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Jirui Yang, Feng Shen, Mo Qiu, Xinhua Qi
This paper reports a nonreductive dechlorination pathway (dehydrochlorination) of lindane in the presence of N-MWCNTs (CNT-N1 and CNTN2) under environmentally relevant conditions. The enhanced catalytic dehydrochlorination at mild pH values (7.0-9.0) was mainly attributed to the Lewis base nature of nitrogen functional groups on the surface of N-MWCNTs, based on FT-IR spectra, X-ray photoelectron spectroscopy and CO2-TPD profile. Amine and pyridinic nitrogen species were inferred as the main basic sites that were responsible for the dehydrochlorination of lindane...
October 17, 2017: Science of the Total Environment
Yi Yang, Natalie L Cápiro, Jun Yan, Tyler F Marcet, Kurt D Pennell, Frank E Löffler
Bioremediation treatment (e.g. biostimulation) can decrease groundwater pH with consequences for Dehalococcoides mccartyi (Dhc) reductive dechlorination activity. To explore the pH resilience of Dhc, the Dhc-containing consortium BDI was exposed to pH 5.5 for up to 40 days. Following 8- and 16-day exposure periods to pH 5.5, dechlorination activity and growth recovered when returned to pH 7.2; however, the ability of the culture to dechlorinate VC to ethene was impaired (i.e. decreased rate of VC transformation)...
October 9, 2017: FEMS Microbiology Ecology
B Matturro, E Frascadore, S Rossetti
In this study six PCE-to-ethene dechlorinating cultures, fed with a fermentable substrate (lactate) or hydrogen as electron donor, were obtained from PCB and PCE dechlorinating microcosms constructed with PCB contaminated marine sediments.A novel Chloroflexi member (OTU-DIS1) affiliated to Dehalococcoidales Incertae Sedis, only distantly related to known dechlorinating bacteria, dominated the enrichment cultures (up to 86% of total OTUs). Sulfate-, thiosulfate- and sulfur-reducing bacteria affiliated to genera Desulfobacter, Dethiosulfatibacter and Desulfuromusa were also found to lesser extent...
October 11, 2017: FEMS Microbiology Ecology
Jacob E Munro, Önder Kimyon, Deborah J Rich, Joanna Koenig, Sihui Tang, Adrian Low, Matthew Lee, Mike Manefield, Nicholas V Coleman
1,2-dichloroethane (DCA) is a problematic groundwater pollutant. Factors influencing the distribution and activities of DCA-degrading bacteria are not well-understood, which has hampered their application for bioremediation. Here, we used quantitative PCR (qPCR) to investigate the distribution of putative DCA-dehalogenating bacteria at a DCA-impacted site in Sydney (Australia). The dehalogenase genes dhlA, tceA and bvcA were detected in all groundwater samples (n = 15), while vcrA was found in 11/15 samples...
October 12, 2017: FEMS Microbiology Ecology
Dimin Fan, Ying Lan, Paul G Tratnyek, Richard L Johnson, Jan Filip, Denis Michael O'Carroll, Ariel Nunez Garcia, Abinash Agrawal
Iron-based materials used in water treatment and groundwater remediation-especially micro- and nano-sized zerovalent iron (nZVI)-can be more effective when modified with lower-valent forms of sulfur (i.e., "sulfidated"). Controlled sulfidation for this purpose (using sulfide, dithionite, etc.) is the main topic of this review, but insights are derived by comparison with related and comparatively well-characterized processes such as corrosion of iron in sulfidic waters and abiotic natural attenuation by iron sulfide minerals...
October 16, 2017: Environmental Science & Technology
Ahmadreza Yazdanbakhsh, Akbar Eslami, Gholamreza Moussavi, Mohammad Rafiee, Amir Sheikhmohammadi
This research was aimed at evaluating the performance UV only and sulfite-mediated photoreduction process (an advanced reduction process) in the degradation, dechlorination and mineralization of 2, 4, 6-trichlorophenol (TCP). Firstly efficiency of sulfite-mediated photoreduction (SMP) process in the degradation of TCP was investigated and obtained the complete degradation of TCP (250 mg L(-1)) under the selected conditions (pH, 7.0; [sulfite]/[TCP] = 3.13; UV irradiation, 87 μW cm(-2) and dissolved oxygen (DO), 2 mg L(-1)) at 80 min whereas degradation rate of TCP by UV only was 73% at similar time...
