A new operation mode solving clogging problems of horizontal subsurface constructed wetlands
Horizontal subsurface constructed wetland (SSFCW) has been widely used to treat wastewater, however the capacity of SSFCW is severely confined by clogging problems which are very common during the lifespan of a SSFCW. Therefore it is of great practical significance to improve the performance of SSFCW. In this study, a new operation mode by changing the flow direction periodically was executed and the performance on the pollutants removal was studied. Three years' experimental results showed that the SSFCW with new operation mode achieved better pollutant removal efficiency compared with the performance obtained under traditional operation mode. The microorganism test showed that the reciprocating SSFCW had larger quantity microorganism which effectively prevented organic compounds accumulation. The readings of gauge glass in the traditional SSFCW rose gradually, while the water level kept stable in reciprocating one, which also reflected the severity of the clogging problem in the two wetlands. During the whole operation period, the SSFCW with reciprocating operation mode didn't have any infiltration problem, while SSFCW with traditional operation mode had visible clogging problems as a result of pollutants accumulation in the inlet zone.
Keywords: clogging problem, reciprocating operation mode, removal efficiency, SSFCW