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Deng Z, Xu A, Zhang X, Zhang K, Pan B. Effects of Chelators on Fluoride Removal by AlCl 3 and Al 13 Coagulation: Performance and Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2025; 59:3297-3308. [PMID: 39918795 DOI: 10.1021/acs.est.4c11302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2025]
Abstract
Aluminum (Al) coagulation is one of the most widely used techniques for the defluoridation of industrial effluents. This study examined the influence of two common chelating agents, i.e., ethylenediaminetetraacetic acid (EDTA) and citric acid (CA), on fluoride removal during coagulation using monomeric Al (AlCl3) and polymeric aluminum species [Al13O4(OH)24(H2O)127+, Al13]. The results revealed that EDTA reduced the fluoride removal efficiency by up to 95.4% with AlCl3 and by 28.3% with Al13. In contrast, CA inhibited fluoride removal by up to 100% with AlCl3 and 90.6% with Al13. Both chelators impaired fluoride removal primarily by disrupting floc formation. Advanced analytical techniques, including 19F/27Al NMR spectroscopy combined with DFT calculations, demonstrated that this interference was due to the formation of EDTA-Al-F ternary complexes and Al-CA binary complexes. Additionally, the formation of a bridging fluoride (μ-F) in the Al13 structure enhanced its thermodynamic stability against chelators. Specifically, Al13 maintained structural stability even in the presence of up to 1.50 mmol/L EDTA, whereas CA progressively destabilized the Al13 structure by forming soluble Al-CA complexes. These findings are believed to help guide the rational design of Al-based coagulants and optimize water treatment strategies aimed at defluoridation of industrial effluents.
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Affiliation(s)
- Ziniu Deng
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - An Xu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Xiaolin Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
- Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China
| | - Kaisheng Zhang
- Chinese Acad Sci, Inst Solid State Phys, Environm Mat & Pollut Control Lab, HFIPS, Hefei 230031, China
| | - Bingcai Pan
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
- Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China
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Wang S, Li Y, Cai L, Yang X, Pi K, Li Z. Enhanced coagulation of Microcystis aeruginosa using titanium xerogel coagulant. CHEMOSPHERE 2025; 370:144017. [PMID: 39732406 DOI: 10.1016/j.chemosphere.2024.144017] [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: 08/18/2024] [Revised: 12/03/2024] [Accepted: 12/21/2024] [Indexed: 12/30/2024]
Abstract
Cyanobacterial blooms are prevalent globally and present a significant threat to water security. Titanium salt coagulants have garnered considerable attention due to their superior coagulation properties and the absence of metal residue risks. This paper explored the influencing factors in the coagulation process of titanium xerogel coagulant (TXC), the alterations in cell activity during floc storage, and the release of cyanobacterial organic matters, thereby determining the application scope of TXC for cyanobacterial water treatment. The findings indicated that at a TXC dosage of 8 mg Ti/L, the removal rate of Microcystis aeruginosa (M. aeruginosa) exceeded 86% across a pH range of 5-9. The coagulation performance with anions HCO3-, CO32- and H2PO4-/HPO42- was unsatisfactory at concentrations of 10, 20, and 50 mg/L, with corresponding chlorophyll a (Chl-a) levels of 168, 129, and 196 μg/L, respectively. While the presence of Cl-, NO3-, SO42-, K+, NH4+, Ca2+ and Mg2+ had little influence on the removal efficiency. At sodium alginate (SA) concentration of 6 mg/L, the Chl-a content was 116 μg/L, with humic acid (HA) not affecting M. aeruginosa removal but hindering turbidity reduction, leaving a residual turbidity of 11 NTU. Following TXC treatment, a floc storage study with cyanobacteria-laden surface water showed a decrease in microcystins (MCs) content. The low residual titanium concentration post-TXC coagulation (<0.06 mg/L) and MCs reduction contributed to reduced effluent toxicity, indicating TXC's versatile applicability for treating cyanobacterial-contaminated waters.
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Affiliation(s)
- Shulian Wang
- Key Laboratory of Health Intelligent Perception and Ecological Restoration of River and Lake, Ministry of Education, Hubei University of Technology, Wuhan, 430068, China.
| | - Yanqun Li
- Key Laboratory of Health Intelligent Perception and Ecological Restoration of River and Lake, Ministry of Education, Hubei University of Technology, Wuhan, 430068, China.
| | - Lu Cai
- Key Laboratory of Ecological Impacts of Hydraulic-Projects and Restoration of Aquatic Ecosystem, Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences, Wuhan, 430079, China.
| | - Xian Yang
- Key Laboratory of Health Intelligent Perception and Ecological Restoration of River and Lake, Ministry of Education, Hubei University of Technology, Wuhan, 430068, China.
| | - Kewu Pi
- Key Laboratory of Health Intelligent Perception and Ecological Restoration of River and Lake, Ministry of Education, Hubei University of Technology, Wuhan, 430068, China.
| | - Zhu Li
- Key Laboratory of Health Intelligent Perception and Ecological Restoration of River and Lake, Ministry of Education, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, 430068, China.
