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PubMed2002

Measuring and modelling VOC biotransformation rates.

A new protocol was used to determine biotransformation rate coefficients for volatile organic compounds in activated sludge systems. The values obtained from the protocol were compared to biotransformation rates obtained from a pilot plant. It was seen that biotransformation rates were easier to obtain from the protocol. Observations also showed that acclimation of the microorganisms to the volatile organic compounds did not change the biotransformation rates. The experimental conditions were then modelled using TOXCHEM+, a mechanistic model to predict volatile organic compound behaviour. The TOXCHEM+ predictions, using system default biotransformation rates, compared favourably with the low biotransformation rates measured by the protocol for bromoform and the chlorinated compounds, while under predicting the biotransformation rates for the non-chlorinated volatile organic compounds.

Biotransformation↗
PubMed1987

Immunotoxicologic evaluation of chlorine-based drinking water disinfectants, sodium hypochlorite and monochloramine.

Male Sprague-Dawley rats were exposed to chlorine-based disinfectants in the drinking water from weaning to 12 weeks of age, at which time they were terminated and assessed for immune competence. Chlorine-based drinking water disinfectants used were sodium hypochlorite (5, 15 and 30 ppm) and monochloramine (9, 19 and 38 ppm). Parameters of immunity measured were spleen and thymus weights, antibody production, delayed-type hypersensitivity (DTH) reactions, natural killer cell (NKC) cytotoxicity, oxidative metabolism response (i.e chemiluminescence-CL) and phagocytosis by macrophages, and production of 2 immunoregulatory cytokines, interleukin 2 (IL2) and prostaglandin E2 (PGE2). Significant (P less than or equal to 0.05) reductions of spleen weight, DTH reactions, and oxidative metabolism by macrophages were observed only in groups of rats exposed to high levels (30 ppm) of sodium hypochlorite, while PGE2 production was elevated. Rats exposed to the higher doses of monochloramine had reduced spleen weights (38 ppm), decreased antibody synthesis (9 and 19 ppm) and augmented PGE2 production (19 and 38 ppm). These results extend the earlier observations of others that macrophage function of laboratory rodents may be impaired by exposure to high concentrations of chlorinated drinking water. Furthermore, the function of other major populations of immunocytes and types of immune responses may also be altered following subchronic exposure to high concentrations of chlorinated drinking water. These types of effects on the immune system are a previously unrecognized potential side-effect of the ubiquitous practice of disinfection of water with chlorine compounds. Alteration of immune function of chlorine-based disinfectant-exposed rats in this study was only evident at relatively high doses, and only selected immune responses were altered. It appears, therefore, that these chlorine-based disinfectants are not particularly strong immunodepressants. However, further studies in different species may be warranted in order to better extrapolate to implications to human health following chronic low-level exposure.

Animals↗
PubMed1997

Active compost biofiltration of toluene.

Composting of leaves and alfalfa (i.e. active compost) was used for the biofiltration of toluene-contaminated air in a 6-L biofilter (initial bed height: 180 mm). During the thermophilic phase (45 to 55 degrees C), toluene biodegradation rates reached 110 g toluene.m-3.h-1 at an inlet concentration of about 5 g.m-3 and a gas residence time of 90 seconds. The highest rates were obtained in the thermophilic phase suggesting a microbial adaptation was occurring. Biodegradation rates decreased rapidly (50% in 48 h) in the cooling stage. Under mesophilic conditions, the maximum biodegradation rates that could be obtained by increasing the inlet toluene concentration were near 89 g toluene.m-3.h-1 which is similar to that reported in the literature for mature compost biofilters. No volatile by-product was detected by gas chromatherapy. Mineralization of 14C-toluene and benzene showed that they were completely degraded into CO2 and H2O under both thermophilic and mesophilic conditions. Bacteria isolated from late mesophilic stage had the capacity to degrade all BTEX compounds but were not able to transform chlorinated compounds. No organisms were isolated which could use toluene as their sole source of carbon and energy at 50 degrees C. Active compost biofiltration should be an excellent process for the treatment of gaseous BTEX by biofiltration. This is the first report of thermophilic biofiltration of toluene.

Biodegradation, Environmental↗
PubMed2001

Determination of volatile organic compounds in emissions by coal-fired power stations from Spain.

