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Raoelison OD, Das TK, Visweswaran A, Guyett K, Spallone S, Ramos R, Merrifield R, Dittrich TM, Mohanty SK. Do drinking water treatment residuals underperform in the presence of compost in stormwater media filters? THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166635. [PMID: 37647961 DOI: 10.1016/j.scitotenv.2023.166635] [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: 03/03/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/01/2023]
Abstract
Drinking water treatment residuals (WTR), a waste-derived product, are often recommended to use as an amendment in stormwater biofilters to enhance their capacity to remove phosphate and microbial pollutants. However, their efficacy has been assumed to remain high in the presence of compost, one of the most common amendments used in biofilters. This study tests the validity of that assumption by comparing the removal capacities of WTR-amended biofilters with and without the presence of compost. Our results show that amending sand with WTR increased E. coli removal by at least 1-log, but the addition of compost in the sand-WTR media lowered the removal capacity by 13 %. Similarly, the addition of WTR to sand improved phosphate removal to nearly 1177 %, but the removal decreased slightly by 8 % when adding compost to the media. The results confirmed that dissolved organic carbon (DOC) leached from the compost could compete for adsorption sites for bacteria and phosphate, thereby lowering WTR's adsorption capacity based on the amount of DOC adsorbed on WTR. Collectively, these results indicate that the stormwater treatment industry should avoid mixing compost with WTR to get the maximum benefits of WTR for bacterial removal and improve the performance lifetime of WTR-amended biofilters.
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Affiliation(s)
- Onja D Raoelison
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA.
| | - Tonoy K Das
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Ananya Visweswaran
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Keegan Guyett
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Sophia Spallone
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Roxana Ramos
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Rachel Merrifield
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA
| | - Timothy M Dittrich
- Civil and Environmental Engineering, Wayne State University, Detroit 48202, USA
| | - Sanjay K Mohanty
- Civil and Environmental Engineering, University of California, Los Angeles 90095, USA.
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2
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Qiao M, Zhang J, Mao R, Zhao X. Inactivation of Escherichia Coli by mixed-valent nanoparticles in-situ generated during Fe electrocoagulation. WATER RESEARCH 2023; 247:120818. [PMID: 37925859 DOI: 10.1016/j.watres.2023.120818] [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: 07/30/2023] [Revised: 10/14/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
Electrocoagulation (EC) is promising for the removal of chemical and microbial contaminants. Although the removal of pathogens from wastewater is efficient by conventional Fe-EC in the presence of dissolved oxygen (DO), the non-inactivated pathogens in the sediment still have a risk. Herein, the inactivation of Escherichia coli (E. coli) with the mixed-valent iron nanoparticles, magnetite and green rust (GR), in-situ generated from Fe-EC process in the absence of DO was investigated. The inactivation efficiency was significantly higher with magnetite (4.7 log cells) and GR (3.2 log cells) compared with FeOOH (0.7-1.7 log cells) generated at 50 mA in 10 min. The unstable in-situ generated magnetite with positive charges was prone to adsorb onto E. coli, damaging the cell membrane, inactivating the bacteria. The unstable in-situ generated GR was prone to coagulate with E. coli, delivering Fe2+ into the cell and inducing the generation of endogenous ROS, inactivating the bacteria. Fe-EC in the absence of DO was proved to be efficient for the inactivation of E. coli (4.2-4.3 log cells) in real wastewater. These findings identified the ignored inactivation effect and mechanism of E. coli with magnetite and GR generated in situ from Fe-EC process, which will provide theoretical support for real applications.
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Affiliation(s)
- Meng Qiao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Junke Zhang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ran Mao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xu Zhao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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3
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Chen R, Liu H, Zhang P, Ma J, Jin M. Co-response of Fe-reducing/oxidizing bacteria and Fe species to the dynamic redox cycles of natural sediment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:152953. [PMID: 34999076 DOI: 10.1016/j.scitotenv.2022.152953] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/29/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
Fe(III)-reducing bacteria (FRB) and Fe(II)-oxidizing bacteria (FOB) play essential roles in the biogeochemical cycling of iron (Fe). Although the redox transformation of Fe species mediated by FRB/FOB has been extensively studied, the co-responses of FRB and FOB and Fe species transformation in natural sediment under dynamic redox conditions are poorly known. This study explored the variations of potential FRB and FOB abundances and Fe species transformation in natural sediment during successive anoxic-oxic-anoxic-oxic-anoxic cycles. Compared with the pristine sediment sample, the FRB abundance increased 121-793% (initial: (2.6 ± 0.6) × 107 copies/g) in the anoxic stages, while it decreased by 38-64% in the oxic stages. The increase in FRB abundance was ascribed to energy gain of FRB from the reduction of the amorphous Fe(III) (Fe(III)am) and the crystalline Fe(III) (Fe(III)cry) to the aqueous Fe(II) (Fe(II)aq), the adsorbed Fe(II) (Fe(II)ad) and the amorphous Fe(II) (Fe(II)am), while the decrease was attributed to the oxidative stress caused by the reactive oxidant produced from the abiotic oxidation of Fe(II)aq, Fe(II)ad and Fe(II)am to Fe(III)am and Fe(III)cry. The FOB abundance decreased 38-44% (initial: (5 ± 1.8) × 107 copies/g) in the second and third anoxic stages, while slightly fluctuated in the oxic periods. This observation was contrary to the variation of FRB, which might be attributed to the strong resistance to oxidative stress of FOB and its ability to obtain energy under oxic conditions. Although the functions of FRB and FOB were impaired during anoxic-oxic cycles, the transformation of Fe(II)/Fe(III) was not immediately affected, which may be related to the residual reactivity of dead bacteria and the bio-availability of Fe(II)/Fe(III) species. In the anoxic-oxic alternation process, the iron cycle is mainly the mutual transformation between Fe(II)aq, Fe(II)ad, Fe(II)am and Fe(III)am, Fe(III)cry. This finding deepens our understanding of the biogeochemical cycling of Fe in the redox-dynamic environments.