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Jathan Y, Marchand EA. Enhanced coagulation for removal of dissolved organic nitrogen in water: A review. CHEMOSPHERE 2024; 366:143429. [PMID: 39349069 DOI: 10.1016/j.chemosphere.2024.143429] [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: 06/11/2024] [Revised: 09/14/2024] [Accepted: 09/26/2024] [Indexed: 10/02/2024]
Abstract
Wastewater treatment plants (WWTPs) meeting strict nutrient discharge regulations typically effectively remove inorganic nitrogen, leaving dissolved organic nitrogen (DON) as the main component of total nitrogen in the effluent. DON in treated effluent from both WWTPs and drinking water treatment plants (DWTPs) has the potential to induce eutrophication and contribute to the formation of nitrogenous disinfection byproducts (N-DBP). While numerous studies have investigated DON in different water sources, a limited number of studies have focused on its removal through enhanced coagulation. The variable removal efficiencies of dissolved organic carbon (DOC) and DON in treatment processes highlight the need for comprehensive research on enhanced coagulation for DON removal. Enhanced coagulation is a viable option for DON removal, but underlying mechanisms and influencing factors are still being actively researched. The effectiveness of enhanced coagulation depends on DON characteristics and coagulant properties, but knowledge gaps remain regarding their influence on treatment. DON is a complex mixture of compounds, with only a small fraction identified, such as proteins, degraded amino acids, urea, chelating agents, humic substances, and soluble microbial products. Understanding molecular-level characteristics of DON is crucial for identifying unknown compounds and understanding its fate and transformation during treatment processes. This review identifies knowledge gaps regarding enhanced coagulation process for DON removal, including the role of coagulant aids, novel coagulants, and pretreatment options. It discusses DON characteristics, removal mechanisms, and molecular-level transformation of DON during enhanced coagulation. Addressing these gaps can lead to process optimization, promote efficient DON removal, and facilitate safe water production.
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Affiliation(s)
- Yasha Jathan
- Department of Civil and Environmental Engineering University of Nevada, Reno, Reno, NV, 89557, USA
| | - Eric A Marchand
- Department of Civil and Environmental Engineering University of Nevada, Reno, Reno, NV, 89557, USA.
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4
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Mao Y, Hu Z, Li H, Zheng H, Yang S, Yu W, Tang B, Yang H, He R, Guo W, Ye K, Yang A, Zhang S. Recent advances in microplastic removal from drinking water by coagulation: Removal mechanisms and influencing factors. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 349:123863. [PMID: 38565391 DOI: 10.1016/j.envpol.2024.123863] [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: 02/26/2024] [Accepted: 03/23/2024] [Indexed: 04/04/2024]
Abstract
Microplastics (MPs) are emerging contaminants that are widely detected in drinking water and pose a potential risk to humans. Therefore, the MP removal from drinking water is a critical challenge. Recent studies have shown that MPs can be removed by coagulation. However, the coagulation removal of MPs from drinking water remains inadequately understood. Herein, the efficiency, mechanisms, and influencing factors of coagulation for removing MPs from drinking water are critically reviewed. First, the efficiency of MP removal by coagulation in drinking water treatment plants (DWTPs) and laboratories was comprehensively summarized, which indicated that coagulation plays an important role in MP removal from drinking water. The difference in removal effectiveness between the DWTPs and laboratory was mainly due to variations in treatment conditions and limitations of the detection techniques. Several dominant coagulation mechanisms for removing MPs and their research methods are thoroughly discussed. Charge neutralization is more relevant for small-sized MPs, whereas large-sized MPs are more dependent on adsorption bridging and sweeping. Furthermore, the factors influencing the efficiency of MP removal were jointly analyzed using meta-analysis and a random forest model. The meta-analysis was used to quantify the individual effects of each factor on coagulation removal efficiency by performing subgroup analysis. The random forest model quantified the relative importance of the influencing factors on removal efficiency, the results of which were ordered as follows: MPs shape > Coagulant type > Coagulant dosage > MPs concentration > MPs size > MPs type > pH. Finally, knowledge gaps and potential future directions are proposed. This review assists in the understanding of the coagulation removal of MPs, and provides novel insight into the challenges posed by MPs in drinking water.
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Affiliation(s)
- Yufeng Mao
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China; Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing, 400044, China
| | - Zuoyuan Hu
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Hong Li
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing, 400044, China
| | - Huaili Zheng
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing, 400044, China
| | - Shengfa Yang
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Weiwei Yu
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Bingran Tang
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing, 400044, China
| | - Hao Yang
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Ruixu He
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Wenshu Guo
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Kailai Ye
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Aoguang Yang
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China
| | - Shixin Zhang
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing, 400074, China.