This study concerns the emissions of volatile organic compounds (VOCs) by coal fired power stations. The main compounds are monoaromatic hydrocarbons and aliphatic hydrocarbons, chlorinated compounds have less importance. The influence of combustion parameters can not be clearly established. Emissions factors were calculated and they are smaller than those of other anthropogenic combustions. A comparative study of two sources of VOCs, power stations and motor vehicles, indicates that the environmental impact of the latter are most important.

Air Pollutants↗
PubMedDate not supplied

Lipophylic compounds from Euphorbia peplis L.--a halophytic plant from the Bulgarian Black Sea coast.

The chemical composition of the lipophylic fraction from the halophytic plant Euphorbia peplis L. was investigated. Compared to other terrestrial higher plants an increase of triacylglycerols and especially of glycolipids was observed. The main phospholipid was phosphatidyl choline, followed by almost equal concentrations of phosphatidyl ethanolamine and phosphatidyl glycerol. A relatively high concentration of phosphatidic acids (6.5% of the total phospholipids) was found. The main sterol appeared to be sitosterol and significant amounts of tetracyclic triterpene alcohols were found. The composition of the volatile compounds is relatively simple and only one chlorinated compound, identified as 2,2-diethoxy-1-chloroethane, was found. There was a strong toxicity of the total lipophylic extract towards Artemia salina.

Bulgaria↗
PubMed1991

Fever and respiratory symptoms after welding on painted steel.

Electric-arc welding generates particles and gases that can induce chronic bronchitis and airway obstruction. In this case report two welders are described who had fever, spirometric deterioration, and bronchial hyperreactivity after welding steel painted with chloro-containing polymer lacquer. Pyrolysis of this paint releases many different compounds, for example, hydrogen chloride and complex chlorinated compounds.

Air Pollutants, Occupational↗
PubMed2004

Comet and micronucleus assays in zebra mussel cells for genotoxicity assessment of surface drinking water treated with three different disinfectants.

The aim of this research was to study the influence of classic (sodium hypochlorite and chlorine dioxide) and alternative (peracetic acid [PAA]) disinfectants on the formation of mutagens in surface waters used for human consumption. For this proposal, in vivo genotoxicity tests (Comet and micronucleus assay) were performed in an experimental pilot plant set up near Lake Trasimeno (Central Italy). The effects were detected in different tissues (haemocytes for the Comet assay and gills for the micronucleus test [MN]) of Dreissena polymorpha exposed in experimental basins supplied with lake water with/without the different disinfectants. Specimen collection was performed before disinfectant input for both tests and after the start of disinfection (3 h and 20 days for the Comet assay and 10 and 20 days for micronucleus test, respectively) to assess short- and long- term exposure effects during three sampling campaigns (October 2000, February 2001, and June 2001). Seasonal differences in baseline levels of DNA migration and micronucleus frequency were observed. Raw water quality modulation on disinfection by-product formation was shown. The results of the micronucleus and Comet assays on zebra mussel cells after in situ exposure to water disinfected with the two chlorinated compounds clearly indicate DNA/by-product interaction. PAA did not induce either clastogenic/aneugenic effects or DNA damage on this bioindicator.

Animals↗
PubMed2006

Study on inactivation kinetics of hepatitis A virus and enteroviruses with peracetic acid and chlorine. New ICC/PCR method to assess disinfection effectiveness.

The virucidal activity of chlorine-compounds was studied using hepatitis A virus (HAV) and Poliovirus 2 and comparing the disinfectant efficiency of peracetic acid. HAV presented a higher resistance to HClO than Poliovirus did. With ClO2 the inactivation times of HAV were markedly shorter. A comparison between these data and those resulting from the kinetics with peracetic acid (PA) showed that PA is less effective than chlorine. As a preliminary to future research, the PCR-test integrated with cell-cultures was experimentally introduced for a quick evaluation of the HAV-infectiveness, with the aim of possible application in the field of disinfection and of viruses-isolation from environmental and food samples.

Cell Culture Techniques↗
PubMed2006

Hepatic antioxidant enzymes and total glutathione of Cyprinus carpio exposed to three disinfectants, chlorine dioxide, sodium hypochlorite and peracetic acid, for superficial water potabilization.

