Field trials of a TiO2 pellet‐based photocatalytic reactor for off‐gas treatment at a soil vapor extraction well
16
Citation
8
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract A field trial of a pilot‐scale TiO2 photocatalytic reactor for treatment of off‐gases from a soil vapor extraction (SVE) well at a chlorinated solvent spill site at the Savannah River Site near Aiken, SC, is described. Trichloroethylene (TCE), perchloroethylene (PCE), 1,1‐dichloroethylene (1,1 ‐DCE), and 1,1,1 ‐trichloroethane (1,1,1 ‐TCA) were treated at flow rates up to 6 1/min and space times of 5.1 x 107 to 1.2 x 109 g/mol. The TiO2 used was in the form of porous pellets with a surface area of 150 m2/g. Operation of the reactor with the undiluted waste stream (5000 ppmv) at 80, 100, and 110°C yielded many undesirable byproducts, such as phosgene, chloroform, carbon tetrachloride, and penta‐ and hexachloroethane, even though the conversion of PCE and TCE approached 100%. After diluting the waste stream with ambient air to below 1000 ppmv and maintaining space times around 5 x 108 g/mol, a conversion >99.5% was achieved with the production of only small amounts (<10 ppmv) of hexachloroethane. The reactor was Operated continuously for 8 d, with no noticeable deterioration in catalyst activity. In a subsequent laboratory study to determine the mass balance, CO2 determined in the reactor effluent accounted for 80% of the influent carbon. Key words: gas‐phase photocatalysistitanium dioxideperchloroethylenesoil vapor extractionsoil remediation.Keywords:
Soil vapor extraction
Tetrachloroethylene
Savannah River Site
Groundwater at an abandoned industrial area near Bergamo, Italy, was historically contaminated by tetrachloroethylene (PCE) (>100 µg/L) and, to a lesser extent, by trichlorethylene (TCE), dichloropropane (DP) and 1,1,2,2-tetrachloroethane (R-130).A liquid reagent (EHC ® Liquid) was selected for remediation of groundwater at the site.The reagent is provided in two parts: EHC ® Liquid Mix (a soluble organo-iron salt), and ELS ® Microemulsion (a lecithin-based carbon substrate), and is designed to promote both in situ chemical reduction (ISCR) and enhanced reductive dechlorination (ERD) to destroy chlorinated organic compounds.The two components are mixed with water and injected into the subsurface.Once in groundwater, EHC ® Liquid rapidly generates highly reduced conditions, favouring both biotic and abiotic dechlorination reactions.Less than 6 months after the injection of EHC ® Liquid in the main source area, concentrations of the target contaminants had reached the site-specific remediation target values (CSC Legislative Decree 152/06) in the main monitoring piezometers present in the area, thus demonstrating the effective establishment of enhanced biotic and abiotic reducing conditions and degradation of the target compounds.
Tetrachloroethylene
Reductive Dechlorination
Contaminated groundwater
Cite
Citations (1)
Tetrachloroethylene
Cite
Citations (0)
Abstract A series of human absorption experiments was conducted in which the skin of the hands was exposed to carbon tetrachloride, trichloroethylene, tetrachloroethylene, methylene chloride, or 1,1,1-trichloroethane. The amount of the compound in the alveolar air during the skin exposure and in the postexposure period was determined using gas chromatographic methods. The significance of the skin exposure was estimated by comparing the concentration of the solvent in the alveolar breath following the skin exposure with previously obtained data of the alveolar breath concentration following a vapor exposure to a known concentration of the solvent. The amount of solvent penetrating the skin was related to the area of skin exposed, the method of application to the surface of the skin, the type of skin exposed, and the duration of exposure.
Tetrachloroethylene
Methylene
Methylene blue
Carbon disulfide
Cite
Citations (164)
Abstract Levels of trichloroethylene, tetrachloroethylene and p‐dichlorobenzene in several groundwaters have been determined. Generally, the levels were below 2 μg/1 for the former two compounds, and below 0.1 μg/1 for the latter compound. However, much higher levels (up to 70 μg/1 of trichloroethylene and 4 μg/1 of tetrachloroethylene) were found at two sites. These high levels are likely to be due to gross pollution of the aquifer.