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Liu M, Lu Q, Siddique MS, Yu W. Molecular-weight dependent promotion and competition effects of natural organic matter on dissolved black carbon removal by coagulation. CHEMOSPHERE 2024; 356:141940. [PMID: 38588894 DOI: 10.1016/j.chemosphere.2024.141940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/03/2024] [Accepted: 04/06/2024] [Indexed: 04/10/2024]
Abstract
Dissolved black carbon (DBC) is the ubiquitous component of dissolved organic matter pools with the high reactivity for disinfection byproducts formation. However, it is unknown that the influence of molecular weight (MW) of natural organic matter (NOM) on the DBC removal from potable water sources. Therefore, it was studied that the DBC removal by coagulation in the presence of the NOM with various molecular weights. The DBC removal was promoted due to the presence of NOM and the promotion degree decreased with decreasing MW of NOM. Furthermore, the removal ratio of humic-like component increased as the MW of NOM decreased, suggesting that the competition between DBC and NOM increased with decreasing MW. The functional groups after coagulation were the same with that before coagulation as the MW of NOM varied, suggesting that the molecular structure was not the key factor of influencing the DBC removal. This study will give the deep insight into the prediction of the DBC removal ratio by coagulation based on the MW of NOM in water sources.
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Affiliation(s)
- Minmin Liu
- Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
| | - Qingxuan Lu
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China.
| | - Muhammad Saboor Siddique
- Institute of Environment and Ecology, Tsinghua-Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, Guangdong, China.
| | - Wenzheng Yu
- Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
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Liu M, Liu X, Graham NJD, Yu W. Uncovering the neglected role of anions in trivalent cation-based coagulation processes. WATER RESEARCH 2024; 254:121352. [PMID: 38401286 DOI: 10.1016/j.watres.2024.121352] [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: 11/09/2023] [Revised: 01/08/2024] [Accepted: 02/20/2024] [Indexed: 02/26/2024]
Abstract
Coagulation efficiency is heavily contingent upon a profound comprehension of the underlying mechanisms, facilitated by the evolution of coagulation theory. However, the role of anions, prevalent components in raw and wastewaters, has been relatively overlooked in this context. To address this gap, this study has investigated the impact of three common anions (i.e., chloride, sulfate, and phosphate) on Al-based coagulation. The results have shown that the influence of anions on coagulation depends predominantly on their ability to compete with hydroxyl groups throughout the entire coagulation process, encompassing hydrolysis, aggregation, and the growth of large flocs. Moreover, this competition is subject to the dual influence of both anion concentration and hydroxyl concentration (i.e., pH). The results have revealed the intricate interplay between anions and coagulants, their impact on floc structure, and their importance in optimizing coagulation efficiency and ensuring the production of high-quality water.
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Affiliation(s)
- Mengjie Liu
- Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xun Liu
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Nigel J D Graham
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Wenzheng Yu
- Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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7
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He Y, Huang X, van Leeuwen J, Feng C, Shi B. Compositional and structural identification of organic matter contributing to high residual soluble aluminum after coagulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:168005. [PMID: 37875206 DOI: 10.1016/j.scitotenv.2023.168005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/04/2023] [Accepted: 10/19/2023] [Indexed: 10/26/2023]
Abstract
Understanding the complexation of aluminum (Al) with dissolved organic matter (DOM) is of great significance for the control of residual Al in drinking water after treatment. Here, we used high-resolution and accurate mass measurements to identify the composition and structure of DOM contributing to the formation of soluble organically-bound Al during coagulation at near neutral pH (pH 7.50). The results showed that the organic compounds contributing to soluble organically-bound Al were primarily phenolic compounds and aliphatic compounds. Among them, phenolic compounds with a sulfonic acid group could greatly enhance the hydrolysis of polymeric Al and the formation of high concentrations of monomeric/oligomeric Al-DOM complexes. These organic molecules had a mass-to-charge ratio concentrated below 350. Based on the assumption that oxygen-containing functional groups providing unsaturation in the molecular structure were carboxyl groups, it was inferred that the maximum number of carboxyl groups in phenolic compounds and aliphatic compounds was concentrated between 1-2 and 2-4, respectively. The presence of these molecules was responsible for soluble organically-bound Al accounting for over 80 % of the total soluble Al in the supernatant after coagulation in this study. These findings deepen the understanding of the complexation of Al with DOM. In drinking water treatment plants, the combination of coagulation with processes that can remove such characteristic organics is beneficial for controlling residual Al.
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Affiliation(s)
- Yitian He
- 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
| | - Xin Huang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - John van Leeuwen
- Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Chenghong Feng
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Baoyou Shi
- 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.
