Aerobic Biodegradation of Aromatic and Chlorinated Hydrocarbons Commonly Detected in Landfill Leachates

1988 ◽  
Vol 23 (3) ◽  
pp. 460-475 ◽  
Author(s):  
Della J. Berwanger ◽  
James F. Barker
Keyword(s):  
Hydrogen Peroxide ◽  
Surface Sediment ◽  
Chlorinated Hydrocarbons ◽  
Aerobic Biodegradation ◽  
Ethyl Benzene ◽  
Landfill Leachates ◽  
Toxic Level ◽  
Benzene Toluene ◽  
Hazardous Organics

Abstract Aromatic and chlorinated hydrocarbons are hazardous organics which persist in groundwater impacted by landfill leachate. Recent studies have indicated that the aromatics biodegrade readily under aerobic conditions. Similarly, methane-oxidizers are reported to metabolize trichloroethylene. This study investigates an in-situ biorestoration scheme involving stimulating aerobic biodegradation in a contaminated anaerobic, methane-saturated groundwater using hydrogen peroxide as an oxygen source. Batch biodegradation experiments were conducted with groundwater and core obtained from the Gloucester Landfill, Ottawa, Canada. Hydrogen peroxide, added at a non-toxic level, provided oxygen which promoted the rapid biodegradation of benzene, toluene, ethyl benzene, o-, m-, and p-xylene. Morphologically different methane-oxidizing cultures were obtained from Gloucester groundwater and a surface sediment. Both cultures degraded trichloroethylene in microcosms containing a mineral media and Gloucester core. Degradation was not observed when the mineral madia was replaced with Gloucester groundwater, or when other chlorinated hydrocarbons were added. Additional research is required to identify and overcome this inhibition to trichloroethylene biodegradation, before this remedial strategy can be employed.

Sequential anaerobic/aerobic biodegradation of chlorinated hydrocarbons in activated carbon barriers

2002 ◽  
Vol 2 (2) ◽  
pp. 51-58 ◽  
Author(s):  
A. Tiehm ◽  
M. Gozan ◽  
A. Müller ◽  
H. Schell ◽  
H. Lorbeer ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Biological Activity ◽  
Activated Carbon ◽  
Vinyl Chloride ◽  
Reductive Dechlorination ◽  
Chlorinated Hydrocarbons ◽  
Aerobic Biodegradation ◽  
Anaerobic Conditions ◽  
Biological Activated Carbon ◽  
Batch Tests

The aim of this study is to develop a long lasting, sequential anaerobic/aerobic biological activated carbon barrier. In the biobarrier, pollutant adsorption on granular activated carbon (GAC) and biodegradation occur simultaneously. Trichloroethene (TCE), chlorobenzene (CB), and benzene were used as model pollutants. In the first barrier, that was operated under anaerobic conditions with sucrose and ethanol as auxiliary substrates, TCE was completely converted to lower chlorinated metabolites, predominantly cis-dichloroethene (cis-DCE). The reductive dechlorination process was stable for about 300 d, although the concomitant sulphate-reducing and methanogenic processes varied considerably. In the second barrier, that was operated with addition of hydrogen peroxide and nitrate, dechlorination was limited by a lack of oxygen and restricted mainly to CB biodegradation. Additional aerobic batch tests revealed that the metabolites of anaerobic TCE dechlorination, i.e. cis-DCE and vinyl chloride, were oxidatively dechlorinated in the presence of suitable auxiliary substrates such as ethene, CB, benzene, or sucrose and ethanol. During periods of low biological activity, elimination of TCE and CB occurred by adsorption in the GAC barriers. The pre-sorbed pollutants were available for subsequent biodegradation resulting in a bioregeneration of the activated carbon barriers.

Biodegradation of Btex in Subsurface Materials Contaminated with Gasoline: Granger, Indiana

1990 ◽  
Vol 22 (6) ◽  
pp. 53-62 ◽  
Author(s):  
J. M. Thomas ◽  
V. R. Gordy ◽  
S. Fiorenza ◽  
C. H. Ward
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Unleaded Gasoline ◽  
Subsurface Material ◽  
Benzene Toluene ◽  
Contaminated Area ◽  
Microbial Numbers ◽  
Core Materials

The microbial ecology and potential for biodegradation of benzene, toluene, ethylbenzene, and o- and m-xylene (BTEX) in core materials contaminated with unleaded gasoline were investigated. The site studied was unique because a portion of the contaminated area was biostimulated in a demonstration of the use of hydrogen peroxide as an oxygen source in in situ biorestoration. Two years after termination of the field demonstration, core samples were collected from uncontaminated, contaminated, and biostimulated areas at the site and analyzed for inorganic nutrients, microbial numbers, mineralization potential of glucose, benzene, and toluene using liquid scintillation counting, and biotransformation of BTEX using gas chromatography. The results indicated that the subsurface microflora at the site was active and capable of degrading a variety of compounds. Microbial numbers and contaminant biodegradation potential in samples from the biostimulated area were greater than in uncontaminated and contaminated zones. Toluene, ethylbenzene, and m-xylene were removed in all core materials, whereas o-xylene was recalcitrant. Mineralization experiments indicated that toluene was mineralized to a greater extent than benzene. These data indicated that the biodegradation potential of the subsurface material from the biostimulated zone, which still contained residual hydrocarbon, remained enhanced for at least 2 yr after the in situ biorestoration process had been terminated.

scholarly journals A five year record of high-frequency in situ measurements of non-methane hydrocarbons at Mace Head, Ireland

