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Dykstra CM, Pavlostathis SG. Hydrogen sulfide affects the performance of a methanogenic bioelectrochemical system used for biogas upgrading. WATER RESEARCH 2021; 200:117268. [PMID: 34098269 DOI: 10.1016/j.watres.2021.117268] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 06/12/2023]
Abstract
Methanogenic bioelectrochemical systems (BESs) can convert carbon dioxide (CO2) to methane (CH4) and may be used for anaerobic digester biogas upgrading. However, the effect of hydrogen sulfide (H2S), a common biogas component, on BES performance is unknown. Thus, the objective of this study was to assess the effect of H2S addition to the cathode headspace on BES performance at a range of initial gas-phase H2S concentrations (0-6% v/v), as well as its effect on the anode and cathode microbial communities. As the initial cathode headspace H2S increased from 0 to 2% (v/v), biocathodic CH4 production increased by two-fold to 3.56 ± 0.36 mmol/L-d, due to dissolved H2S transport from the cathode to the anode where H2S was oxidized. Elemental sulfur and sulfate were H2S oxidation products detected in the anode. Above 3% initial cathode headspace H2S, biocathodic CH4 production declined due to inhibition. A phylotype most closely related to Methanobrevibacter arboriphilus dominated the cathode archaeal communities. In the sulfide-amended BES, a phylotype similar to the exoelectrogen Ochrobactrum anthropi was enriched in both the anode and cathode, whereas phylotypes related to sulfate-reducing and sulfur oxidizing Bacteria were detected in the bioanode. Thus, sulfide transport and oxidation in the anode play an important role in methanogenic BESs treating sulfide-bearing biogas.
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Affiliation(s)
- Christy M Dykstra
- School of Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, United States; Department of Civil, Construction and Environmental Engineering, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, United States.
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, United States
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Fang C, Huang R, Dykstra CM, Jiang R, Pavlostathis SG, Tang Y. Energy and Nutrient Recovery from Sewage Sludge and Manure via Anaerobic Digestion with Hydrothermal Pretreatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1147-1156. [PMID: 31790234 DOI: 10.1021/acs.est.9b03269] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Global expectation for sustainability has prompted the transition of practices in wastewater treatment plants toward not only waste management but also energy and nutrient recovery. It has been shown that low-temperature hydrotherm (HT) treatment can enhance downstream biogas production via anaerobic digestion (AD). Yet, because the application of combined HT and AD is still at an early stage, a systematic understanding of the dynamic speciation evolution of important elements is still lacking. This study investigates energy and nutrient recovery from sewage sludge and swine manure via combined HT-AD treatment. Bench-scale investigation was conducted to evaluate biogas production and understand the dynamic evolution of organic carbon (C) and phosphorus (P) speciation. C and P speciations were characterized using complementary chemical and spectroscopic techniques, including 13C nuclear magnetic resonance (NMR) spectroscopy, P X-ray absorption near edge structure (XANES) spectroscopy, and sequential chemical extraction. Results from this study suggest that low-temperature HT pretreatment can achieve enhanced biogas production for sludge compared to the minimal effect on the biogas production from manure. It also provides guidance for P recovery from liquid digestate and solid residue after the AD process.
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Affiliation(s)
- Ci Fang
- School of Earth and Atmospheric Sciences , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0340 , United States
- Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences , China Agricultural University , Beijing 100193 , China
| | - Rixiang Huang
- School of Earth and Atmospheric Sciences , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0340 , United States
| | - Christy M Dykstra
- School of Civil and Environmental Engineering , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0512 , United States
| | - Rongfeng Jiang
- Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences , China Agricultural University , Beijing 100193 , China
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0512 , United States
| | - Yuanzhi Tang
- School of Earth and Atmospheric Sciences , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0340 , United States
- School of Civil and Environmental Engineering , Georgia Institute of Technology , 311 Ferst Dr. , Atlanta , Georgia 30332-0512 , United States
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Zhang C, Wang S, Lv Z, Zhang Y, Cao X, Song Z, Shao M. NanoFe 3O 4 accelerates anoxic biodegradation of 3, 5, 6-trichloro-2-pyridinol. CHEMOSPHERE 2019; 235:185-193. [PMID: 31255759 DOI: 10.1016/j.chemosphere.2019.06.114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 02/12/2019] [Accepted: 06/14/2019] [Indexed: 06/09/2023]
Abstract
3, 5, 6-trichloro-2-pyridinol (TCP) is a widespread organic pollutant with persistent, mobile and high antimicrobial effects. Here, nanoFe3O4 was firstly introduced into the anoxic biodegradation of TCP. It was found that nanoFe3O4 significantly accelerated TCP biodegradation. The removal rate of TCP (100 mg L-1) increased from 83.03% to 98.74% within 12 h in the presence of nanoFe3O4, and the addition of nanoFe3O4 also promoted the accumulation of CO2. Reductive dechlorination mechanism was involved in anoxic biodegradation of TCP. Molecular approaches further revealed that nanoFe3O4 distinctly induced the shifts of bacterial community. The dominant genus Ochrobactrum was converted to genus Delftia in nanoFe3O4 treatment, and the relative abundance of Delftia increased from 10.26% to 44.62%. Meanwhile, the total relative abundance of bacteria related to TCP dechlorination and degradation significantly increased in the presence of nanoFe3O4. These results indicated that nanoFe3O4 induced the enrichment of TCP-degrading bacteria to promote the anoxic biodegradation of TCP.
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Affiliation(s)
- Chen Zhang
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shenghui Wang
- College of Life Science, Liaocheng University, Liaocheng, 252059, China.
| | - Zhiwei Lv
- College of Life Science, Liaocheng University, Liaocheng, 252059, China
| | - Yang Zhang
- College of Life Science, Liaocheng University, Liaocheng, 252059, China
| | - Xueting Cao
- College of Life Science, Liaocheng University, Liaocheng, 252059, China
| | - Zhifeng Song
- College of Life Science, Liaocheng University, Liaocheng, 252059, China
| | - Mingzhu Shao
- College of Life Science, Liaocheng University, Liaocheng, 252059, China
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Chen H, Lu D, Chen L, Wang C, Xu X, Zhu L. A study of the coupled bioelectrochemical system-upflow anaerobic sludge blanket for efficient transformation of 2,4-dichloronitrobenzene. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:13002-13013. [PMID: 30895540 DOI: 10.1007/s11356-019-04751-9] [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: 12/26/2018] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
Coupled bioelectrochemical system-upflow anaerobic sludge blanket (BES-UASB) was utilized for wastewater treatment containing 2,4-dichloronitrobenzene (DClNB). The results indicated that a proper voltage enhanced the DClNB reduction, however, over high voltage presented a negative impact (2.0 V). Synergistic effect of external voltage and anaerobic sludge was observed, and dechlorination efficiency reached 57.8 ± 5.4% in the coupled BES, which was higher than the sum of anaerobic sludge and electric system (48.2%). Moreover, the coupled system was more tolerant of high salinity and pollutant concentration. Dehydrogenase activity (DHA) was related to microbial electron transfer activity and DHA reached a maximum 453 ± 33 μgTF g-1VSS h-1 in the coupled reactor which was 1.6-fold that of the control, meanwhile, extracellular polymeric substances (EPS) content was significantly enhanced in the presence of external voltage. In summary, the coupled BES-UASB systems could be an alternative for removal of recalcitrant pollutants such as DClNB.
