Long-term operation of Kickuth-type constructed wetland applied to municipal wastewater treatment in temperate climate

The purpose of this paper is to discuss the problem of changes of effectiveness of Kickuth-type constructed wetland with subsurface flow applied to domestic wastewater treatment. This study is based on an example of a wetland 3000 m² in surface, serving 800 inhabitants, located in Poland. The results of chemical analysis showed that after an initial year of 'start-up time', the efficiency of pollutant removal gradually increased to reach an apex in the 6th year of operation. Such maximum efficiency continued up to the 10th year of operation; afterwards it gradually dropped. Moreover, after 12 years of operation, a serious problem with overland flow was observed, which indicated the porous media clogging processes.