keyword
MENU ▼
Read by QxMD icon Read
search

Dechlorination

keyword
https://www.readbyqxmd.com/read/28088720/role-of-dissolved-mn-iii-in-transformation-of-organic-contaminants-non-oxidative-versus-oxidative-mechanisms
#1
Erdan Hu, Ya Zhang, Shuyan Wu, Jun Wu, Liyuan Liang, Feng He
Mn(III) is a strong oxidant for one electron transfer, which may be important in the transformation of organic contaminants during water/wastewater treatment and biogeochemical redox processes. This study explored the reaction mechanisms of dissolved Mn(III) with organics. The role of dissolved Mn(III) either as a catalyst or an oxidant in reactions with organics was recognized. Aquo and/or hydroxo (or free) Mn(III), generated from the bisulfite activated permanganate process, facilitated efficient N-dealkylation of atrazine via a β-elimination mechanism, resulting no net redox reaction...
January 7, 2017: Water Research
https://www.readbyqxmd.com/read/28087526/rapid-enrichment-of-dehalococcoides-like-bacteria-by-partial-hydrophobic-separation
#2
Hanna R Temme, Kipp Sande, Tao Yan, Paige J Novak
: Organohalide respiring bacteria can be difficult to enrich and isolate, which can limit research on these important organisms. The goal of this research was to develop a method to rapidly (minutes to days) enrich these organisms from a mixed community. The method presented is based on the hypothesis that organohalide respiring bacteria would be more hydrophobic than other bacteria as they dehalogenate hydrophobic compounds. The developed method tests this hypothesis by separating a portion of putative organohalide respiring bacteria, those phylogenetically related to Dehalococcoides mccartyi, at the interface between a hydrophobic organic solvent and aqueous media...
January 13, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28075122/acetylene-fuels-tce-reductive-dechlorination-by-defined-dehalococcoides-pelobacter-consortia
#3
Xinwei Mao, Ronald S Oremland, Tong Liu, Sara Gushgari, Abigail Amanda Landers, Shaun M Baesman, Lisa Alvarez-Cohen
Acetylene (C2H2) can be generated in contaminated groundwater sites as a consequence of chemical degradation of trichloroethene (TCE) by in situ minerals, and C2H2 is known to inhibit bacterial dechlorination. In this study, we show that while high C2H2 (1.3 mM) concentrations reversibly inhibit reductive dechlorination of TCE by Dehalococcoides mccartyi isolates as well as enrichment cultures containing D. mccartyi sp., low C2H2 (0.4 mM) concentrations do not inhibit growth or metabolism of D. mccartyi. Co-cultures of Pelobacter SFB93, a C2H2-fermenting bacterium, with D...
January 11, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28043044/ascorbic-acid-induced-atrazine-degradation
#4
Xiaojing Hou, Xiaopeng Huang, Zhihui Ai, Jincai Zhao, Lizhi Zhang
In this study, we systematically investigated the degradation efficiency and the degradation mechanism of atrazine in the presence of ascorbic acid at different pH values. Although atrazine could be degraded by ascorbic acid in a wide pH range from 4 to 12, its degradation under either acidic (pH≤4) or alkaline (pH≥12) condition was more efficient than under neutral condition (pH=7). This pH dependent atrazine degradation was related to the reactive characteristic of atrazine and the reductive activity of ascorbic acid...
December 27, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28038879/microbial-polychlorinated-biphenyl-dechlorination-in-sediments-by-electrical-stimulation-the-effect-of-adding-acetate-and-nonionic-surfactant
#5
Hui Yu, Hui Wan, Chunhua Feng, Xiaoyun Yi, Xiaoping Liu, Yuan Ren, Chaohai Wei
The necessity for developing an efficient and cost-effective in situ bioremediation technology for sediments contaminated with polychlorinated biphenyls (PCBs) has prompted the application of low-voltage electrical fields to anaerobic digestion systems. Here we show that the use of a sediment-based bio-electrochemical reactor (BER) poised at a potential of -0.50V (vs. a standard calomel electrode, SCE) substantially enhanced the reduction of 2,3,4,5-tetrachlorobiphenyl (PCB 61) when acetate was added as a carbon source...