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Affiliation(s)
- Hui Chen
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Donghui Lu
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Linlin Chen
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Caiqin Wang
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Xiangyang Xu
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
- Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China
| | - Liang Zhu
- Institute of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
- Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China.
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Wang S, Zhang C, Lv Z, Huang H, Cao X, Song Z, Shao M. Degradation of 3,5,6-trichloro-2-pyridinol by a microbial consortium in dryland soil with anaerobic incubation. Biodegradation 2019; 30:161-171. [DOI: 10.1007/s10532-019-09873-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 03/25/2019] [Indexed: 02/05/2023]
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Dykstra CM, Pavlostathis SG. Zero-Valent Iron Enhances Biocathodic Carbon Dioxide Reduction to Methane. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12956-12964. [PMID: 28994592 DOI: 10.1021/acs.est.7b02777] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Methanogenic bioelectrochemical systems (BESs), which convert carbon dioxide (CO2) directly to methane (CH4), promise to be an innovative technology for anaerobic digester biogas upgrading. Zero-valent iron (ZVI), which has previously been used to improve CH4 production in anaerobic digesters, has not been explored in methanogenic biocathodes. Thus, the objective of this study was to assess the effect of biocathode ZVI on BES performance at 1 and 2 g/L initial ZVI concentrations and at various cathode potentials (-0.65 to -0.80 V versus SHE). The total CH4 produced during a 7-day feeding cycle with 1 and 2 g/L initial ZVI was 2.8- and 2.9-fold higher, respectively, than the mean CH4 production in the four prior cycles without ZVI addition. Furthermore, CH4 production by the ZVI-amended biocathodes remained elevated throughout three subsequent feeding cycles, despite catholyte replacement and no new ZVI addition. The fourth cycle following a single ZVI addition of 1 g/L and 2 g/L yielded 123% and 231% more total CH4 than in the non-ZVI cycles, respectively. The higher CH4 production could not be fully explained by complete anaerobic oxidation of the ZVI and utilization of produced H2 by hydrogenotrophic methanogens. Microbial community analysis showed that the same phylotype, most closely related to Methanobrevibacter arboriphilus, dominated the archaeal community in the ZVI-free and ZVI-amended biocathodes. However, the bacterial community experienced substantial changes following ZVI exposure, with more Proteobacteria and fewer Bacteroidetes in the ZVI-amended biocathode. Furthermore, it is likely that a redox-active precipitate formed in the ZVI-amended biocathode, which sorbed to the electrode and/or biofilm, acted as a redox mediator, and enhanced electron transfer and CH4 production. Thus, ZVI may be used to increase biocathode CH4 production, assist in the start-up of an electromethanogenic biocathode, and/or maintain microbial activity during voltage interruptions.
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Affiliation(s)
- Christy M Dykstra
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States
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Dykstra CM, Pavlostathis SG. Methanogenic Biocathode Microbial Community Development and the Role of Bacteria. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:5306-5316. [PMID: 28368570 DOI: 10.1021/acs.est.6b04112] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The cathode microbial community of a methanogenic bioelectrochemical system (BES) is key to the efficient conversion of carbon dioxide (CO2) to methane (CH4) with application to biogas upgrading. The objective of this study was to compare the performance and microbial community composition of a biocathode inoculated with a mixed methanogenic (MM) culture to a biocathode inoculated with an enriched hydrogenotrophic methanogenic (EHM) culture, developed from the MM culture following pre-enrichment with H2 and CO2 as the only externally supplied electron donor and carbon source, respectively. Using an adjacent Ag/AgCl reference electrode, biocathode potential was poised at -0.8 V (versus SHE) using a potentiostat, with the bioanode acting as the counter electrode. When normalized to cathode biofilm biomass, the methane production in the MM- and EHM-biocathode was 0.153 ± 0.010 and 0.586 ± 0.029 mmol CH4/mg biomass-day, respectively. This study showed that H2/CO2 pre-enriched inoculum enhanced biocathode CH4 production, although the archaeal communities in both biocathodes converged primarily (86-100%) on a phylotype closely related to Methanobrevibacter arboriphilus. The bacterial community of the MM-biocathode was similar to that of the MM inoculum but was enriched in Spirochaetes and other nonexoelectrogenic, fermentative Bacteria. In contrast, the EHM-biocathode bacterial community was enriched in Proteobacteria, exoelectrogens, and putative producers of electron shuttle mediators. Similar biomass levels were detected in the MM- and EHM-biocathodes. Thus, although the archaeal communities were similar in the two biocathodes, the difference in bacterial community composition was likely responsible for the 3.8-fold larger CH4 production rate observed in the EHM-biocathode. Roles for abundant OTUs identified in the biofilm and inoculum cultures were highlighted on the basis of previous reports.
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Affiliation(s)
- Christy M Dykstra
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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Zhang S, Wondrousch D, Cooper M, Zinder SH, Schüürmann G, Adrian L. Anaerobic Dehalogenation of Chloroanilines by Dehalococcoides mccartyi Strain CBDB1 and Dehalobacter Strain 14DCB1 via Different Pathways as Related to Molecular Electronic Structure. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:3714-3724. [PMID: 28233989 DOI: 10.1021/acs.est.6b05730] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dehalococcoides mccartyi strain CBDB1 and Dehalobacter strain 14DCB1 are organohalide-respiring microbes of the phyla Chloroflexi and Firmicutes, respectively. Here, we report the transformation of chloroanilines by these two bacterial strains via dissimilar dehalogenation pathways and discuss the underlying mechanism with quantum chemically calculated net atomic charges of the substrate Cl, H, and C atoms. Strain CBDB1 preferentially removed Cl doubly flanked by two Cl or by one Cl and NH2, whereas strain 14DCB1 preferentially dechlorinated Cl that has an ortho H. For the CBDB1-mediated dechlorination, comparative analysis with Hirshfeld charges shows that the least-negative Cl discriminates active from nonactive substrates in 14 out of 15 cases and may represent the preferred site of primary attack through cob(I)alamin. For the latter trend, three of seven active substrates provide strong evidence, with partial support from three of the remaining four substrates. Regarding strain 14DCB1, the most positive carbon-attached H atom discriminates active from nonactive chloroanilines in again 14 out of 15 cases. Here, regioselectivity is governed for 10 of the 11 active substrates by the most positive H attached to the highest-charge (most positive or least negative) aromatic C carrying the Cl to be removed. These findings suggest the aromatic ring H as primary site of attack through the supernucleophile Co(I), converting an initial H bond to a full electron transfer as start of the reductive dehalogenation. For both mechanisms, one- and two-electron transfer to Cl (strain CBDB1) or H (strain 14DCB1) are compatible with the presently available data. Computational chemistry research into reaction intermediates and pathways may further aid in understanding the bacterial reductive dehalogenation at the molecular level.