This study was carried out in order to assess the effects of disinfectant-treatment on antioxidant response of Cyprinus carpio L. Therefore, enzymatic activities of glutathione S-transferases, glyoxalase I, glyoxalase II, glutathione peroxidases, glutathione reductase, catalase and total glutathione content of carp liver, exposed to surface water treated with three disinfectants for potabilization, sodium hypochlorite, chlorine dioxide and peracetic acid were investigated. Specimens of carp were exposed in four experimental tanks supplied with a continuous water flow from Lake Trasimeno (Italy), three of them treated with constant concentration of sodium hypochlorite, chlorine dioxide and peracetic acid, for 10 and 20 days, while the control tank was supplied with untreated lake water. Differences in biochemical parameters were observed in specimens following exposure to these disinfectants and mainly, chlorine compounds induced marked biochemical variations of carp liver, compared to those induced by peracetic acid treatment. Our results showed that antioxidant parameters of Cyprinus carpio could be used as biomarkers of oxidative stress when this species is exposed to disinfectants for water potabilization.

Animals↗
PubMed2001

Transport issues and bioremediation modeling for the in situ aerobic co-metabolism of chlorinated solvents.

For aerobic co-metabolism of chlorinated solvents to occur, it is necessary that oxygen, a primary substrate, and the chlorinated compound all be available to an appropriate microorganism--that is, a microorganism capable of producing the nonspecific enzyme that will promote degradation of the contaminant while the primary substrate is aerobically metabolized. Thus, the transport processes that serve to mix the reactants are crucial in determining the rate and extent of biodegradation, particularly when considering in situ biodegradation. These transport processes intersect, at a range of scales, with the biochemical reactions. This paper reviews how the important processes contributing to aerobic co-metabolism of chlorinated solvents at different scales can be integrated into mathematical models. The application of these models to field-scale bioremediation is critically examined. It is demonstrated that modeling can be a useful tool in gaining insight into the physical, chemical, and biological processes relevant to aerobic co-metabolism, designing aerobic co-metabolic bioremediation systems, and predicting system performance. Research needs are identified that primarily relate to gaps in our current knowledge of inter-scale interactions.

Aerobiosis↗
PubMed1979

Effect of chlorine substitution on the bacterial metabolism of various polychlorinated biphenyls.

Of 36 pure isomers (chlorine numbers 1 to 5) of polychlorinated biphenyls examined, 23 compounds were metabolized by Alcaligenes sp. strain Y42, and 33 compounds were metabolized by Acinetobacter sp. strain P6. The major pathway of many polychlorinated biphenyl isomers examined was considered to proceed through 2',3'-dihydro-2',3'-diol compounds, concomitant dehydrogenated 2',3'-dihydroxy compounds, subsequently the 1',2'-meta-cleavage compounds (chlorinated derivatives of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acids), and then chlorobenzoic acids. The meta-cleavage products were usually converted to chlorobenzoic acids upon further incubation in many polychlorinated biphenyls, but they accumulated specifically in the metabolism of 2,4'-, 2,4,4'-, and 2,5,4'-chlorobiphenyls, which are all chlorinated at the 2,4'-position in the molecules in common. Dihydroxy compounds accumulated mainly in the metabolism of 2,6-, 2,3,6-, 2,4,2',5'-, 2,5,2',5'-, and 2,4,5,2',5'-chlorobiphenyls by Acinetobacter sp. P6. The 2,3,2',3'-, 2,3,2',5'-, and 2,4,5,2',3'-chlorobiphenyls, which are chlorinated at the 2,3-position of one of the rings, were metabolized in a different fashion. Two major metabolites of a chlorobenzoic acid and an unknown compound accumulated always in the metabolism of this group of polychlorinated biphenyls. 2,4,6-Trichlorobiphenyl was metabolized quite differently between the two organisms. Alcaligenes sp. Y42 metabolized this compound very slowly to trichlorobenzoic acid by the major oxidative route. In contrast, Acinetobacter sp. P6 metabolized it to a trihydroxy compound via a dihydroxy compound.

Acinetobacter↗
PubMedDate not supplied

Comparisons of PCBs dechlorination occurrences in various contaminated sediments.