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Affiliation(s)
- Rong Chen
- School of Environmental Studies, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China
| | - Hui Liu
- School of Environmental Studies, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China.
| | - Peng Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China
| | - Jie Ma
- School of Environmental Studies, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China
| | - Menggui Jin
- School of Environmental Studies, China University of Geosciences, 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan, Hubei 430078, PR China
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4
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Removal of phosphate in secondary effluent from municipal wastewater treatment plant by iron and aluminum electrocoagulation: Efficiency and mechanism. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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5
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Effect of pH on Escherichia coli Removal by Electrocoagulation and Elimination Kinetics after Treatment. J CHEM-NY 2022. [DOI: 10.1155/2022/5249368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
There are different techniques for removing microorganisms in wastewater, each with its own advantages and disadvantages. Electrocoagulation because of its simplicity has gained great attention and is used for the removal of various ions, organic matters, and microorganisms. In this study, the effectiveness and mechanism of Escherichia coli (E. coli) removal by electrocoagulation process using aluminum and ordinary steel electrodes at different initial-pH and the kinetics of elimination of E. coli in solution after treatment were investigated. Artificial wastewater contaminated by E. coli culture was used in the experiments. The results show that the initial-pH influences significantly the effectiveness of E. coli removal. Under the experimental conditions used, more than 5 log removal of E. coli is obtained, irrespective of the nature of the electrode (ordinary steel or aluminum) and the value of the initial pH. On the one hand, the best rates of elimination are obtained for solutions that are slightly acidic (pH 5.5) and for an alkaline pH (8.5 and 10). On the other hand, the elimination decreases for a neutral solution and for a very acidic solution (pH 2.9) because of the strong resistance developed by E. coli at those pH values. For optimal treatment, the choice of electrode material depends on the initial pH. Furthermore, the study of the kinetics of elimination of E. coli after treatment shows the remanent power of the electrocoagulation process. It allows reducing treatment time and energy consumption, thus reducing the cost of treatment.
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Lu J, Zhang P, Li J. Electrocoagulation technology for water purification: An update review on reactor design and some newly concerned pollutants removal. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 296:113259. [PMID: 34256295 DOI: 10.1016/j.jenvman.2021.113259] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/30/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
Water shortage and quality deterioration are plaguing people all over the world. Providing sustainable and affordable treatment solutions to these problems is a need of the hour. Electrocoagulation (EC) technology is a burgeoning alternative for effective water treatment, which offers the virtues such as compact equipment, easy operation, and low sludge production. Compared to other water purification technologies, EC shows excellent removal efficacy for a wide range of contaminants in water and has great potential for addressing limitations of conventional water purification technologies. This review summarizes the latest development of principle, characteristics, and reactor design of EC. The design of key parameters including reactor shape, power supply type, current density, as well as electrode configuration is further elaborated. In particular, typical water treatment systems powered by renewable energy (solar photovoltaic and wind turbine systems) are proposed. Further, this review provides an overview on expanded application of EC in the removal of some newly concerned pollutants in recent years, including arsenite, perfluorinated compounds, pharmaceuticals, oil, bacteria, and viruses. The removal efficiency and mechanisms of these pollutants are also discussed. Finally, future research trend and focus are further recommended. This review can bridge the large knowledge gap for the EC application that is beneficial for environmental researchers and engineers.
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Affiliation(s)
- Jianbo Lu
- School of Civil Engineering, Yantai University, Yantai, Shandong, 264005, China.
| | - Peng Zhang
- School of Civil Engineering, Yantai University, Yantai, Shandong, 264005, China
| | - Jie Li
- School of Economics and Management, Yantai University, Yantai, Shandong, 264005, China
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7
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Huang Y, Zhao S, Liu H, Chen R, Zhao L, Liu S. Co-existing siderite alleviates the Fe(II) oxidation-induced inactivation of Fe(III)-reducing bacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 781:146489. [PMID: 33798884 DOI: 10.1016/j.scitotenv.2021.146489] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/25/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
Abiotic Fe (II) oxidation widely occurs in the natural subsurface environment and engineered dynamic processes, which possibly impacts the growth of indigenous microbes. As previously discovered, the oxidation of aqueous Fe2+ at neutral pH effectively inactivates iron-reducing bacteria Shewanella oneidensis strain MR-1 (MR-1). Herein, the impacts of co-existing iron mineral on the oxidation of aqueous Fe2+ and the subsequent disinfection activity on MR-1 were investigated with siderite selected as a representative iron mineral in the subsurface environment. The oxidation rate of aqueous Fe2+ and the amount of generated OH radical increased as the content of siderite increased, while the MR-1 inactivation was alleviated. An initial concentration of 2.0 × 106 CFU/mL MR-1 was inactivated by about 2.7 orders of magnitude during oxidation of 0.2 mM FeSO4 alone for 30 min, which was reduced to only about 0.6 orders of magnitude in the presence of 4.3 mM co-existing siderite. ROS scavenging results confirmed that the OH radical generated in the bulk solution was not the leading role for the inactivation of MR-1. Morphological changes of the cells observed by SEM demonstrated that the disruption of the cell membrane was alleviated by siderite, which was further supported by the XRD and FTIR spectra. The underlying mechanism was proposed to be the reduced contact time of Fe2+ and MR-1 cells due to the accelerated oxidation. This work provides new insights into the disinfection behavior of heterogeneous Fe (II) oxidation on iron cycling bacterial in the natural environment.