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Affiliation(s)
- Shangwei Zhang
- Institute for Organic Chemistry, Technical University Bergakademie Freiberg , Leipziger Straße 29, 09596 Freiberg, Germany
| | - Dominik Wondrousch
- Institute for Organic Chemistry, Technical University Bergakademie Freiberg , Leipziger Straße 29, 09596 Freiberg, Germany
| | | | - Stephen H Zinder
- Department of Microbiology, Cornell University , Ithaca, New York 14853, United States
| | - Gerrit Schüürmann
- Institute for Organic Chemistry, Technical University Bergakademie Freiberg , Leipziger Straße 29, 09596 Freiberg, Germany
| | - Lorenz Adrian
- Fachgebiet Applied Biochemistry, Technische Universität Berlin , Gustav-Meyer-Allee 25, 13355 Berlin, Germany
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Sohn SY, Häggblom MM. Reductive dehalogenation activity of indigenous microorganism in sediments of the Hackensack River, New Jersey. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 214:374-383. [PMID: 27108041 DOI: 10.1016/j.envpol.2016.04.022] [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: 02/17/2016] [Revised: 03/25/2016] [Accepted: 04/06/2016] [Indexed: 06/05/2023]
Abstract
Organohalogen pollutants are of concern in many river and estuarine environments, such as the New York-New Jersey Harbor estuary and its tributaries. The Hackensack River is contaminated with various metals, hydrocarbons and halogenated organics, including polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins. In order to examine the potential for microbial reductive dechlorination by indigenous microorganisms, sediment samples were collected from five different estuarine locations along the Hackensack River. Hexachlorobenzene (HCB), hexabromobenzene (HBB), and pentachloroaniline (PCA) were selected as model organohalogen pollutants to assess anaerobic dehalogenating potential. Dechlorinating activity of HCB and PCA was observed in sediment microcosms for all sampling sites. HCB was dechlorinated via pentachlorobenzene (PeCB) and trichlorobenzene (TriCB) to dichlorobenzene (DCB). PCA was dechlorinated via tetrachloroaniline (TeCA), trichloroanilines (TriCA), and dichloroanilines (DCA) to monochloroaniline (MCA). No HBB debromination was observed over 12 months of incubation. However, with HCB as a co-substrate slow HBB debromination was observed with production of tetrabromobenzene (TeBB) and tribromobenzene (TriBB). Chloroflexi specific 16S rRNA gene PCR-DGGE followed by sequence analysis detected Dehalococcoides species in sediments of the freshwater location, but not in the estuarine site. Analysis targeting 12 putative reductive dehalogenase (rdh) genes showed that these were enriched concomitant with HCB or PCA dechlorination in freshwater sediment microcosms.
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Affiliation(s)
- Seo Yean Sohn
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901, USA.
| | - Max M Häggblom
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901, USA.
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Ou C, Zhang S, Liu J, Shen J, Han W, Sun X, Li J, Wang L. Enhanced reductive transformation of 2,4-dinitroanisole in a anaerobic system: the key role of zero valent iron. RSC Adv 2015. [DOI: 10.1039/c5ra11197h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Accelerated reduction of typical multi-substituted nitroaromatic compounds (NACs),i.e., 2,4-dinitroanisole (DNAN), was achieved in an anaerobic system coupled with zero valent iron (ZVI), with the underlying role of ZVI in this process elucidated.
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Affiliation(s)
- Changjin Ou
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Shuai Zhang
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Jianguo Liu
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Jinyou Shen
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Weiqing Han
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Xiuyun Sun
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Jiansheng Li
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Lianjun Wang
- Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse
- School of Environmental and Biological Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
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11
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Dykstra CM, Giles HD, Banerjee S, Pavlostathis SG. Fate and biotransformation of phytosterols during treatment of pulp and paper wastewater in a simulated aerated stabilization basin. WATER RESEARCH 2015; 68:589-600. [PMID: 25462765 DOI: 10.1016/j.watres.2014.10.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 10/09/2014] [Accepted: 10/13/2014] [Indexed: 06/04/2023]
Abstract
Pulp and paper wastewater (PPW) contains significant concentrations of phytosterols, suspected of inducing endocrine disruption in aquatic species. Aerated stabilization basins (ASBs) are commonly used for the treatment of PPW, but phytosterol removal varies among treatment systems. The objective of this study was to better understand the removal processes and biotransformation of phytosterols within an ASB treatment system fed with untreated PPW. PPW settled solids and supernatant fractions showed that phytosterols are primarily associated with settleable solids, which carry phytosterols to ASB sediment where anoxic/anaerobic conditions prevail. Bioassays with supernatant and settled PPW fractions of the raw wastewater conducted under aerobic and anaerobic conditions, respectively, showed that solids disintegration and hydrolysis results in phytosterol release in ASBs. A simulated ASB, fed with PPW and operated for 2.4 years at three hydraulic retention times (HRTs; 22.2, 11.1 and 5.6 d) with total phytosterol and solids loading rates from 10 to 42 μg/L-d and 44-178 mg/L-d, respectively, was used to determine the steady-state effluent quality and sediment characteristics. Although effluent COD and phytosterol concentrations were relatively low and stable (84-88% total COD removal; 82-94% total phytosterol removal) across the range of HRTs tested, sediment COD and phytosterol concentrations increased with increasing loading rate. On average, 51% of the phytosterols entering the ASB were removed via biotransformation, 40% were retained in the sediment, and the remaining 9% exited with the effluent. This study demonstrates the role of sediment as a source of phytosterol release in ASBs and highlights the importance of HRT and the PPW characteristics for predicting phytosterol fate in ASBs.
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Affiliation(s)
- Christy M Dykstra
- School of Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, USA
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Tezel U, Tandukar M, Hajaya MG, Pavlostathis SG. Transition of municipal sludge anaerobic digestion from mesophilic to thermophilic and long-term performance evaluation. BIORESOURCE TECHNOLOGY 2014; 170:385-394. [PMID: 25156875 DOI: 10.1016/j.biortech.2014.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/30/2014] [Accepted: 08/02/2014] [Indexed: 05/28/2023]
Abstract
Strategies for the transition of municipal sludge anaerobic digestion from mesophilic to thermophilic were assessed and the long-term stability and performance of thermophilic digesters operated at a solids retention time of 30days were evaluated. Transition from 36°C to 53.3°C at a rate of 3°C/day resulted in fluctuation of the daily gas and volatile fatty acids (VFAs) production. Steady-state was reached within 35days from the onset of temperature increase. Transitions from either 36 or 53.3°C to 60°C resulted in relatively stable daily gas production, but VFAs remained at very high levels (in excess of 5000mg COD/L) and methane production was lower than that of the mesophilic reactor. It was concluded that in order to achieve high VS and COD destruction and methane production, the temperature of continuous-flow, suspended growth digesters fed with mixed municipal sludge should be kept below 60°C.
