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Liu Y, Niu X, Zhang D, Zhou L, Tao C, Lin Y, Chen S, Chen Y, Lin Z, Kong S. Insight into enhancing the performance of sludge dewatering using a novel flocculant CS-TA prepared through free radical-mediated conjugation. ENVIRONMENTAL TECHNOLOGY 2024:1-18. [PMID: 39010782 DOI: 10.1080/09593330.2024.2377797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 05/15/2024] [Indexed: 07/17/2024]
Abstract
Flocculation is one of the most significant conditioning methods for sludge dewatering. In the study, a novel flocculant CS-TA, prepared through free radical-mediated conjugation of tannic acid (TA) and chitosan (CS), was proposed to improve sludge dewatering. The characterisation using Fourier transform infra-red spectroscopy and X-ray diffraction analysis shows that the CS chain was the backbone of CS-TA, and the presence of CS-TA aromatic rings confirmed the conjugation of CS with TA. Moreover, the conditioning of CS-TA yielded the best dewatering performance at 30 mg g TS-1 with the water content of sludge cake by press filtration (Wsc) of 59.78% ± 0.3% and capillary suction time (CST) of 11.8s ± 0.35 s, compared to 98.2% ± 0.15% and 56.2 s ± 0.16 in raw sludge. The results of different influencing factors (e.g. pH and temperature) on flocculation efficiency indicated that CS-TA possessed the capacity for enhancing sludge dewaterability over a wide range of pH, and the optimal temperature was observed to be 35 °C. Furthermore, the increase of particle size and zeta potential implied the addition of CS-TA favoured the formation of larger particles charge neutralisation and adsorption bridging effect. In addition, extracellular polymer substances (EPS) analysis indicated that the decrease in the polysaccharide and protein contents in EPS after CS-TA addition could increase the relative hydrophobicity of sludge. Moreover, the contents of heavy metals in sludge and their leaching toxicity and environmental risk were reduced. This study provides comprehensive insights into the exploration of CS-TA for sludge dewatering and the maintenance of ecological security in an eco-friendly.
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Affiliation(s)
- Yuejin Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, People's Republic of China
| | - Xiaojun Niu
- School of Environment and Energy, South China University of Technology, Guangzhou, People's Republic of China
- School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, People's Republic of China
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, People's Republic of China
| | - Dongqing Zhang
- School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, People's Republic of China
| | - Lingling Zhou
- School of Environment and Energy, South China University of Technology, Guangzhou, People's Republic of China
| | - Chunyang Tao
- School of Environment and Energy, South China University of Technology, Guangzhou, People's Republic of China
| | - Yu Lin
- Guangzhou Urban Drainage Company Limited, Guangzhou, People's Republic of China
| | - Siping Chen
- School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, People's Republic of China
| | - Yawen Chen
- School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, People's Republic of China
| | - Zhang Lin
- School of Environment and Energy, South China University of Technology, Guangzhou, People's Republic of China
| | - Suying Kong
- School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, People's Republic of China
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Guo B, Zeng J, Bai H, Hao Y, Yan X, Wang S. Revitalizing urban lake cleanup: optimizing flocculation and dewatering of dredged sludge using cation polyacrylamide. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:119462-119472. [PMID: 37924408 DOI: 10.1007/s11356-023-30666-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/20/2023] [Indexed: 11/06/2023]
Abstract
This study investigated the effect of cation polyacrylamide (CPAM) on the dewatering performance of dredged sludge by batch experiments and compared it with a novel organic agent (DRC-300) and a traditional inorganic agent (PAC). The results of batch experiments suggested that the CPAM could promote the dewatering performance of dredged sludge inland lake. And at the dosage of 0.07% g/g suspended solids (SS), the moisture content of 37% could be achieved with CAPM. CPAM could reduce the sludge resistance filtration (SRF) and capillary adsorption time (CST) by 73% and 62%, respectively. Mechanism experiments revealed that CPAM improved the dewatering performance of dredged mud by increasing the sedimentation rate, accelerating the dissolution of organic matter, neutralizing the surface charge of sludge, and improving the void structure. Furthermore, CPAM outperformed DRC-300 and PAC in above aspects.
