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Jiang T, Li X, Yang J, Wang L, Wang W, Zhang L, Wang B. Potential of free nitrous acid (FNA) for sludge treatment and resource recovery from waste activated sludge: A review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 360:121170. [PMID: 38749134 DOI: 10.1016/j.jenvman.2024.121170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 04/18/2024] [Accepted: 05/11/2024] [Indexed: 06/05/2024]
Abstract
The escalating production of waste activated sludge (WAS) presents significant challenges to wastewater treatment plants (WWTPs). Free nitrous acid (FNA), known for its biocidal effect, has gained a growing focus on sludge dewatering, sludge reduction, and resource recovery from WAS due to its eco-friendly and cost-effective properties. Nevertheless, there have been no attempts made to systematically summarize or critically analyze the application of FNA in enhancing treatment and resource utilization of sludge. In this paper, we provided an overview of the current understanding regarding the application potential and influencing factors of FNA in sludge treatment, with a specific focus on enhancing sludge dewatering efficiency and reducing volume. To foster resource development from sludge, various techniques based on FNA have recently been proposed, which were comprehensively reviewed with the corresponding mechanisms meticulously discussed. The results showed that the chemical oxidation and interaction with microorganisms of FNA played the core role in improving resource utilization. Furthermore, current challenges and future prospects of the FNA-based applications were outlined. It is expected that this review can refine the theoretical framework of FNA-based processes, providing a theoretical foundation and technical guidance for the large-scale demonstration of FNA.
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Affiliation(s)
- Tan Jiang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Xiaodi Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Jiayi Yang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Lu Wang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Wen Wang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Li Zhang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Bo Wang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
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2
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Li Z, Chen S, Liu L, Qian D, Yuan M, Yu J, Chen Z, Yang J, Su X, Hu J, Hou H. Formation mechanism of persistent free radicals during pyrolysis of Fenton-conditioned sewage sludge: Influence of NOM and iron. WATER RESEARCH 2024; 254:121376. [PMID: 38489852 DOI: 10.1016/j.watres.2024.121376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/31/2024] [Accepted: 02/23/2024] [Indexed: 03/17/2024]
Abstract
The present study provided an innovative insight into the formation mechanism of persistent free radicals (PFRs) during the pyrolysis of Fenton-conditioned sludge. Fenton conditioners simultaneously improve the dewatering performance of sewage sludge and catalyze the pyrolysis of sewage sludge for the formation of PFRs. In this process, PFRs with a total number of spins of 9.533×1019 spins/g DS could be generated by pyrolysis of Fenton-conditioned sludge at 400°C. The direct thermal decomposition of natural organic matter (NOM) fractions contributed to the formation of carbon-centered radicals, while the Maillard reaction produced phenols precursors. Additionally, the reaction between aromatic proteins and iron played a crucial role in the formation of phenoxyl or semiquinone-type radicals. Kinetics analysis using discrete distributed activation energy model (DAEM) demonstrated that the average activation energy for pyrolysis was reduced from 178.28 kJ/mol for raw sludge to 164.53 KJ/mol for Fenton conditioned sludge. The reaction factor (fi) indicated that the primary reaction in Fenton-conditioned sludge comprised of 27 parallel first-order reactions, resulting from pyrolysis cleavage of the NOM fractions, the Maillard reaction, and iron catalysis. These findings are significant for understanding the formation process of PFRs from NOM in Fenton-conditioned sludge and provide valuable insight for controlling PFRs formation in practical applications.
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Affiliation(s)
- Zhen Li
- 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 Recycling, Wuhan 430074, PR China
| | - Sijing Chen
- 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 Recycling, Wuhan 430074, PR China
| | - Lu 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 Recycling, Wuhan 430074, PR China
| | - Dingkang Qian
- 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 Recycling, Wuhan 430074, PR China
| | - Mengjiao Yuan
- 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 Recycling, Wuhan 430074, PR China
| | - Jie Yu
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China
| | - Zhuqi Chen
- School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science and 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 Recycling, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China
| | - Xintai Su
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, 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 Recycling, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), 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 Recycling, Wuhan 430074, PR China.
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Hou J, Hong C, Ling W, Hu J, Feng W, Xing Y, Wang Y, Zhao C, Feng L. Research progress in improving sludge dewaterability: sludge characteristics, chemical conditioning and influencing factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119863. [PMID: 38141343 DOI: 10.1016/j.jenvman.2023.119863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/29/2023] [Accepted: 12/12/2023] [Indexed: 12/25/2023]
Abstract
Sludge from wastewater treatment processes with high water content and large volume has become an inevitable issue in environmental management. Due to the challenging dewatering properties of sludge, current mechanical dewatering methods are no longer sufficient to meet the escalating water content standards of sludge. This paper summarizes the characteristics of various sludge and raises reasons for the their dewaterability differences. Affected by extracellular polymeric substances, biological sludge is hydrophilic and negatively charged, which limits the dewatering degree. The rheological properties, flocs, ionic composition, and solid phase concentration of the sludge also influence the dewatering to some extent. For these factors, the chemical conditioning measures with simple operation and excellent effect improve its dewaterability, which mainly include flocculation/coagulation, acid/alkali treatment, advanced oxidation, surfactant treatment and combined treatment. There is a growing necessity to explore the development of new chemical conditioning agents, even though traditional agents continue to remain widely used. However, the development of these new agents should prioritize finding a balance between various factors such as efficiency, effectiveness, ease of operation, environmental safety, and cost-effectiveness. Electrochemical dewatering enhances solid-liquid separation, and its coupling with chemical conditioning is also an excellent means to further reduce water content. In addition, the improvement of press filter is an effective way, which is influenced by pressure, processing time, sludge cake thickness and pore structure, filter media etc. In general, it is essential to develop new conditioning agents and enhance mechanical filtration press technology based on a thorough understanding of various sludge properties. Concurrently, an in-depth study of the principles of mechanical pressure filtration will contribute to establishing a theoretical foundation for effective deep sludge dewatering and propel further advancements in this field.
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Affiliation(s)
- Jiachen Hou
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chen Hong
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Wei Ling
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jiashuo Hu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Weibo Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yi Xing
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yijie Wang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chengwang Zhao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Lihui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
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Li T, Yang J, Zhou Y, Liu X, Luo Y, Fang D, Liang J, Li J, Zhou L. Promoting dewatering efficiency of sludge by bioleaching coupling chemical flocculation. ENVIRONMENTAL RESEARCH 2023; 237:117014. [PMID: 37652216 DOI: 10.1016/j.envres.2023.117014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 08/14/2023] [Accepted: 08/27/2023] [Indexed: 09/02/2023]
Abstract
In recent years, bioleaching has emerged as a cost-effective technology for enhancing the dewaterability of sludge. However, the lengthy treatment time involved in sludge bioleaching processes limits daily treatment capacity for sludge. Here, a novel approach was developed through a short time of sludge bioleaching with A. ferrooxidans LX5 (A. f) and A. thiooxidans TS6 (A. t) followed by polyferric sulfate (PFS) flocculation (A. f + A. t + PFS). After 12.5 h of the A. f + A. t + PFS treatment (30% A. f, 10% A. t, 40 mg/g DS S0, 60 mg/g DS FeSO4•7H2O, and 120 mg/g DS PFS), the reduction efficiency of specific resistance to filtration (SRF) and sludge cake moisture content reached 94.0% and 11.6%, respectively, which were comparable to the results achieved through 24 h of completed bioleaching treatment. In pilot-scale applications, the mechanical dewatering performance was notably improved following A. f + A. t + PFS treatment, with the low moisture content of the treated sludge cake (∼59.2%). This study provides new insights into the A. f + A. t + PFS process and holds potential for developing efficient and promising sludge dewatering strategies in engineering application.