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Affiliation(s)
- Ulas Tezel
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
| | - Madan Tandukar
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
| | - Malek G Hajaya
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
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13
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Zhu L, Gao K, Qi J, Jin J, Xu X. Enhanced reductive transformation of p-chloronitrobenzene in a novel bioelectrode-UASB coupled system. BIORESOURCE TECHNOLOGY 2014; 167:303-309. [PMID: 24997372 DOI: 10.1016/j.biortech.2014.05.116] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 05/27/2014] [Accepted: 05/31/2014] [Indexed: 06/03/2023]
Abstract
The laboratory-scale upflow anaerobic sludge blanket (UASB) reactor equipped with a pair of bioelectrodes was established for the enhancement of p-chloronitrobenzene (p-ClNB) reductive transformation via the electrolysis. Results showed that a stable COD removal efficiency over 99% and high p-ClNB transformation rate of 0.328 h(-1) were achieved in the bioelectrode-UASB coupled system with influent COD and p-ClNB loading rates of 2.1-4.2 kg COD m(-3)d(-1) and 60 gm(-3)d(-1), respectively. The bioelectrodes were supplied with a voltage of 2.5-5.0 V and the effective current was above 2 mA, which resulted in a continuous supply of H2. Compared with the traditional UASB reactor (R1), the production of H2 was promoted in the bioelectrode-UASB coupled system (R2), and was consumed as an internal electron donor for p-ClNB reductive transformation by anaerobic microbes simultaneously. Furthermore, the cyclic voltammetry curve (CV) analysis of biocathodes showed a positive shift in the reductive peak potential and a dramatic increase in the reductive peak current, which demonstrated the catalytic reduction of p-ClNB by biocathode in the combined system.
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Affiliation(s)
- Liang Zhu
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058, China.
| | - Kaituo Gao
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China
| | - Jiaoqin Qi
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China; Yixing Urban Supervision and Inspection Administration of Product Quality, National Supervision and Inspection Center of Environmental Protection Equipment Quality, Yixing 214205, China
| | - Jie Jin
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China
| | - Xiangyang Xu
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058, China.
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Liu H, Park JW, Häggblom MM. Enriching for microbial reductive dechlorination of polychlorinated dibenzo-p-dioxins and dibenzofurans. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 184:222-230. [PMID: 24060741 DOI: 10.1016/j.envpol.2013.08.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Revised: 08/12/2013] [Accepted: 08/14/2013] [Indexed: 06/02/2023]
Abstract
Anaerobic enrichment cultures derived from contaminated Kymijoki River sediments dechlorinated 1,2,3,4-tetrachlorodibenzofuran (1,2,3,4-tetra-CDF), octachlorodibenzofuran (octa-CDF) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-tetra-CDD). 1,2,3,4-tetra-CDF was dechlorinated via 1,2,3-, 2,3,4-, and 1,3,4/1,2,4-tri-CDFs to 1,3-, 2,3-, and 2,4-di-CDFs and finally to 4-mono-CDF. The dechlorination rate of 1,2,3,4-tetra-CDF was generally slower than that of 1,2,3,4-tetra-CDD. The rate and extent of 1,2,3,4-tetra-CDD dechlorination was enhanced by addition of pentachloronitrobenzene (PCNB) as a co-substrate. Dechlorination of spiked octa-CDF was observed with the production of hepta-, hexa-, penta- and tetra-CDFs over 6 months. Two major phylotypes of the Chloroflexi community showed an increase, one of which was identical to the Dehalococcoides mccartyi Pinellas subgroup. A set of twelve putative reductive dehalogenase (rdh) genes increased in abundance with addition of 1,2,3,4-tetra-CDF, 1,2,3,4-tetra-CDD and/or PCNB. This information will aid in understanding how indigenous microbial communities impact the fate of PCDFs and in developing strategies for bioremediation of PCDD/F contaminated sediments.
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Affiliation(s)
- Hui Liu
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, The State University of New Jersey, 76 Lipman Drive, New Brunswick, NJ 08901, USA
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Toxicity and Microbial Degradation of Nitrobenzene, Monochloronitrobenzenes, Polynitrobenzenes, and Pentachloronitrobenzene. J CHEM-NY 2014. [DOI: 10.1155/2014/265140] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nitrobenzene and its derivatives (NBDs) are highly toxic compounds that have been released into the environment by anthropogenic activities. Many bacteria and fungi have been well-characterized for their ability to degrade NBDs. The biochemical and molecular characterization of the microbial degradation of NBDs has also been studied. In this review, we have summarized the toxicity and degradation profiles of nitrobenzene, monochloronitrobenzenes, polynitrobenzenes, and pentachloronitrobenzene. This review will increase our current understanding of toxicity and microbial degradation of NBDs.
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16
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Liu Z, Sun P, Pavlostathis SG, Zhou X, Zhang Y. Inhibitory effects and biotransformation potential of ciprofloxacin under anoxic/anaerobic conditions. BIORESOURCE TECHNOLOGY 2013; 150:28-35. [PMID: 24140947 DOI: 10.1016/j.biortech.2013.09.125] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/24/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
The inhibitory effects and biotransformation potential of the fluoroquinolone antibiotic ciprofloxacin (CIP) under anoxic (i.e., nitrate reducing) and anaerobic (i.e., sulfate reducing and methanogenic) conditions were investigated. Fermentation and sulfate reduction was inhibited in 10-80 mg/L CIP-amended sulfate-reducing cultures but recovered with prolonged incubation. Methanogenesis in the mixed culture was significantly inhibited at 80-100 mg CIP/L. No significant decrease of CIP concentration was observed under both sulfate-reducing and methanogenic conditions. However, a low degree of CIP biotransformation was observed in a fed-batch denitrifying culture after a lag time even though the microbial, denitrifying activity was gradually inhibited at 24-40 mg CIP/L. Furthermore, the degradation of CIP was accelerated with a CIP reamendment of the denitrifying culture. Two CIP biotransformation products in the denitrifying culture were detected and their proposed chemical structures suggest that the antibiotic quinolone moiety of CIP was intact.
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Affiliation(s)
- Zhanguang Liu
- Key Laboratory of Yangtze Water Environment of Ministry of Education, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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17
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Hong J, Tezel U, Okutman Tas D, Pavlostathis SG. Influence of quaternary ammonium compounds on the microbial reductive dechlorination of pentachloroaniline. WATER RESEARCH 2013; 47:6780-6789. [PMID: 24075473 DOI: 10.1016/j.watres.2013.09.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/01/2013] [Accepted: 09/05/2013] [Indexed: 06/02/2023]
Abstract
The inhibitory effect of two widely used quaternary ammonium compounds (QACs)--alkyl benzyl dimethyl (AB) and hexadecyl trimethyl (HD) ammonium chloride--on fermentation, methanogenesis and pentachloroaniline (PCA) dechlorination was assessed using a mixed, methanogenic, PCA-dechlorinating culture amended with AB or HD at a concentration range from 5 to 70 μM. PCA dechlorination was inhibited at 5 μM AB and was completely inhibited at 25 or 5 μM by AB or HD, respectively. However, the PCA dechlorination pathway was the same in both the QACs-free and QACs-amended culture series. Fermentation (acidogenesis) and methanogenesis were inhibited by both AB and HD at and above 25 μM but to a lesser degree than PCA dechlorination. Overall, HD resulted in a more severe inhibition of the mixed culture than AB. Adsorption of both QACs to the mixed culture biomass followed the Freundlich isotherm model. The adsorption affinity of HD for the mixed culture biomass was significantly higher than that of AB, which may be related to the observed higher inhibitory effects of HD compared to AB. Both AB and HD were not degraded in the mixed, dechlorinating culture used in this study.