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Affiliation(s)
- Bing Guo
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China.
| | - Jiachen Zeng
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China
| | - He Bai
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China
| | - Yuchi Hao
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China
| | - Xiaowei Yan
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China
| | - Sheng Wang
- CCCC National Engineering Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, 200082, China
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Nguyen TH, Nguyen LPD, Nguyen TTP, Le MXA, Kieu LTT, To HT, Bui TT. Optimization Conditions to Obtain Cationic Polyacrylamide Emulsion Copolymers with Desired Cationic Degree for Different Wastewater Treatments. Polymers (Basel) 2023; 15:2693. [PMID: 37376339 DOI: 10.3390/polym15122693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/11/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
The synthesis of cationic polyacrylamides (CPAMs) with the desired cationic degree and molecular weight is essential for various industries, including wastewater treatment, mining, paper, cosmetic chemistry, and others. Previous studies have already demonstrated methods to optimize synthesis conditions to obtain high-molecular-weight CPAM emulsions and the effects of cationic degrees on flocculation processes. However, the optimization of input parameters to obtain CPAMs with the desired cationic degrees has not been discussed. Traditional optimization methods are time-consuming and costly when it comes to on-site CPAM production because the input parameters of CPAM synthesis are optimized using single-factor experiments. In this study, we utilized the response surface methodology to optimize the synthesis conditions, specifically the monomer concentration, the content of the cationic monomer, and the content of the initiator, to obtain CPAMs with the desired cationic degrees. This approach overcomes the drawbacks of traditional optimization methods. We successfully synthesized three CPAM emulsions with a wide range of cationic degrees: low (21.85%), medium (40.25%), and high (71.17%) levels of cationic degree. The optimized conditions for these CPAMs were as follows: monomer concentration of 25%, content of monomer cation of 22.5%, 44.41%, and 77.61%, respectively, and initiator content of 0.475%, 0.48%, and 0.59%, respectively. The developed models can be utilized to quickly optimize conditions for synthesizing CPAM emulsions with different cationic degrees to meet the demands of wastewater treatment applications. The synthesized CPAM products performed effectively in wastewater treatment, with the treated wastewater meeting the technical regulation parameters. 1H-NMR, FTIR, SEM, BET, dynamic light scattering, and gel permeation chromatography were employed to confirm the structure and surface of the polymers.
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Affiliation(s)
- Tung Huy Nguyen
- Center for Polymer Composite and Paper, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Linh Pham Duy Nguyen
- Center for Polymer Composite and Paper, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Thao Thi Phuong Nguyen
- Center for Polymer Composite and Paper, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Minh Xuan Anh Le
- Department of Pharmaceutical Chemistry and Pesticides Tech, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Linh Thi Thuy Kieu
- Department of Chemical Process Equipment, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Huong Thi To
- Lab of Petrochemical Refining & Catalysis, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
| | - Thanh Tien Bui
- Center for Polymer Composite and Paper, School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi 11600, Vietnam
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Li J, Ru S, Yuan C, Wu B, Ji Y, Dai Z, Lei Z, Zhang Z, Yuan T, Li F, Liu M. An all-organic conditioning method to achieve deep dewatering of waste activated sludge and the underlying mechanism. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 327:116923. [PMID: 36470188 DOI: 10.1016/j.jenvman.2022.116923] [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: 06/16/2022] [Revised: 11/04/2022] [Accepted: 11/27/2022] [Indexed: 06/17/2023]
Abstract
Among the common treatment/disposal routes of excessive activated sludge from municipal wastewater treatment plant, dewatering process functions as an essential pre-/post-treatment for volume minimization and transportation facilitation. Since inorganic coagulants have long been criticized for their high dosage and solid residue in sludge cake, there is an urgent need for investigations regarding the potential of applying organic chemicals as the conditioner. In this study, combined use of poly dimethyldiallylammonium chloride (PDMD) and tannic acid (TA) were investigated as an all-organic co-conditioning method for sewage sludge pre-treatment. Results showed that this all-organic conditioning strategy can effectively improve the dewaterability of sewage sludge. The capillary suction time reduced from 128.8 s to 23.1 s, and the filtration resistance reduced from 1.24 × 1012 cm/g to 7.38 × 1010 cm/g. The moisture content of dewatered sludge cake decreased to as low as 55.83%, showing the highest dewatering efficiency reported so far. In addition, the combination of PDMD and TA maximized the treating efficiency with very limited consumption of conditioners (added up to 4% of total solid). Based on the physic-chemical and rheological property investigation, it was proposed that the intermediate molecular weight polymer-based flocculation process and the TA agent-based protein precipitation process, could remarkably strengthen the compactness and structure robustness of sludge. In all, this PDMD-TA-based conditioning method suggested practical significance in consideration of its cost-effectiveness and disposal convenience of sludge cake.