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Affiliation(s)
- Yao Huang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Shufeng Zhao
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Hui Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
| | - Rong Chen
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Lei Zhao
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Shan Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
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8
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Bicudo B, van Halem D, Trikannad SA, Ferrero G, Medema G. Low voltage iron electrocoagulation as a tertiary treatment of municipal wastewater: removal of enteric pathogen indicators and antibiotic-resistant bacteria. WATER RESEARCH 2021; 188:116500. [PMID: 33059157 DOI: 10.1016/j.watres.2020.116500] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/15/2020] [Accepted: 10/05/2020] [Indexed: 06/11/2023]
Abstract
In this paper we analyse the feasibility of low voltage iron electrocoagulation as a means of municipal secondary effluent treatment with a focus on removal of microbial indicators, Antibiotic Resistant Bacteria (ARB) and nutrients. A laboratory scale batch unit equipped with iron electrodes was used on synthetic and real secondary effluent from a municipal wastewater treatment plant. Synthetic secondary effluent was separately assayed with spiked Escherichia coli WR1 and with bacteriophage ΦX174, while real effluent samples were screened before and after treatment for E. coli, Extended Spectrum Betalactamase-producing E. coli, Enterococci, Vancomycin Resistant Enterococci, Clostridium perfringens spores and somatic coliphages. Charge dosage (CD) and charge dosage rate (CDR) were used as the main process control parameters. Experiments with synthetic secondary effluent showed >4log10 and >5log10 removal for phage ΦX174 and for E. coli WR1, respectively. In real effluents, bacterial indicator removal exceeded 3.5log10, ARB were removed below detection limit (≥2.5log10), virus removal reached 2.3log10 and C. perfringens spore removal exceeded 2.5log10. Experiments in both real and synthetic wastewater showed that bacterial removal increased with increasing CD and decreasing CDR. Virus removal increased with increasing CD but was irresponsive to CDR. C. perfringens spore removal increased with increasing CD yet reached a removal plateau, being also irresponsive to CDR. Phosphate removal exceeded 99%, while total nitrogen and chemical oxygen demand removal were below 15% and 58%, respectively. Operational cost estimates were made for power and iron plate consumption, and were found to be in the range of 0.01 to 0.24€/m3 for the different assayed configurations. In conclusion, low voltage Fe-EC is a promising technology for pathogen reduction of secondary municipal effluents, with log10 removals comparable to those achieved by conventional disinfection methods such as chlorination, UV or ozonation.
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Affiliation(s)
- Bruno Bicudo
- Faculty of Civil Engineering and Geosciences, Water Management Department, TU Delft, The Netherlands.
| | - Doris van Halem
- Faculty of Civil Engineering and Geosciences, Water Management Department, TU Delft, The Netherlands
| | - Shreya Ajith Trikannad
- Faculty of Civil Engineering and Geosciences, Water Management Department, TU Delft, The Netherlands
| | - Giuliana Ferrero
- Water Supply, Sanitation and Environmental Engineering Department, IHE Delft Institute for Water Education, The Netherlands
| | - Gertjan Medema
- Faculty of Civil Engineering and Geosciences, Water Management Department, TU Delft, The Netherlands; KWR Watercycle Research Institute, The Netherlands; Michigan State University, Michigan, USA
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9
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Oh C, Pak S, Han YS, Ha NTH, Hong M, Ji S. Field demonstration of solar-powered electrocoagulation water treatment system for purifying groundwater contaminated by both total coliforms and arsenic. ENVIRONMENTAL TECHNOLOGY 2021; 42:397-409. [PMID: 31179862 DOI: 10.1080/09593330.2019.1629634] [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: 01/07/2019] [Accepted: 06/02/2019] [Indexed: 06/09/2023]
Abstract
People who drink groundwater in rural areas of Southeast Asia are exposed to pathogens and arsenic (As)-related health problems. A water treatment system consisting of electrocoagulation reactors, using iron (Fe) electrodes and a filtration tank, was designed to treat complex contaminated groundwater for drinking. Its applicability was demonstrated near the Red River in Vietnam. The water treatment system reduced 10.3 CFU/mL of total coliform and 376 μg/L of As(III) in the groundwater to 0 CFU/mL and 6.68 μg/L, respectively. Total coliforms were attenuated by Fe(II) infiltration or enmeshed during Fe precipitate formation. Of the total As, 43% formed As(III) complexation with the Fe precipitates and the other 57% was oxidized to As(V) then adsorbed to Fe precipitates. The Fe precipitates, containing total coliforms and As, were separated from the discharge water in the filtration tank. The system required 49 W of power to operate, which equates to 423 kWh/year, to continuously purify 0.5 t water/day. This requirement was powered by a 380-750 W solar panel, without external energy supply, making the water treatment system an appropriate option for addressing drinking water problems in rural areas.