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Zhao J, Yang L, Yang J, Zhang H, Wang H, Liu D, Wang J, Cheng X, Zhu X, Liang H. Overlooked flocs in electrocoagulation-based ultrafiltration systems: A new understanding of the structural interfacial properties. WATER RESEARCH 2023; 246:120675. [PMID: 37827039 DOI: 10.1016/j.watres.2023.120675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/25/2023] [Accepted: 09/26/2023] [Indexed: 10/14/2023]
Abstract
An integrated ferrate-induced electrocoagulation-ultrafiltration (FECUF) process is proposed to cope with the growing demand for water treatment. Although flocs formed during the electrocoagulation (EC) process are useful for contaminant reduction and mitigation of membrane fouling, few studies have been focused on their structures and properties. Herein, we investigated the formation and structural transformations of flocs and their responses to organic matter, as well as the relationships between their interfacial properties and membrane fouling mitigation. It was found that ferrate contributed to the fast formation of flocs during the ferrate-induced electrocoagulation (FEC) process, which accelerated the FECUF process. Physicochemical analyses indicated that the flocs formed in the FEC process were mainly composed of Fe(III)-(hydr)oxides with abundant hydroxyl groups and poor crystallinity, which allowed complexation with NOM. Therefore, the mobilities of the NOM and the soluble coagulant ions were reduced. The responses of flocs to NOM suggested that the period of 0-20 min resulted in the most efficient NOM removal. In addition, two patterns revealed the relationships between the interfacial properties of the small colloidal particles (SCPs) and the membrane filtration performance: i) the decline in the initial flux was closely related to the composition (gel-type substances or metal-(hydr)oxides) of the SCPs and ii) the steady-state flux was influenced by the energy barrier between the SCPs. However, when the SCPs had the same composition, the interfacial properties influenced both the initial flux and the steady-state flux. This study provides an alternative FECUF process for intensive upgrades of centralized water treatment systems.
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Affiliation(s)
- Jing Zhao
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Liu Yang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Jiaxuan Yang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Han Zhang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Hesong Wang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Dongqing Liu
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
| | - Jinlong Wang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China.
| | - Xiaoxiang Cheng
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, PR China
| | - Xuewu Zhu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, PR China
| | - Heng Liang
- State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China
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Jathan Y, Pagilla KR, Marchand EA. Understanding the influence of dissolved organic nitrogen characteristics on enhanced coagulation performance for water reuse. CHEMOSPHERE 2023; 337:139384. [PMID: 37414300 DOI: 10.1016/j.chemosphere.2023.139384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/08/2023]
Abstract
With the recent focus on using advanced water treatment processes for water reuse, interest is growing for utilizing enhanced coagulation to remove dissolved chemical species. Up to 85% of the nitrogen in wastewater effluent is made up of dissolved organic nitrogen (DON), but there is a knowledge gap regarding its removal during coagulation, which can be influenced by DON characteristics. To address this issue, tertiary-treated wastewater samples were analyzed before and after coagulation with polyaluminum chloride and ferric chloride. Samples were size-fractionated into four molecular weight fractions (0.45 μm, 0.1 μm, 10 kDa, and 3 kDa) using vacuum filtration and ultrafiltration. Each fraction was further evaluated by coagulating it separately to assess DON removal during enhanced coagulation. The size fractionated samples were also separated into hydrophilic and hydrophobic fractions using C18 solid phase extraction disks. Fluorescence excitation-emission matrices were used to investigate the characteristics of dissolved organic matter contributing to DON during the coagulation process. The results showed that DON compounds of size <3 kDa constituted a majority of the total DON. Coagulation removed more than 80% DON from size fractions 0.45 μm-0.1 μm and 0.1 μm-10 kDa, but less than 20% was removed from 10 kDa to 3 kDa and <3 kDa fractions. Coagulation on pre-filtered samples removed 19% and 25% of the <3 kDa DON fraction using polyaluminum chloride and ferric chloride, respectively. In all molecular weight fractions, hydrophilic DON compounds were found to be dominant (>90%), and enhanced coagulation was not effective in removing hydrophilic DON compounds. LMW fractions respond poorly to enhanced coagulation due to their hydrophilic nature. Enhanced coagulation effectively removes humic acid-like substances, but poorly removes proteinaceous compounds such as tyrosine and tryptophan. This study's findings provide insights into DON behavior during coagulation and factors affecting its removal, potentially improving wastewater treatment strategies.
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Affiliation(s)
- Yasha Jathan
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Reno, NV, 89557, USA
| | - Krishna R Pagilla
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Reno, NV, 89557, USA
| | - Eric A Marchand
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Reno, NV, 89557, USA.