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Affiliation(s)
- Jie Li
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China.
| | - Shaoqin Ru
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China
| | - Chenwei Yuan
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China
| | - Bo Wu
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China
| | - Yiwen Ji
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China
| | - Zijun Dai
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444, China
| | - Zhongfang Lei
- Faculty of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Zhenya Zhang
- Faculty of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Tian Yuan
- Faculty of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Fengting Li
- College of Environmental Science & Engineering, State Key Laboratory of Pollution Control and Resource Reuse Study, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Misha Liu
- National Engineering Research Center of Dredging Technology and Equipment, 10 Gucui Road, Shanghai, 201314, China; Faculty of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
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Chi N, Liu J, Lei M, Feng L. Preparation of amphiphilic cationic polyacrylamide (CPAM) with cationic microblock structure to enhance printing and dyeing sludge dewatering and condition performance. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:13079-13093. [PMID: 36125686 DOI: 10.1007/s11356-022-23067-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 09/13/2022] [Indexed: 06/15/2023]
Abstract
Flocculation is an important pretreatment technology for sludge dewatering, and the flocculant's performance is the key factor to determine the flocculation effect. Cationic polyacrylamide (CPAM) is commonly used in dewatering and conditioning of printing and dyeing sludge (PD sludge), and the research of high-efficiency flocculant is a hot spot in the field of PD sludge dewatering. Hydrophobic butylacrylate (BA) and (2-(Methacryloyloxy)ethyl) trimethylammonium chloride (DMC) were introduced into the copolymer, and amphiphilic (hydrophilic/lipophilic) CPAM, namely TP-ADB, with microblock structure was synthesized by ultrasonic initiated template copolymerization in this study. The functional group composition of TP-ADB was determined by FTIR and 1H NMR. Thermogravimetric analysis (TGA) showed that TP-ADB had good thermal stability. The amphiphilic rheological properties of the copolymer were measured according to the apparent viscosity. In addition, 1H NMR and TGA results confirmed the existence of microblock structure in the copolymer chain. The polymerization mechanism was discussed by association coefficient (KM) measurement. The results showed that the template copolymerization initiated by ultrasonic followed the law of free radical copolymerization. The pre-adsorption of DMC with sodium polyacrylate template (NaPAA) before the reaction confirmed that the template polymerization accorded with ZIP I mechanism. The cationic microblock structure and hydrophobic association of TP-ADB promoted the dewatering performance of PD sludge (FCMC = 72.9%, turbidity removal rate = 98.9%, SRF = 4.2 × 1012 m·kg-1). Hydrophobic association enhanced the bridging, sweeping, and net catching effect, and promoted the growth of floc size and fractal dimension. Cationic microblock structure can produce compact floc with higher mechanical strength by enhancing electrical neutralization and electrical patching. As a skeleton, the compressibility of filter cake was reduced and the permeability was enhanced, and the PD sludge dewatering effect was significantly improved.
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Affiliation(s)
- Nianping Chi
- School of Municipal and Geomatics Engineering, Hunan City University, Hunan Province Engineering & Technology Research Center for Rural Water Quality Safety, Hunan, 413000, Yiyang, People's Republic of China
| | - Jiajun Liu
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China
| | - Minghua Lei
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China
| | - Li Feng
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China.