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Affiliation(s)
- Ting Li
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jiawei Yang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yujun Zhou
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Xuan Liu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yixin Luo
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Di Fang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing, 210095, China
| | - Jianru Liang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing, 210095, China
| | - Jiansheng Li
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Lixiang Zhou
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing, 210095, China.
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5
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Zhang YL, Zhang H, Liu WH, Sun P, Zheng SM, Gao YY, Zeng YP, Wang HF, Zeng RJ. Enhancing data reliability in quantitative characterization of moisture distribution in sludge using DSC: Impact of sample attributes and test parameters. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 346:119017. [PMID: 37738720 DOI: 10.1016/j.jenvman.2023.119017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/02/2023] [Accepted: 09/14/2023] [Indexed: 09/24/2023]
Abstract
Exploring moisture distribution, especially bound water content, is vital for studying and applying sludge dewatering. The differential scanning calorimetry (DSC) method has been extensively utilized for the quantitative characterization of moisture distribution in sludge. However, this method has certain limitations, such as low reproducibility of results, leading to controversial parameter values in different papers and hindering result comparison. In this study, we investigated the influence of key sample attributes on measuring sludge bound water using the DSC method.The findings demonstrated that the moisture content and mass of sludge samples substantially influenced the reproducibility and stability of DSC test results. To ensure data reliability, the moisture content of the sludge sample should be minimized and kept below 84%, with the mass not exceeding 10 mg. Compared to the influence of sludge moisture content and sample mass, the heating rate (1⁓5 °C/min) minimally affected DSC test results. This study offers a comprehensive insight into how sample attributes and test parameters affect the quantitative characterization of bound water in sludge using the DSC method. Furthermore, practical strategies are presented to enhance the method's applicability in sludge bound water characterization.
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Affiliation(s)
- Ya-Li Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hao Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Wen-Hui Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Ping Sun
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shao-Ming Zheng
- Fujian Fiber Inspection Center, Fujian Provincial Key Laboratory of Textiles Inspection Technology, Fuzhou, 350002, China
| | - Yun-Yan Gao
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yuan-Ping Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hou-Feng Wang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
| | - Raymond Jianxiong Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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6
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Li T, Yang J, Zhou Y, Luo Y, Zhou B, Fang D, Li J, Zhou L. Enhancing sludge dewatering efficiency through bioleaching facilitated by increasing reactive oxygen species. WATER RESEARCH 2023; 231:119622. [PMID: 36680824 DOI: 10.1016/j.watres.2023.119622] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 01/09/2023] [Accepted: 01/15/2023] [Indexed: 06/17/2023]
Abstract
Bioleaching facilitated by iron-oxidizing bacteria is regarded as a promising sludge dewatering method due to excellent dewaterability and low cost. However, a two-days bioleaching time for sludge conditioning decreased its daily treatment capacity. In fact, Fe2+ easily reacts with O2 to produce reactive oxygen species (ROS) with high oxidizing activity. Can bioleaching performed in Fe2+-rich system generate ROS to decompose sludge extracellular polymeric substances (EPS)? Here both contribution of ROS produced in bioleaching to improve sludge dewaterability and the increase of ROS content to shorten sludge bioleaching treatment time were investigated. The introduction of H2O2 in sludge bioleaching treatment (BS+H2O2) to increase ROS could simultaneously improve sludge dewaterability and decrease bioleaching time. Specific resistance to filtration (SRF) and capillary suction time (CST) reduction ratios (90.3% and 80.9%) in BS+H2O2 process were much higher than those in other processes after only 30 min reaction. Mechanisms of improving sludge dewaterability in BS+H2O2 mainly included ROS oxidation and Fe3+ flocculation by analysis of the contribution factors. These findings not only provide an effectively method to promote sludge dewatering efficiency of bioleaching, but also give new sights into the design of cost-efficient processes for improving the sludge dewatering.
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Affiliation(s)
- Ting Li
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiawei Yang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yujun Zhou
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Yixin Luo
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Bo Zhou
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Di Fang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiansheng Li
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Lixiang Zhou
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
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Zhang Q, Cui G, He X, Wang Z, Tang T, Zhao Q, Liu Y. Effects of voltage and pressure on sludge electro-dewatering process and the dewatering mechanisms investigation. ENVIRONMENTAL RESEARCH 2022; 212:113490. [PMID: 35594958 DOI: 10.1016/j.envres.2022.113490] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/31/2022] [Accepted: 05/14/2022] [Indexed: 06/15/2023]
Abstract
Electro-dewatering technology shows a good application prospect because of its high efficiency in removing water from sludge and low energy consumption, but the potential mechanisms of sludge electro-dewatering have not been investigated in depth, which seriously limits the further development and application of electro-dewatering technology. In this study, the effects of voltage and pressure on sludge electro-dewatering performance, physicochemical characteristics and extracellular polymeric substances (EPS) compositions and distributions were investigated. The spatial distributions of EPS main components, including polysaccharide (PS) and protein (PN), were characterized by a confocal laser scanning microscopy (CLSM). The experimental results showed that under the conditions of a voltage of 40 V and a pressure of 90 kPa, the moisture content of sludge was reduced from 83.15% to 53.12%, and the bound water content of sludge in the anode layer, middle layer and cathode layer were decreased significantly from 1.16 g/g dry solid (DS) to 0.20, 0.47 and 0.35 g/g DS, respectively. The PN content of EPS in anode layer was significantly lower than that in cathode layer due to the electrochemical oxidation, while the variation of PS content showed the opposite trend, which agreed with the results visualized by CLSM. Pearson's correlation coefficient and hierarchical cluster analysis revealed that PN in TB-EPS was the major factor influencing the effect of sludge electro-dewatering. This work can be helpful to understand the potential mechanisms of electro-dewatering and provide theoretical support for the further popularization and application of electro-dewatering technology.
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Affiliation(s)
- Qiming Zhang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Guodong Cui
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Xiao He
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Zheng Wang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Tian Tang
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China
| | - Qing Zhao
- State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum, Beijing, 102249, China
| | - Yangsheng Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China.