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10
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Song Q, Yang B, Liu M, Song S, Graham N, Yu W. Floc aging: Crystallization and improving low molecular weight organic removal in re-coagulation. WATER RESEARCH 2023; 243:120328. [PMID: 37459797 DOI: 10.1016/j.watres.2023.120328] [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: 04/13/2023] [Revised: 06/26/2023] [Accepted: 07/07/2023] [Indexed: 09/07/2023]
Abstract
Iron coagulants have been used extensively in drinking water treatment. This typically produces substantial quantities of insoluble iron hydrolysis products which interact with natural and anthropogenic organic substances during the coagulation process. Previous studies have shown that the removal of low molecular weight (MW) organics is relatively poor by coagulation, which leads to their presence during disinfection, with the formation of halogenated byproducts, and in treated water supplies as potentially biodegradable material. Currently, there is little knowledge about the changes that occur in the nature of coagulant flocs as they age with time and how such changes affect interactions with organic matter, especially low MW organics. To improve this deficiency, this study has investigated the variation of aged flocs obtained from two commonly used iron salts and their impact on representative organic contaminants, natural organic matter (NOM) and tetracycline antibiotic (TC), in a real surface water. It was found that aging resulted in increasing crystallization of the flocs, which can play a beneficial role in activating persulfate oxidant to remove the representative organics. Furthermore, acidification was also found to further improve the removal of low MW natural organics and tetracycline. In addition, the results showed that the low MW fractions of NOM (<1 K Dalton) were substantially removed by the aging flocs. These results are in marked contrast to the poor removal of low MW organic substances by conventional coagulation, with or without added oxidants, and show that aged flocs have a high potential of reuse for re-coagulation and activation of oxidants to reduce low MW organics, and enhance drinking water quality.
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Affiliation(s)
- Qingyun Song
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bingqian Yang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mengjie Liu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shian Song
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Nigel Graham
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Wenzheng Yu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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11
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Zhao S, Zhang J, Yang W, Liu M, Yan Y, Jia W. Application of laminarin as a novel coagulant aid to improve coagulation-ultrafiltration efficiency. ENVIRONMENTAL RESEARCH 2023; 228:115909. [PMID: 37060989 DOI: 10.1016/j.envres.2023.115909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/10/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023]
Abstract
Polyacrylamide (PAM) is the most commonly used coagulant aid in coagulation-ultrafiltration (C-UF) systems; however, its hydrolyzed monomer is harmful to the human nervous system. In this study, laminarin (LA), was extracted from Laminaria japonica and used as a novel coagulant aid to improve coagulation efficiency and reduce membrane fouling during the C-UF process. Optimal LA usage conditions were systematically examined and compared with those of PAM to evaluate their potential for industrial applications. The results revealed that coagulation efficiency could be enhanced by 15-35% with moderate LA addition, which exhibited comparable aid effects to PAM. LA exhibited the highest coagulation aid effect at pH 8-9, and under this condition, turbidity and natural organic matter (NOM) removal achieved 82% and 54%, respectively. Compared with a one-time LA dosing strategy, the pollutant removal capacity of batch dosing was superior. Even in lower water temperatures (5-15 °C), coagulation efficiency was still satisfied, which exhibited a good practical application perspective. The coagulation aid role of LA should be attributed to its long-chain molecular structure, which enhances the bridging role between micro flocs and assists floc growth, thus facilitating the formation of large flocs. In addition, LA adsorption on floc surface was conducive to the direct electrostatic repulsion effect of electronegative membrane, which resulted in a more porous cake layer and higher membrane flux. Therefore, LA exhibits excellent application potential for eliminating NOM while simultaneously reducing membrane fouling through the C-UF process.
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Affiliation(s)
- Shuang Zhao
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
| | - Jianguo Zhang
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
| | - Weihua Yang
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
| | - Mingkai Liu
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
| | - Yan Yan
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
| | - Wenlin Jia
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221000, China.
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12
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Li Y, Wang Y, Jin J, Tian Z, Yang W, Graham NJD, Yang Z. Enhanced removal of trace pesticides and alleviation of membrane fouling using hydrophobic-modified inorganic-organic hybrid flocculants in the flocculation-sedimentation-ultrafiltration process for surface water treatment. WATER RESEARCH 2023; 229:119447. [PMID: 36476382 DOI: 10.1016/j.watres.2022.119447] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Pesticide concentrations in surface water occasionally exceed regulated values due to seasonal events (rainy season in high intensity agricultural areas) or intermittent discharges (leakage, spillage, or other emergency events). The need to remove pesticide compounds in these situations poses a challenge for drinking water treatment plants (DWTPs). In this work, the performance of dosing hydrophobic-modified inorganic-organic hybrid flocculants (HOC-M; lower acute toxicity than corresponding metal salt coagulants; acceptable economic costs when M=Al or Fe; prepared in large-scale quantities), for the removal of four different pesticides (each initial concentration: 0.25 μg/L) from Yangtze River water, and in mitigating membrane fouling, by an integrated flocculation-sedimentation-ultrafiltration (FSUF) process, was evaluated over a period of 40 days; the FSUF is well-established in many DWTPs. The mechanisms underlying the treatment were unveiled by employing a combination of instrumental characterizations, chemical computations, material flow analyses, and statistical analyses. Efficient pesticide removal (80.3%∼94.3%) and membrane fouling reduction (26.6%∼37.3% and 28.3%∼57.6% for reversible and irreversible membrane resistance, respectively) in the FSUF process were achieved by dosing HOC-M, whereas conventional inorganic coagulants were substantially inferior for pesticide removal (< 50%) and displayed more severe fouling development. Hydrophobic association between the pesticides and the hydrophobic organic chain of HOC-M played a predominant role in the improvement in pesticide removal; coexisting particulate/colloid inorganic minerals and natural organic matter with HOC-M adsorbed on the surface, acting as floc building materials, provided sites for the indirect combination of pesticides into flocs. The observed fouling alleviation from dosing HOC-M was ascribed to both the pre-removal of fouling-causing materials in the flocculation-sedimentation prior to UF, and a stable hydrophilization modification effect of residual HOC-M in the UF unit. The latter effect resulted from a hydrophobic association between the PVDF substrate of the membranes and the hydrophobic organic chains of the HOC-M, causing the hydrophilic ends of the HOC-M to be exposed away from the membrane surface, thereby inhibiting foulant accumulation. This work has not only demonstrated the superior performance of dosing HOC-M in the FSUF process for trace pesticide removal in DWTPs, but also clarified the underlying mechanisms.