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6
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Cai M, Qian Z, Xiong X, Dong C, Song Z, Shi Y, Wei Z, Jin M. Cationic polyacrylamide (CPAM) enhanced pressurized vertical electro-osmotic dewatering of activated sludge. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 818:151787. [PMID: 34808190 DOI: 10.1016/j.scitotenv.2021.151787] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/10/2021] [Accepted: 11/14/2021] [Indexed: 06/13/2023]
Abstract
Pressurized vertical electro-osmotic dewatering (PVEOD) has been regarded as a feasible method to achieve sludge deep-dewatering, but the dewatering efficiency is still challenged by high electric resistance. This study employed cationic polyacrylamide (CPAM) as a skeleton builder to enhance electro-osmotic flow in PVEOD. The sludge dewatering efficiency and synergistic effect of CPAM and PVEOD were elucidated. The sludge morphology, surface property, extracellular polymeric substances (EPS) destruction and migration, spatial distributions of proteins and polysaccharides, and current changes were investigated. After the addition of optimal CPAM dose, the sludge formed a uniform and porous structure that provided water channels and enhanced electric transport, thus promoting EPS destruction. The sludge moisture content (MC) analysis indicated the more liberation of bound water due to EPS destruction. Besides, the re-flocculation of disintegrated sludge flocs improved the sludge filtration and thus dewaterability. Instantaneous energy consumption (Et,0.5) was optimized and two-step synergistic mechanism was thus proposed. These findings indicated that the combination of CPAM and PVEOD is a promising strategy to broaden the scope of industrial application of sludge deep-dewatering.
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Affiliation(s)
- Meiqiang Cai
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zhuohui Qian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Xingaoyuan Xiong
- Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Universitetsbyen 36, 8000 Aarhus C, Denmark
| | - Chunying Dong
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
| | - Zhijun Song
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Yuejing Shi
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zongsu Wei
- Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Universitetsbyen 36, 8000 Aarhus C, Denmark
| | - Micong Jin
- Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China; Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China
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Wang H, Yang Y, Wu B, Chai X, Dai X. Highly efficient solid-liquid separation of anaerobically digested liquor of food waste: Conditioning approach screening and mechanistic analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 811:152416. [PMID: 34923015 DOI: 10.1016/j.scitotenv.2021.152416] [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: 10/20/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
Anaerobic digestion is known for its effectiveness and environmental friendliness in treating food waste. However, it produces anaerobically digested liquor (ADL). ADL usually has a high solid content and high concentrations of nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) carried by suspended solids (SS). Thus, when ADL with amounts of SS reaches the subsequent biochemical treatment units, they negatively impact the microbial stability of corresponding processes, causing unstable effluent qualities. For this reason, the solid-liquid separation of ADL acts as a crucial step for the wide application of anaerobic digestion. In this work, the typical sludge conditioning approaches, including flocculation/coagulation, coagulation, oxidation and advanced oxidation processes (AOPs), were systematically screened for their feasibility in enhancing the solid-liquid separation of ADL. The modified Fenton treatment combined with centrifugation was found to be the most effective approach, which realized the removal of 91.36% SS with FeSO4•7 H2O (5.96 g/L) and H2O2 (2.79 g/L) but without pH adjustment of ADL. The mechanism analysis showed that the modified Fenton promoted ADL colloidal aggregates to form looser medium-sized flocs with pores, increased the zeta potential to -17.6 mV, and highly reduced the total interfacial free energy. Also, extracellular polymeric substances (EPS) were released into liquid phase, which further eliminated the water-retaining properties of solid compositions. The analysis of surface chemical composition suggested that the modified Fenton decreased the hydrophilic component from 53.37% to 43.81% and the relative content of protein-N from 45.43% to 23.57%, while increased carbon chain and hydrocarbyl species. Furthermore, principal component analysis (PCA) suggested that SS, zeta potential, Lewis acid-base interfacial free energy, two-dimensional fractal index (2-Df) and C-(N, O) relative content were more sensitive to variations in conditioning approaches than protein-N relative content, and hydroxyl free radical (•OH) played the key role for the modified Fenton to improve SS removal from ADL.
