shuangyi Tao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Yang Lv
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Sha Liang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Wei Fan
- School of Urban and Environmental Science, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Suiyi Zhu
- School of Urban and Environmental Science, Northeast Normal University, Changchun, Jilin, 130024, China.
| | - Bingchuan Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Huijie Hou
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| | - Jingping Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China
| |
Collapse
|
29
|
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.
Collapse
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
| |
Collapse
|
30
|
Wang K, Wu Y, Wang Z, Wang W, Ren N. Insight into effects of electro-dewatering pretreatment on nitrous oxide emission involved in related functional genes in sewage sludge composting. Bioresour Technol 2018; 265:25-32. [PMID: 29864734 DOI: 10.1016/j.biortech.2018.05.089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 04/11/2018] [Revised: 05/22/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Electro-dewatering (ED) pretreatment could improve sludge dewatering performance and remove heavy metal, but the effect of ED pretreatment on nitrous oxide (N2O) emission and related functional genes in sludge composting process is still unknown, which was firstly investigated in this study. The results revealed that ED pretreatment changed the physicochemical characteristics of sludge and impacted N2O related functional genes, resulting in the reduction of cumulative N2O emission by 77.04% during 60 days composting. The higher pH and NH4+-N, but lower moisture, ORP and NO2--N emerged in the composting of ED sludge compared to mechanical dewatering (MD) sludge. Furthermore, ED pretreatment reduced amoA, hao, narG, nirK and nosZ in ED sludge on Day-10 and Day-60 of composting. It was found that nirK reduction was the major factor impacting N2O generation in the initial composting of ED sludge, and the decline of amoA restricted N2O production in the curing period.
Collapse
Affiliation(s)
- Ke Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
| | - Yiqi Wu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Zhe Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Wei Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Nanqi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| |
Collapse
|
31
|
Yu Y, Wei H, Yu Y, Yu L, Wang S, Sun C. Influence of calcium compounds as a compression framework on activated sludge dewaterability and calorific value. Environ Technol 2018; 39:1025-1031. [PMID: 28402222 DOI: 10.1080/09593330.2017.1319422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 03/14/2015] [Accepted: 04/08/2017] [Indexed: 06/07/2023]
Abstract
Calcium compounds have been known to be important for enhancing aggregation and dewaterability of activated sludge. In this study, the effect of calcium compounds (CaO, Ca(OH)2, CaCl2, CaSO4 and CaCO3, respectively) on sludge dewaterability and calorific value was investigated. Upon addition of CaO, Ca(OH)2, CaCl2, CaSO4 and CaCO3 (112 mg/g dry sludge) into activated sludge, after compressed filtration the moisture content of sludge was found to be 49.7%, 55.7%, 57.1%, 65.3% and 56.5%, respectively. The addition of calcium compounds altered the structure of sludge by CaCO3 and Ca(OH)2 production, which improved sludge filterability and provided frameworks and water passages during compression. Furthermore, sludge conditioned by CaO addition had better dewaterability than other calcium compounds. The heat generated from the CaO hydration and high pH might damage flocs' structure and improve dewaterability of sludge. Moreover, it was found that excess addition of calcium compounds led to low calorific value in combustion process. The study concluded that CaO is the optimal additive for sludge further dewatering by compressed filtration.
Collapse
Affiliation(s)
- Yang Yu
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
- b School of Environmental Sciences and Engineering , Nanjing Tech University , Nanjing , People's Republic of China
| | - Huangzhao Wei
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
| | - Yonghui Yu
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
| | - Li Yu
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
| | - Sen Wang
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
| | - Chenglin Sun
- a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China
| |
Collapse
|
32
|
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.
Collapse
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.
| |
Collapse
|
33
|
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.
Collapse
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
| |
Collapse
|
34
|
Visigalli S, Turolla A, Gronchi P, Canziani R. Performance of electro-osmotic dewatering on different types of sewage sludge. Environ Res 2017; 157:30-36. [PMID: 28511078 DOI: 10.1016/j.envres.2017.05.015] [Citation(s) in RCA: 10] [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: 07/27/2016] [Revised: 04/26/2017] [Accepted: 05/11/2017] [Indexed: 06/07/2023]
Abstract
The feasibility of pressure-driven electro-dewatering (EDW) on sludge samples taken after different biological processes, stabilisation methods or mechanical dewatering techniques was assessed. First, the influence of potential values on EDW of anaerobically and aerobically stabilised, mechanically dewatered, sludge samples was investigated. Preliminary tests carried out by applying a constant potential (10, 15 and 20V) in a lab-scale device confirmed the possibility to reach a dry solid (DS) content of up to 42.9%, which corresponds to an increase of 15% of the dry content in dewatered sludge without the application of the electrical field. Dewatering increased with the applied potential but at the expense of a higher energy consumption. A potential equal to 15V was chosen as the best compromise for EDW performance, in terms of DS content and energy consumption. Then, the influence of the mechanical dewatering was studied on aerobically stabilised sludge samples with a lower initial DS content: the higher initial water content led to a lower final DS content but with a considerable reduction of energy consumption. Finally, the biological process, studied by comparing sludge samples from conventional activated sludge and membrane bioreactor processes, didn't evidence any influence on EDW. Experimental results shown that DS obtained after mechanical dewatering, volatile solids and conductivity are the main factors influencing EDW. Anaerobically digested sludge reached the highest DS content, thanks to lower organic fraction.