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Affiliation(s)
- Yunyun Li
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China
| | - Yadong Wang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China
| | - Jin Jin
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China
| | - Ziqi Tian
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315000, China
| | - Weiben Yang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China
| | - Nigel J D Graham
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Zhen Yang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China.
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13
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Liu B, Han Z, Han Q, Shu Y, Li L, Chen B, Wang Z, Pedersen JA. Redispersion Behavior of 2D MoS 2 Nanosheets: Unique Dependence on the Intervention Timing of Natural Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:939-950. [PMID: 36516400 DOI: 10.1021/acs.est.2c05282] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The aggregation-redispersion behavior of nanomaterials determines their transport, transformation, and toxicity, which could be largely influenced by the ubiquitous natural organic matter (NOM). Nonetheless, the interaction mechanisms of two-dimensional (2D) MoS2 and NOM and the subsequent influences on the redispersion behavior are not well understood. Herein, we investigated the redispersion of single-layer MoS2 (SL-MoS2) nanosheets as influenced by Suwannee River NOM (SRNOM). It was found that SRNOM played a decisive role on the redispersion of MoS2 2D nanosheets that varied distinctly from the 3D nanoparticles. Compared to the poor redispersion of MoS2 aggregates in the absence or post-addition of SRNOM to the aggregates, co-occurrence of SRNOM in the dispersion could largely enhance the redispersion and mobility of MoS2 by intercalating into the nanosheets. Upon adsorption to SL-MoS2, SRNOM enhanced the hydration force and weakened the van der Waals forces between nanosheets, leading to the redispersion of the aggregates. The SRNOM fractions with higher molecular mass imparted better dispersity due to the preferable sorption of the large molecules onto SL-MoS2 surfaces. This comprehensive study advances current understanding on the transport and fate of nanomaterials in the water system and provides fresh insights into the interaction mechanisms between NOM and 2D nanomaterials.
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Affiliation(s)
- Bei Liu
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Zixin Han
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Qi Han
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Yufei Shu
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Li Li
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Beizhao Chen
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Zhongying Wang
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen518055, China
| | - Joel A Pedersen
- Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland21218, United States
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Zhang J, Li G, Yuan X, Li P, Yu Y, Yang W, Zhao S. Reduction of Ultrafiltration Membrane Fouling by the Pretreatment Removal of Emerging Pollutants: A Review. MEMBRANES 2023; 13:77. [PMID: 36676884 PMCID: PMC9862110 DOI: 10.3390/membranes13010077] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/24/2022] [Accepted: 01/06/2023] [Indexed: 05/28/2023]
Abstract
Ultrafiltration (UF) processes exhibit high removal efficiencies for suspended solids and organic macromolecules, while UF membrane fouling is the biggest obstacle affecting the wide application of UF technology. To solve this problem, various pretreatment measures, including coagulation, adsorption, and advanced oxidation, for application prior to UF processes have been proposed and applied in actual water treatment processes. Previously, researchers mainly focused on the contribution of natural macromolecular pollutants to UF membrane fouling, while the mechanisms of the influence of emerging pollutants (EPs) in UF processes (such as antibiotics, microplastics, antibiotic resistance genes, etc.) on membrane fouling still need to be determined. This review introduces the removal efficiency and separation mechanism for EPs for pretreatments combined with UF membrane separation technology and evaluates the degree of membrane fouling based on the UF membrane's materials/pores and the structural characteristics of the cake layer. This paper shows that the current membrane separation process should be actively developed with the aim of overcoming specific problems in order to meet the technical requirements for the efficient separation of EPs.