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Affiliation(s)
- Hao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Yifeng Yang
- Shanghai Municipal Engineering Design Institute (Group) Co., Ltd, 901 Zhongshan North 2nd Road, Shanghai 200092, China
| | - Boran Wu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
| | - Xiaoli Chai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Xiaohu Dai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
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Li M, Wei D, Zhang Z, Fan D, Du B, Zeng H, Li D, Zhang J. Enhancing 2,6-dichlorophenol degradation and nitrate removal in the nano-zero-valent iron (nZVI) solid-phase denitrification system. CHEMOSPHERE 2022; 287:132249. [PMID: 34555584 DOI: 10.1016/j.chemosphere.2021.132249] [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: 03/23/2021] [Revised: 07/11/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
Nano-zero-valent iron (nZVI), as a typical nano-material, has been recently used in wastewater treatment and combination with bioreactors. Using nZVI coupled denitrification system research the effect and influence of nZVI enhanced denitrification sludge on the degradation of toxic compounds and system performance. The nZVI coupled denitrification system showed better resistance to 2,6-DCP impact, and the concentrations of effluent NO2- and NO3- were below 2.0 mg/L. At the same time, the addition of nZVI enabled the denitrification system to quickly adapt to the toxic environment of 2,6-DCP within 15 days, and the degradation efficiency of 2,6-DCP reached 99.9%. The released SMP reduced after nZVI coupled with denitrification sludge in 2,6-DCP environment, which could improve the effluent water quality. Nuclear magnetic resonance spectroscopy showed that the addition of nZVI would change the structure of EPS in denitrification sludge. After 90 days of operation, the dominant bacteria in the denitrifying sludge have undergone great changes. Moreover, Thauera was responsible as the dominant bacteria for degrading 2,6-DCP in the denitrification system. The increased in the proportion of functional bacteria with nitrate_reduction, nitrogen_respiration, nitrate_respiration and nitrite_respiration in the presence of NZVI further reveals the mechanism of enhanced denitrification.
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Affiliation(s)
- Mingrun Li
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China; School of Resources and Environment, University of Jinan, Jinan, 250022, PR China
| | - Dong Wei
- School of Resources and Environment, University of Jinan, Jinan, 250022, PR China; Anhui Guozhen Environmental Protection Technology Joint Stock Co., Ltd, Hefei, 230088, PR China.
| | - Zhaoran Zhang
- Jinan Environmental Research Academy, Jinan, 250102, PR China
| | - Dawei Fan
- School of Resources and Environment, University of Jinan, Jinan, 250022, PR China
| | - Bin Du
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China
| | - Huiping Zeng
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China
| | - Dong Li
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China.
| | - Jie Zhang
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, PR China
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Hu P, Shen S, Zhao D, Wei H, Ge J, Jia F, Zhang X, Yang H. The influence of hydrophobicity on sludge dewatering associated with cationic starch-based flocculants. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 296:113218. [PMID: 34246906 DOI: 10.1016/j.jenvman.2021.113218] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Coagulation/flocculation is an extensive and effective pretreatment technology for improving the sludge dewaterability. A series of hydrophobically associated cationic starch-based flocculants (CS-DMRs) with different degrees of hydrophobicity but similar charge densities were designed and synthesized. The CS-DMRs exhibited excellent sludge dewatering performance. The dewaterability of sludge increased with the hydrophobicity of the CS-DMRs, and the filter cake moisture content (FCMC) and specific resistance to filtration (SRF) could be reduced from 95.47% and 7.09 × 1012 m/kg to 79.26% and 2.258 × 1012 m/kg, respectively, at a constant pressure of 0.05 MPa after conditioned by the starch-based flocculant with the highest hydrophobicity at its optimal dose. Moreover, due to their amphiphilic structures, CS-DMRs could closely interact with the negatively charged extracellular polymeric substances (EPS), efficiently compress the protein and polysaccharide in EPS, and release the bound water. A second-order polynomial model was proposed according to the phenomenological theory to quantitatively analyze the effect of hydrophobicity in these starch-based flocculants on the sludge dewaterability. The structure-activity relationship was built, and the optimal dose and corresponding FCMC could be theoretically estimated accordingly. The results were in good agreement with the experimental results. The dewatering mechanisms were also discussed in detail on the basis of the changes in the FCMC, SRF, capillary suction time, properties of sludge flocs, compression coefficient, microstructures of sludge cakes, EPS fractions and components, and spatial distributions of the proteins and polysaccharides. In addition to charge neutralization, the hydrophobic association effects of CS-DMRs played an important role in the formation of drainage channels and net-like porous structures in the sludge cake to improve its permeability and filterability. This study thus provided a good understanding of the structural effects of the starch-based flocculants on the sludge dewaterability. The results are greatly beneficial to the fabrication and utilization of environment-friendly and high-performance natural polymeric conditioners for sludge treatment.
