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Dynamic distribution and correlation analysis of indicator- and pathogenic microorganisms in a surface-flow constructed wetland.

SONG Zhi-wen**, SUN Qun, XU Ai-ling, QIAN Sheng-cai, LIU Ling-li, FENG Meng-xue   

  1. (Institute of Environment and Municipal Engineering, Qingdao Technological University, Qingdao 266033, China)
  • Online:2013-01-10 Published:2013-01-10

Abstract: More and more attention has been paid to the potential of constructed wetland in reducing the indicator- and pathogenic microorganisms in wastewater. In this study, six indicator- and pathogenic microorganisms (total coliforms, faecal coliforms,  fecal  streptococci, Escherichia coli, Clostridium perfringens, and Salmonella spp.) were selected to evaluate their removal rate, correlations, and dynamic distribution features in a full scale free-surface flow constructed wetland by the methods of multi-tube fermentation and plate culture. Among the six indicator- and pathogenic microorganisms in the influent of the wetland, Salmonella spp. had the highest individual number, followed by total coliforms, faecal coliforms, C. perfringens, E. coli, and fecal streptococci. The constructed wetland could effectively remove the total coliforms, faecal coliforms, and E. coli, with an average annual removal rate of 94.1%, 93.4%, and 84.0%, respectively. However, the removal rate of Salmonella spp. and C. perfringens was relatively low, with an average annual removal rate of 55.8% and 63.6%, respectively, and existing greater fluctuation. The individual number of fecal streptococci was higher in effluent than in influent. No significant difference was observed in the removal rate of indicator- and pathogenic microorganisms between different seasons, but significant differences were found in the influent total coliforms concentration, influent and effluent Salmonella spp. concentrations, and influent C. perfringens concentration between different seasons. Correlation analysis indicated that there were stronger correlations among the total coliforms, fecal coliforms, and Escherichia coli, but weaker correlations between the Salmonella spp. and fecal coliforms and between the C. perfringens and the total coliforms and fecal coliforms.