| Ventilation and air conditioning system and air conditioner is an essential part of the building.If the operation and maintenance of air condit ioning is not proper,the polluted microorganis ms will mult iply in a large number under the appropriate temperature and humidity and enter the room with the air supply.Therefore,in view of the air conditioning microbial pollution problem,this paper mainly carries on the following research:In this study,the effects of duct material(phenolic composite board,glass magnesium composite board,color steel glass fiber composite board,galvanized iron sheet),airflow parameters(temperature,relative humidity)and time on the growth of dust associated microorganisms were studied on the air conditioning duct model test-bed with controllable airflow parameters.The results showed that the relationship of bacterial concentration on different duct materials was: glass magnesium composite board < color steel glass fiber composite board < phenolic composite board < galvanized iron sheet;the relationship of fungal concentration was:glass magnesium composite board < phenolic composite board < color steel glass fiber composite board < galvanized iron sheet,therefore glass magnesium composite board had the strongest inhibitory effect on microbial growth.With the increase of temperature or relative humidity,the growth rate of dust associated bacteria and dust associated fungi increased,and the microbial concentration re ached the peak at 24 h or 36 h,and then decreased significantly.The influence of temperature and relative humidity on bacteria is greater than that on fungi.Furthermore,through the orthogonal experiment analysis,it is concluded that the glass magnesium composite board has the strongest inhibitory effect on the growth of dust associated microorganisms at 21°C and 40-50%RH.The dust of air conditioning system(filter screen,fans,air cooler,supply air duct and indoor)in block A of campus library and air conditioning unit(filter screen)in block B of library were sampled,and the dust of air condit ioner or indoor windowsill in office,laboratory,classroom and dormitory were sampled.The results are as follows: because the air cond itioning unit of library A was not cleaned before sampling,according to the hygienic standard,the dust at each sampling point was seriously over the standard,the total number of dust associated bacteria and dust associated fungi reached the standard,but the total number of dust associated bacteria in the filter screen barely met the standard;because the air conditioning unit of library B has been cleaned before sampling,according to the cleaning specifications,the dust residue,dust associated bacteria and dust associated fungi in the filter screen are far from the standard,so the cleaning effect of the air conditioning unit of library B is not ideal;the air conditioner filter screen and indoor windowsill of office,laboratory,classroom and dormitory are polluted seriously by microorganism.The Metagenome sequencing was used to analyze the diversity of all measured samples and experimental samples under certain condit ions.The results showed that the main bacteria in the sequencing samples were Burkholderia,Phenylobacterium,Bacillus,Methylobacterium,Sphingomonas,etc.;the main fungi were C ladosporium,Aspergillus,Aureobasidium,Alternaria,Schizophyllum,Penicillium,etc.Correlation analysis of sequencing samples,bacterial correlation results: all samples are positive correlation,the overall correlation is good,some correlation coefficient is more than0.8,with significant correlation;fungal correlation: except for three samples,the rest of the samples are posit ive correlation,the overall correlation is good,some samples have significant correlation.In this paper,experimental research,field test and Metagenome sequencing are effectively combined to provide scientific reference for improving air conditioning system,air conditioner and indoor microbial environment. |