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Geng N, Wang Y, Zhang D, Fan X, Li E, Han Z, Zhao X. An electro-peroxone oxidation-Fe(III) coagulation sequential conditioning process for the enhanced waste activated sludge dewatering: Bound water release and organics multivariate change. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 833:155272. [PMID: 35427618 DOI: 10.1016/j.scitotenv.2022.155272] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/07/2022] [Accepted: 04/10/2022] [Indexed: 06/14/2023]
Abstract
As a by-product of wastewater treatment, waste activated sludge (WAS) has complex composition, strong hydrophilic extracellular polymeric substance (EPS), which make it difficult to dewater. In this study, an electro-peroxone oxidation-Fe(III) coagulation (E-peroxone-Fe(III)) sequential conditioning approach was developed to improve WAS dewaterability. At E-peroxone oxidation stage, hydrogen peroxide was generated through 2-electron path on a carbon polytetrafluoroethylene cathode, and reacted with the sparged O3 to produce hydroxyl radicals. At the subsequent coagulation stage, Fe(III) was dosed to coagulate the small WAS fragments and release water from WAS. Along E-peroxone-Fe(III) subsequent conditioning process, the physicochemical properties of WAS, main components, functional groups and evolution of protein secondary structure, and typical amino acids in EPS, as well as the type and semi-quantitative of elements in WAS, were investigated. The results indicated that under the optimal conditions, the reductions of specific resistance to filterability (SRF) and capillary suction time (CST) for WAS equalled 78.18% and 71.06%, respectively, and its bound water content decreased from 8.87 g/g TSS to 7.67 g/g TSS. After E-peroxone oxidation, part of protein and polysaccharide migrated outside from TB-EPS to slime, the ratio of α-helix/(β-sheet + random coil) declined, even some of organic-N disintegrated to inorganic-N. At Fe(III) coagulation stage, re-coagulation of the dispersed WAS fragments and easy extraction from inner EPS for protein and polysaccharide occurred. Furthermore, the protein secondary structure of β-sheet increased by 13.48%, the contents of hydrophobic and hydrophilic amino acids also increased. In addition, a strong negative correlation between the hydrophobic amino acid content of Met in slime and CST or SRF (R2CST = -0.999, p < 0.05 or R2SRF = -0.948, p < 0.05) occurred, while a strong positive correlation between the hydrophilic amino acid content of Cys in TB-EPS and CST or SRF (R2CST = 0.992, p < 0.05 or R2SRF = 0.921, p < 0.05) occurred, which could be related to the WAS dewaterability.
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Affiliation(s)
- Nannan Geng
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Yili Wang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
| | - Daxin Zhang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; School of Soil & Water Conservation, Beijing Forestry University, Beijing 100083, China
| | - Xiaoyang Fan
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Enrui Li
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Zhibo Han
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Xiaoqi Zhao
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
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9
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Sha L, Wu Z, Ling Z, Liu X, Yu X, Zhang S. Investigation on the improvement of activated sludge dewaterability using different iron forms (ZVI vs. Fe(II))/peroxydisulfate combined vertical electro-dewatering processes. CHEMOSPHERE 2022; 292:133416. [PMID: 34953873 DOI: 10.1016/j.chemosphere.2021.133416] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/08/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
The high moisture content (MC) of activated sludge dewatered by traditional vertical electro-dewatering (VED) is unable to meet the disposal requirements. Therefore, different iron forms (ZVI vs. Fe(II))/peroxydisulfate (PDS) combined VED (ZVI/PDS-VED and Fe(II)/PDS-VED) were employed to enhance the dewaterability of activated sludge. The dewatering behaviors of the two combined dewatering processes and the underlying mechanism related to the sludge characteristics were investigated and compared. Sludge was conditioned using ZVI/PDS and Fe(II)/PDS, respectively, and then dewatered by the VED in the experiment. Experimental results showed that with 0.3 g (g dry solids (DS))-1 of iron activators, 0.583 g (g DS) -1 of PDS, and 30 V of voltage, the MC of sludge after ZVI/PDS-VED and Fe(II)/PDS-VED reached the minimum values of 50.6 ± 1.2% and 32.1 ± 1.5%, respectively. ZVI/PDS and Fe(II)/PDS conditioning reduced the MC difference of sludge between the anode and the cathode during the VED, facilitating the water homogenization in the sludge cake. ZVI/PDS-VED and Fe(II)/PDS-VED could effectively reduce the bound water and the free water. Free water had high correlations with α-helix (r = 0.999, p < 0.05) and CO (r = 0.998, p < 0.05). Compared with the traditional VED and the ZVI/PDS-VED, the Fe(II)/PDS-VED had a greater improvement of sludge dewaterability due to the more efficient degradation of extracellular polymeric substances and the increase of sludge surface hydrophobicity. This study promoted the development of the new sludge deep-dewatering technology.
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Affiliation(s)
- Li Sha
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Zhangxiang Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Zichen Ling
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xingxin Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China
| | - Xiaoyan Yu
- School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, 030008, China
| | - Shuting Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China.
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10
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Wang S, Zhao Q, Jiang J, Wang K. Insight into the organic matter degradation enhancement in the bioelectrochemically-assisted sludge treatment wetland: Transformation of the organic matter and microbial community evolution. CHEMOSPHERE 2022; 290:133259. [PMID: 34914954 DOI: 10.1016/j.chemosphere.2021.133259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 11/29/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Sludge treatment wetland (STW) has been widely used to dewater and mineralize the various sludge, but the low degradation ability of organic matter can limit its application. Bioelectrochemistry has been proven to accelerate the degradation of organic compounds and recover bioenergy from the sludge. In this study, a bioelectrochemical-assisted sludge treatment wetland (BE-STW) system was constructed to determine the most common types of degraded organic matter and the functional bacterial community. It was found that the bioelectrochemistry process contributed to a further removal of the total chemical oxygen demand (TCOD) by 19% (±0.6) and the additional soluble chemical oxygen demand (SCOD) value was 64.10% (±0.63), with a voltage output of 0.961 V and a power density of 0.351 W/m3. The hydrophilic and hydrophobic acid fractions of the sludge were preferentially removed in BE-STW. The tryptophan-like protein and fulvic acid-like substances were totally removed, whereas, the hydrolysis of aromatic organic compounds in the neutral and hydrophobic acid fractions was enhanced. Also, the enrichment of Longilinea and Methylophilus improved the hydrolysis of organic matter. Moreover, the high relative abundance of Thauera, Dechloromonas, and Syntrophorhabdus could accelerate the degradation of aromatic compounds in the BE-STW system. The bacteria from the genus Geobacter was predominantly detected (2.48%) in the anodic biofilm on BE-STW. The results showed that bioelectrochemistry could improve the sludge stabilization degree in STW, accelerate the organic matter degradation and hydrolysis efficiency, and harvest bioelectricity, simultaneously. This technology can provide a new pathway to increase the efficiency of the traditional STW systems.
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Affiliation(s)
- Shutian Wang
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Qingliang Zhao
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China; State Key Laboratory of Urban Water Resources and Environments (SKLUWRE), School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
| | - Junqiu Jiang
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China; State Key Laboratory of Urban Water Resources and Environments (SKLUWRE), School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
| | - Kun Wang
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China; State Key Laboratory of Urban Water Resources and Environments (SKLUWRE), School of Environment, Harbin Institute of Technology, Harbin, 150090, China
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11
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Liu C, Zhou X, Zhou L, Wei Y, Liu J. Enhancement of sludge electro-dewatering by anthracite powder modification. ENVIRONMENTAL RESEARCH 2021; 201:111510. [PMID: 34147466 DOI: 10.1016/j.envres.2021.111510] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 06/12/2023]
Abstract
Electro-dewatering of sludge has received considerable attention due to its low energy consumption for sludge deep-dewatering. However, prior studies have shown the resistance of dried sludge near anode significantly hinders electro-dewatering. The dewatering performance may be improved by reducing the resistance with the addition of conductive material into sludge. We conditioned municipal sludge by anthracite powder, an inexpensive product, to increase solid conductivity, followed by electro-dewatering. After running for 20 min under a constant voltage of 30 V, when the anthracite powder mass was 10%-22% of raw sludge dry solids mass (DS), the final dry solids content of the mud cake after dehydration was 6.2%-12.9% higher than that from dehydration of unconditioned sludge. The average filtrate flow rate ranged from 0.0243 to 0.0285 g s-1. The lowest unit energy consumption, 0.19 kW h·kgwater-1, which was 14% lower than that of control, was reached when 18% DS of anthracite was added. Our theoretical analysis indicates that properly increasing solid conductivity of sludge can reduce the adverse effect caused by the high electrical resistance of sludge near anode. The experimental results, along with the theoretical analysis, show that using anthracite powder for sludge modification is an economical approach to improve sludge dewatering rate and reduce energy consumption.