Collapse
Affiliation(s)
- Simone Visigalli
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci, 32, I 20133 Milano, Italy
| | - Andrea Turolla
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci, 32, I 20133 Milano, Italy
| | - Paolo Gronchi
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, I 20133 Milano, Italy
| | - Roberto Canziani
- Department of Civil and Environmental Engineering - Environmental Section, Politecnico di Milano, Piazza Leonardo da Vinci, 32, I 20133 Milano, Italy.
| |
Collapse
|
35
|
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]
|
36
|
Ma D, Qian J, Zhu H, Zhai J. Drying characteristics of electro-osmosis dewatered sludge. Environ Technol 2016; 37:3046-3054. [PMID: 27063252 DOI: 10.1080/09593330.2016.1175511] [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] [Indexed: 06/05/2023]
Abstract
Electro-osmotic dewatering (EDW) is one of the effective deeply dewatering technologies that is suitable for treating sludge with 55-80% of moisture content. Regarding EDW as the pre-treatment process of drying or incinerating, this article investigated the drying characteristics of electro-osmosis-dewatered sludge, including shear stress test, drying curves analysis, model analysis, and energy balance calculation. After EDW pre-treatment, sludge adhesion was reduced. The sludge drying rate was higher compared to the non-pre-treated sludge, especially under high temperatures (80-120°C). In addition, it is better to place the sludge cake with cathode surface facing upward for improving the drying rate. An adjusted model based on the Logarithmic model could better describe the EDW sludge drying process. Using the energy balance calculation, EDW can save the energy consumed in the process of sludge incineration and electricity generation and enable the system to run without extra energy input.
Collapse
Affiliation(s)
- Degang Ma
- a School of Environmental Science and Engineering , Tianjin University , Tianjin , People's Republic of China
| | - Jingjing Qian
- a School of Environmental Science and Engineering , Tianjin University , Tianjin , People's Republic of China
| | - Hongmin Zhu
- a School of Environmental Science and Engineering , Tianjin University , Tianjin , People's Republic of China
| | - Jun Zhai
- a School of Environmental Science and Engineering , Tianjin University , Tianjin , People's Republic of China
| |
Collapse
|
37
|
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).
Collapse
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
| |
Collapse
|
38
|
Davey KR, Chandrakash S. Modelling the effect of pH, sodium chloride and sodium pyrophosphate on the thermal resistance of Escherichia coli 0157:H7 in ground beef. Food Res Int 2015; 75:11-12. [PMID: 28454936 DOI: 10.1016/j.foodres.2015.05.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022]
Affiliation(s)
- K R Davey
- School of Chemical Engineering, The University of Adelaide, 5005, Australia.
| | - S Chandrakash
- School of Chemical Engineering, The University of Adelaide, 5005, Australia
| |
Collapse
|
39
|
Abstract
Electro-dewatering (ED) is a novel technology to reduce the overall costs of residual biosolids processing, transport, and disposal. In this study, we investigated Joule heating and pH as parameters controlling the dewaterability limit, dewatering rate, and energy efficiency. Temperature-controlled electrodes revealed that Joule heating enhances water removal by increasing evaporation and electro-osmotic flow. High temperatures increased the dewatering rate, but had little impact on the dewaterability limit and energy efficiency. Analysis of horizontal layers after 15-min ED suggests electro-osmotic flow reversal, as evidenced by a shifting of the point of minimum moisture content from the anode toward the cathode. This flow reversal was also confirmed by the pH at the anode being below the isoelectric point, as ascertained by pH titration. The important role of pH on ED was further studied by adding acid/base solutions to biosolids prior to ED. An acidic pH reduced the biosolids charge while simultaneously increasing the dewatering efficiency. Thus, process optimization depends on trade-offs between speed and efficiency, according to physicochemical properties of the biosolids microstructure.
Collapse
Affiliation(s)
- Tala Navab-Daneshmand
- †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Raphaël Beton
- †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Reghan J Hill
- ‡Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada
| | - Dominic Frigon
- †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| |
Collapse
|
40
|
Navab-Daneshmand T, Enayet S, Gehr R, Frigon D. Bacterial pathogen indicators regrowth and reduced sulphur compounds' emissions during storage of electro-dewatered biosolids. Chemosphere 2014; 113:109-115. [PMID: 25065797 DOI: 10.1016/j.chemosphere.2014.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [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: 08/12/2013] [Revised: 04/03/2014] [Accepted: 04/04/2014] [Indexed: 06/03/2023]
Abstract
Electro-dewatering (ED) increases biosolids dryness from 10-15 to 30-50%, which helps wastewater treatment facilities control disposal costs. Previous work showed that high temperatures due to Joule heating during ED inactivate total coliforms to meet USEPA Class A biosolids requirements. This allows biosolids land application if the requirements are still met after the storage period between production and application. In this study, we examined bacterial regrowth and odour emissions during the storage of ED biosolids. No regrowth of total coliforms was observed in ED biosolids over 7d under aerobic or anaerobic incubations. To mimic on-site contamination during storage or transport, ED samples were seeded with untreated sludge. Total coliform counts decreased to detection limits after 4d in inoculated samples. Olfactometric analysis of ED biosolids odours showed that odour concentrations were lower compared to the untreated and heat-treated control biosolids. Furthermore, under anaerobic conditions, odorous reduced sulphur compounds (methanethiol, dimethyl sulphide and dimethyl disulphide) were produced by untreated and heat-treated biosolids, but were not detected in the headspaces above ED samples. The data demonstrate that ED provides advantages not only as a dewatering technique, but also for producing biosolids with lower microbial counts and odour levels.
Collapse
Affiliation(s)
- Tala Navab-Daneshmand
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Samia Enayet
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Ronald Gehr
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Dominic Frigon
- Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada.
| |
Collapse
|
41
|
Weng C, Lin Y, Yuan C, Lin Y. Dewatering of bio-sludge from industrial wastewater plant using an electrokinetic-assisted process: Effects of electrical gradient. Sep Purif Technol 2013; 117:35-40. [DOI: 10.1016/j.seppur.2013.06.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|