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Affiliation(s)
- Pan Hu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Shaohang Shen
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Donghua Zhao
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Hua Wei
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Jun Ge
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Feiyue Jia
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Xiangxiang Zhang
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Hu Yang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Quanzhou Institute for Environmental Protection Industry, Nanjing University, Beifeng Road, Quanzhou, 362000, PR China.
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Chen J, Xu X, Nie R, Feng L, Li X, Liu B. Chitosan Modified Cationic Polyacrylamide Initiated by UV-H 2O 2 for Sludge Flocculation and New Insight on the Floc Characteristics Study. Polymers (Basel) 2020; 12:E2738. [PMID: 33218149 PMCID: PMC7698928 DOI: 10.3390/polym12112738] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/13/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022] Open
Abstract
In the present study, a novel graft modified flocculant CTS-g-PAMD was synthesized and applied to conduct sludge conditioning and dewatering. CTS-g-PAMD was copolymerized with AM, DMC and chitosan (CTS) under UV-H2O2 initiation. In addition, the effects of single factor experiments on the molecular weight (MW) CTS grafting efficiency (GE) of CTS-g-PAMD were determined and the optimal copolymerization conditions were achieved. The GE of CTS-g-PAMD reached 91.1% and the MW was 4.82 × 106 Da. As revealed from the characterized results of Fourier-transform infrared spectra (FT-IR), 1H/ NMR, X-ray diffraction (XRD), scanning electron microscopic (SEM) and X-ray photoelectron spectroscopy (XPS), the successful synthesis of CTS-g-PAMD was confirmed, which is considered to be conducive to explaining sludge dewatering performance. Under the optimal conditions (pH = 7.0, flocculant dosage = 35 mg/L), the best flocculating performance (FCMC: 73.7%; SRF: 4.7 × 1012 m·kg-1, turbidity: 9.4 NTU) and large and dense sludge flocs (floc size d50 = 379.142 µm, floc fractal dimension Df = 1.58) were formed. The DMC and CTS chain segments exhibiting cationic properties significantly improved the positive charge density and enhanced the electrical patching effect of CTS-g-PAMD. The long molecular chain of CTS-g-PAMD exhibited superior extensibility, which enhanced bridging effect on adsorption. Moreover, the sludge floc after undergoing CTS-g-PAMD conditioning exhibited robust shear resistance and regeneration ability. After the sludge floc was crushed and broken, a large and dense sludge floc was formed, helping significantly reduce the sludge specific resistance (SRF), turbidity and cake moisture content (FCMC) and enhance the sludge dewatering effect. The novel CTS-g-PAMD flocculant shows promising practical applications and high market value.
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Affiliation(s)
- Jie Chen
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; (J.C.); (X.X.); (R.N.)
| | - Xiaojun Xu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; (J.C.); (X.X.); (R.N.)
| | - Rui Nie
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; (J.C.); (X.X.); (R.N.)
| | - Li Feng
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China; (X.L.); (B.L.)
| | - Xuhao Li
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China; (X.L.); (B.L.)
| | - Bingzhi Liu
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China; (X.L.); (B.L.)