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Affiliation(s)
- Chamteut Oh
- Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Seungil Pak
- Department of Environmental Engineering, Kwangwoon University, Seoul, South Korea
| | - Young-Soo Han
- Geological Environment Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, South Korea
| | | | - Moonil Hong
- Wooyoung Engineering Co., Ltd, Seongnam, South Korea
| | - Sangwoo Ji
- Climate Change Mitigation and Sustainability Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, South Korea
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10
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Cao D, Qiao M, Li A, Hao J, Zhao X. Advantage of selective production of green rusts for Sb(V) removal in Fe(0) electrocoagulation. CHINESE CHEM LETT 2020. [DOI: 10.1016/j.cclet.2020.07.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Bandaru SRS, van Genuchten CM, Kumar A, Glade S, Hernandez D, Nahata M, Gadgil A. Rapid and Efficient Arsenic Removal by Iron Electrocoagulation Enabled with in Situ Generation of Hydrogen Peroxide. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:6094-6103. [PMID: 32315523 DOI: 10.1021/acs.est.0c00012] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Millions of people are exposed to toxic levels of dissolved arsenic in groundwater used for drinking. Iron electrocoagulation (FeEC) has been demonstrated as an effective technology to remove arsenic at an affordable price. However, FeEC requires long operating times (∼hours) to remove dissolved arsenic due to inherent kinetics limitations. Air cathode Assisted Iron Electrocoagulation (ACAIE) overcomes this limitation by cathodically generating H2O2 in situ. In ACAIE operation, rapid oxidation of Fe(II) and complete oxidation and removal of As(III) are achieved. We compare FeEC and ACAIE for removing As(III) from an initial concentration of 1464 μg/L, aiming for a final concentration of less than 4 μg/L. We demonstrate that at short electrolysis times (0.5 min), i.e., high charge dosage rates (1200 C/L/min), ACAIE consistently outperformed FeEC in bringing arsenic levels to less than WHO-MCL of 10 μg/L. Using XRD and XAS data, we conclusively show that poor arsenic removal in FeEC arises from incomplete As(III) oxidation, ineffective Fe(II) oxidation and the formation of Fe(II-III) (hydr)oxides at short electrolysis times (<20 min). Finally, we report successful ACAIE performance (retention time 19 s) in removing dissolved arsenic from contaminated groundwater in rural California.
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Affiliation(s)
- Siva R S Bandaru
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
| | | | - Arkadeep Kumar
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Sara Glade
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
| | - Dana Hernandez
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
| | - Mohit Nahata
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
| | - Ashok Gadgil
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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12
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Abstract
Insufficient funding and operator training, logistics of chemical transport, and variable source water quality can pose challenges for small drinking water treatment systems. Portable, robust electrochemical processes may offer a strategy to address these challenges. In this study, electrocoagulation (EC) and electrooxidation (EO) were investigated using two model surface waters and two model groundwaters to determine the efficacy of sequential EC-EO for mitigating Escherichia coli. EO alone (1.67 mA/cm2, 1 min) provided 0.03 to 3.9 logs mitigation in the four model waters. EC alone (10 mA/cm2, 5 min) achieved ≥1 log E. coli mitigation in all model waters. Sequential EC-EO did not achieve greater mitigation than EC alone. To enhance removal of natural organic matter, the initial pH was decreased. Lower initial pH (pH 5–6) improved E. coli mitigation during both stages of EC-EO. EC-EO also had slightly greater E. coli mitigation than EC alone at lower pH. However, EO alone provided more energy efficient E. coli mitigation than either EC or EC-EO.
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13
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Heffron J, McDermid B, Maher E, McNamara PJ, Mayer BK. Mechanisms of virus mitigation and suitability of bacteriophages as surrogates in drinking water treatment by iron electrocoagulation. WATER RESEARCH 2019; 163:114877. [PMID: 31349091 DOI: 10.1016/j.watres.2019.114877] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/14/2019] [Accepted: 07/15/2019] [Indexed: 05/03/2023]
Abstract
Emerging water treatment technologies using ferrous and zero-valent iron show promising virus mitigation by both inactivation and adsorption. In this study, iron electrocoagulation was investigated for virus mitigation in drinking water via bench-scale batch experiments. Relative contributions of physical removal and inactivation, as determined by recovery via pH 9.5 beef broth elution, were investigated for three mammalian viruses (adenovirus, echovirus, and feline calicivirus) and four bacteriophage surrogates (fr, MS2, P22, and ΦX174). Though no one bacteriophage exactly represented mitigation of the mammalian viruses in all water matrices, bacteriophage ΦX174 was the only surrogate that showed overall removal comparable to that of the mammalian viruses. Bacteriophages fr, MS2, and P22 were all more susceptible to inactivation than the three mammalian viruses, raising concerns about the suitability of these common surrogates as indicators of virus mitigation. To determine why some bacteriophages were particularly susceptible to inactivation, mechanisms of bacteriophage mitigation due to electrocoagulation were investigated. Physical removal was primarily due to inclusion in flocs, while inactivation was primarily due to ferrous iron oxidation. Greater electrostatic attraction, virus aggregation, and capsid durability were proposed as reasons for virus susceptibility to ferrous-based inactivation. Results suggest that overall treatment claims based on bacteriophage mitigation for any iron-based technology should be critically considered due to higher susceptibility of bacteriophages to inactivation via ferrous oxidation.
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Affiliation(s)
- Joe Heffron
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 W. Wisconsin Ave., Milwaukee, WI, 53233, USA
| | - Brad McDermid
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 W. Wisconsin Ave., Milwaukee, WI, 53233, USA
| | - Emily Maher
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 W. Wisconsin Ave., Milwaukee, WI, 53233, USA
| | - Patrick J McNamara
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 W. Wisconsin Ave., Milwaukee, WI, 53233, USA
| | - Brooke K Mayer
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 W. Wisconsin Ave., Milwaukee, WI, 53233, USA.
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14
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Heffron J, Ryan DR, Mayer BK. Sequential electrocoagulation-electrooxidation for virus mitigation in drinking water. WATER RESEARCH 2019; 160:435-444. [PMID: 31174071 DOI: 10.1016/j.watres.2019.05.078] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 05/03/2023]
Abstract
Electrochemical water treatment is a promising alternative for small-scale and remote water systems that lack operational capacity or convenient access to reagents for chemical coagulation and disinfection. In this study, the mitigation of viruses was investigated using electrocoagulation as a pretreatment prior to electrooxidation treatment using boron-doped diamond electrodes. This research is the first to investigate a sequential electrocoagulation-electrooxidation treatment system for virus removal. Bench-scale, batch reactors were used to evaluate mitigation of viruses in variable water quality via: a) electrooxidation, and b) a sequential electrocoagulation-electrooxidation treatment train. Electrooxidation of two bacteriophages, MS2 and ΦX174, was inhibited by natural organic matter and turbidity, indicating the probable need for pretreatment. However, the electrocoagulation-electrooxidation treatment train was beneficial only in the model surface waters employed. In model groundwaters, electrocoagulation alone was as good or better than the combined electrocoagulation-electrooxidation treatment train. Reduction of human echovirus was significantly lower than one or both bacteriophages in all model waters, though bacteriophage ΦX174 was a more representative surrogate than MS2 in the presence of natural organic matter and turbidity. Compared to conventional treatment by ferric salt coagulant and free chlorine disinfection, the electrocoagulation-electrooxidation system was less effective in model surface waters but more effective in model groundwaters. Sequential electrocoagulation-electrooxidation was beneficial for some applications, though practical considerations may currently outweigh the benefits.