December 27, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/28013464/in-situ-remediation-of-contaminated-marinesediment-an-overview
#6
G Lofrano, G Libralato, D Minetto, S De Gisi, F Todaro, B Conte, D Calabrò, L Quatraro, M Notarnicola
Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level...
December 24, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28008985/an-exceptionally-facile-two-step-structural-isomerization-and-detoxication-via-a-water-assisted-double-lossen-rearrangement
#7
Feng Li, Chun-Hua Huang, Lin-Na Xie, Na Qu, Jie Shao, Bo Shao, Ben-Zhan Zhu
N-hydroxyphthalimide (NHPI), which is best known as an organocatalyst for efficient C-H activation, has been found to be oxidized by quinoid compounds to its corresponding catalytically active nitroxide-radical. Here, we found that NHPI can be isomerized into isatoic anhydride by an unusually facile two-step method using tetrachloro-1,4-benzoquinone (TCBQ, p-chloranil), accompanied by a two-step hydrolytic dechlorination of highly toxic TCBQ into the much less toxic dihydroxylation product, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid)...
December 23, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28007851/complete-genome-sequence-of-dehalococcoides-mccartyi-strain-wbc-2-capable-of-anaerobic-reductive-dechlorination-of-vinyl-chloride
#8
Olivia Molenda, Shuiquan Tang, Elizabeth A Edwards
Dehalococcoides mccartyi strain WBC-2 dechlorinates carcinogen vinyl chloride to ethene in the West Branch Canal Creek (WBC-2) microbial consortium used for bioaugmentation. We assembled and closed the complete genome sequence of this prokaryote using metagenomic sequencing from an enrichment culture.
December 22, 2016: Genome Announcements
https://www.readbyqxmd.com/read/28004913/geochemical-parameters-and-reductive-dechlorination-determine-aerobic-cometabolic-vs-aerobic-metabolic-vinyl-chloride-biodegradation-at-oxic-anoxic-interface-of-hyporheic-zones
#9
Siavash Atashgahi, Yue Lu, Javier Ramiro-Garcia, Peng Peng, Farai Maphosa, Detmer Sipkema, Winnie Dejonghe, Hauke Smidt, Dirk Springael
Hyporheic zones mediate vinyl chloride (VC) biodegradation in groundwater discharging into surface waters. At the oxic/anoxic interface (OAI) of hyporheic zones subjected to redox oscillations, VC is degraded via co-existing aerobic ethenotrophic and anaerobic reductive dechlorination pathways. However, the identity of aerobic VC degradation pathways (cometabolic vs metabolic) and their interactions with reductive dechlorination in relation to riverbed sediment geochemistry remain ill-defined. We addressed this using microcosms containing OAI sediments incubated under fluctuating oxic/anoxic atmosphere...
December 22, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/28002948/survival-of-vinyl-chloride-respiring-dehalococcoides-mccartyi-under-long-term-electron-donor-limitation
#10
Koshlan Mayer-Blackwell, Mohammad F Azizian, Jennifer K Green, Alfred M Spormann, Lewis Semprini
In anoxic groundwater aquifers, the long-term survival of Dehalococcoides mccartyi populations expressing the gene vcrA (or bvcA) encoding reductive vinyl chloride dehalogenases are important for complete dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE) to non-chlorinated ethene. The absence or inactivity of vcrA-containing Dehalococcoides results in the accumulation of the harmful chlorinated intermediates dichloroethene (DCE) and vinyl chloride (VC). While vcrA-containing Dehalococcoides subpopulations depend on synergistic interaction with other organohalide-respiring populations generating their metabolic electron acceptors (DCE and VC), their survival requires successful competition for electron donor within the entire organohalide-respiring microbial community...