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Affiliation(s)
- Jianguo Zhang
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
| | - Gaotian Li
- School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Xingcheng Yuan
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
| | - Panpan Li
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
| | - Yongfa Yu
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
| | - Weihua Yang
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
| | - Shuang Zhao
- School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, China
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15
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Floc formation and growth during coagulation removing humic acid: Effect of stirring condition. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Yu J, Xu H, Wang D, Sun H, Jiao R, Liu Y, Jin Z, Zhang S. Variations in NOM during floc aging: Effect of typical Al-based coagulants and different particle sizes. WATER RESEARCH 2022; 218:118486. [PMID: 35504159 DOI: 10.1016/j.watres.2022.118486] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 06/14/2023]
Abstract
Most studies on the interaction between coagulation and NOM (natural organic matter) currently focus on pollutant removal and coagulant species distribution, while studies on floc aging are lacking. Investigation onto the effects of floc aging could guide further processes that utilize flocs, such as densadeg sludge recirculation, floc predeposition for ultrafiltration, sludge condensation, and other traditional sludge reflux processes. In this study, flocs generated by Al13 and AlCl3 in microparticle- and nanoparticle-containing water were investigated, and the effect of floc aging on NOM was quantified based on several organic matter characterization techniques. Flocs absorb and release organics during aging. The flocs generated from micro-SiO2 have a significant absorbing effect for LWM-N (low-molecular-weight neutral substances) and protein-like substances, while the absorption of NOM by flocs generated from nano-SiO2 is insignificant. HS (humic substances) with high aromaticity are released during floc aging. From the molecular perspective, the molecules released during floc aging are those with higher double bond equivalents and higher aromaticity, while the absorbed molecules are those with lower double bond equivalents and lower aromaticity. 2D-COS (two-dimensional correlation spectroscopy) demonstrated that the flocs generated by Al13 and AlCl3 had the same organic release patterns but different intensities, while the flocs generated in the micro-SiO2 and nano-SiO2 systems had different organics release patterns. Abundant aluminum hydrolysates with low polymerization and amorphous Al(OH)3 would be produced from AlCl3 during the coagulation process and then undergo hydroxyl‑bridging reaction and crystallization during floc aging, thus releasing more HS with high aromaticity into the supernatant; in comparison, prehydrolyzed Al13 produces a more stable floc and releases less HS during aging. The flocs produced by nano-SiO2 and Al-based coagulants release higher aromaticity HS into the water than those produced by micro-SiO2, which may be related to the formation of more highly polymerized degree hydrolysates and nanocrystalline Al(OH)3 in the nano-SiO2 system. The flocs generated in water with micro-SiO2 may contain a large amount of Al-OH and have a loose structure, thus further absorbing NOM, such as protein-like substances and LWM-N. In contrast, the flocs generated from nano-SiO2 possess abundant adsorbed water and a denser structure; thus, organic matter cannot be absorbed stably.
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Affiliation(s)
- Junjie Yu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Yangtze River Delta Branch, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Yiwu City, Zhejiang Province 322000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hui Xu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Yangtze River Delta Branch, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Yiwu City, Zhejiang Province 322000, China
| | - Dongsheng Wang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Hongyan Sun
- School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
| | - Ruyuan Jiao
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Yangtze River Delta Branch, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Yiwu City, Zhejiang Province 322000, China
| | - Yang Liu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiyuan Jin
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuo Zhang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
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17
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Wang Z, Li Y, Hu M, Lei T, Tian Z, Yang W, Yang Z, Graham NJD. Influence of DOM characteristics on the flocculation removal of trace pharmaceuticals in surface water by the successive dosing of alum and moderately hydrophobic chitosan. WATER RESEARCH 2022; 213:118163. [PMID: 35151090 DOI: 10.1016/j.watres.2022.118163] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 01/11/2022] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Hydrophobically-modified chitosan (HC) has emerged as a promising flocculant for trace pharmaceutical removal from surface water. However, the variation in the characteristics of dissolved organic matter (DOM) in different water sources influences the efficacy of HC in removing pharmaceutical compounds. In this work, the flocculation performance of sequentially dosing alum and HC (alum+HC) for the treatment of five water types (three synthetic waters, and samples of two real waters collected from the Yangtze River and the Thames River), having different DOM and five representative pharmaceuticals (initial concentration: 100 ng/L), was assessed by bench-scale jar tests. The DOM characteristics were correlated quantitatively with the removal efficiencies (REs) of the pharmaceuticals. Density functional theory computations were performed to illuminate the interfacial interactions in the flocculation. Alum+HC exhibited a remarkably higher RE of all five pharmaceuticals (maximum RE: 73%-95%) from all waters compared to a conventional coagulant or flocculant (alum or polyacrylamide, respectively). In contrast to using HC alone, alum+HC also achieved a higher RE of pharmaceuticals with nearly half the HC dosage, thereby enhancing the cost-effectiveness of the alum+HC dosing system. Among the different key DOM characteristics, the surface charge and molecular weight of DOM had no evident correlation with RE(pharmaceutical), but the hydrophobic/hydrophilic nature and functional group composition of organic carbon of DOM were strongly correlated: Strongly hydrophobic fractions, with C-C & C=C functional groups (binding pharmaceuticals via hydrophobic association), were beneficial, while hydrophilic fractions with C-OH groups were less effective, for pharmaceutical removal. This work showed the enhanced performance of the alum+HC dosing combination in the removal of different pharmaceutical compounds from different waters, and filled the knowledge gap regarding the performance of hydrophobically-modified flocculants in the treatment of different surface water sources.