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Affiliation(s)
- Jinglan Hong
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA; School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
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18
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Misiti TM, Tezel U, Tandukar M, Pavlostathis SG. Aerobic biotransformation potential of a commercial mixture of naphthenic acids. WATER RESEARCH 2013; 47:5520-5534. [PMID: 23863388 DOI: 10.1016/j.watres.2013.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 06/09/2013] [Accepted: 06/15/2013] [Indexed: 06/02/2023]
Abstract
The biotransformation potential of a commercial naphthenic acid (NA) mixture (NA sodium salt; TCI Chemicals) under aerobic conditions was investigated using mixed aerobic cultures developed under various levels and duration of NA exposure. A culture enriched using the commercial NA mixture as the sole carbon source degraded NAs in a range of NA concentrations, regardless of culture age and the presence of a co-substrate; however, only 28.5% of the NA-carbon was detected as CO2 while 44% was utilized for biomass growth. A fraction of the NA mixture (15-26%) was persistent under all conditions studied. In contrast, a culture fed with a degradable synthetic wastewater only (NA un-amended culture) and another culture fed with the same wastewater and 50 mg NA/L (NA-amended culture), over time lost their ability to degrade NAs. Analysis of the 16S rRNA gene based clone library revealed that 80% of the NA-enriched culture belonged to the γ-Proteobacteria class and was largely dominated by phylotypes most closely related to known NA and hydrocarbon degraders such as Pseudomonas and Microbulbifer. The results of this study indicate that although significant NA degradation is possible, only a small fraction of the NA mixture is completely mineralized to CO2. Further investigation into the biotransformation products and conditions affecting NA biodegradation under realistic refinery and environmental conditions will help to design effective treatment and bioremediation processes.
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Affiliation(s)
- Teresa M Misiti
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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19
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Zhu L, Lin H, Qi J, Xu X. Enhanced transformation and dechlorination of p-chloronitrobenzene in the combined ZVI-anaerobic sludge system. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:6119-6127. [PMID: 23536276 DOI: 10.1007/s11356-013-1631-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/04/2013] [Indexed: 06/02/2023]
Abstract
The combination of zero-valent iron (ZVI) with anaerobic sludge for enhancing reductive transformation and dechlorination of p-chloronitrobenzene (p-ClNB) was investigated in this study. p-ClNB was quickly reduced into p-chloroaniline (p-ClAn) and subsequently dechlorinated into aniline in the complex system, and the strengthening factor for pseudo-first-order transformation rate constant of p-ClNB (Q, k ZVI + sludge/(k sludge + k ZVI)) was above 3. The Q values for the different ZVI types with anaerobic sludge were as following: Reduced ZVI (RZVI) > Industrial ZVI > Nanoscale ZVI (NZVI). Thereinto, the aggregation of NZVI occurred, and its reaction activity declined. Furthermore, the increase of ZVI dosage promoted the p-ClNB transformation, but the p-ClAn dechlorination rate and Q value were not improved. With the anaerobic biomass increasing, the dechlorination rate of p-ClAn was significantly enhanced, and the Q value had positive relation with the mass ratio of anaerobic sludge to RZVI.
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Affiliation(s)
- Liang Zhu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
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20
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Misiti T, Tandukar M, Tezel U, Pavlostathis SG. Inhibition and biotransformation potential of naphthenic acids under different electron accepting conditions. WATER RESEARCH 2013; 47:406-418. [PMID: 23134740 DOI: 10.1016/j.watres.2012.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/05/2012] [Accepted: 10/08/2012] [Indexed: 06/01/2023]
Abstract
Naphthenic acids (NAs) are a complex group of alkyl-substituted acyclic, monocyclic and polycyclic carboxylic acids present in crude oil, oil sands process water and tailings ponds, as well as in refinery wastewater. Bioassays were performed to investigate the biotransformation potential and inhibitory effect of a commercial NA mixture to nitrification, denitrification and fermentation/methanogenesis using mixed cultures not previously exposed to NAs. NAs inhibited nitrification in a mixed aerobic heterotrophic/nitrifying culture at concentrations as low as 80 mg NA/L, whereas, an enriched nitrifying culture was only affected at 400 mg NA/L. The lower nitrification inhibition in the latter assay is attributed to the higher population size of nitrosofying and nitrifying bacteria compared to the mixed heterotrophic/nitrifying culture. The NA mixture was not inhibitory to denitrifiers up to 400 mg/L. At higher NA concentrations, cell lysis was pronounced and lysis products were the main source of degradable carbon driving denitrification in culture series prepared without an external carbon source. In the presence of a degradable external carbon source, no difference was observed in nitrate reduction rates or nitrogen gas production at all NA concentrations tested. Methanogenesis was completely inhibited at NA concentrations equal to or higher than 200 mg/L. Methanogenic culture series amended with 80 mg NA/L were transiently inhibited and methane production in culture series prepared with NAs and an external carbon source or NAs only recovered in 136 and 41 days, respectively. Accumulation of volatile fatty acids was observed at inhibitory NA concentrations; however, carbon dioxide production was not affected by NAs, indicating that fermentation and acidogenesis were not affected by NAs. NAs were not degraded under nitrate-reducing or fermentative/methanogenic conditions used in the present study, regardless of the presence or not of another, degradable carbon/energy source.
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Affiliation(s)
- Teresa Misiti
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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21
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Zhu L, Lin HZ, Qi JQ, Xu XY, Qi HY. Effect of H2 on reductive transformation of p-ClNB in a combined ZVI-anaerobic sludge system. WATER RESEARCH 2012; 46:6291-6299. [PMID: 23069076 DOI: 10.1016/j.watres.2012.08.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 08/14/2012] [Accepted: 08/20/2012] [Indexed: 06/01/2023]
Abstract
Using a combined zero-valent iron (ZVI) and anaerobic sludge system as the platform, the hydrogen utilization and reductive mechanism of p-chloronitrobenzene (p-ClNB) were investigated in the study. Results showed that the corrosion of ZVI could be used as a source of electron donor for anaerobic microorganisms, and then enhanced reductive transformation of p-ClNB and production of methane. Thereinto, the transformation of p-ClNB was observed to have priority for the utilization of H(2). The enhancement factors (Q') for the reductive transformation of p-ClNB with exogenous H(2), reduced ZVI (RZVI), industrial ZVI (IZVI), and nanoscale ZVI (NZVI) as electron donors were 4.1-5.6, 14.8-35.1, 2.8-4.6, and 1.5-5.7, respectively. Results demonstrated that RZVI was the most effective type of electron donors, which was attributed to the production and utilization of H(2)/[H] simultaneously via the ZVI corrosion and microbial metabolism. It is hopeful for the application of ZVI to enhance the reductive transformation of analogous persistent organic pollutants in the anaerobic sludge system.