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11
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Wu B, Dai X, Chai X. Critical review on dewatering of sewage sludge: Influential mechanism, conditioning technologies and implications to sludge re-utilizations. WATER RESEARCH 2020; 180:115912. [PMID: 32422413 DOI: 10.1016/j.watres.2020.115912] [Citation(s) in RCA: 227] [Impact Index Per Article: 56.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 04/21/2020] [Accepted: 05/02/2020] [Indexed: 05/17/2023]
Abstract
Sewage sludge (mainly composed of excessive bio-sludge) is an inevitable by-product of biological wastewater treatment process and contains various toxic substances, such as pathogens, heavy metals, and organic contaminants. The production of sewage sludge may cause serious pollution risks without appropriate disposals. As the essential step of sludge treatment, dewatering plays significant roles in minimizing the sludge volume, facilitating the transportation, increasing the calorific value and even reducing the leachate production in landfill sites. This paper presents a comprehensive review on the issues related to dewatering of sewage sludge. Section 1 starts with the environmental implications of sludge dewatering. Section 2 deals with the concepts and challenges about differentiation of bound water fractions, and also reviews the recent progress of in-situ visualization of water occurrence states in bio-flocs. Section 3 discusses about how various physiochemical properties influence the sludge dewaterability, and the insufficiency in in-situ micro-characterization of sludge constituents is pointed out. Section 4 reviews the existing conditioning technologies for sludge dewaterability improvement, and the advantages/disadvantages of each technology in terms of applicable occasions, material consumption, energy consumption and environmental impacts are evaluated. The last section (section 5) specifically analyzes the feasibility of integrating sludge dewatering and re-utilization, and raises attention to the potential environmental risks of dewatering conditioning. Based on the above discussion, we propose that a unified theory for sludge dewaterability improvement remains to be established. Especially, how the molecular structures of sludge compositions affect the solid-water interface behavior requires to be deepened, which will further unravel the mechanism behind strong water-holding capacities of bio-flocs. Additionally, we believe that the key challenges for sludge dewatering is how to select the appropriate conditioning technique according to the physiochemical properties of target sludge. The reliable indicators for real-time control of conditioning operations are still deficient, e.g., dynamic dosage control of conditioning chemicals. Accordingly, the potential environmental risks of excessive conditioning chemicals should be taken into more consideration.
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Affiliation(s)
- Boran Wu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai, 200092, China
| | - Xiaohu Dai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai, 200092, China
| | - Xiaoli Chai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai, 200092, China.
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12
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Sun Y, Ren M, Sun W, Xiao X, Xu Y, Zheng H, Wu H, Liu Z, Zhu H. Plasma-induced synthesis of chitosan-g-polyacrylamide and its flocculation performance for algae removal. ENVIRONMENTAL TECHNOLOGY 2019; 40:954-968. [PMID: 29210322 DOI: 10.1080/09593330.2017.1414312] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 12/03/2017] [Indexed: 06/07/2023]
Abstract
Chitosan (CS)-g-polyacrylamide (PAM) is a highly efficient and environmentally friendly flocculant, which was synthesized through plasma-induced graft copolymerization of CS and acrylamide (AM). The effects of monomer concentration, AM:CS ratio, discharge power, discharge time, post-polymerization temperature, and post-polymerization time on the intrinsic viscosity, grafting ratio, and grafting efficiency of CS-g-PAM were investigated. The optimum conditions of graft copolymerization were as follows: 20% monomer concentration, 7:3 AM:CS ratio, 40 W discharge power, 90 s discharge time, 50°C post-polymerization temperature, and 24 h post-polymerization time. The structural characteristics of CS-g-PAM were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. CS-g-PAM exhibited better flocculation efficiency than the commercially available PAM in both diatomite-simulated wastewater and low-turbidity algal water. The optimal turbidity removal efficiency for the diatomite-simulated wastewater was 99.9%, which was obtained with 6 mg L-1 of CS-g-PAM at pH 11.0 and 250 s-1 of velocity gradient. In low-turbidity algal water, the optimal removal efficiencies for chlorophyll-a, turbidity, and COD were 93.6%, 94.5%, and 98.2%, respectively.