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Affiliation(s)
- Joe Heffron
- Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI, 53233, USA
| | - Donald R Ryan
- Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI, 53233, USA
| | - Brooke K Mayer
- Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI, 53233, USA.
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15
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Lee S, Uliana A, Taylor MK, Chakarawet K, Bandaru SRS, Gul S, Xu J, Ackerman CM, Chatterjee R, Furukawa H, Reimer JA, Yano J, Gadgil A, Long GJ, Grandjean F, Long JR, Chang CJ. Iron detection and remediation with a functionalized porous polymer applied to environmental water samples. Chem Sci 2019; 10:6651-6660. [PMID: 31367318 PMCID: PMC6624977 DOI: 10.1039/c9sc01441a] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 05/21/2019] [Indexed: 12/11/2022] Open
Abstract
Iron is one of the most abundant elements in the environment and in the human body. As an essential nutrient, iron homeostasis is tightly regulated, and iron dysregulation is implicated in numerous pathologies, including neuro-degenerative diseases, atherosclerosis, and diabetes. Endogenous iron pool concentrations are directly linked to iron ion uptake from environmental sources such as drinking water, providing motivation for developing new technologies for assessing iron(ii) and iron(iii) levels in water. However, conventional methods for measuring aqueous iron pools remain laborious and costly and often require sophisticated equipment and/or additional processing steps to remove the iron ions from the original environmental source. We now report a simplified and accurate chemical platform for capturing and quantifying the iron present in aqueous samples through use of a post-synthetically modified porous aromatic framework (PAF). The ether/thioether-functionalized network polymer, PAF-1-ET, exhibits high selectivity for the uptake of iron(ii) and iron(iii) over other physiologically and environmentally relevant metal ions. Mössbauer spectroscopy, XANES, and EXAFS measurements provide evidence to support iron(iii) coordination to oxygen-based ligands within the material. The polymer is further successfully employed to adsorb and remove iron ions from groundwater, including field sources in West Bengal, India. Combined with an 8-hydroxyquinoline colorimetric indicator, PAF-1-ET enables the simple and direct determination of the iron(ii) and iron(iii) ion concentrations in these samples, providing a starting point for the design and use of molecularly-functionalized porous materials for potential dual detection and remediation applications.
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Affiliation(s)
- Sumin Lee
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
| | - Adam Uliana
- Department of Chemical and Biomolecular Engineering , University of California , Berkeley , CA 94720 , USA
| | - Mercedes K Taylor
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
| | | | - Siva Rama Satyam Bandaru
- Department of Civil and Environmental Engineering , University of California , Berkeley , CA 94720 , USA
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Jun Xu
- Department of Chemical and Biomolecular Engineering , University of California , Berkeley , CA 94720 , USA
| | - Cheri M Ackerman
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Hiroyasu Furukawa
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
| | - Jeffrey A Reimer
- Department of Chemical and Biomolecular Engineering , University of California , Berkeley , CA 94720 , USA
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA .
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
| | - Ashok Gadgil
- Department of Civil and Environmental Engineering , University of California , Berkeley , CA 94720 , USA
| | - Gary J Long
- Department of Chemistry , Missouri University of Science and Technology , University of Missouri , Rolla , MO 65409 , USA
| | - Fernande Grandjean
- Department of Chemistry , Missouri University of Science and Technology , University of Missouri , Rolla , MO 65409 , USA
| | - Jeffrey R Long
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
- Department of Chemical and Biomolecular Engineering , University of California , Berkeley , CA 94720 , USA
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA .
| | - Christopher J Chang
- Department of Chemistry , University of California , Berkeley , CA 94720 , USA .
- Department of Molecular and Cell Biology , University of California , Berkeley , CA 94720 , USA
- Howard Hughes Medical Institute , University of California , Berkeley , CA 94720 , USA
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16
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Müller S, Behrends T, van Genuchten CM. Sustaining efficient production of aqueous iron during repeated operation of Fe(0)-electrocoagulation. WATER RESEARCH 2019; 155:455-464. [PMID: 30870635 DOI: 10.1016/j.watres.2018.11.060] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
Iron-electrocoagulation is a promising contaminant (e.g. arsenic) removal technology that is based on electrochemical Fe(II) production from steel electrodes and subsequent transport of Fe(II) to the bulk solution, where contaminant removal occurs. Although Fe-electrocoagulation systems have been shown to effectively remove contaminants in extended field trials, the efficiency of field systems can be lower than in laboratory studies. One hypothesis for this disparity is that the Faradaic efficiency of short-term laboratory experiments is higher than field systems operated over extended periods. The Faradaic efficiency is a pivotal performance indicator that we define as the measured Fe dosage normalized by the theoretical Fe dosage calculated by Faraday's law. In this work, we investigated the Faradaic efficiency in laboratory experiments for up to 35 operating cycles (>2 months) with varied Fe(0) anode purity, charge dosage rate, and electrolyte composition. Our results showed that the Faradaic efficiency decreased continuously during repeated operation under typical field conditions (charge dosage rate = 4 C/L/min, synthetic groundwater) regardless of the Fe(0) anode purity, leading to a Faradaic efficiency ≈ 0.6 after 2 months. By contrast, increasing the charge dosage rate to ≥15 C/L/min produced a Faradaic efficiency >0.85 over the entire experiment for both Fe(0) anode purities. Electrolyte solutions free of oxyanions also resulted in sustained Faradaic efficiency >0.85, regardless of the charge dosage rate. Our results confirm a previously proposed relationship between low Faradaic efficiency and the formation of macroscopic electrode surface layers, which consist of Fe (oxyhydr)oxides on the anode and a mixture of Fe (oxyhydr)oxides and calcite on the cathode. Based on these results, we discuss potential strategies to maintain a high Faradaic efficiency during Fe-electrocoagulation field treatment.