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Affiliation(s)
- Liang Zhu
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China
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Huang J, Wen Y, Ding N, Xu Y, Zhou Q. Effect of sulfate on anaerobic reduction of nitrobenzene with acetate or propionate as an electron donor. WATER RESEARCH 2012; 46:4361-4370. [PMID: 22704132 DOI: 10.1016/j.watres.2012.05.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 05/12/2012] [Accepted: 05/20/2012] [Indexed: 06/01/2023]
Abstract
Sulfate is frequently found in wastewaters that contain nitrobenzene. To reveal the effect of sulfate on the reductive transformation of nitrobenzene to aniline--with acetate or propionate as potential electron donors in anaerobic systems--an acetate series (R1-R5) and a propionate series (R6-R10) were set up. Each of these was comprised of five laboratory-scale sequence batch reactors. The two series were amended with the same amount of nitrobenzene and electron donor electron equivalents, whereas with increasing sulfate concentrations. Results indicated that the presence of sulfate could depress nitrobenzene reduction. Such depression is linked to the inhibition of nitroreductase activity and/or the shift of electron flow. In the acetate series, although sulfate did not strongly compete with nitrobenzene for electron donors, noncompetitive inhibition of specific nitrobenzene reduction rates by sulfate was observed, with an inhibition constant of 0.40 mM. Propionate, which can produce intermediate H₂ as preferred reducing equivalent, is a more effective primary electron donor for nitrobenzene reduction as compared to acetate. In the propionate series, sulfate was found to be a preferential electron acceptor as compared to nitrobenzene, resulting in a quick depletion of propionate and then a likely termination of H₂-releasing under higher sulfate concentrations (R9 and R10). In such a situation, nitrobenzene reduction slowed down, occurring two-stage zero-order kinetics.
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Affiliation(s)
- Jingang Huang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
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23
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Cui Z, Meng F, Hong J, Li X, Ren X. Effects of electron donors on the microbial reductive dechlorination of hexachlorocyclohexane and on the environment. J Biosci Bioeng 2012; 113:765-70. [DOI: 10.1016/j.jbiosc.2012.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 12/13/2011] [Accepted: 01/07/2012] [Indexed: 11/29/2022]
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Zeng T, Chin YP, Arnold WA. Potential for abiotic reduction of pesticides in Prairie pothole porewaters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:3177-87. [PMID: 22313175 DOI: 10.1021/es203584d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Prairie pothole lakes (PPLs) are critical hydrological and ecological components of central North America and represent one of the largest inland wetland systems on Earth. These lakes are located within an agricultural region, and many of them are subject to nonpoint-source pesticide pollution. Limited attention, however, has been paid to understanding the impact of PPL water chemistry on the fate and persistence of pesticides. In this study, the abiotic reductive transformation of seven dinitroaniline pesticides was investigated in PPL sediment porewaters containing naturally abundant levels of reduced sulfur species (i.e., bisulfide (HS(-)) and polysulfides (S(n)(2-))) and dissolved organic matter (DOM). Target dinitroanilines underwent rapid degradation in PPL porewaters and were transformed into corresponding amine products. While the largest fraction of the transformation could be attributed to reduced sulfur species, experimental evidence suggested that other reactive entities in PPL porewaters, such as DOM and mineral phases, might also affect the reaction rates of dinitroanilines. Results from this study highlight the importance of reductive transformation as an abiotic natural attenuation pathway for pesticides entering the PPL sedimentary environment.
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Affiliation(s)
- Teng Zeng
- Department of Civil Engineering, University of Minnesota, 500 Pillsbury Drive Southeast, Minneapolis, Minnesota 55455, United States
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25
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Degradation of chlorinated nitroaromatic compounds. Appl Microbiol Biotechnol 2012; 93:2265-77. [PMID: 22331236 DOI: 10.1007/s00253-012-3927-1] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 01/24/2012] [Accepted: 01/27/2012] [Indexed: 10/28/2022]
Abstract
Chlorinated nitroaromatic compounds (CNAs) are persistent environmental pollutants that have been introduced into the environment due to the anthropogenic activities. Bacteria that utilize CNAs as the sole sources of carbon and energy have been isolated from different contaminated and non-contaminated sites. Microbial metabolism of CNAs has been studied, and several metabolic pathways for degradation of CNAs have been proposed. Detoxification and biotransformation of CNAs have also been studied in various fungi, actinomycetes and bacteria. Several physicochemical methods have been used for treatment of wastewater containing CNAs; however, these methods are not suitable for in situ bioremediation. This review describes the current scenario of the degradation of CNAs.
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Khan F, Prakash D, Jain R. Development of an HPLC method for determination of pentachloronitrobenzene, hexachlorobenzene and their possible metabolites. BMC CHEMICAL BIOLOGY 2011; 11:2. [PMID: 22112041 PMCID: PMC3341572 DOI: 10.1186/1472-6769-11-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 11/23/2011] [Indexed: 11/10/2022]
Abstract
Background Pentachloronitrobenzene (PCNB) and hexachlorobenzene (HCB) are highly toxic and widespread in every environmental compartment. Some of metabolic products such as amino/nitro containing chlorinated aromatic compounds can be determined by gas chromatography coupled with electron capture detector (GC-ECD). However, it is difficult to identify some of chlorophenolic and chloroquinolic intermediates produced from PCNB and HCB by the above mentioned technique. Therefore, for analysis of these compounds and their metabolites, we have developed a high performance liquid chromatography (HPLC) based method. Results The extraction of PCNB and HCB from soil and minimal salt medium was carried out with ethyl acetate and hexane respectively with good recoveries (98% for PCNB and 97% for HCB). The validation of the proposed extraction and HPLC method was done by analysis of PCNB and HCB biodegradation and their metabolites identification from anaerobic enriched soil samples. Conclusion A rapid, sensitive and simple HPLC based analytical method was developed for the analysis of PCNB, HCB and their possible intermediates.
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Affiliation(s)
- Fazlurrahman Khan
- Institute of Microbial Technology (CSIR), Sector 39-A, Chandigarh-160036, India.