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Affiliation(s)
- Changyuan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China
| | - Xingqiu Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, PR China.
| | - Lang Zhou
- Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin, 301 E. Dean Keeton Street, Austin, TX, 78712, United States
| | - Yijun Wei
- Shenzhen Water (Group) CO., LTD, Futian Branch Company, Shenzhen, 518000, PR China
| | - Jiangyan Liu
- Shenzhen Shenshui Ecological & Environmental Technology CO., LTD., Shenzhen, 518000, PR China
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12
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13
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Wang S, Liu Z, Yang M, Zhou Y, Yang M, Long M, Fang F, Guo J. The differences in characteristics of extracellular polymeric substances of flocs and anammox granules impacted aggregation. Bioprocess Biosyst Eng 2021; 44:1711-1720. [PMID: 33768321 DOI: 10.1007/s00449-021-02554-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/16/2021] [Indexed: 10/21/2022]
Abstract
Extracellular polymeric substances (EPS) are considered crucial components in the formation of microbial aggregates such as biofilms, flocs and granules. However, the role of EPS in sludge aggregation is still unclear. In this study, the differences in EPS characteristics of anammox granular sludge (AG), anammox floc sludge (AF) and activated floc sludge (AS) were investigated to clarify its role in granular aggregation. The results showed that the flocculation ability of EPS extracted from AG (62.8 ± 2.3%) was notably higher than that of EPS extracted from AF (35.7 ± 1.7%) and AS (17.3 ± 1.5%). The zeta potential and hydrophobicity of EPS showed the same tendency. In addition, the PN/PS ratio of AG, AF and AS were 7.66, 4.62 and 3.93, respectively. FTIR, XPS and 3D-EEM fluorescence spectra results revealed that anammox granular sludge has a higher ratio of hydrophobic groups, α-helixs/(β-sheets and random coils), intermolecular hydrogen bonds, and aromatic amino acids, and a lower ratio of electronegative groups. Anammox granular sludge exhibited high aggregation ability, because its EPS had higher zeta potential, hydrophobicity and intermolecular hydrogen bond ratio. This work provides a better understanding of the high aggregation ability of anammox granules and a theoretical basis for improving granules proportion and retention ability of microbes in reactor system.
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Affiliation(s)
- Shuai Wang
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
| | - Zihan Liu
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
| | - Mingming Yang
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China.,Yangtze Ecology and Environment Co., Ltd, Wuhan, 430062, China
| | - Yang Zhou
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
| | - Mansu Yang
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
| | - Man Long
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
| | - Fang Fang
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China.
| | - Jinsong Guo
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, China
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14
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Gao S, Wang Y, Zhang D, Fan X, Guo Y, Li E, Zheng H. Insight to peroxone-Fe(III) joint conditioning-horizontal electro-dewatering process on water reduction in activated sludge: Performance and mechanisms. JOURNAL OF HAZARDOUS MATERIALS 2021; 402:123441. [PMID: 32688188 DOI: 10.1016/j.jhazmat.2020.123441] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 06/11/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Peroxone disintegration-Fe(III) coagulation (peroxone-Fe(III)) joint conditioning was proposed to enhance the horizontal electro-dewatering (HED) effect of activated sludge (AS). Operating parameters were optimized and the evolutions of AS physicochemical properties, water fractions distribution, organic matter, extracellular polymeric substance (EPS) key components, functional groups, and protein secondary structures during the process were identified. Under the optimized joint conditioning parameters, dewatered AS achieved a final water content of 84.88 ± 0.17% and its bound water content (BWC) was decreased by 1.88 ± 0.28 g/g dry solid. During peroxone pretreatment, the yielded HO decreased the AS floc size, disintegrated the EPS network structure and cell wall, released the bound water, and extracted proteins, polysaccharides, and humic acid-like materials. Furthermore, soluble microbial byproduct-like materials (SMBP) in the EPS layers and tyrosine in tightly bound EPS significantly increased. Protein structures were destroyed, decreasing their water affinity. Subsequent Fe(III) addition re-coagulated broken flocs fragments and EPS fractions, built water flow channels, removed tyrosine and SMBP, and reduced α-helix percentage in slime, facilitating AS dewatering. After joint conditioning, the bound water and intracellular substances were further released by HED. Therefore, the peroxone-Fe(III)-HED process exhibited an excellent performance in AS water reduction.
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Affiliation(s)
- Shihui Gao
- 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.
| | - Daxin Zhang
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China
| | - Xiaoyang Fan
- 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
| | - 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
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15
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Zhou X, Jin W, Wang L, Ding W, Chen C, Xu X, Tu R, Han SF, Feng X, Lee DJ. Improving primary sludge dewaterability by oxidative conditioning process with ferrous ion-activated peroxymonosulfate. KOREAN J CHEM ENG 2020. [DOI: 10.1007/s11814-020-0517-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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16
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Li Y, Wang D, Xu Q, Liu X, Wang Y, Wu Y, Yang G, Yuan X, Wu Z, Guan R, Xiong T, He D, Fu Q. New insight into modification of extracellular polymeric substances extracted from waste activated sludge by homogeneous Fe(II)/persulfate process. CHEMOSPHERE 2020; 247:125804. [PMID: 31931311 DOI: 10.1016/j.chemosphere.2019.125804] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/26/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
Fe(II)/persulfate process has been proven to be a promising technique for disintegrating sludge, while during the Fe(II)/persulfate treatment the direct information about the variation of extracellular polymeric substances (EPS) properties, which is a key factor affecting sludge dewatering, is still lacked. In this work, different dosages of Fe(II)/persulfate were employed to treat EPS fractions extracted from waste activated sludge. The experiment results showed that EPS fractions were modified by Fe(II)/persulfate process. An oxidation/flocculation process was raised to unveil how Fe(II)/persulfate modified EPS fractions: Firstly, SO4- and OH were formed by chemical reactions of Fe(II) activating persulfate and radical interconversion, respectively. Then these species nonselectively fragmented EPS fractions through decomposing their components, which facilitated decrement of the hydrophilic components and high/mid molecular weight of organics in EPS fractions. Furthermore, these radicals transformed the secondary structure of EPS proteins by affecting the hydrogen bonds at specific positions and inducing the cleavage of the S-S bonds in cysteine residues of proteins, which led to loose layout of protein molecules and thus increased exposure of the hydrophobic groups hidden in EPS protein molecules. Secondly, Fe(III), i.e., the oxidation product of Fe(II), assembled the ruptured colloids particles through lessening electronegativity. Consequently, Fe(II)/persulfate process elevated the flocculability and hydrophobicity of EPS fractions, which would improve physicochemical and rheological properties of sludge to facilitate its dewaterability.
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Affiliation(s)
- Yifu Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China.
| | - Qiuxiang Xu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Xuran Liu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Yali Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Yanxin Wu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Guojing Yang
- College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, PR China.
| | - Xingzhong Yuan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Zhibin Wu
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, PR China
| | - Renpeng Guan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Ting Xiong
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Dandan He
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Qizi Fu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
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17
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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] [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.
