Oxides of nitrogen (NOx) [nitrogen oxide (NO) + nitrogen dioxide (NO2)] and sulfur dioxide (SO2) are removed individually in traditional air pollution control technologies. This study proposes a combined plasma scrubbing (CPS) system for simultaneous removal of SO2 and NOx. CPS consists of a dielectric barrier discharge (DBD) and wet scrubbing in series. DBD is used to generate nonthermal plasmas for converting NO to NO2. The water-soluble NO2 then can be removed by wet scrubbing accompanied with SO2 removal. In this work, CPS was tested with simulated exhausts in the laboratory and with diesel-generator exhausts in the field. Experimental results indicate that DBD is very efficient in converting NO to NO2. More than 90% removal of NO, NOx, and SO2 can be simultaneously achieved with CPS. Both sodium sulfide (Na2S) and sodium sulfite (Na2SO3) scrubbing solutions are good for NO2 and SO2 absorption. Energy efficiencies for NOx and SO2 removal are 17 and 18 g/kWh, respectively. The technical feasibility of CPS for simultaneous removal of NO, NO2, and SO2 from gas streams is successfully demonstrated in this study. However, production of carbon monoxide as a side-product (approximately 100 ppm) is found and should be considered. 相似文献
The obvious disadvantages of biotrickling filters (BTFs) are the long start-up time and low removal efficiency (RE) when treating refractory hydrophobic volatile organic compounds (VOCs), which limits its industrial application. It is worthwhile to investigate how to reduce the start-up period of the BTF for treating hydrophobic VOCs. Here, we present the first study to evaluate the strategy of toluene induction combined with toluene-styrene synchronous acclimatization during start-up in a laboratory-scale BTF inoculated with activated sludge for styrene removal, as well as the effects of styrene inlet concentration (0.279 to 2.659 g·m?3), empty bed residence time (EBRT) (i.e., 136, 90, 68, 45, 34 sec), humidity (7.7% to 88.9%), and pH (i.e., 4, 3, 2.5, 2) on the performance of the BTF system. The experiments were carried out under acidic conditions (pH 4.5) to make fungi dominant in the BTF. The start-up period for styrene in the BTF was shortened to about 28 days. A maximum elimination capacity (ECmax) of 126 g·m?3·hr?1 with an RE of 80% was attained when styrene inlet loading rate (ILR) was below 180 g·m?3·hr?1. The highest styrene RE(s) [of BTF] that could be achieved were 95% and 93.4%, respectively, for humidity of 7.7% and at pH 2. A single dominant fungal strain was isolated and identified as Candida palmioleophila strain MA-M11 based on the 26S ribosomal RNA gene. Overall, the styrene induction with the toluene-styrene synchronous acclimatization could markedly reduce the start-up period and enhance the RE of styrene. The BTF dominated by fungi exhibited good performance under low pH and humidity and great potential in treating styrene with higher inlet concentrations.
Implications: The application of the toluene induction combined with toluene-styrene synchronous acclimatization demonstrated to be a promising approach for the highly efficient removal of styrene. The toluene induction can accelerate biofilm formation, and the adaptability of microorganisms to styrene can be improved rapidly by the toluene-styrene synchronous acclimatization. The integrated application of two technologies can shorten the start-up period of biotrickling filters markedly and promote its industrial application. 相似文献
To investigate the chemical composition, size distribution, and mixing state of aerosol particles on heavy pollution days, single-particle aerosol mass spectrometry was conducted during 9–26 October 2015 in Xi’an, China. The measured particles were classified into six major categories: biomass burning (BB) particles, K-secondary particles, elemental carbon (EC)–related particles, metal-containing particles, dust, and organic carbon (OC) particles. BB and EC-related particles were the dominant types during the study period and mainly originated from biomass burning, vehicle emissions, and coal combustion. According to the ambient air quality index, two typical episodes were defined: clean days (CDs) and polluted days (PDs). Accumulation of BB particles and EC-related particles was the main reason for the pollution in Xi’an. Most types of particle size were larger on PDs than CDs. Each particle type was mixed with secondary species to different degrees on CDs and PDs, indicating that atmospheric aging occurred. The mixing state results demonstrated that the primary tracers were oxidized or vanished and that the amount of secondary species was increased on PDs. This study provides valuable information and a dataset to help control air pollution in the urban areas of Xi’an.
Food and Environmental Virology - We present the results of environmental surveillance for poliovirus (PV) and non-poliovirus (NPEV) around the switch from trivalent to bivalent oral polio-vaccine... 相似文献
In this study, we performed a highly time-resolved chemical characterization of nonrefractory submicron particles(NR-PM_1) in Beijing by using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer(HR-ToF-AMS). The results showed the average NR-PM_1 mass concentration to be 56.4 ± 58.0 μg/m~3, with a peak at 307.4 μg/m~3. Due to the high frequency of biomass burning in autumn, submicron particles significantly increased in organic content, which accounted for 51% of NR-PM_1 on average. Secondary inorganic aerosols(sulfate + nitrate + ammonium) accounted for 46% of NR-PM_1, of which sulfate,nitrate, and ammonium contributed 15%, 20%, and 11%, respectively. To determine the intrinsic relationships between the organic and inorganic species, we used the positive matrix factorization(PMF) model to merge the high-resolution mass spectra of the organic species and NO+and NO_2~+ions. The PMF analysis separated the mixed organic and nitrate(NO+and NO_2~+) spectra into four organic factors, including hydrocarbon-like organic aerosol(HOA), oxygenated organic aerosol(OOA), cooking organic aerosol(COA), and biomass burning organic aerosol(BBOA), as well as one nitrate inorganic aerosol(NIA) factor. COA(33%) and OOA(30%) contributed the most to the total organic aerosol(OA) mass, followed by BBOA(20%) and HOA(17%). We successfully quantified the mass concentrations of the organic and inorganic nitrates by the NO+and NO2+ions signal in the organic and NIA factors. The organic nitrate mass varied from 0.01-6.8 μg/m~3, with an average of 1.0 ±1.1 μg/m~3, and organic nitrate components accounted for 10% of the total nitrate mass in this observation. 相似文献