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Affiliation(s)
- Simon Müller
- Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University, 3584CB Utrecht, the Netherlands
| | - Thilo Behrends
- Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University, 3584CB Utrecht, the Netherlands
| | - Case M van Genuchten
- Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University, 3584CB Utrecht, the Netherlands.
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17
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Govindan K, Angelin A, Rangarajan M. Critical evaluation of mechanism responsible for biomass abatement during electrochemical coagulation (EC) process: A critical review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 227:335-353. [PMID: 30199730 DOI: 10.1016/j.jenvman.2018.08.100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 08/15/2018] [Accepted: 08/26/2018] [Indexed: 06/08/2023]
Abstract
This is a first review paper that delineates fundamental disinfection mechanism undergoes during the simple electrochemical coagulation (EC) process. The elucidation of detailed mechanistic phenomenon of EC process involved would help to enhance the disinfection efficiency. In this context, the biomass (bacteria, virus and algae) abatement mechanism by EC is critically reviewed and rationalized based on the experimental demonstration performed from the recent decade. Whereas, the effect of most significant abiotic operating parameters, dissolved contents and bacteria cell wall composition on biomass reduction are explored in detail. From these analyses, physical removal and chemical inactivation routes are identified for bacteria abatement mechanism during the EC process using sacrificial electrodes. Which includes (i) enmeshment of microbial contaminants by EC flocs, (ii) sweeping flocculation is preferentially for destabilization of negatively charged biomass, and (iii) inactivation/attenuation of micro-organism cell walls by electrochemically induced reactive oxygen species (ROS) or direct interaction of electric field. Perhaps, the overall abatement mechanism attributes due to the aforementioned phenomenon endures independently and/or synergistically during the EC process. Nonetheless, to obtain better understanding of virus and algae abatement mechanism, we require more experimental investigation on algae and virus removal. Eventually, more intensive research efforts on biomass attenuation by EC are most important to reinforce this claim.
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Affiliation(s)
- Kadarkarai Govindan
- Center of Excellence in Advanced Materials and Green Technologies, Department of Chemical Engineering and Material Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Amrita University, Coimbatore, Tamil Nadu, 641 112, India.
| | - Arumugam Angelin
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, 641 114, Tamil Nadu, India
| | - Murali Rangarajan
- Center of Excellence in Advanced Materials and Green Technologies, Department of Chemical Engineering and Material Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Amrita University, Coimbatore, Tamil Nadu, 641 112, India
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18
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Chen R, Liu H, Tong M, Zhao L, Zhang P, Liu D, Yuan S. Impact of Fe(II) oxidation in the presence of iron-reducing bacteria on subsequent Fe(III) bio-reduction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 639:1007-1014. [PMID: 29929270 DOI: 10.1016/j.scitotenv.2018.05.241] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 06/08/2023]
Abstract
The interplay of Fe(II) oxidation and Fe(III) bio-reduction occurs widely in both natural and engineered redox-dynamic systems. This study aimed to unravel the impact of Fe(II) oxidation by O2 in the presence of iron-reducing bacteria on subsequent Fe(III) bio-reduction. Mixed solutions of Fe2+ (0.1-0.5 mM) and Shewanella oneidensis strain MR-1 (MR-1, 2.0 × 107 CFU/mL) at neutral pH were first exposed to laboratory air for Fe(II) oxidation and bacterial inactivation, and then the resultant Fe(III) suspensions were switched to anoxic conditions for bio-reduction by the surviving bacteria. In the oxidation step, the coexisting MR-1 was inactivated by 0.8-1.71 orders of magnitude within 60 min. In the subsequent bio-reduction step, the resultant Fe(III) was bio-reduced by the surviving MR-1. Bio-reduction of the resultant Fe(III) by the surviving MR-1 was 1.8-2.5 times faster than that of the Fe(III) that was produced from Fe2+ oxidation without MR-1 by fresh MR-1 cells at 2.0 × 107 CFU/mL. Although MR-1 inactivation during Fe(II) oxidation may inhibit Fe(III) bio-reduction, the increase in bio-availability of the resultant Fe(III) and the residual reactivity of dead cells led to net enhancement of bio-reduction under the tested conditions. Lepidocrocite was the sole Fe(III) mineral that was produced from Fe2+ oxidation without MR-1, while 19% ferrihydrite was produced from Fe2+ oxidation in the presence of MR-1. The formation of low-crystallinity ferrihydrite accounts for the increase in bio-availability of the Fe(III) minerals. The findings of this study highlight an important but overlooked impact underlying the interplay of Fe(II) oxidation and Fe(III) bio-reduction.