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Okutman Tas D, Prytula MT, Mulholland JA, Pavlostathis SG. Theoretical investigation of the sequential reductive dechlorination pathways of chlorobenzenes and chloroanilines. Biotechnol Bioeng 2010; 105:574-87. [DOI: 10.1002/bit.22559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Okutman Tas D, Pavlostathis SG. Microbial transformation of pentachloronitrobenzene under nitrate reducing conditions. Biodegradation 2010; 21:691-702. [DOI: 10.1007/s10532-010-9335-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 01/22/2010] [Indexed: 11/30/2022]
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Liu CY, Jiang X, Yang XL, Song Y. Hexachlorobenzene dechlorination as affected by organic fertilizer and urea applications in two rice planted paddy soils in a pot experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:958-964. [PMID: 19889446 DOI: 10.1016/j.scitotenv.2009.10.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 09/30/2009] [Accepted: 10/10/2009] [Indexed: 05/28/2023]
Abstract
Reductive dechlorination is a crucial pathway for HCB degradation, the applications of organic materials and nitrogen can alter microbial activity and redox potential of soils, thus probably influence HCB dechlorination. To evaluate hexachlorobenzene (HCB) dechlorination as affected by organic fertilizer (OF) and urea applications in planted paddy soils, a pot experiment was conducted in two types of soils, Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An). After 18 weeks of experiment, HCB residues decreased by 28.2-37.5% of the initial amounts in Ac, and 42.1-70.9% in An. The amounts of HCB metabolites showed that dechlorination rates in An were higher than in Ac, which was mainly attributed to the higher pH and dissolved organic carbon (DOC) content of An. Both in Ac and An, the additions of 1% and 2% OF had negative effect on HCB dechlorination, which was probably because excessive nitrogen in OF decreased degraders' activity and the degradation of organic carbon in OF accepted electrons. The application of 0.03% urea could enhance HCB dechlorination rates slightly, while 0.06% urea accelerated HCB dechlorination significantly both in Ac and An. It could be assumed that urea served as an electron donor and stimulated degraders to dechlorinate HCB. In addition, the methanogenic bacteria were involved in dechlorination process, and reductive dechlorination in planted paddy soil might be impeded for the aerenchyma and O(2) supply into the rhizosphere. Results indicated that soil types, rice root system, methanogenic bacteria, OF and urea applications all had great effects on dechlorination process.
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Affiliation(s)
- C Y Liu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China
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Thomas SH, Sanford RA, Amos BK, Leigh MB, Cardenas E, Löffler FE. Unique ecophysiology among U(VI)-reducing bacteria as revealed by evaluation of oxygen metabolism in Anaeromyxobacter dehalogenans strain 2CP-C. Appl Environ Microbiol 2010; 76:176-83. [PMID: 19897758 PMCID: PMC2798628 DOI: 10.1128/aem.01854-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 11/02/2009] [Indexed: 11/20/2022] Open
Abstract
Anaeromyxobacter spp. respire soluble hexavalent uranium, U(VI), leading to the formation of insoluble U(IV), and are present at the uranium-contaminated Oak Ridge Integrated Field Research Challenge (IFC) site. Pilot-scale in situ bioreduction of U(VI) has been accomplished in area 3 of the Oak Ridge IFC site following biostimulation, but the susceptibility of the reduced material to oxidants (i.e., oxygen) compromises long-term U immobilization. Following oxygen intrusion, attached Anaeromyxobacter dehalogenans cells increased approximately 5-fold from 2.2x10(7)+/-8.6x10(6) to 1.0x10(8)+/-2.2x10(7) cells per g of sediment collected from well FW101-2. In the same samples, the numbers of cells of Geobacter lovleyi, a population native to area 3 and also capable of U(VI) reduction, decreased or did not change. A. dehalogenans cells captured via groundwater sampling (i.e., not attached to sediment) were present in much lower numbers (<1.3x10(4)+/-1.1x10(4) cells per liter) than sediment-associated cells, suggesting that A. dehalogenans cells occur predominantly in association with soil particles. Laboratory studies confirmed aerobic growth of A. dehalogenans strain 2CP-C at initial oxygen partial pressures (pO2) at and below 0.18 atm. A negative linear correlation [micro=(-0.09xpO2)+0.051; R2=0.923] was observed between the instantaneous specific growth rate micro and pO2, indicating that this organism should be classified as a microaerophile. Quantification of cells during aerobic growth revealed that the fraction of electrons released in electron donor oxidation and used for biomass production (fs) decreased from 0.52 at a pO2 of 0.02 atm to 0.19 at a pO2 of 0.18 atm. Hence, the apparent fraction of electrons utilized for energy generation (i.e., oxygen reduction) (fe) increased from 0.48 to 0.81 with increasing pO2, suggesting that oxygen is consumed in a nonrespiratory process at a high pO2. The ability to tolerate high oxygen concentrations, perform microaerophilic oxygen respiration, and preferentially associate with soil particles represents an ecophysiology that distinguishes A. dehalogenans from other known U(VI)-reducing bacteria in area 3, and these features may play roles for stabilizing immobilized radionuclides in situ.
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Affiliation(s)
- Sara H. Thomas
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
| | - Robert A. Sanford
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
| | - Benjamin K. Amos
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
| | - Mary Beth Leigh
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
| | - Erick Cardenas
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
| | - Frank E. Löffler
- School of Civil and Environmental Engineering, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, Department of Geology, University of Illinois, Urbana, Illinois 61801-2352, Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824
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Badawi HM, Förner W, Al-Saadi AA. Structural stability, NH2 inversion and vibrational assignments of 2,4,6-trichloroaniline and 2,3,5,6-tetrachloroaniline. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2009.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Influence of sulfate reduction on the microbial dechlorination of pentachloroaniline in a mixed anaerobic culture. Biodegradation 2009; 21:43-57. [DOI: 10.1007/s10532-009-9280-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 06/12/2009] [Indexed: 11/25/2022]
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Longoria A, Tinoco R, Vázquez-Duhalt R. Chloroperoxidase-mediated transformation of highly halogenated monoaromatic compounds. CHEMOSPHERE 2008; 72:485-490. [PMID: 18439646 DOI: 10.1016/j.chemosphere.2008.03.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Revised: 03/02/2008] [Accepted: 03/03/2008] [Indexed: 05/26/2023]
Abstract
Peroxidase transformations of widely distributed pollutants, tetra- and penta-chlorinated phenols and anilines, were studied using different peroxidases. Chloroperoxidase from Caldariomyces fumago was able to transform tetra- and penta-chlorinated phenols and anilines, while horseradish peroxidase, lignin peroxidase from Phanerochaete chrysosporium and versatile peroxidase from Bjerkandera adusta were able only to transform the halogenated phenols. Chloroperoxidase showed a specific activity on pentachlorophenol two orders of magnitude higher than lignin peroxidase and horseradish peroxidase, and one order of magnitude higher than versatile peroxidase. The main product from peroxidase oxidation in all cases was a polymeric and insoluble material. The insolubilization of halogenated phenols and anilines permits their removal, reduces their bioavailability, and thus reduces their environmental impact. The other minor products from the enzymatic transformation of highly chlorinated compounds were determined by mass spectrometry. Tetrachloroquinone, dimers and trimers of halogenated compounds were also identified. Chloroperoxidase was able to halogenate tetrachloroaniline to form pentachloroaniline.
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Affiliation(s)
- Adriana Longoria
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
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Tas DO, Pavlostathis SG. Effect of nitrate reduction on the microbial reductive transformation of pentachloronitrobenzene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:3234-3240. [PMID: 18522099 DOI: 10.1021/es702261w] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The effect of nitrate reduction onthe reductive biotransformation of pentachloronitrobenzene (PCNB), an organochlorine fungicide, was assessed with a mixed fermentative/methanogenic culture enriched from a contaminated estuarine sediment. Glucose and methanol served asthe electron and carbon source. PCNB at an initial concentration of 3 microM was transformed to pentachloroaniline (PCA) simultaneously with nitrate reduction in cultures amended with 10 to 200 mg N/L nitrate. PCA sequentially dechlorinated to dichlorinated anilines (mainly 2,5-DCA) in the nitrate-free control culture, and the culture which was amended with 10 mg N/L nitrate. PCA partially dechlorinated to tetrachloroanilines (TeCAs), and methanogenesis was completely inhibited in the cultures amended with 50-200 mg N/L nitrate, whereas fermentation was only inhibited in the cultures amended with 200 mg N/L nitrate. The impact of nitrate reduction on the sequential dechlorination of PCA was attributed to the production of nitric oxide (NO) and nitrous oxide (N2O). Partial nitrate reduction to ammonia was observed in the cultures amended with 50, 100, or 200 mg N/L nitrate and PCNB (3 microM). Therefore, nitrate concentrations at or above 50 mg N/L lead to accumulation of toxic compounds such as highly chlorinated anilines (i.e., PCA, TeCAs) and denitrification intermediates (i.e., NO, N2O). These findings have significant environmental implications in terms of the fate and transformation of PCNB in subsurface environments where nitrate is present.