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Affiliation(s)
- Zhangzheng Wang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China
| | - Yunyun Li
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China
| | - Min Hu
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China
| | - Tao Lei
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China
| | - Ziqi Tian
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315000, China
| | - Weiben Yang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China
| | - Zhen Yang
- School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China.
| | - Nigel J D Graham
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK
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18
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Zhang Y, Wang X, Li Y, Wang H, Shi Y, Li Y, Zhang Y. Improving nanoplastic removal by coagulation: Impact mechanism of particle size and water chemical conditions. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:127962. [PMID: 34894513 DOI: 10.1016/j.jhazmat.2021.127962] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/20/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
Plastic particles may bring potential threats to the ecosystem. Coagulation, as a widely used method to remove particles, has been rarely studied for plastic particles in the nanometer range. In this work, the coagulation removal of polystyrene nanoplastic particles (PSNPs, 50-1000 nm) was conducted in a model system containing coagulants aluminum chlorohydrate (PAC) and polyacrylamide (PAM). The optimal removal efficiency (98.5%) was observed in the coagulation process at pH= 8.0, 0.4 g·L-1 PAC and 20 mg·L-1 PAM. The inhibition impact of humic acid was also noticed, due to its competitive adsorption with PSNPs onto flocs. The interaction energies between PSNPs and PAC were calculated by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, which showed that electrical neutralization resulted in the difference of the remove efficiency in different sizes and coagulant concentrations. The formation of Al-O bond between PSNPs and PAC/PAM flocs promoted the removal of PSNPs. Excessive PAM (> 20 mg·L-1) increased clusters size and solution viscosity, which resulted in the settling of clusters being controlled by buoyancy and the reduced remove efficiency. The findings suggest that the chemical coagulation dominants the removal of NPs, and the coagulation efficiency can be optimized by choosing suitable coagulant and water chemical conditions.
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Affiliation(s)
- Yunhai Zhang
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Xinjie Wang
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Ying Li
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Hao Wang
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Yuexiao Shi
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Yang Li
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
| | - Yongjun Zhang
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China.
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19
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Yang Z, Ma J, Liu F, Zhang H, Ma X, He D. Mechanistic insight into pH-dependent adsorption and coprecipitation of chelated heavy metals by in-situ formed iron (oxy)hydroxides. J Colloid Interface Sci 2022; 608:864-872. [PMID: 34785461 DOI: 10.1016/j.jcis.2021.10.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 11/30/2022]
Abstract
Fe(III) coagulation-precipitation process has been widely used to remove heavy metals from industrial effluents; however, the influences of organic ligands on the sequestration of different heavy metals in the Fe(III)/metal-EDTA ternary system are not well understood. In this study, the pH-dependent mechanisms of CuII-EDTA and NiII-EDTA removed by in-situ formed iron (oxy)hydroxides were studied using surface complex modeling and a suite of characterization techniques. Results of surface complex model indicated that there should be minimal difference between removal of CuII-EDTA and NiII-EDTA by iron (oxy)hydroxides if adsorption was the dominant mechanism. However, through the speciation analysis and characterization of the precipitates generated after coagulation and precipitation, we have demonstrated that at neutral pH the complexation of Fe(III) and EDTA influenced the surface properties of iron (oxy)hydroxides formed, with the higher removal of Cu2+ (compared to Ni2+) contributed by its coprecipitation with Fe(III). Moreover, at basic pH, decomplexation of CuII-EDTA occurred on the iron (oxy)hydroxides surface with the released copper ions involved in the formation of (oxy)hydroxides. The low removal of nickel (from NiII-EDTA) was ascribed to the higher conditional stability constant of NiII-EDTA. Results of this study have advanced our understanding of the complicated interactions among Fe(III), organic ligands and heavy metals in the industrial effluents, and provide insight to optimization of the process efficiency.
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Affiliation(s)
- Zhengheng Yang
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Jinxing Ma
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Fang Liu
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Hailong Zhang
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Xiaoming Ma
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Di He
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, PR China.
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20
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Wu Y, Jiang J, Sun Q, An Y, Zhao R, Zheng H, Li H. Efficient removal of both positively and negatively charged colloidal contaminants using amphoteric starch-based flocculants synthesized by low-pressure UV initiation. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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21
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Xu M, Luo Y, Wang X, Zhou L. Coagulation-ultrafiltration efficiency of polymeric Al-, Fe-, and Ti- coagulant with or without polyacrylamide composition. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.119957] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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