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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
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18
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Wu P, Pi K, Shi Y, Li P, Wang Z, Zhang H, Liu D, Gerson AR. Dewaterability and energy consumption model construction by comparison of electro-dewatering for industry sludges and river sediments. ENVIRONMENTAL RESEARCH 2020; 184:109335. [PMID: 32169737 DOI: 10.1016/j.envres.2020.109335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
Electro-dewatering (EDW) is an emerging technology for improved sludge/sediment dewatering enabling subsequent cost effective treatment for toxicity and pathogenic reduction if required and/or disposal, but the effects of sediment/sludge properties on the efficacy of EDW remain unclear. Here we investigate EDW in the absence of chemical conditioning which can result in secondary pollution. The influence of sediment/sludge volatile solids content (VS), electrical conductivity (EC), pH and zeta potential (ζ), on mechanical and electrical behaviors determining dewaterability and energy consumption (PE) was investigated. Optimization of EDW parameters increased the final solids content (DSf) from 40 wt% to more than 55 wt% for river sediment, while the solids content in municipal sludge was only increased from 10 wt% to 15-20 wt%. Multiple linear regression and statistical analysis showed that electro-dewatering performance is primarily affected by VS and PE is mainly affected by EC. A theoretical basis for engineering design and selection of operational parameters for sludge/sediment electro-dewatering is provided by this study.
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Affiliation(s)
- Pan Wu
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China; Future Industries Institute, Mawson Lakes Campus, University of South Australia (UniSA), South Australia, Adelaide, Australia
| | - Kewu Pi
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China.
| | - Yafei Shi
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Pian Li
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Zheng Wang
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Huiqin Zhang
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Defu Liu
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Andrea R Gerson
- Blue Minerals Consultancy, Wattle Grove, Tasmania, 7109, Australia
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Wang J, B H, Yang M, Liu R, Hu C, Liu H, Qu J. Anaerobically-digested sludge disintegration by transition metal ions-activated peroxymonosulfate (PMS): Comparison between Co 2+, Cu 2+, Fe 2+ and Mn 2. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 713:136530. [PMID: 31951845 DOI: 10.1016/j.scitotenv.2020.136530] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/30/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
This study investigates anaerobically-digested sludge (ADS) disintegration by activated peroxymonosulfate (PMS) with transition metal ions of Co2+, Cu2+, Fe2+, and Mn2+ (PMS-Me2+). The activating performances of Me2+ are quantitatively compared by capillary suction time (CST), extracellular polymeric substances (EPS), bound water content (BWC), particle size distribution, and metal speciation. At Me2+ dose of 1.2 mmol/g VSS, PMS-Fe2+ and PMS-Cu2+ achieve the lowest normalized CST, i.e., CST/CST0, of 0.47, and the higher normalized CST values of 0.71 and 0.74 are observed for PMS-Mn2+ and PMS-Co2+, respectively. BWC shows little extent of decrease upon PMS-Me2+ oxidation, and the most significant decrease from 89.5% to 88.3% is observed for PMS-Mn2+. PMS-Co2+ contributes to the decrease of DOC in total EPS fractions (DOCtot) from 698.0 mg/L to 496.6 mg/L, whereas the increased DOCtot to 713.6, 734.4, and 755.0 mg/L is observed with the introduction of Cu2+, Fe2+, and Mn2+, respectively. Fe2+ tends to transform to Fe3+ and the coagulation effect increases the median particle diameter (D50) from 15.8 μm to 91.1 μm. Comparatively, much lower D50 values of below 20.0 μm are observed for other divalent ions. The European Community Bureau of Reference (BCR) sequential extraction method is used to analyze the metal speciation in ADS sediment after PMS-Me2+ disintegration. The dominant species of Co and Mn are acid extractable fractions with the ratios of 91.0% and 87.3%, whereas the main Fe and Cu species are observed to be residual and oxidizable fractions. The pre-captured Me2+ ions with 50-days aging interestingly exhibit activating efficacy towards PMS, and CST values were observed to decrease by 11.5%, 30.5%, 11.8%, and 27.3% with the presence of pre-captured Co2+, Cu2+, Fe2+, and Mn2+ at 1.2 mmol/g VSS. This study proposes the potentially valuable strategy for the disintegration and dewatering of sludge with high contents of transition metal ions.
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Affiliation(s)
- Jiaqi Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hasaer B
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Yang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruiping Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chengzhi Hu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Huijuan Liu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jiuhui Qu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
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20
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Li Y, Wang D, Yang G, Yuan X, Xu Q, Yang Q, Liu Y, Wang Q, Ni BJ, Tang W, Jiang L. Enhanced dewaterability of anaerobically digested sludge by in-situ free nitrous acid treatment. WATER RESEARCH 2020; 169:115264. [PMID: 31710916 DOI: 10.1016/j.watres.2019.115264] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 06/10/2023]
Abstract
As the protonated form of nitrite, free nitrous acid (FNA) is a renewable chemical that can be produced on site from the anaerobic digestion liquor by nitritation, and has been widely employed to improve the fermentation of waste activated sludge (WAS). However, it is not clear whether and how FNA improves the dewaterability of anaerobically digested sludge (ADS). This work therefore aims to provide such supports through comparing the dewaterability of ADS treated by nitrite at different concentrations (0-250 mg/L) under three pH values (5.5, 6.3, or 7.2). Environmental results showed that nitrite was completely denitrified within 12 h, and its addition improved the dewaterability of ADS in all the cases. The optimal normalized capillary suction time of 18.0 ± 0.4 s L/g VSS was obtained at nitrite 50 mg/L and pH 5.5 (equivalent of 0.35 mg/L FNA) in comparison with corresponding value of 23.2 ± 0.4 s L/g·VSS at pH 5.5 (equivalent of 0 mg/L FNA). Under this scenario, 80.5% ± 2.0% of water content was obtained in the FNA-treated sample after press filtration while the corresponding value was 88.5% ± 1.7% in the control. The mechanism investigations showed that FNA treatment reduced surface negative charge of ADS flocs and caused disruption of extracellular polymeric substances and release of intracellular substances, which enhanced the flocculability, hydrophobicity, and flowability, but decreased the bound water content, fractal dimension, and viscosity of ADS. Additionally, FNA treatment altered the secondary structure of proteins through destroying the hydrogen bond, which led to a loose structure of protein, benefiting the exposure of hydrophobic sites or groups in EPS proteins. The findings obtained deepen our understanding of FNA affecting sludge dewatering and provide strong supports to sustainable operation of wastewater treatment plants.
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Affiliation(s)
- Yifu Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China.
