Medium clogging and the dynamics of organic matter accumulation in constructed wetlands

The side-to-side comparative studies were conducted on the unplanted plot and planted plots with two macrophyte species in a Small-Scale Experimental Constructed Wetland System operated under high hydraulic loading condition over a period of one year until the wetland medium was completely clogged. Accumulation dynamics of each organic matter component, and its correlation with the medium permeability coefficient were studied during the clogging process. Our results show that growing plants delayed the medium clogging process in the wetland, and for this purpose Canna indica is more effective than Cyperus alternifolius. The percentage of each component of organic matter was affected by the type of plants. C. indica promoted more strongly the accumulation of the active organic matter whereas C. alternifolius was more effective in enhancing production of fulvic acid. Both plant species led to lower humin contents in the wetland medium. Among all the components of organic matter, labile organic matter and fulvic acid were the leading factors causing wetland clogging, with the former playing the most prominent role in the process.