| Owing to the worsening of outdoor and indoor air pollution nowadays,indoor air quality are attracting more and more attentions from government and individual persons. The distribution of aerosol particulate is one of the most important pollutants. Because indoor air pollution is an important factor on human health, some effective measures must be adopted to maintain the indoor environment cleanly. Sum-up method was utilized to study indoor particle source and characteristics in the paper. And field sampling and experimental analysis method is used to analyze the physical, chemical and microbial behavior of dust in air-conditioning system, such as quantity of dust per unit area, bulk density of the dust, moisture content, Ph value and dust particle size distribution, etc. Ion chromatography is applied to analyze ion concentration of dust, including Na+,NH4+,K+,Ca(2+),Mg2+,SO42-,NO3-,Cl-,F-. Burning oxidation-nondispersive infrared absorption method is applied to analyze carbonaceous matter dust, including organic carbon (TOC), inorganic carbon(IC) and total carbon (TC). Microorganism training method was used to analyze concentrations of bacteria and fungi in different parts of air-conditioning system. Influence from the carbonaceous matter and water-soluble ion to microorganism growth were selective analyzed. The results revealed that: (1) Internal personnel quantity and personnel flow condition in building has a close relationship with the quantity of dust in air-conditioning system duct. The average particle size of particles deposited in underside of duct is the biggest in three kinds of wall. And the average particle size of particles deposited in top surface of duct is the biggest in three kinds of wall. Along with the increase of particle size, the ratio of particle deposited in the underside increased gradually. For the same type air-conditioning system and using the same kind of material duct, the ratio of dust capacity in bottom area and duct is stable relatively. (2) With the exception of the fresh air section, the average particle sizes of dust fall into the range of 6 and 20μm (the average particle size of dust in the fresh air section is up to 41.30μm). Water-soluble ion concentration of dust in different parts of air-conditioning system is between 7%-20%. TOC, TC, IC concentration of dust in different parts of air-conditioning system is between 2%-7.5%, 2.5%-8.5%, 0.7%-1.2% respectively. Bacteria and fungi concentration of dust in different parts of air-conditioning system is between 60000-210000 CFU/g, 60000-140000 CFU/g respectively. (3) The content of carbon and water soluble ions increases with the decrease of average particle size of dust. Along the supply air direction, the microorganism number of per unit quality dust is a growing trend, however, it is the highest in cooling section. (4) The bacteria number is more than fungi quantity in same sample dust. The correlation between bacteria number and TOC content and water-soluble ion content in dust is more significant than fungi. (5) The microbial concentration per unit area had positive correlation with the content of soluble organic carbon per unit area. Therefore, the filter with high grade efficiency to small particles should be adopted. And disinfection measures should be adopted in the air-conditioning system, especially for fresh air section and cooling section. |
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