Papers by Keyword: Bioaerosol

Abstract: Bioaerosol is commonly present indoors, which may affect human health. In this study, the feasibility of water-soluble chitosan as a biochemical environment protestant to remove bioaerosol from the outpatient clinic was evaluated. Results indicated the predominant bacteria existed in the outpatient clinic included Klebsiella pneumoniae, Bacillus amyloliquefaciens, Corynebacterium callunae, Bacillus cereus and Moraxella sp. The minimum inhibitory concentration (MIC) and inhibition zone of water-soluble chitosan against these strains ranged from 3500-6500 ppm and 2-6 mm, respectively. When the vaporized water-soluble chitosan (500-4000 ppm) was applied in removing bioaerosol from the outpatient clinic, >90% efficiency was achieved at 50 ml/h after 4 h treatment. However, the bioaerosol removal was also attained to 90% after 50 h continuous treatment by a diluted water-soluble chitosan solution (100 ppm). Based on the cost and efficiency consideration, the bioaerosol reduction using a diluted water-soluble chitosan solution for a long-term treatment was practical. These results clearly illustrated that water-soluble chitosan has a great potential as a biochemical environment protestant to remove bioaerosol.

Abstract: Lidar is the main standoff detection system against bioagent/bioaerosol, An infrared lidar has been developed for bioagent/bioaerosol monitoring. The overall architecture and specifications of the lidar were described. The results of overlap coefficient, horizontal and slant measurements at Hefei, such as comparison of observed horizontal extinction coefficients between commercial MPL Lidar and the IRLidar, the slant path time-space extinction coefficient distributions have been revealed and discussed. The results show that the IRLidar is a reliable lidar with advanced performances.

Abstract: A novel DC corona discharge technology was applied on inactivation of bioaerosol in indoor air. A wide range of initial concentration of microorganisms (from 35×10⁴ CFU/m³ to 3×10⁶ CFU/m³) was tested to show excellent germicidal properties for its high inactivation efficiency. Over 99.997% of microbe into the reactor were inactivated at t=150s, E_P 2kV/cm and initial population was 3.0×10⁶ CFU/m³. The effects of active species produced by a DC corona discharge on the inactivation of a mixture of bacteria in flowing aerosol were proved. The active radicals like OH radical which acted on microbes in the way of direct oxidation were the most significant factors influencing the microbe inactive efficiency through the assessment of heat variety, ultraviolet emission and ozones generation. The active radicals generation in the process of sterilization can be simply controlled by regulating applied voltage before ozone generated. The results indicate that use DC corona discharge technology in the future application of indoor air decontamination.

Abstract: The paper presents the research results of the airborne bacteria collected at the wastewater treatment plants working with activated sludge system. Samples were taken by a six-stage Andersen Impactor placed near the aeration chambers. Bacteria cought at Petri plates were incubated at room temperature for 4 days, then analyzed in a macroscopic and microscopic way. This initial investigation was aimed at morphological characteristics of colonies and breeding characteristics of particular strains to giver general overwiev. Bacteria were identified on the basis of their metabolic properties using API biochemical tests. The essential studies were carried out using JOEL scanning electron microscope (FE-SEM model with field gun 7600[F]), equipped with "Cryo-SEM”, which gives the possibility of testing delicate biological samples in a frozen state. Its high resolving power and large depth of field allows to obtain images of surface structure of microorganisms in a magnification range from 1 000x to 70 000x. Bacteria samples were analyzed also in a fructured state what revealed internal structes and the thickness of cell walls which was in the range of 0,080-0,180 [μm]. Moreover, elemental composition of the surface layer of bacterial was also examined using photoelectron spectroscopy (XPS). Dominant elements were carbon, oxygen and nitrogen. Analysis of main line (C1s, O1s, N1s) allowed the identification of chemical composition of studied bioaerosols. Investigation found that the main compounds were polymers such as peptides and polysaccharides, as well hydrocarbon like compounds.