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Affiliation(s)
- Yongjun Sun
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
- b Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction , College of Environment, Nanjing Tech University , Nanjing , People's Republic of China
| | - Mengjiao Ren
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
| | - Wenquan Sun
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
- b Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction , College of Environment, Nanjing Tech University , Nanjing , People's Republic of China
| | - Xuefeng Xiao
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
| | - Yanhua Xu
- b Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction , College of Environment, Nanjing Tech University , Nanjing , People's Republic of China
| | - Huaili Zheng
- c Key laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education , Chongqing University , Chongqing , People's Republic of China
| | - Huifang Wu
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
| | - Zhiying Liu
- b Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction , College of Environment, Nanjing Tech University , Nanjing , People's Republic of China
| | - Hui Zhu
- a College of Urban Construction, Nanjing Tech University , Nanjing , People's Republic of China
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13
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Shi C, Sun W, Sun Y, Chen L, Xu Y, Tang M. Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD. Polymers (Basel) 2019; 11:E95. [PMID: 30960079 PMCID: PMC6402025 DOI: 10.3390/polym11010095] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 12/27/2018] [Accepted: 12/30/2018] [Indexed: 11/16/2022] Open
Abstract
Carboxymethyl chitosan (CMCS), acrylamide, and methacryloxyethyltrimethyl ammonium chloride were used as co-monomers to produce a sludge dewatering agent carboxymethyl chitosan-graft-poly(acrylamide-methacryloxyethyltrimethyl ammonium chloride) (CCPAD) by UV-induced graft polymerization. Single-factor experiments and response surface methodology were employed to investigate and optimize the grafting rate, grafting efficiency, and intrinsic viscosity influenced by the total monomer concentration, CMCS concentration, cationic degree, pH value, and illumination time. The structure, surface morphology, and thermal stability of CCPAD were characterized by infrared spectroscopy, hydrogen nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, and differential thermal-thermogravimetry. The raw sludge with 97.9% water content was sourced from the concentrated tank of a sewage treatment plant and used in the sludge condition experiments. In addition, CCPAD was applied as the sludge conditioner to investigate the effects of cationic degree, intrinsic viscosity, and pH on the supernatant turbidity, moisture content, specific resistance to filtration, and sludge settling ratio. Moreover, the mechanism of sludge conditioning by CCPAD was discussed by examining the zeta potential and extracellular polymeric substance (EPS) content of the supernatant. The sludge dewatering results confirmed that CCPAD had excellent performance for improving sludge dewaterability.
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Affiliation(s)
- Chunhong Shi
- School of Energy and Environmental Engineering, University of Science and Technology Bejing, Bejing 100083, China.
| | - Wenquan Sun
- College of Urban Construction, Nanjing Tech University, Nanjing 211800, China.
| | - Yongjun Sun
- College of Urban Construction, Nanjing Tech University, Nanjing 211800, China.
| | - Lei Chen
- Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction, College of Environment, Nanjing Tech University, Nanjing 211800, China.
| | - Yanhua Xu
- Jiangsu Key Laboratory of Industrial Water-Conservation & Emission Reduction, College of Environment, Nanjing Tech University, Nanjing 211800, China.
| | - Mengdan Tang
- College of Urban Construction, Nanjing Tech University, Nanjing 211800, China.
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14
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Characterization and sludge dewatering performance evaluation of the photo-initiated cationic flocculant PDD. J Taiwan Inst Chem Eng 2018. [DOI: 10.1016/j.jtice.2018.07.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Wei H, Gao B, Ren J, Li A, Yang H. Coagulation/flocculation in dewatering of sludge: A review. WATER RESEARCH 2018; 143:608-631. [PMID: 30031298 DOI: 10.1016/j.watres.2018.07.029] [Citation(s) in RCA: 253] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 05/03/2023]
Abstract
Sludge disposal is an integral part of wastewater treatment systems, and its cost usually accounts for more than half of the total operation cost. Sludge disposal technology is facing challenges and opportunities simultaneously and can still be improved. Sludge dewatering is an essential process in sludge disposal, and it is important for the effective reduction of the final processing cost. Coagulation/flocculation is a relatively mature, cost-effective, user-friendly sludge dewatering technology. In this work, coagulation/flocculation and their combinations with other pretreatments, including dewatering mechanisms, are reviewed. Various coagulants/flocculants used in sludge dewatering, including inorganic coagulants, organic synthetic and natural polymeric flocculants, and bioflocculants, are introduced in detail because coagulants/flocculants are the key in coagulation/flocculation. The different factors that influence the dewatering performance of these coagulants/flocculants are also presented briefly. Moreover, aiming at the complicated composition of sludge and its treatment difficulty, the prospects and technical developments of coagulation/flocculation in sludge dewatering are discussed.
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Affiliation(s)
- Hua Wei
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Boqiang Gao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Jie Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Aimin Li
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Hu Yang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China.
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