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At least 1,477 records · Page 82Linked to original sources
PubMed2002

Assessment of the estrogenic activity of flue gases from burning processes by means of the yeast based human estrogen receptor (hER) bioassay.

Combustion processes are known to produce organic micro-pollutants in the flue gas at concentrations ranging over several orders of magnitude. Some organic micro-pollutants are suspected of being pseudo-estrogens and as such they can affect the public health. In this study, the possible application of the yeast based human estrogen receptor (hER) bioassay to screen flue gas streams for the presence of estrogenic active micro-pollutants was explored. Specifically, the protocol was modified to allow the detection and quantification of the potential estrogenic active non-polar organic micro-pollutants contained in the flue gas matrix. The modified assay was calibrated using a model estrogenic compound (17-alpha-ethinylestradiol (EE2)) dissolved in methylene chloride at concentrations ranging from 3 ng l(-1) to 3000 ng l(-1). The effective concentration to elucidate a 50% response (EC50) was 87 ng l(-1) of equivalent dissolved in methylene chloride. Samples of methylene chloride used to trap non-polar micro-pollutants in flue gas from combustion of pine wood were found to clearly register estrogenic activity by the bioassay under certain conditions. The combustion tests were performed with pinewood alone and with pine wood in the presence of both Copper-naphthenate and copper(II)chloride at 600 degrees C and 1000 degrees C. These conditions must be considered as experimental rather than practical. Overall, the results suggest that, by means of this modified assay, it is possible and warranted to screen systematically for estrogens in flue gas combustion processes.

Air Pollutants↗
PubMed1991

Indoor and outdoor concentrations of inorganic acidic aerosols and gases.

Annular denuder-filter pack sampling systems were used to make indoor and outdoor measurements of aerosol strong H+, SO4(2-), NH4+, NO3- and NO2-, and the gaseous pollutants SO2, HNO3, HONO and NH3 during summer and winter periods in Boston, Massachusetts. Outdoor levels of SO2, HNO3, H+ and SO4(2-) exceeded their indoor concentrations during both seasons. Winter indoor/outdoor ratios were lower than during the summer, probably due to lower air exchange rates during the winter period. During both monitoring periods, indoor/outdoor ratios of aerosol strong H+ were 40-50 percent of the indoor/outdoor SO4(2-) ratio. Since aerosol strong acidity is typically associated with SO4(2-), this finding is indicative of neutralization of the acidic aerosol by the higher indoor NH3 levels. Geometric mean indoor/outdoor NH3 ratios of 3.5 and 23 respectively were measured for the summer and winter sampling periods. For HONO, NH3, NH4+ and NO2-, indoor concentrations were significantly higher than ambient levels. Indoor levels of NO3- were slightly less than outdoor concentrations.

Acids↗
PubMed2002

The utilization of catalyst sorbent in scrubbing acid gases from incineration flue gas.

Catalyst sorbents based on alumina-supported CuO, CeO2, and CuO-CeO2 were applied to a dry scrubber to clean up the SO2/HCl/NO simultaneously from pilot-scale fluidized-bed incineration flue gas. In the presence of organic compounds, CO and the submicron particles SO2 and HCI removed by the fresh catalyst sorbents and NO reduced to N2 by NH3 under the catalysis of fresh and spent desulfurization/dechloridization (DeSO2/DeHCl) catalyst sorbents (copper compounds, Cu, CuO, and CuSO4) were evaluated in this paper. The fresh and spent catalyst sorbents were characterized by the Brunner-Emmett-Teller method (BET), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), inductively coupled plasma-mass spectrometry (ICP-MS), and the elemental analyzer (EA). The study showed that the performances of CuO, CeO2, and CuO-CeO2/gamma-Al2O3 were better than that of Ca(OH)2. The removal efficiency of SO2 and HCl was 80-95% in the dry scrubber system. Under NH3/NO = 1, NO could not be reduced to N2 because it was difficult to control the ratio of air/fuel in the flue gas. For estimating the feasibility of regenerating the spent catalyst sorbents, BET and EA analyses were used. They indicated that the pore structures were nearly maintained and a small amount of carbon accumulated on their surface.

Absorption↗
PubMed2002

Removal of PCDD/F from incinerator flue gases by entrained-phase adsorption.

The emission abatement of polychlorinated dioxins and furans (PCDD/F) Issued from municipal solid waste incineration is growing in importance because of more stringent emission standards and general concern about their toxic characteristics. These substances cannot be separated by conventional gas cleanup processes but are successfully removed through adsorption onto carbonaceous materials. The simplest technique is the entrained-phase injection of pulverized adsorbents in the flue gas, followed by fabric filter separation. The various related techniques are briefly reviewed here. Operating conditions and results obtained from Flemish MSWIs are given. The results illustrate the excellent overall removal efficiency. Furans are adsorbed to a slightly higher extent than dioxins. PCDD/F removal by carbonaceous adsorbents is thereafter modeled from first principles for the contribution of both entrained-phase (eta1) and cake filtration (eta2) to the overall efficiency (etaT). Application of the model equations and comparison of measured and predicted overall efficiencies for the Flemish municipal solid waste incinerators (MSWIs) demonstrate that the approach is meaningful and that the dominant parameters are the operating temperature, the dosage and activity of adsorbent, and the fraction of adsorbent in the filter cake. The model equations enable the MSWI operators to predict the adsorption efficiencies for any combination of operating parameters and to assess the sensitivity of the process to varying operating conditions.

Adsorption↗
PubMed2005

Biodegradation of trace gases in simulated landfill soil cover systems.

The attenuation of methane and seven volatile organic compounds (VOCs) was investigated in a dynamic methane and oxygen counter gradient system simulating a landfill soil cover. The VOCs investigated were: Tetrachloromethane (TeCM), trichloromethane (TCM), dichloromethane (DCM), trichloroethylene (TCE), vinyl chloride (VC), benzene, and toluene. Soil was sampled at Skellingsted landfill, Denmark. The soil columns showed a high capacity for methane oxidation, with oxidation rates up to 184 g/m2/d corresponding to a 77% reduction of inlet methane. Maximal methane oxidation occurred at 15-20 cm depth, in the upper part of the column where there were overlapping gradients of methane and oxygen. All the chlorinated hydrocarbons were degraded in the active soil columns with removal efficiencies higher than 57%. Soil gas concentration profiles indicated that the removal of the fully chlorinated compound TeCM was because of anaerobic degradation, whereas the degradation of lower chlorinated compounds like VC and DCM was located in the upper oxic part of the column. Benzene and toluene were also removed in the active column. This study demonstrates the complexity of landfill soil cover systems and shows that both anaerobic and aerobic bacteria may play an important role in reducing the emission of trace components into the atmosphere.

Air Pollutants↗