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Affiliation(s)
- Rong Chen
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Hui Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
| | - Man Tong
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Lei Zhao
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Peng Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Deng Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Songhu Yuan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
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19
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20
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Barazesh J, Prasse C, Wenk J, Berg S, Remucal CK, Sedlak DL. Trace Element Removal in Distributed Drinking Water Treatment Systems by Cathodic H 2O 2 Production and UV Photolysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:195-204. [PMID: 29240414 PMCID: PMC5772888 DOI: 10.1021/acs.est.7b04396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
As water scarcity intensifies, point-of-use and point-of-entry treatment may provide a means of exploiting locally available water resources that are currently considered to be unsafe for human consumption. Among the different classes of drinking water contaminants, toxic trace elements (e.g., arsenic and lead) pose substantial operational challenges for distributed drinking water treatment systems. Removal of toxic trace elements via adsorption onto iron oxides is an inexpensive and robust treatment method; however, the presence of metal-complexing ligands associated with natural organic matter (NOM) often prevents the formation of iron precipitates at the relatively low concentrations of dissolved iron typically present in natural water sources, thereby requiring the addition of iron which complicates the treatment process and results in a need to dispose of relatively large amounts of accumulated solids. A point-of-use treatment device consisting of a cathodic cell that produced hydrogen peroxide (H2O2) followed by an ultraviolet (UV) irradiation chamber was used to decrease colloid stabilization and metal-complexing capacity of NOM present in groundwater. Exposure to UV light altered NOM, converting ∼6 μM of iron oxides into settable forms that removed between 0.5 and 1 μM of arsenic (As), lead (Pb), and copper (Cu) from solution via adsorption. After treatment, changes in NOM consistent with the loss of iron-complexing carboxylate ligands were observed, including decreases in UV absorbance and shifts in the molecular composition of NOM to higher H/C and lower O/C ratios. Chronoamperometric experiments conducted in synthetic groundwater revealed that the presence of Ca2+ and Mg2+ inhibited intramolecular charge-transfer within photoexcited NOM, leading to substantially increased removal of iron and trace elements.
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Affiliation(s)
- James
M. Barazesh
- Department
of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, California 94720 United States
- Carollo
Engineers, Inc., Costa Mesa, California 92626, United States
| | - Carsten Prasse
- Department
of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, California 94720 United States
| | - Jannis Wenk
- Department
of Chemical Engineering and Water Innovation & Research Centre, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
| | - Stephanie Berg
- Environmental
Chemistry & Technology Program, University
of Wisconsin-Madison, Madison, Wisconsin 53706 United States
| | - Christina K. Remucal
- Environmental
Chemistry & Technology Program, University
of Wisconsin-Madison, Madison, Wisconsin 53706 United States
- Department
of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 United States
| | - David L. Sedlak
- Department
of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, California 94720 United States
- E-mail:
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21
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Choi S, Kim B, Han J. Integrated pretreatment and desalination by electrocoagulation (EC)-ion concentration polarization (ICP) hybrid. LAB ON A CHIP 2017; 17:2076-2084. [PMID: 28518195 DOI: 10.1039/c7lc00258k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Conventional water treatment process is composed of multiple stages, including desalination (salt removal) and pre/post-treatment of desalination to remove particles, chemicals, and other potential foulants for desalination. In this work, we developed a microfluidic proof-of-concept for a single device water treatment system, which removes both salt ions and non-salt contaminants. Our system combines electrocoagulation (EC), a versatile contaminant removal process, and ion concentration polarization (ICP) desalination, which is an electromembrane desalination process. We demonstrated a continuous EC-ICP operation that removed >95% of suspended solids and reduced the salinity from brackish range (20 mM NaCl) to a potable level (<8.6 mM NaCl). We also demonstrated that our system is flexible in terms of the type and concentration of contaminants it can handle. Combining two different electrochemical processes into a single system, we can reduce unnecessary voltage drop by having a shared anode, and achieve both seamless integration and energy efficient operation. Our system will find applications as a small-scale water treatment system, if properly scaled up in the future.
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Affiliation(s)
- Siwon Choi
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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22
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Kim JH, Maitlo HA, Park JY. Treatment of synthetic arsenate wastewater with iron-air fuel cell electrocoagulation to supply drinking water and electricity in remote areas. WATER RESEARCH 2017; 115:278-286. [PMID: 28284094 DOI: 10.1016/j.watres.2017.02.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 06/06/2023]
Abstract
Electrocoagulation with an iron-air fuel cell is an innovative arsenate removal system that can operate without an external electricity supply. Thus, this technology is advantageous for treating wastewater in remote regions where it is difficult to supply electricity. In this study, the possibility of real applications of this system for arsenate treatment with electricity production was verified through electrolyte effect investigations using a small-scale fuel cell and performance testing of a liter-scale fuel cell stack. The electrolyte species studied were NaCl, Na2SO4, and NaHCO3. NaCl was overall the most effective electrolyte for arsenate treatment, although Na2SO4 produced the greatest electrical current and power density. In addition, although the current density and power density were proportional to the concentrations of NaCl and Na2SO4, the use of concentrations above 20 mM of NaCl and Na2SO4 inhibited arsenate treatment due to competition effects between anions and arsenate in adsorption onto the iron hydroxide. The dominant iron hydroxide produced at the iron anode was found to be lepidocrocite by means of Raman spectroscopy. A liter-scale four-stack iron-air fuel cell with 10 mM NaCl electrolyte was found to be able to treat about 300 L of 1 ppm arsenate solution to below 10 ppb during 1 day, based on its 60-min treatment capacity, as well as produce the maximum power density of 250 mW/m2.
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Affiliation(s)
- Jung Hwan Kim
- Department of Civil and Environmental Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Hubdar Ali Maitlo
- Department of Civil and Environmental Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Joo Yang Park
- Department of Civil and Environmental Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Republic of Korea.
