Water Footprint of Constructed Wetlands – Lutopecny Case Study

¹ Výzkumný ústav vodohospodářský T. G. Masaryka, Podbabská 2582/30, 160 00 Praha, Czech Republic
² Výzkumný ústav vodohospodářský T. G. Masaryka, Mojmírovo náměstí 16, 612 00 Brno, Czech Republic
³ České vysoké učení technické v Praze, Fakulta stavební. Thákurova 2077/7, 166 29 Praha, Czech Republic

^* Corresponding author: libor.ansorge@vuv.cz

Abstract

Constructed wetlands (CWs) are effective low-cost applications of nature-based solutions to the treatment of wastewater from small municipalities and isolated dwellings. One type of evaluation of CWs is focused on the effectiveness of wastewater treatment. Another type of CWs evaluation is focused on water balance because wetland plants are adapted to growth in conditions of unlimited water availability, which is associated with a high rate of evapotranspiration. In this study, the water footprint (WF) was used for joining these two evaluations. The blue WF describes water loss from CWs. The grey WF is an indicator of the effectiveness of CW in terms of pollution reduction. This is the first study of CWs that compares the importance of blue and grey WF under different climatic conditions during the year. Data from different seasons were used to calculate the WF of the CW in a temperate climate zone. During cold days, the grey WF is several times higher than the blue WF. Another situation occurs on hot summer days when the blue WF is higher than the grey WF. On all assessed days, the grey WF reduction was higher than the blue WF reduction; it means that the CW saves more clean water in the recipient (needed to dilute discharged pollution) than losses by evapotranspiration.