Research On Filtration Performances Of Glass And Synthetic Fibrous Filter Media For Airborne Bacteria Particles

With the development of the air conditioning, bioaerosol contaminant goes into people’s eyes. Bioaerosol can lead to the sick building symptom and respiratory infection. The existence of bioaerosol threatens people’s health and indoor air environment. Until now the methods of controlling bioaerosol are UV disinfection, chemical coating and filtration. Air filtration is the most economical and safe method of all. Filter medias are an important part of filtration process. Filtration media can be divided into glass fibers and chemical fibers. Fiber glass filter material has a wide range of applications in high efficiency air filters. And chemical filter material can be loaded with electrostatic, which leads to higher efficiency and lower resistance. So electrostatic filters are also widely used in markets.Filtration of indoor particulates has been studied extensively[1]. However, the experimental and theoretical study for indoor bioareosol is not comprehensive and systemic because people paid less attention to it before. Three are some reasons for this. The characterized bioaerosol is different from each other. And bioaerosol is different from particles in shape, density and other characters and so on. Senior students did lots of work in bioaerosol filtration. They studied the efficiency of medium efficiency filters and dust loading influence. Our study is based on the former work and studies the bioaerosol efficiency of high efficiency filters at different velocities. The results indicated that the efficiency of Serratia marcescens as the representative of the microbial aerosol on sub-high efficiency and high efficiency filters is very high, close to 100%. Therefore, in microbial less demanding situations, the use of sub-high efficiency or high efficiency filter can already meet the requirements. With the increase of filtration rate, high efficiency filter media for aerosol filtration efficiency of micro-organisms becomes smaller, but the trend is not obvious.As early as in 1930, the practical application of electrostatic in the filter had begun. However, charge strength of electrostatic filter material decreases owing to various reasons, the charge on the filter and may be discharged, resulting the reduce of filtration performance. Filtration performance degradation will lead to the air quality down to standard. For the electrostatic filters, the efficiency after the removal of static electricity is "minimum efficiency." The method of measuring the minimum efficiency with electrostatic filter material is recommended in the EU standard EN779, which is the use of isopropyl alcohol dipping method for anti-static treatment electrostatic filter and then tests the filtration efficiency. The experimental methods we used are fumigation and steaming treatment besides the dipping method. We make comparisons with the three experiments. We measured the filtration efficiency of processing in the initial 4 hours, 8 hours, 24 hours and 48 hours. The results showed that the efficiency obtained by fumigation and steaming shows a similar trend. In the first four hours, the filtration efficiency declines fastest and then keeps stable. The efficiency of dipping approach to the minimum efficiency is much higher than the other two methods, the efficiency. Above all, three kinds of treatment did not cause structural changes in the filter.