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23
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Delaire C, Amrose S, Zhang M, Hake J, Gadgil A. How do operating conditions affect As(III) removal by iron electrocoagulation? WATER RESEARCH 2017; 112:185-194. [PMID: 28160698 DOI: 10.1016/j.watres.2017.01.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/14/2017] [Accepted: 01/17/2017] [Indexed: 06/06/2023]
Abstract
Iron electrocoagulation (Fe-EC) has been shown to effectively remove arsenic from contaminated groundwater at low cost and has the potential to improve access to safe drinking water for millions of people. Understanding how operating conditions, such as the Fe dosage rate and the O2 recharge rate, affect arsenic removal at different pH values is crucial to maximize the performance of Fe-EC under economic constraints. In this work, we improved upon an existing computational model to investigate the combined effects of pH, Fe dosage rate, and O2 recharge rate on arsenic removal in Fe-EC. We showed that the impact of the Fe dosage rate strongly depends on pH and on the O2 recharge rate, which has important practical implications. We identified the process limiting arsenic removal (As(III) oxidation versus As(V) adsorption) at different pH values, which allowed us to interpret the effect of operating conditions on Fe-EC performance. Finally, we assessed the robustness of the trends predicted by the model, which assumes a constant pH, against lab experiments reproducing more realistic conditions where pH is allowed to drift during treatment as a result of equilibration with atmospheric CO2. Our results provide a nuanced understanding of how operating conditions impact arsenic removal by Fe-EC and can inform decisions regarding the operation of this technology in a range of groundwaters.
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Affiliation(s)
- Caroline Delaire
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States.
| | - Susan Amrose
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States
| | - Minghui Zhang
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States
| | - James Hake
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720-1710, United States
| | - Ashok Gadgil
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States; Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
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24
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Delaire C, van Genuchten CM, Amrose SE, Gadgil AJ. Bacteria attenuation by iron electrocoagulation governed by interactions between bacterial phosphate groups and Fe(III) precipitates. WATER RESEARCH 2016; 103:74-82. [PMID: 27438902 DOI: 10.1016/j.watres.2016.07.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/04/2016] [Accepted: 07/10/2016] [Indexed: 06/06/2023]
Abstract
Iron electrocoagulation (Fe-EC) is a low-cost process in which Fe(II) generated from an Fe(0) anode reacts with dissolved O2 to form (1) Fe(III) precipitates with an affinity for bacterial cell walls and (2) bactericidal reactive oxidants. Previous work suggests that Fe-EC is a promising treatment option for groundwater containing arsenic and bacterial contamination. However, the mechanisms of bacteria attenuation and the impact of major groundwater ions are not well understood. In this work, using the model indicator Escherichia coli (E. coli), we show that physical removal via enmeshment in EC precipitate flocs is the primary process of bacteria attenuation in the presence of HCO3(-), which significantly inhibits inactivation, possibly due to a reduction in the lifetime of reactive oxidants. We demonstrate that the adhesion of EC precipitates to cell walls, which results in bacteria encapsulation in flocs, is driven primarily by interactions between EC precipitates and phosphate functional groups on bacteria surfaces. In single solute electrolytes, both P (0.4 mM) and Ca/Mg (1-13 mM) inhibited the adhesion of EC precipitates to bacterial cell walls, whereas Si (0.4 mM) and ionic strength (2-200 mM) did not impact E. coli attenuation. Interestingly, P (0.4 mM) did not affect E. coli attenuation in electrolytes containing Ca/Mg, consistent with bivalent cation bridging between bacterial phosphate groups and inorganic P sorbed to EC precipitates. Finally, we found that EC precipitate adhesion is largely independent of cell wall composition, consistent with comparable densities of phosphate functional groups on Gram-positive and Gram-negative cells. Our results are critical to predict the performance of Fe-EC to eliminate bacterial contaminants from waters with diverse chemical compositions.
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Affiliation(s)
- Caroline Delaire
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States.
| | - Case M van Genuchten
- Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, Utrecht 3508TA, The Netherlands
| | - Susan E Amrose
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States
| | - Ashok J Gadgil
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, United States; Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
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25
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Chellam S, Sari MA. Aluminum electrocoagulation as pretreatment during microfiltration of surface water containing NOM: A review of fouling, NOM, DBP, and virus control. JOURNAL OF HAZARDOUS MATERIALS 2016; 304:490-501. [PMID: 26619048 DOI: 10.1016/j.jhazmat.2015.10.054] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 10/23/2015] [Accepted: 10/24/2015] [Indexed: 06/05/2023]
Abstract
Electrocoagulation (EC) is the intentional corrosion of sacrificial anodes (typically aluminum or iron) by passing electricity to release metal-ion coagulant species and destabilize a wide range of suspended, dissolved, and macromolecular contaminants. It can be integrated ahead of microfiltration (MF) to effectively control turbidity, microorganisms, and disinfection by-products (DBPs) and simultaneously maintain a high MF specific flux. This manuscript summarizes the current knowledge on MF pretreatment by aluminum EC particularly focusing on mechanisms of (i) electrocoagulant dosing, (ii) (bio)colloid destabilization, (iii) fouling reductions, and (iv) enhanced removal of viruses, natural organic matter (NOM), and DBP precursors. Electrolysis efficiently removes hydrophobic NOM, viruses, and siliceous foulants. Aluminum effectively electrocoagulates viruses by physically encapsulating them in flocs, neutralizing their surface charge and reducing electrostatic repulsion, and increasing hydrophobic interactions between any sorbed NOM and free viruses. New results included herein demonstrate that EC achieves DBP control by removing NOM, reducing chlorine-reactivity of remaining NOM, and inducing a slight shift toward more brominated trihalomethanes and haloacetic acids. EC reduces MF fouling by forming large flocs that tend to deposit on the membrane surface, i.e. decrease pore penetration and forming more permeable cakes and by reducing foulant mass in case of significant floc-flotation.
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Affiliation(s)
- Shankararaman Chellam
- Zachry Department of Civil Engineering, Texas A&M University, College Station, TX 77843-3136, United States.
| | - Mutiara Ayu Sari
- Zachry Department of Civil Engineering, Texas A&M University, College Station, TX 77843-3136, United States
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