Clogging Mechanism in Vertical-Flow Constructed Wetland: Clogging Cause and Accumulation Distribution Characteristics

In order to solve the problem of clogging in the vertical-flow constructed wetland,the reason of clogging and the distribution rule of clogging substance in the vertical-flow constructed wetland was investigated first.Based on the correlativity of accumulation quantity and banked-up water area or lacuna rate in constructed wetland systems,the results show that the accumulation of non-filter materials is the main reason of clogging.The banked-up phenomenon will occur when the accumulation of non-filter materials is more than 18.23 mg in the per milliliter substrate.Under the condition of this experiment,the clogging phenomenon is easy to take place around current outlet,and accumulation materials mainly distribute in the 10-20 cm upper layer under water pipe.In the substrate,the accumulation degree of that of non-filter inorganic is more obvious than non-filter organic,with the trend of migrating along the water direction. The accumulation of organic and the depth of substrate is negatively correlated,i.e.deeper substrate,less organic content.The organic content in the surface layer of substrate is higher than that in other layers after banking up.