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China.
| | - Guojing Yang
- College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, PR China.
| | - Xingzhong Yuan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Qiuxiang Xu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Qi Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Yiwen Liu
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Qilin Wang
- 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
| | - Wangwang Tang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Longbo Jiang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
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21
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Li Y, Liu Y, Yu X, Li Q, Zhang R, Zhang S. Enhancement of sludge electro-dewaterability during biological conditioning. RSC Adv 2020; 10:3153-3165. [PMID: 35497773 PMCID: PMC9048689 DOI: 10.1039/c9ra09126b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/31/2019] [Indexed: 11/24/2022] Open
Abstract
Electro-dewatering (EDW) is considered as one of the most promising dewatering technologies due to saving power consumption. In this study, the potential effects of anaerobic biological conditioning (BC) on sludge EDW treatments was investigated. The results showed that without any additives BC pretreatment of sludge enhanced EDW dewaterability and energy efficiency. At 35 °C BC for 3 days, the dry solids (DS) of sludge dewaterability limit could increase up to 49%, which corresponded to an increase of 13% of DS in dewatered sludge cake without BC pretreatment, and the dewatering time was shortened by 22%. There was an economic advantage saving in energy consumption of around 49.5% in the case of BC-EDW when the DS of sludge was up to 38%. Then, the mechanism of BC to improve EDW performance was studied. The principal component regression (PCR) analysis showed that the DS content of dewaterability limit mainly depended on the degradation of organic matter and the change of conductivity in sludge. Fourier transform infrared spectroscopy (FTIR), zeta potential and bound water in sludge were also determined in an attempt to explain the observed changes in sludge BC-EDW. It was indicated that the increase of negatively charged hydroxyl groups on the surface of sludge particles resulted in an increase of the absolute value of the zeta potential and significantly promoted EDW. The tightly bound EPS (TB-EPS) decreased and it loosened the bond between water or metal cations and sludge particles, and the bound water was also found to be released into free water in sludge during BC. An effective deep dewatering process of coupling biological conditioning and electro-dewatering was proposed and analyzed.![]()
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Affiliation(s)
- Yingte Li
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Yong Liu
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Xiaoyan Yu
- School of Energy and Chemical Engineering
- Liaoning Technical University
- Huludao 125105
- China
| | - Qian Li
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
| | - Rui Zhang
- School of Energy and Safety Engineering
- Tianjin Chengjian University
- Tianjin 300384
- China
| | - Shuting Zhang
- School of Environmental Science and Engineering
- Tianjin University
- Tianjin 300354
- China
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22
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Li Y, Pan L, Zhu Y, Yu Y, Wang D, Yang G, Yuan X, Liu X, Li H, Zhang J. How does zero valent iron activating peroxydisulfate improve the dewatering of anaerobically digested sludge? WATER RESEARCH 2019; 163:114912. [PMID: 31362211 DOI: 10.1016/j.watres.2019.114912] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
Zero valent iron (ZVI) activating peroxydisulfate (PDS) was demonstrated to be effective in improving the dewaterability of anaerobically digested sludge (ADS). However, details of how ZVI/PDS enhances the dewaterability remain largely unknown. This work therefore aims to reveal the facts of what happen in ZVI/PDS involved ADS systems. Experimental results showed that ZVI/PDS treatment remarkably improved the dewaterability of ADS, with the minimal normalized capillary suction time of 8.6 ± 0.5 s L/g·VSS being obtained at the dosages of 2 g/g TSS ZVI and 0.5 g/g TSS PDS, which was 42.5% of that in the control. In this case, 71.2% ± 1.8% of water content (press filtration) was measured, which was 16.9% lower than that determined in the control. The mechanism investigations showed that ZVI activating PDS produced substantially reactive species, i.e., SO4•- and •OH, and these strong oxidative radicals decreased surface negative charges of ADS flocs, caused disruption of extracellular polymeric substances (EPS) and release of intracellular substances, and changed the secondary structure of proteins. Additionally, the products of ZVI oxidation, i.e., Fe2+ and Fe3+, were effective flocculants, thus their generation benefited the coagulation of ADS flocs through compressing double electric layers and neutralizing negative charges of sludge colloidal particles. As a result, the flocculability, hydrophobicity, and flowability of ADS were enhanced, but the bound water content, fractal dimension, and viscosity of ADS were decreased, which were responsible for the improvement of dewaterability. Further analyses exhibited that the contributions of these major contributors were different, and their contributions to the dewaterability improvement were in the order of SO4·- > ·OH > Fe2+/Fe3+. It was also found that ZVI/PDS treatment enhanced the degradation of recalcitrant organics, inactivation of the fecal coliforms, and mitigation of the toxicity of heavy metals in the dewatered sludge, which were beneficial to its land application.
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Affiliation(s)
- Yifu Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China.
| | - Liuyi Pan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Yeqing Zhu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Yuanyuan Yu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China.
| | - Guojing Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China; College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, PR China.
| | - Xingzhong Yuan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Xuran Liu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
| | - Hailong Li
- School of Energy Science and Engineering, Central South University, Changsha, 410083, PR China
| | - Jin Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, PR China
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23
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Ni BJ, Yan X, Sun J, Chen X, Peng L, Wei W, Wang D, Mao S, Dai X, Wang Q. Persulfate and zero valent iron combined conditioning as a sustainable technique for enhancing dewaterability of aerobically digested sludge. CHEMOSPHERE 2019; 232:45-53. [PMID: 31152902 DOI: 10.1016/j.chemosphere.2019.05.148] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/24/2019] [Accepted: 05/18/2019] [Indexed: 05/06/2023]
Abstract
Aerobic digestion followed by dewatering is a widely applied method for sludge stabilization and reduction in decentralized wastewater treatment plants. It is important to enhance the sludge dewaterability of the aerobically digested sludge due to its considerable impact on cost of sludge disposal and management. In this study, an innovative technique is developed for improving the dewaterability of aerobically digested sludge by combined conditioning with persulfate (PS) and zero valent iron (ZVI). The results demonstrated that the dewaterability of aerobically digested sludge could be significantly enhanced with the PS and ZVI dosage in the range of 0-0.5 g/gTS and 0-0.4 g/gTS, respectively. The highest improvement was achieved at 0.05 g ZVI/g TS with 0.1 g PS/g TS, and the capillary suction time was reduced by ∼80%. The extracellular polymeric substances (EPS) characterization revealed that the combined PS-ZVI treatment could largely reduce proteins, polysaccharides and humic acids-like compounds in the tightly bounded EPS of the aerobically digested sludge, leading to bound water releasing from sludge flocs. The recovery of the ZVI particles could reach around 45%-80% after the treatment, further proved the sustainability of the approach. The proposed PS-ZVI conditioning would not have significant impact on the final choice of sludge disposal and the mainstream wastewater treatment. However, plant-scale test are still required for better assessing the proposed technique.
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Affiliation(s)
- Bing-Jie Ni
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China
| | - Xiaofang Yan
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Jing Sun
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
| | - Xueming Chen
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia
| | - Lai Peng
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia
| | - Wei Wei
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia
| | - Dongbo Wang
- Key Laboratory of Environmental Biology and Pollution Control, College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
| | - Shun Mao
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China
| | - Xiaohu Dai
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China
| | - Qilin Wang
- School of Engineering and Built Environment & Centre for Clean Environment and Energy & Environmental Futures Research Institute, Griffith University, QLD, 4111, Australia
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24
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Zhang W, Dong B, Dai X. Mechanism analysis to improve sludge dewaterability during anaerobic digestion based on moisture distribution. CHEMOSPHERE 2019; 227:247-255. [PMID: 30991199 DOI: 10.1016/j.chemosphere.2019.03.150] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/12/2019] [Accepted: 03/23/2019] [Indexed: 06/09/2023]
Abstract
Previous studies have demonstrated that anaerobic digestion (AD) enhances sludge dewaterability. However, the mechanism of AD influence on digested sludge dewaterability is still not well understood. In this study, moisture distribution and bond energy were used to evaluate the influence of AD on sludge dewaterability. The change from free moisture (FM) to mechanically bound moisture (MBM) was analysed, along with degradation of organic fractions in extracellular polymeric substances (EPSs) of the sludge during AD. Results indicated that the AD process, with a 41.9% reduction in volatile solids (VS) and cumulative methane production of 283.2 mL/g VS, improved sludge dewaterability by disintegrating macro-molecular organic matter into micro-molecular matter. MBM reduction reached 7% in 40 days. Correlations between FM/MBM and extracellular protein (extra-PN) were significant (R = -0.861, p < 0.01; R = 0.869, p < 0.01). Therefore, it can be concluded that the degradation of protein in the extra-microcolony polymer (EMPS) layer results in the destruction of the bond between organic fractions and moisture. As a result, the release of mechanically bound moisture is accelerated. In addition, the moisture content, as well as the extra-PN, continued to vary when AD entered the stabilisation stage, that is, the destruction of protein in EMPS stimulated mechanically bound moisture release during AD. The results of this work provide a better understanding on the effect of AD on sludge reduction.
