25 years of research and experiences about the application of constructed wetlands in southeastern Poland

This paper is a review of research and experiences related to the application of constructed wetland systems (CWs) in southeastern Poland in 1992-2016. On the basis of literature data, a comparison between pollutant removal efficiencies of one-stage and hybrid CWs was made. Some problems regarding the operation of these treatment plants were also presented. Data from various facilities indicate that one-stage CWs with horizontal or vertical flow were characterised by a quite high (80-89%) efficiency of removal of BOD5, COD and total suspended solids, but were less efficient in removing of biogenic compounds nitrogen and phosphorus - respectively 59 and 66%. Significantly higher removal efficiencies for the basic pollutants (above 92%) were observed in hybrid CWs with a VF-HF bed configuration. Those facilities removed ca. 65% of total nitrogen and 89% of total phosphorus. A statistical analysis revealed that hybrid VF-HF type CWs were characterised by a very high, about 99%, operation reliability. Lower reliabilities were achieved by one-stage CWs, especially those with a VF bed. Twenty five years of research on and experiences in the application of CWs in southeastern Poland indicate that one-stage CWs can be used on a larger scale in Polish conditions in rural areas with a scattered housing structure. Hybrid systems, on the other hand, can be applied successfully in recreational centres or in protected areas, especially in national parks, where a high pollutant removal efficiency is required. It has been shown that the use of hybrid CWs is consistent with the idea of sustainable development.