Study On Concentration Prediction And Removal Method Of Biological Contaminants In High Level Biosafety Facility

The distribution and removal of the inner biological contaminants in high level biosafety facility have influenced on human and environment significantly. But in our country, the facts of the comparatively late start on biosafety and the lack of the studies on biological contaminants'distribution, protection and removal in high level biosafety facility leaded to the short of basic theory, the slow design of biosafety facility and underdeveloped decontaminated technology, which constrains the development of the capability of controlling the biohazard of China.In this paper, based on the analysis of the characteristic, transport and removal methods on indoor biological agent and the specialty of high level biosafety facility, a concentration prediction model was set up by integrating with the mass balance model, concentration uniformity and first order decay model hypothesis.According to the review of studies on chamber in the world and the current situation of the high level biosafety facility in our country, this paper analyzed and researched its critical parts, such as physical containment, pressure difference control scheme and test methods. Then the experimental chamber, which meets the biosafety of level four requirement of biosafety facility, is built.In the experimental chamber mentioned above, this paper carried on the experiments on contaminant uniform distribution and gained the exposure condition. Then, using the serratia marcescens (ATCC 8039) as the biocontaminant, the removal efficiency of the microbe was investigated after the exposure condition was established. And a comparison experiment was then conducted with polystyrene latex spheres (PSL) as general particles under the same environmental condition. The results indicated that the indoor biocontaminant was removed effectively and the factors like characteristics andcontaminant size will affect the removal efficiency. And the prediction model was validated at the special condition by comparing with the calculated value by prediction model and the measured value.The part of the research was to determine the decontaminated efficiency of chlorine dioxide (CD) gas on the spores in the high level biosafety facility, choosing Bacillus subtilis var. niger (ATCC 9372) spore as the microbiological indicators. In this study, some experiments were conducted to assess the inactivation of spores in the air under the different CT value (product of CD concentration and disinfection time) of the CD gas generated by the reaction of a chlorine gas–nitrogen mixture and sodium chlorite chips, while other experiments were conducted to assess the inactivation of spores inoculated on six materials (stainless steel, painted steel, PVC, PU, glass and cotton cloth) by CD gas. The CD concentration was measured by the iodine quantity method. The results indicated the spores in the air and surface were effectively decontaminated by CD gas. The factors like recovery ratio of spores, characteristics of materials and prehumidification will affect the log reduction of spores by CD gas.