2011 ◽  
Vol 4 (1) ◽  
pp. 913-937 ◽  
Author(s):  
A. Grant ◽  
E. L. Yates ◽  
P. G. Simmonds ◽  
R. G. Derwent ◽  
A. J. Manning ◽  
...  
Keyword(s):  
High Frequency ◽  
Temporal Trends ◽  
Kendall Test ◽  
In Situ Measurements ◽  
Ethyl Benzene ◽  
Air Masses ◽  
Benzene Toluene ◽  
Northern Hemispheric ◽  
Eastern Edge

Abstract. Continuous high-frequency in situ measurements of a range of non-methane hydrocarbons have been made at Mace Head since January 2005. Mace Head is a background Northern Hemispheric site situated on the eastern edge of the Atlantic. Five year measurements (2005–2009) of eleven non-methane hydrocarbons, namely C2–C5 alkanes, benzene, toluene, ethyl-benzene and the xylenes, have been separated into baseline Northern Hemispheric and European polluted air masses, among other sectors. Seasonal cycles in baseline Northern Hemispheric air masses and European polluted air masses arriving at Mace Head have been studied. Baseline air masses show a broad summer minima between June and September for shorter lived species, longer lived species show summer minima in July/August. All species displayed a winter maxima in February. European air masses showed baseline elevated mole fractions for all non-methane hydrocarbons, largest elevations (of up to 360 ppt for ethane maxima) from baseline data were observed in winter maxima, with smaller elevations observed during the summer. Analysis of temporal trends using the Mann-Kendall test showed small (<6%/year) but statistically significant decreases in the butanes, i-pentane and o-xylene between 2005 and 2009 in European air. Toluene was found to have an increasing trend of 34%/year in European air. No significant trends were found for any species in baseline air.

Mechanistische Untersuchungen zum reversiblen Gleichgewicht von metallorganischen Tripeldecker- und Sandwichkomplexen des Typs [Bis{(η5-CpR)Co}-μ-{η4:η4-aren}] und [(η5-CpR)Co(η6-aren)] / Mechanistic Studies towards the Reversible Equilibrium between Metal Organic Triple Decker and Sandwich Complexes [Bis{(η5 -CpR)Co}-μ-{η4 :η4-arene}] and [{(η5-CpR)Co(η6-arene)]

1998 ◽  
Vol 53 (11) ◽  
pp. 1267-1272 ◽  
Author(s):  
Jörg J. Schneider ◽  
Dirk Wolf
Keyword(s):  
Ligand Exchange ◽  
Sandwich Complexes ◽  
Valuable Metal ◽  
H Nmr ◽  
Synthetic Utility ◽  
Metal Organic ◽  
Arene Ligand ◽  
Benzene Toluene

The arene ligand exchange mechanism of slipped arene triple deckers [Bis{(η5-CpR)Co}-μ-{η4:η4-arene}] (R = Me5, 1,2,4 tri-tert butyl, arene = benzene, toluene) 1 was studied by 1H-NMR spectroscopy for different concentrations and solvents. It has been found that triple deckers of type 1 decompose slowly in solution. A unique equilibrium, between these triple deckers and the mixed sandwich complexes [(η6-arene)Co(η5-CpR)] and 14 e [(η5-Cp)Co]solv fragments generated in situ by decomposition o f 1 exists. In addition to this equilibrium arene lability of the thus formed mixed sandwich complex type has been detected by NMR making slipped triple deckers 1 ideal single source compounds for the generation of two [(η5-Cp)Co] fragments in one reaction step. Such fragments are valuable metal ligand components with high synthetic utility in organometallic chemistry.

scholarly journals Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3844
Author(s):  
Lijuan Li ◽  
Bingdong Li ◽  
Liwei Feng ◽  
Xiaoqiu Zhang ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Reaction Medium ◽  
Pure Tio2 ◽  
H2o2 Production ◽  
Tio2 Photocatalyst ◽  
H2o2 Decomposition ◽  
Spin Resonance ◽  
Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

Effects of hydrogen peroxide and hypochlorite on membrane potential of mitochondria in situ in rat heart cells

1991 ◽  
Vol 69 (11) ◽  
pp. 1705-1712 ◽  
Author(s):  
Noburu Konno ◽  
K. J. Kako
Keyword(s):  
Hydrogen Peroxide ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Isolated Rat Heart ◽  
Heart Mitochondria ◽  
High Concentrations ◽  
Isolated Rat

Hydrogen peroxide (H2O2) and hypochlorite (HOCl) cause a variety of cellular dysfunctions. In this study we examined the effects of these agents on the electrical potential gradient across the inner membrane of mitochondria in situ in isolated rat heart myocytes. Myocytes were prepared by collagenase digestion and incubated in the presence of H2O2 or HOCl. Transmembrane electrical gradients were measured by distribution of [3H]triphenylmethylphosphonium+, a lipophilic cation. The particulate fraction was separated from the cytosolic compartment first by permeabilization using digitonin, followed by rapid centrifugal sedimentation through a bromododecane layer. We found that the mitochondrial membrane potential (161 ± 7 mV, negative inside) was relatively well maintained under oxidant stress, i.e., the potential was decreased only at high concentrations of HOCl and H2O2 and gradually with time. The membrane potential of isolated rat heart mitochondria was affected similarly by H2O2 and HOCl in a concentration- and time-dependent manner. High concentrations of oxidants also reduced the cellular ATP level but did not significantly change the matrix volume. When the extra-mitochondrial free calcium concentration was increased in permeabilized myocytes, the transmembrane potential was decreased proportionally, and this decrease was potentiated further by H2O2. These results support the view that heart mitochondria are equipped with well-developed defense mechanisms against oxidants, but the action of H2O2 on the transmembrane electrical gradient is exacerbated by an increase in cytosolic calcium. Keywords: ATP, calcium, cardiomyocyte, cell defense, mitochondrial membrane potential, oxidant, triphenylmethylphosphonium.

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