October 4, 2017: Chemosphere
Paul B Hatzinger, Rahul Banerjee, Rachael Rezes, Sheryl H Streger, Kevin McClay, Charles E Schaefer
The objective of this research was to evaluate the potential for two gases, methane and ethane, to stimulate the biological degradation of 1,4-dioxane (1,4-D) in groundwater aquifers via aerobic cometabolism. Experiments with aquifer microcosms, enrichment cultures from aquifers, mesophilic pure cultures, and purified enzyme (soluble methane monooxygenase; sMMO) were conducted. During an aquifer microcosm study, ethane was observed to stimulate the aerobic biodegradation of 1,4-D. An ethane-oxidizing enrichment culture from these samples, and a pure culture capable of growing on ethane (Mycobacterium sphagni ENV482) that was isolated from a different aquifer also biodegraded 1,4-D...
October 11, 2017: Biodegradation
Akifumi Hosoda, Yuta Isomura, Syungo Takeo, Takuho Onai, Kazutaka Takeuchi, Minoru Toda, Hiroto Tamura
It is important to construct microbiological treatment systems for organic solvent-contaminated water. We developed a continuous culture supplemented with a biostimulation agent named BD-C, which is formulated from canola oil, and Xanthobacter autotrophicus strain GJ10 for an aerobic dichloromethane (DCM)-dechlorinating microorganism. The continuous culture was a chemostat constructed using a 1 L screw-capped bottle containing artificial wastewater medium with 2.0 mM DCM and 1.0% (v/v) BD-C. The expression of genes for DCM metabolism in the dechlorinating aerobe was monitored and analyzed by reverse transcription-quantitative PCR...
October 11, 2017: Journal of Oleo Science
T Rodríguez-Cabo, I Rodríguez, M Ramil, R Cela
Similarities and differences among the phototransformation routes of four azolic fungicides (diniconazole, DIN, imazalil, IMA; penconazole, PEN; and propiconazole, PRO) in surface water aliquots are investigated. Selected compounds share a common chemical structure consisting on dichlorophenyl and azolic rings connected through an ethylene bridge, which is substituted with different functionalities. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was employed as analytical technique to follow the time-course of precursor fungicides and to detect and to identify their photo-transformation products (TPs)...
October 7, 2017: Science of the Total Environment
Juan Liu, Jinshao Ye, Yifu Chen, Chongshu Li, Huase Ou
Organophosphorus esters (OPEs) are emerging contaminants widely applied as annexing agents in a variety of industrial products, and they are robust against conventional wastewater treatments. Ultraviolet-driven (UV) radical-based advanced oxidation processes have a potential to become cost-effective treatment technologies for the removal of OPEs in water matrix, but residual and newly generated toxicities of degradation products are a concern. This study is a comprehensive attempt to evaluate UV/H2O2 for the degradation of a water dissolved OPE, tris(2-chloroethyl) phosphate (TCEP)...
September 25, 2017: Chemosphere
Yawei Gu, Binbin Wang, Feng He, Miranda J Bradley, Paul G Tratnyek
In water treatment processes that involve contaminant reduction by zerovalent iron (ZVI), reduction of water to dihydrogen is a competing reaction that must be minimized to maximize the efficiency of electron utilization from the ZVI. Sulfidation has recently been shown to decrease H2 formation significantly, such that the overall electron efficiency of (or selectivity for) contaminant reduction can be greatly increased. To date, this work has focused on nanoscale ZVI (nZVI) and solution-phase sulfidation agents (e...
October 18, 2017: Environmental Science & Technology
Yi Liang, Xikun Liu, Michael A Singletary, Kai Wang, Timothy E Mattes
Bioremediation of vinyl chloride (VC) contamination in groundwater could be mediated by three major bacterial guilds: anaerobic VC-dechlorinators, methanotrophs, and ethene-oxidizing bacteria (etheneotrophs) via metabolic or cometabolic pathways. We collected 95 groundwater samples across 6 chlorinated ethene-contaminated sites and searched for relationships among VC biodegradation gene abundance and expression and site geochemical parameters (e.g., VC concentrations). Functional genes from the three major VC-degrading bacterial guilds were present in 99% and expressed in 59% of the samples...
October 19, 2017: Environmental Science & Technology
Peng Zhang, Chao Ren, Hongwen Sun, Lujuan Min
In this study, the sorption, desorption and degradation of three neonicotinoids, imidacloprid (IMI), clothianidin (CLO) and thiacloprid (THI), and their effects on microorganisms in four different agricultural soils were systematically evaluated. The sorption of neonicotinoids on the soils was generally low with distribution coefficients (Kd) up to 16.2L/kg at Ce of 0.05mg/L following the order THI>IMI≈CLO, and the sorption were mainly influenced by the soil organic carbon content. The percentage degradation rates of the pesticides in different soils ranged from 25...
September 29, 2017: Science of the Total Environment
Yingying Li, Wu Chen, Yunsheng Wang, Kun Luo, Yue Li, Lianyang Bai, Feng Luo
Quinclorac is a widely used herbicide in rice filed. Unfortunately, quinclorac residues are phytotoxic to many crops/vegetables. The degradation of quinclorac in nature is very slow. On the other hand, degradation of quinclorac using bacteria can be an effective and efficient method to reduce its contamination. In this study, we isolated a quinclorac bioremediation bacterium strain F4 from quinclorac contaminated soils. Based on morphological characteristics and 16S rRNA gene sequence analysis, we identified strain F4 as Mycobacterium sp...