December 21, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/28002779/degradation-of-chlorinated-paraben-by-integrated-irradiation-and-biological-treatment-process
#11
Shizong Wang, Jianlong Wang, Yuliang Sun
Chlorinated paraben, namely, methyl 3, 5-dichloro-4-hydroxybenzoate (MDHB) is the by-product of chlorination disinfection of paraben and frequently detected in the aquatic environments, which exhibited higher persistence and toxicity than paraben itself. In this paper, the combined irradiation and biological treatment process was employed to investigate the removal of MDHB from aqueous solution. The results showed that the removal efficiency of MDHB and total organic carbon (TOC) by irradiation process increased with radiation dose no matter what the initial concentration of MDHB was...
December 18, 2016: Journal of Environmental Management
https://www.readbyqxmd.com/read/27934265/cosolvent-effects-on-dechlorination-of-soil-sorbed-polychlorinated-biphenyls-using-bentonite-clay-templated-nanoscale-zero-valent-iron
#12
Kai Yu, G Daniel Sheng, Wesley McCall
Zero-valent iron synthesized using bentonite clay as a template (CZVI) was tested for its reactivity toward polychlorinated biphenyl (PCB) dechlorination in soil slurries. Aqueous-phase decachlorobiphenyl (PCB209) was rapidly dechlorinated by CZVI with a reaction rate 10 times greater than that by conventional nanoscale zerovalent iron. This superior reactivity was due largely to the nanoscale size (∼0.5 nm) of the ZVI particles located in the clay galleries. In soil slurries where PCB209 was strongly soil-bound, adding ethanol as an organic cosolvent led to increased PCB209 desorption into the liquid phase, thereby enhancing the PCB209 dechlorination with CZVI...
December 6, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27934264/reductive-dechlorination-of-trichloroethene-by-zero-valent-iron-nanoparticles-reactivity-enhancement-through-sulfidation-treatment
#13
Yanlai Han, Weile Yan
Zero-valent iron nanoparticles (nZVI) synthesized in the presence of reduced sulfur compounds have been shown to degrade trichloroethene (TCE) at significantly higher rates. However, the applicability of sulfidation as a general means to enhance nZVI reactivity under different particle preparation conditions and the underlying cause for this enhancement effect are not well understood. In this study, the effects of sulfidation reagent, time point of sulfidation, and sulfur loading on the resultant particles were assessed through TCE degradation experiments...
December 6, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27934256/black-carbon-facilitated-dechlorination-of-ddt-and-its-metabolites-by-sulfide
#14
Kai Ding, Wenqing Xu
1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) and its metabolites 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), are often detected in soils and sediments containing high concentrations of black carbon. Sulfide (∼5 mM) from biological sulfate reduction often coexists with black carbon and serves as both a strong reductant and a nucleophile for the abiotic transformation of contaminants. In this study, we found that the abiotic transformation of DDT, DDD, and DDE (collectively referred to as DDX) require both sulfide and black carbon...
December 6, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27909745/dechlorination-of-three-tetrachlorobenzene-isomers-by-contaminated-harbor-sludge-derived-enrichment-cultures-follows-thermodynamically-favorable-reactions
#15
Yue Lu, Javier Ramiro-Garcia, Pieter Vandermeeren, Steffi Herrmann, Danuta Cichocka, Dirk Springael, Siavash Atashgahi, Hauke Smidt
Dechlorination patterns of three tetrachlorobenzene isomers, 1,2,3,4-, 1,2,3,5-, and 1,2,4,5-TeCB, were studied in anoxic microcosms derived from contaminated harbor sludge. The removal of doubly, singly, and un-flanked chlorine atoms was noted in 1,2,3,4- and 1,2,3,5-TeCB fed microcosms, whereas only singly flanked chlorine was removed in 1,2,4,5-TeCB microcosms. The thermodynamically more favorable reactions were selectively followed by the enriched cultures with di- and/or mono-chlorobenzene as the main end products of the reductive dechlorination of all three isomers...