Tetrachloroethylene
Dichlorobenzene
Cite
Citations (10)
Tetrachloroethylene (PCE) and trichloroethylene (TCE), common industrial solvents, are among the most frequent contaminants found in groundwater supplies. Due to the potential toxicity and carcinogenicity of chlorinated ethylenes, knowledge about their transformation potential is important in evaluating their environmental fate. The results of this study confirm that PCE can be transformed by reductive dehalogenation to TCE, dichloroethylene, and vinyl chloride (VC) under anaerobic conditions. In addition, [14C]PCE was at least partially mineralized to CO2. Mineralization of 24% of the PCE occurred in a continuous-flow fixed-film methanogenic column with a liquid detention time of 4 days. TCE was the major intermediate formed, but traces of dichloroethylene isomers and VC were also found. In other column studies under a different set of methanogenic conditions, nearly quantitative conversion of PCE to VC was found. These studies clearly demonstrate that TCE and VC are major intermediates in PCE biotransformation under anaerobic conditions and suggest that potential exists for the complete mineralization of PCE to CO2 in soil and aquifer systems and in biological treatment processes.
Tetrachloroethylene
Biotransformation
Reductive Dechlorination
Cite
Citations (645)
Tetrachloroethylene
Inhalation exposure
Cite
Citations (2)
An innovative environmental restoration technology, in situ air stripping, has been demonstrated at the US Department of Energy (DOE) Savannah River Site (SRS) in South Carolina. This process, using horizontal wells, is designed to concurrently remediate unsaturated-zone soils and ground water containing Volatile Organic Compounds (VOC). In situ technologies have the potential to substantially reduce costs and time required for remediation as well as improve effectiveness of remediation. Horizontal wells were selected to deliver and extract fluids from the subsurface because their geometry can maximize the efficiency of a remediation system and they have great potential for remediating contaminant sources under existing facilities. The first demonstration of this new technology was conducted for a period of twenty weeks. A vacuum was first drawn on the vadose zone well until a steady-state removal of VOCs was obtained. Air was then injected at three different rates and at two different temperatures. An extensive characterization program was conducted at the site and an extensive monitoring network was installed prior to initiation of the test. Significant quantities of VOCs have been removed from the subsurface (equivalent to an eleven-well, 500-gpm, pump-and-treat system at the same site). Concentrations of VOCs in the ground water havemore » been significantly reduced in a number of the monitoring wells.« less
Savannah River Site
Soil vapor extraction
Remedial action
Air stripping
Water well
Groundwater Remediation
Human decontamination
Stripping (fiber)
Cite
Citations (0)
Biodegradation of trichloroethylene and tetrachloroethylene under aerobic conditions was studied in a sediment column. Cumulative mass balances indicated 87 and 90% removal for trichloroethylene and tetrachloroethylene, respectively. These studies suggest the potential for simultaneous aerobic and anaerobic biotransformation processes under bulk aerobic conditions.
Tetrachloroethylene
Reductive Dechlorination
Biotransformation
Cite
Citations (69)
Exposure of the general population to trichloroethylene and tetrachloroethylene under normal environmental conditions, achieved with biological monitoring, was assessed, and the possible influence of these compounds via drinking water on the body burden was revealed. A total of 79 subjects with no known solvent exposure was selected, by stratified sampling, from the residents of the city of Zagreb. Trichloroethylene and tetrachloroethylene were determined in blood, and trichloroethanol and trichloroacetic acid were determined in plasma and urine. Drinking water samples were also analyzed for trichloroethylene and tetrachloroethylene. Concentrations of trichloroethylene and tetrachloroethylene in blood, trichloroacetic acid in plasma, trichloroacetic acid in urine, trichloroethylene in drinking water, and tetrachloroethylene in drinking water were as follows: < 0.015 to 0.090 micrograms/l, < 0.010 to 0.239 micrograms/l, 8.6 to 148.1 micrograms/l, 1.67 to 102.3 micrograms/24 h, < 0.05 to 22.93 micrograms/l, and 0.21 to 7.80 micrograms/l, respectively. The variation in all results presented is probably a reflection of different environmental contamination with trichloroethylene and tetrachloroethylene in the different city areas. Correlation analyses revealed significant relationships between trichloroethylene and tetrachloroethylene in blood (r = .402, p = .0004); trichloroacetic acid in urine and in plasma (r = .522, p = .0000); and trichloroethylene and tetrachloroethylene in drinking water (r = .800, p = .0000). A division of all parameters into a subgroup (n = 58), taking drinking water concentrations of trichloroethylene above 3 micrograms/l as a basis, demonstrated the same significant relationships as mentioned above.(ABSTRACT TRUNCATED AT 250 WORDS)
Tetrachloroethylene
Trichloroacetic acid
Cite
Citations (11)
Gas-liquid balance gas chromatography was introduced to measure the trichloroethylene and tetrachloroethylene in drinking water and source water. in this paper. Examination limits of trichloroethylene and tetrachloroethylene were 0.4ug/L and 0.04ug/L, and the recovery were 97%～103% and 96%～104% respectively.
Tetrachloroethylene
Cite
Citations (0)