2017: PloS One
Charles E Schaefer, Paul Ho, Christopher Gurr, Erin Berns, Charles Werth
Laboratory batch experiments were performed to assess the impacts of temperature and mineralogy on the abiotic dechlorination of tetrachloroethene (PCE) or trichloroethene (TCE) due to the presence of ferrous minerals in natural aquifer clayey soils under anaerobic conditions. A combination of x-ray diffraction (XRD), magnetic susceptibility, and ferrous mineral content were used to characterize each of the 3 natural soils tested in this study, and dechlorination at temperatures ranging from 20 to 55°C were examined...
September 21, 2017: Journal of Contaminant Hydrology
Yingxin Wu, Yu Wang, Xiongfei Huang, Siyuan Chen, Xi Zhong, Zhuobiao Ni, Xinde Cai, Xiaowen Liu, Marie-Odile Simonnot, Rongliang Qiu
Dredging and disposal is commonly used for cleanup of contaminated sediments, leaving the relocated sediments still in need of remediation. In this study, the feasibility of two approaches to using zerovalent iron (ZVI) in conjunction with surfactants to remediate sediments contaminated by polychlorinated biphenyls (PCBs) and Ni was investigated. Approach A is surfactant desorption followed by ZVI treatment and approach B is a simple mixture of ZVI and sediment in surfactant solution. Results of approach A show that 65...
September 13, 2017: Chemosphere
Zhongliang Yao, Xiaoqian Ma
The PVC waste and bamboo were treated by co-hydrothermal carbonization (co-HTC) at three different temperatures. The inorganic-Cl could be removed from the carbon rich solid products (hydrochar) in the form of HCl via hydrolysis, elimination, substitution and aromatization. Due to the high carbon content, the hydrochar could be applied as premium fuel. Bamboo had a synergistic effect on dechlorination with PVC in the HTC process. The bamboo could accelerate the HTC dechlorination of PVC at 200°C because it strengthened the substitution of Cl with OH...
September 19, 2017: Bioresource Technology
Chaofan Zhang, Liang Fu, Zhengxue Xu, Houfeng Xiong, Dandan Zhou, Mingxin Huo
Intimate coupling of photocatalysis and biodegradation (ICPB) provides superior treatment for the degradation of bio-recalcitrant compounds, such as chlorophenol. Photocatalytically generated intermediates can be promptly used by the enclosed biofilms. Chlorophenol degradation can theoretically be accelerated by a co-substrate or be compromised by the competition for photocatalytic reactive oxygen species (ROS); however, studies to examine the comparison are limited in number. Non-chlorinated phenols commonly co-exist in real wastewater; thus, we evaluated the influence of phenol (hard to photo-oxidize) and pyrocatechol (easy to photo-oxidize) on the degradation of 4-chlorophenol (4CP)...
September 24, 2017: Environmental Science and Pollution Research International
Cui-Wei Chu, Bin Liu, Na Li, Shi-Gang Yao, Dan Cheng, Jia-Dong Zhao, Ji-Guo Qiu, Xin Yan, Qin He, Jian He
Thiobencarb is a thiocarbamate herbicide used in rice paddies worldwide. Microbial degradation plays a crucial role in the dissipation of thiobencarb in the environment. However, the physiological and genetic mechanisms underlying thiobencarb degradation remain unknown. In this study, a novel thiobencarb degradation pathway was proposed in Acidovorax sp. T1. Thiobencarb was oxidized and cleaved at the C-S bond, generating diethylcarbamothioic S-acid and 4-chlorobenzaldehyde (4CDA). 4CDA was then oxidized to 4-chlorobenzoic acid (4CBA) and hydrolytically dechlorinated to 4-hydroxybenzoic acid (4HBA)...
September 22, 2017: Applied and Environmental Microbiology
Shaima Kammoonah, Brinda Prasad, Priyadarshini Balaraman, Hemanshu Mundhada, Ulrich Schwaneberg, Erika Plettner
Cytochrome P450cam (a camphor hydroxylase) from the soil bacterium Pseudomonas putida shows potential importance in environmental applications such as the degradation of chlorinated organic pollutants. Seven P450cam mutants generated from Sequence Saturation Mutagenesis (SeSaM) and isolated by selection on minimal media with either 3-chloroindole or the insecticide endosulfan were studied for their ability to oxidize of 3-chloroindole to isatin. The wild-type enzyme did not accept 3-chloroindole as a substrate...
September 18, 2017: Biochimica et Biophysica Acta
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