December 1, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27903429/polyhydroxyalkanoate-as-a-slow-release-carbon-source-for-in-situ-bioremediation-of-contaminated-aquifers-from-laboratory-investigation-to-pilot-scale-testing-in-the-field
#16
Lucia Pierro, Bruna Matturro, Simona Rossetti, Marco Sagliaschi, Salvatore Sucato, Eduard Alesi, Ernst Bartsch, Firoozeh Arjmand, Marco Petrangeli Papini
A pilot-scale study aiming to evaluate the potential use of poly-3-hydroxy-butyrate (PHB) as an electron donor source for in situ bioremediation of chlorinated hydrocarbons in groundwater was conducted. Compared with commercially available electron donors, PHB offers a restricted fermentation pathway (i.e., through acetic acid and molecular hydrogen) by avoiding the formation of any residual carbon that could potentially spoil groundwater quality. The pilot study was carried out at an industrial site in Italy, heavily contaminated by different chlorinated aliphatic hydrocarbons (CAHs)...
November 27, 2016: New Biotechnology
https://www.readbyqxmd.com/read/27898054/refined-experimental-annotation-reveals-conserved-corrinoid-autotrophy-in-chloroform-respiring-dehalobacter-isolates
#17
Po-Hsiang Wang, Shuiquan Tang, Kayla Nemr, Robert Flick, Jun Yan, Radhakrishnan Mahadevan, Alexander F Yakunin, Frank E Löffler, Elizabeth A Edwards
Two novel chlorinated alkane-respiring Dehalobacter restrictus strains CF and DCA were isolated from the same enrichment culture, ACT-3, and characterized. The closed genomes of these highly similar sister strains were previously assembled from metagenomic sequence data and annotated. The isolation of the strains enabled experimental verification of predicted annotations, particularly focusing on irregularities or predicted gaps in central metabolic pathways and cofactor biosynthesis. Similar to D. restrictus strain PER-K23, strains CF and DCA require arginine, histidine and threonine for growth, although the corresponding biosynthesis pathways are predicted to be functional...
November 29, 2016: ISME Journal
https://www.readbyqxmd.com/read/27894722/impact-of-bio-palladium-nanoparticles-bio-pd-nps-on-the-activity-and-structure-of-a-marine-microbial-community
#18
Andrea Nuzzo, Baharak Hosseinkhani, Nico Boon, Giulio Zanaroli, Fabio Fava
Biogenic palladium nanoparticles (bio-Pd NPs) represent a promising catalyst for organohalide remediation in water and sediments. However, the available information regarding their possible impact in case of release into the environment, particularly on the environmental microbiota, is limited. In this study the toxicity of bio-Pd NPs on the model marine bacterium V. fischeri was assessed. The impacts of different concentrations of bio-Pd NPs on the respiratory metabolisms (i.e. organohalide respiration, sulfate reduction and methanogenesis) and the structure of a PCB-dechlorinating microbial community enriched form a marine sediment were also investigated in microcosms mimicking the actual sampling site conditions...
January 2017: Environmental Pollution
https://www.readbyqxmd.com/read/27892815/monitoring-trihalomethanes-and-nitrogenous-disinfection-by-products-in-blending-desalinated-waters-using-solid-phase-microextraction-and-gas-chromatography
#19
Providencia González-Hernández, Manuel Hernández-Padrón, Verónica Pino, Ana M Afonso, Juan H Ayala
A simple and efficient method has been developed for the extraction and determination of 16 common volatile halogenated disinfection by-products (DBPs) (four trihalomethanes, six haloacetonitriles, and six halonitromethanes) in blending desalinated waters, using headspace solid-phase microextraction and gas chromatography with flame ionization detector (HS-SPME/GC-FID). After the optimization using factorial designs of the HS-SPME parameters (optimum: carboxen/polydimethylsiloxane such as fiber, extraction time of 60 min at 30°C, pH 7, addition of 40% (w/v) of sodium chloride, and desorption time of 2 min at 250°C), quantification limits ranged from 3...
December 14, 2016: Environmental Technology
https://www.readbyqxmd.com/read/27889179/estimation-of-rate-constants-of-pcb-dechlorination-reactions-using-an-anaerobic-dehalogenation-model
#20
Filiz Karakas, Ipek Imamoglu
This study aims to estimate anaerobic dechlorination rate constants (km) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway km values are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM...
February 15, 2017: Journal of Hazardous Materials
keyword
keyword
56405
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"