A comparison was made of reductive dechlorination occurrences of polychlorinated biphenyls (PCBs) by microorganisms collected from contaminated sediments including Er-Jen River (Tainan, Taiwan), Hudson River (Ft. Edward, NY), Silver Lake (Pittsfield, MA) and Puget Sound (Washington State). Comparisons was made in terms of chromatographic data (referring to the biological activity, including microbial availability) and thermodynamic data (demonstrating the selectivity of anaerobic microorganisms in the dechlorination of chlorinated compounds). Chromatographic data was established in terms of difference in relative retention time (delta ln RRT) and thermodynamic data was estimated as heat of reaction (delta H(r)0). Both were calculated and correlated to occurrences of dechlorination reactions. Observed dechlorination reactions for individually introducing PCB congener had delta ln RRT levels measured as >0.47 (Er-Jen River), >0.29 (Hudson River), >0.36 (Silver Lake) and >0.45 (Puget Sound, for Aroclor 1254 dechlorination). Critical of delta H(r)0 and delta ln RRT values showed that Hudson River and Silver Lake microorganisms were capable of dechlorinating PCBs through reactions with larger H(r)0 value (lower levels of released energy) and smaller delta ln RRT value compared with those found in Er-Jen River and Puget Sound sediments. Differences in the critical delta ln RRT values of these sediments may be due to differences in their levels of PCB contamination.

Chlorine Compounds↗
PubMed1996

Element-specific determination of chlorine in gases by Laser-Induced-Breakdown-Spectroscopy (LIBS).

An experimental set-up for the detection of elemental chlorine in chlorinated hydrocarbons (CHCs) is described based on a miniaturized system, which could be used for on-line monitoring of chlorinated compounds. With an optimized time-resolved detection chlorine from CHCs like CCl(4) can be determined by Laser-Induced-Breakdown-Spectroscopy (LIBS) with microg/g-detection limits in the gas phase. The application of a miniaturized Nd : YAG laser resulted only in a minor loss in performance, hence it could be used for designing a rugged and small on-line sensor. In addition, preliminary results for the detection of chlorine via the formation of CuCl in the plasma formed by focussing the laser on a copper surface are reported. Utilizing the luminescence of the CuCl D-system at 440 nm, a tenfold improvement in the detection limits was obtained. It appears that the formation of "ad hoc" selected, small molecules in a laser plasma could be a promising alternative for the selective and sensitive analysis of gaseous chlorinated and other species.

Journal Article↗
PubMedDate not supplied

Enhancement of viral transformation of hamster embryo cells by pretreatment with 4-chloromethylbiphenyl.

Treatment of Syrian hamster embryo cells with 4-chloromethylbiphenyl produced reproducible and quantitative concentration-dependent enhancement of viral transformation the statistical significance of which was independent of cell lethality. These results suggest this compound has carcinogenic potential since positive results in this mammalian cell bioassay system closely correlate with the carcinogenic potential of many diverse compounds and with structurally similar agents, especially other chlorinated compounds.

Adenoviridae↗
PubMed2000

Construction and economics of a pilot/full-scale biological trickling filter reactor for the removal of volatile organic compounds from polluted air.

The design and the construction of an actual 8.7-m3 pilot/full-scale biotrickling filter for waste air treatment is described and compared with a previous conceptual scale-up of a laboratory reactor. The reactor construction costs are detailed and show that about one-half of the total reactor costs ($97,000 out of $178,000) was for personnel and engineering time, whereas approximately 20% was for monitoring and control equipment. A detailed treatment cost analysis demonstrated that, for an empty bed contact time of 90 sec, the overall treatment costs (including capital charges) were as low as $8.7/1000 m3air in the case where a nonchlorinated volatile organic compound (VOC) was treated, and $14/1000 m3air for chlorinated compounds such as CH2Cl2. Comparison of these costs with conventional air pollution control techniques demonstrates excellent perspectives for more field applications of biotrickling filters. As the specific costs of building and operating biotrickling filter reactors decrease with increasing size of the reactor, the cost benefit of biotrickling filtration is expected to increase for full technical-scale bioreactors.

Air Pollution↗
PubMed1994

Degradation of halogenated aliphatic compounds: the role of adaptation.

A limited number of halogenated aliphatic compounds can serve as a growth substrate for aerobic microorganisms. Such cultures have (specifically) developed a variety of enzyme systems to degrade these compounds. Dehalogenations are of critical importance. Various heavily chlorinated compounds are not easily biodegraded, although there are no obvious biochemical or thermodynamic reasons why microorganisms should not be able to grow with any halogenated compound. The very diversity of catabolic enzymes present in cultures that degrade halogenated aliphatics and the occurrence of molecular mechanisms for genetic adaptation serve as good starting points for the evolution of catabolic pathways for compounds that are currently still resistant to biodegradation.

Adaptation, Physiological↗