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Affiliation(s)
- Wei Zhang
- School of Environmental Science and Engineering. Tongji University, Shanghai, 200092, PR China
| | - Bin Dong
- School of Environmental Science and Engineering. Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
| | - Xiaohu Dai
- School of Environmental Science and Engineering. Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
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25
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Qian X, Zhou X, Wu J, Liu C, Wei Y, Liu J. Electro-dewatering of sewage sludge: Influence of combined action of constant current and constant voltage on performance and energy consumption. THE SCIENCE OF THE TOTAL ENVIRONMENT 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] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
In this study, mechanically-dewatered sludge was used to investigate the effect of electro-dewatering (EDW) under two electrical modes, which are constant current mode followed by constant voltage mode (CV-EDW), and constant voltage mode followed by constant current mode (VC-EDW). The effect of current and voltage changes on dewatering efficiency and energy consumption of sludge electroosmosis under CV-EDW and VC-EDWs was evaluated The results show that compared with constant current mode (C-EDW), CV-EDW can improve the final dry solids content and reduce the heating rate, and the final dry solids content and unit energy consumption increase with the decrease of current and the increase of voltage. Under CV-EDW, when the dry solids content is 32%, the energy consumption can be reduced by changing to the constant voltage stage, and the energy consumption is 0.093-0.113 kWh/kgwater. Compared with constant voltage mode (V-EDW), VC-EDW significantly improves sludge dewatering rate. Under VC-EDW, the final dry solids content of sludge increases with the decrease of current and voltage. When the voltage is decreased by 10 V, the unit energy consumption is reduced by 27.15 ± 1.77% on average, and the energy consumption is 0.132-0.163 kWh/kgwater. Compared with CV-EDW, the dehydration rate of VC-EDW is increased by 72.9% on average. However, the unit energy consumption required for dehydration increases by 43.09% when the dry solids content is less than 45%.
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Affiliation(s)
- Xu Qian
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Xingqiu Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, Guangdong 510006, PR China.
| | - Jiandong Wu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, Guangdong 510006, PR China
| | - Changyuan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Yijun Wei
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
| | - Jiangyan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China
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26
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Zhang D, Wang Y, Gao H, Fan X, Guo Y, Wang H, Zheng H. Variations in macro and micro physicochemical properties of activated sludge under a moderate oxidation-in situ coagulation conditioning: Relationship between molecular structure and dewaterability. WATER RESEARCH 2019; 155:245-254. [PMID: 30851595 DOI: 10.1016/j.watres.2019.02.047] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
A moderate Mn(Ⅶ) oxidation-in situ Fe(Ⅲ) coagulation (Mn(Ⅶ)-Fe(Ⅱ)) conditioning strategy was proposed to improve sludge filterability and release the water bound in extracellular polymeric substances (EPS). During Mn(Ⅶ)-Fe(Ⅱ) conditioning, flocs disintegration and cell disruption, macro and micro physicochemical properties of activated sludge, especially of EPS, were investigated. Relationships between protein molecular structures in EPS fractions of three layers and sludge dewaterability were also determined. Besides, factor analysis was used to explain the variances of "functional" protein secondary structures, which may have an important effect on sludge dewaterability. Results showed that sludge filterability (CST0/CST) increased by 2.40 times and partial bound water was released at 2 min oxidation of 120 mg/g KMnO4 with subsequent FeCl2 termination at equivalent molar ratio of 1:3. During this strategy, EPS wrapping on cells surface was disintegrated, and a limited influence occurred on cells. It was also found that CST and bound water content were strongly correlated with aggregated strands, random coil and β-turn percentages in slime (R2 >-0.82, p < 0.05). Moreover, the dewaterability also presented strong negative correlations with aggregated strands, β-sheet and β-turn in TB-EPS (R2 >-0.78, p < 0.05). This suggested that unfolding and despiralization of slime protein and moderate weakening rigidity of tightly bound EPS (TB-EPS) protein were beneficial for improvement of sludge dewaterability. In addition, the strong correlation between percentages of "functional" protein secondary structures and factor 1 score (R2 > 0.85, p < 0.05) demonstrated that EPS migration, rather than only EPS disintegration, may have a key impact on the formation of some protein secondary structures in slime and TB-EPS. The observed protein secondary structures, which may affect sludge dewaterability, were probably derived from inner EPS.
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Affiliation(s)
- Daxin Zhang
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China; Xiong'an Institute of Eco-Environment, Hebei University, Baoding, 071002, 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.
| | - Hongyu Gao
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China
| | - Xiaoyang Fan
- 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
| | - Hongjie Wang
- Xiong'an Institute of Eco-Environment, Hebei University, Baoding, 071002, China.
| | - Huaili Zheng
- Key Laboratory of the Three Gorges Reservoir Regions Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, 400045, China
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27
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Xiao J, Yuan H, Huang X, Ma J, Zhu N. Improvement of the sludge dewaterability conditioned by biological treatment coupling with electrochemical pretreatment. J Taiwan Inst Chem Eng 2019. [DOI: 10.1016/j.jtice.2018.12.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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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] [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.![]()
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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
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29
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Guo X, Qian X, Wang Y, Zheng H. Magnetic micro-particle conditioning-pressurized vertical electro-osmotic dewatering (MPEOD) of activated sludge: Role and behavior of moisture and organics. J Environ Sci (China) 2018; 74:147-158. [PMID: 30340668 DOI: 10.1016/j.jes.2018.02.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/21/2018] [Accepted: 02/22/2018] [Indexed: 06/08/2023]
Abstract
In this study, a magnetic micro-particle conditioning-pressurized vertical electro-osmotic dewatering (MPEOD) process with magnetic micro-particle conditioning-drainage under gravity-mechanical compression-electrical compression (MMPC-DG-MC-EC) stages was established to study the distribution and migration of water, extracellular polymeric substances (EPS), and other organic matter in the activated sludge (AS) matrix at each stage. Results showed that the MPEOD process could attain 53.52% water content (WC) in dewatered AS with bound water (BW) and free water (FW) reduction rates of 82.97% and 99.67%, respectively. The coagulation and time-delayed magnetic field effects of magnetic micro-particles (MMPs) along the MMPC-DG-MC stages initiated the transformation of partial BW to FW in AS. EC had a coupling driving effect of electro-osmosis and pressure on BW, and the changes in pH and temperature at EC stage induced the aggregation of AS flocs and the release of partial BW. Additionally, MMPs dosing further improved the dewatering performance of AS by acting as skeleton builders to provide water passages. Meanwhile, MMPs could disintegrate sludge cells and EPS fractions, thereby reducing tryptophan-like protein and byproduct-like material concentrations in LB-EPS as well as protein/polysaccharide ratio in AS matrix, which could improve AS filterability. At EC stage, the former four Ex/Em regions of fluorescence regional integration analysis for EPS were obviously reduced, especially the protein-like substances in LB- and TB-EPS, which contributed to improvement of AS dewaterability.
