Effects of Substrate Particle Size and Plant Density on Fluorescence and Microbial Characteristics during the Purification of Leachate by Constructed Wetlands
To examine the influence of substrate particle size and plant density on fluorescence and Microbial characteristics purification of organic matter in landfill leachate treating constructed wetlands,ceramsite and Iris pseudacorus L.were used as experimental materials to construct three constructed wetland treatment systems:particle size 20 mm+plant density 50 plants/m2(K1),particle size 20 mm+plant density 75 plants/m2(K2),and particle size 5 mm+plant density 50 plants/m2(K3).Three-dimensional fluorescence and denaturing gradient gel electrophoresis were used to analyze them.The results showed that there were significant differences in dissolved organic matter(DOM)removal rate,fluorescence intensity,microbial diversity,between K1 and K3 with different structural particle size,and significant differences in fluorescence intensity and microbial diversity between K1 and K2 with different plant densities.Reducing particle size can significantly improve organic matter purification.After 21 days of purification,the removal rate of DOM of K3 is 29.72%higher than that of K1(P＜0.05),and the fluorescence intensity decreases by 5.04(P＜0.01).The contribution rate of particle size to the changes in microbial structure is as high as 57%(P=0.048);Plant density can also promote organic matter removal that is significantly increasing microbial diversity and structure.K2 has a decrease of 0.72 compared to K1 f450/500.Our results suggest that the reduced particle size matrix and increased plant density elevate the microbial abundance and structural diversity and the positive effects can be effectively removed organic pollutants by constructed wetlands purification landfill leachate.
particle sizeplant densityconstructed wetlandslandfill leachatethree-dimensional fluorescencemicrobial community
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