Dynamic Distributions Of Indicator And Pathogenic Microorganisms In Constructed Wetland

Constructed wetlands(CWs) which are simulating the ecosystems of natural wetlands utilize the cooperation of hydrophyte,soil and microorganisms to purify wastewater.The constructed wetland technology has the advantages of low investment and operation costs,high quality effluent with less dissipation of energy,high loading bearing,simple and convenient operation and management,as well as great value of ecological landscape.So constructed wetlands were widely used for wasterwater treatment,pollutant control and environment improvement.Compared with the traditional secondary wasterwater treatment process,the effects of constructed wetlands to public health and ecological secure should be taken more attention to.The key points of constructed wetland's environmental sanitary assessment are the selection of proper pathogenic and indicator microorganisms,and the study of their behaviors in constructed wetlands.In this study,indicator microorganisms such as total coliforms(TC),faecal coliforms(FC),Escherichia coli(EC),and fecal streptococci(FS),and pathogens such as Clostridium perfringens(CP) and salmonellae(SM) were analyzed from various components of a free water surface constructed wetland.Dynamic distributions and removal efficiency of indicator microorganisms and pathogens in free surface flow constructed wetland were investigated.And the correlation between the indicator and pathogenic microorganisms in the constructed wetland were determined.And the correlation between water quality and the six microorganisms in the constructed wetland were also investigated.The conclusions of the research were shown as follows:(1) Jiaonan sewage treatment system could effectively remove the indicator microorganisms by 99.98%,Salmonella spp.and C.perfringens removal efficiency was relatively low by 98.45%and 96.00%.The constructed wetland could effectively reduce total coliforms by 98.3%,Escherichia coli by 90.9%,fecal coliforms by 84.0%, Salmonella spp.and C.perfringens removal was significantly lower than that of indicator microorganisms by 51.9%and 35.7%,the concentration of fecal streptococci in effluent was higher than that in influent.The quantity of Salmonella spp.in effluent and the C.perfringens in autumn were magnitude greater than indicator organisms.(2) We found strong correlations among total coliforms,fecal coliforms and Escherichia coll.Salmonella spp.showed weak correlations with fecal coliforms,C. perfringens showed weak correlations with total coliforms and fecal coliforms.(3) Total coliforms and fecal coliforms showed a significant correlation with respect to temperature and pH in a certain range.Escherichia coli.showed significant correlations with temperature in a certain range.Fecal streptococci showed significant correlations with NH₄⁺-N,Salmonella spp.showed significant correlations with TN,C. perfringens did not show a correlation with any water quality parameters.