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Affiliation(s)
- Xinxin Guo
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Xu Qian
- Water Resource Development Research Center of Taihu Basin Authority, Shanghai 200434, 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.
| | - Huaili Zheng
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China
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Li Y, Yuan X, Wang D, Wang H, Wu Z, Jiang L, Mo D, Yang G, Guan R, Zeng G. Recyclable zero-valent iron activating peroxymonosulfate synchronously combined with thermal treatment enhances sludge dewaterability by altering physicochemical and biological properties. BIORESOURCE TECHNOLOGY 2018; 262:294-301. [PMID: 29729607 DOI: 10.1016/j.biortech.2018.04.050] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/09/2018] [Accepted: 04/12/2018] [Indexed: 06/08/2023]
Abstract
In this study, zero valent iron (ZVI) activated peroxymonosulfate (PMS) as novel technique (i.e. ZVI-PMS technology) was employed to enhance sludge dewatering. In optimal sludge dewatering conditions of ZVI and KHSO5 dosages, the specific resistance to filtration (SRF) was reduced by 83.6%, which was further decreased to 90.6% after combination of ZVI-PMS with thermal treatment at 50 °C (i.e. ZVI-PMS-T technology). Subsequently, the ESR spectrum and quenching tests demonstrated that OH, rather than SO4-, was predominant radicals in ZVI-PMS conditioning. Thereafter, the variation of physicochemical properties and the distributions and compositions of extracellular polymeric substances (EPS) were further investigated to uncover the influence of these techniques on sludge bulk properties. The results indicated that sludge particles were disintegrated into smaller particles and surface charges were neutralized, sludge flowability were elevated obviously after treatments. In ZVI cycle experiment, the high dewatering efficiency was maintained by ZVI-PMS and ZVI-PMS-T pretreatment.
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Affiliation(s)
- Yifu Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Xingzhong Yuan
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
| | - Hou Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China; School of Chemical & Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 639798, Singapore
| | - Zhibin Wu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, PR China
| | - Longbo Jiang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Dan Mo
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Guojing Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China; College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, PR China
| | - Renpeng Guan
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Guangming Zeng
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
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Li H, Wang Y, Zheng H. Variations of moisture and organics in activated sludge during Fe 0/S 2O 82- conditioning-horizontal electro-dewatering process. WATER RESEARCH 2018; 129:83-93. [PMID: 29132124 DOI: 10.1016/j.watres.2017.11.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/09/2017] [Accepted: 11/02/2017] [Indexed: 06/07/2023]
Abstract
The feasibility of using Fe0/S2O82- conditioning (zero valence iron (ZVI)/persulfate (ps)) integrated with horizontal electro-dewatering (HED) to improve the dewaterability of activated sludge (AS) was evaluated. The removal and migration of free and bound water in the ZVI/ps-HED process were determined, along with the organic matter migration between the solid and liquid phases of AS biosolids. Results showed that the optimum conditioning dosages were determined as 0.35 g ZVI/g dry solids (DS) and 0.15 g ps/g DS on the basis of capillary suction time variation. The lowest final water content (WC) of 83.67% in AS occurred after the HED treatment at 40 V and 120 min as determined using the response surface methodology. Despite the disruption of AS flocs and microbial cells through SO4-· oxidation during the ZVI/ps conditioning, the particle size and mass fractal dimension of the AS flocs remained relatively stable as the zeta potential increased from -8.5 mV to -4.6 mV. The coagulation of Fe3+ from the oxidation of Fe2+ by ps contributed to the relatively stable condition, which favored the subsequent momentum of the electroosmotic flow. Moreover, the ZVI/ps conditioning decreased the bound water content (BWC, from 1.83 g/g DS to 1.38 g/g DS) and increased the free water content (FWC, from 60.27 g/g DS to 60.91 g/g DS), indicating a transformation from free water to bound water. After the ZVI/ps-HED process, the FWC and BWC were removed significantly with ratios of 96.32% and 79.78%, respectively. Along with water removal through the ZVI/ps-HED process, the organic matter in the supernatant/filtrate initially increased and further rose at the HED stage. The analysis of the extracellular polymeric substance (EPS) content showed that the proteins (PNs) and polysaccharides (PSs) at the liquid and solid phases decreased due to oxidative degradation. Furthermore, the ZVI/ps stage significantly reduced the PNs content of slime to 57.22%, the PSs content of EPS to 68.50%, and the PN-like substances in the slime and tightly bound EPS to 74.90% and 52.47%, respectively. In addition, the WC of AS correlated with the contents of PN and microbial by-product-like material in slime, as well as tryptophan in TB-EPS, and the low EPS content in AS indicated good dewaterability. Thus, ZVI/ps should be selected as a pretreatment prior to HED.
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Affiliation(s)
- Haoxuan Li
- 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.
| | - Huaili Zheng
- Key Laboratory of the Three Gorges Reservoir Region´s Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, 400045, China
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Guo X, Wang Y, Wang D. Permanganate/bisulfite (PM/BS) conditioning-horizontal electro-dewatering (HED) of activated sludge: Effect of reactive Mn(III) species. WATER RESEARCH 2017; 124:584-594. [PMID: 28820989 DOI: 10.1016/j.watres.2017.08.027] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/07/2017] [Accepted: 08/10/2017] [Indexed: 06/07/2023]
Abstract
A novel activated sludge (AS) conditioning method through permanganate/bisulfate (PM/BS) process was proposed. The method involved a new conditioner of reactive Mn(III) intermediate. Moreover, a Mn(III) conditioning-horizontal electro-dewatering (Mn(III) C-HED) process was established to improve AS dewatering performance. Underlying mechanisms were unraveled by investigating changes in physicochemical characteristics, scanning electron microscope (SEM) morphology, and transformation of water and organic matters. The optimum dewatering conditions for Mn(III) C-HED process with the final water content of 86.94% were determined as the combination of KMnO4 0.01 mol/L AS and NaHSO3 0.05 mol/L AS at 20 V for 120 min. Results showed that Mn(III) C-HED process effectively reduced free water and bound water with the corresponding removal ratios of 51.68% and 87.62% at the anode-side as well as 36.55% and 85.08% at the cathode-side, respectively. During the PM/BS process, the produced Mn(III), Mn2+, and MnO2 exerted chemical and physical effects on AS conditioning and dewatering. Mn(III) disintegrated extracellular polymeric substances (EPS) fractions and cells in AS, as well as induced partial bound water release. Additionally, flocculation effect induced by Mn2+ and MnO2 skeleton building also benefited AS dewatering. AS cells were further disrupted under the effect of a horizontal electric field. Accordingly, EPS within the AS matrix was solubilized, tightly bound (TB)-EPS or loosely bound (LB)-EPS was converted to their corresponding outer EPS fractions, and AS dewaterability improved. Additionally, changes in pH and temperature at HED stage damaged the AS cells and changed the floc properties, thereby leading to easy separation of liquid and AS particles.
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Affiliation(s)
- Xinxin Guo
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China
| | - Yili Wang
- College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China.
| | - Dongsheng Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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