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Affiliation(s)
- Didem Okutman Tas
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, USA
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Tas DO, Pavlostathis SG. Temperature and pH effect on the microbial reductive transformation of pentachloronitrobenzene. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:5390-8. [PMID: 17552540 DOI: 10.1021/jf0637675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The effect of pH and temperature on the microbial reductive transformation of pentachloronitrobenzene (PCNB), an organochlorine fungicide, was investigated with a mixed fermentative/methanogenic culture developed from a contaminated estuarine sediment. Culture series were incubated at a temperature range from 4 to 45 degrees C at pH 6.9+/-0.1 and at a pH range from 2.7+/-0.1 to 7.6+/-0.1 at 22 degrees C. Significant differences were observed in terms of biotransformation rate, extent, and products as a function of temperature. Incubation at different pH values resulted in differences in biotransformation rate and extent, but not in terms of products formed. PCNB (3 microM) was transformed to pentachloroaniline (PCA) in all culture series. However, sequential dechlorination of PCA was observed only at a temperature range from 4 to 35 degrees C and at a pH range from 6.2+/-0.1 to 7.6+/-0.1. The highest PCA dechlorination rate was observed at 22 degrees C and at pH 7.6+/-0.1. The effect of temperature on the PCA dechlorination rate was modeled using an Arrhenius relationship, which accounts for both enzyme activation and deactivation. The dechlorination of PCA and chlorinated aniline intermediates was simulated using a branched-chain Michaelis-Menten model, and kinetic constants were determined.
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Affiliation(s)
- Didem Okutman Tas
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, USA
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Tezel U, Pierson JA, Pavlostathis SG. Effect of polyelectrolytes and quaternary ammonium compounds on the anaerobic biological treatment of poultry processing wastewater. WATER RESEARCH 2007; 41:1334-42. [PMID: 17287000 DOI: 10.1016/j.watres.2006.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 12/04/2006] [Accepted: 12/06/2006] [Indexed: 05/13/2023]
Abstract
Quaternary ammonium compounds (QACs) and polyelectrolytes are extensively used in poultry processing facilities as sanitizing agents and flocculants, respectively. These chemicals may affect the performance of biological treatment systems resulting in low effluent quality. The impact of these chemicals on the anaerobic treatment of poultry processing wastewater (PPWW) samples, collected before and after a solids separation process, was tested in batch assays using a mixed, mesophilic (35 degrees C) methanogenic culture. The results of this study showed that Vigilquat (VQ), a commercial mixture of four QACs, has a high affinity for the organic solids in the PPWW. Cationic and anionic polyelectrolytes, alone or in combination, did not have any adverse effect on the anaerobic biodegradation of PPWW at concentrations typically used in poultry processing facilities (20 and 5 mg/L, respectively). In spite of the high affinity of VQ for the PPWW solids, VQ at a concentration of 50mg/L and above adversely affected the anaerobic degradation of the PPWW, which resulted in a significantly reduced methane production and accumulation of volatile fatty acids. In the absence of any inhibition, the methane yield varied from 0.76 to 0.98 L methane at STP per g volatile solids added. VQ was not biodegraded under the batch, methanogenic conditions used in this study.
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Affiliation(s)
- Ulas Tezel
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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Tezel U, Pierson JA, Pavlostathis SG. Fate and effect of quaternary ammonium compounds on a mixed methanogenic culture. WATER RESEARCH 2006; 40:3660-8. [PMID: 16899271 DOI: 10.1016/j.watres.2006.06.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 06/07/2006] [Accepted: 06/23/2006] [Indexed: 05/11/2023]
Abstract
The potential inhibitory effect of four quaternary ammonium compounds (QACs) and Vigilquat, a commercial sanitizer which is a mixture of the four QACs, was investigated at concentrations up to 100 mg/L using a mixed, mesophilic (35 degrees C) methanogenic culture. Dextrin and peptone were used as the carbon and energy sources. A batch assay conducted at a range of QAC concentrations showed that QACs were inhibitory to methanogens at and above 25 mg/L. Methanogenesis was more susceptible to QAC inhibition than acidogenesis. Adsorption of QACs on biomass was successfully simulated with the Freundlich isotherm equation. The inhibitory effect of Vigilquat on the mixed methanogenic culture was also investigated in a batch reactor fed with dextrin and peptone. Methanogens were inhibited when the total QAC concentration reached 30 mg/L and volatile fatty acids (VFAs) accumulated. However, methane production recovered in 57 days of incubation, and all VFAs were consumed, suggesting that a prolonged incubation period is necessary for the methanogens to overcome the transient inhibition at a relatively low QAC concentration. None of the QACs tested in this study was biodegraded under methanogenic conditions.
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Affiliation(s)
- Ulas Tezel
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA
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Tas DO, Thomson IN, Löffler FE, Pavlostathis SG. Kinetics of the microbial reductive dechlorination of pentachloroaniline. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:4467-72. [PMID: 16903287 DOI: 10.1021/es052103t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The microbial reductive dechlorination kinetics of pentachloroaniline (PCA) and less chlorinated anilines (CAs) were investigated with a mixed, fermentative/ methanogenic culture. Batch dechlorination assays were performed with all available CAs at an initial concentration of 3 microM, and an incubation temperature of 22 degrees C. Dechlorination of PCA, two tetrachloroanilines (2,3,4,5- and 2,3,5,6-TeCA), five trichloroanilines (2,3,4-, 2,3,5-, 2,4,5-, 2,4,6-, and 3,4,5-TrCA), and one dichloroaniline (3,5-DCA; low extent) was observed but none of the five remaining dichloroanilines and three monochloroanilines were dechlorinated by the enrichment culture during batch assays. The dechlorination rates (k') and half-saturation coefficients (Kc) were measured using nonlinear regression based on the integrated Michaelis-Menten equation under conditions of electron donor saturation and assuming constant biomass concentration over the relatively short batch incubation period. At an initial concentration of CAs of about 3 microM, the values of k' and Kc ranged from 0.25 to 1.19 microM/day and from 0.11 to 1.72 microM, respectively, corresponding to half-lives in the range of 1.5-8.5 days. Model simulations of the sequential dechlorination reactions based on a branched-chain Michaelis-Menten model and using independently measured k' and Kc values matched the experimental data very well.
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Affiliation(s)
- Didem Okutman Tas
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, USA
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