Horizontal Flow Constructed Wetlands

The technology of wastewater treatment by means of constructed wetlands with horizontal sub-surface flow was started in Germany based on research by Käthe Seidel commencing in the 1960s (e.g., Seidel, 1961, 1964, 1965 a,b, 1966) and by Reinhold Kickuth in the 1970s (e.g., Kickuth, 1977, 1978, 1981).

Seidel intensified her trials to grow helophytes and hydrophytes in wastewater and sludge of different origin and she tried to improve the performance of rural and decentralized wastewater treatment which was either septic tank or pond system with low purification effect. She planted helophytes into the shallow embankment of tray-like ditches and created artificial trays and ditches grown with helophytes. The system worked effectively and Seidel named this early system the “hydrobotanical method” (Börner et al., 1998). She improved further this method by using sandy soils with high hydraulic conductivity in sealed module type basins planted with different species of helophytes. To overcome the anaerobic septic tank system she integrated a stage of primary sludge filtration in vertically percolated sandy soils grown with Phragmites australis (Seidel, 1965b). The first vertical stage was so called “filter or filtration bed”. The second horizontal flow stage was called “elimination bed” (Fig. 5-1) and was usually planted with Scirpus lacustris. However, too much significance was attracted to the absorption of nutrients by plants and this has been a target for this fundamental concept have been developed over the years. The system itself was revived later and now it is called a “hybrid system”. Both vertical and horizontal flow stages have been used separately as well. criticism (e.g., Nümann, er, 1970). However, numerous variants based on this fundamental concept have been developed over the years. The system itself was revived later and now it is called a “hybrid system”. Both vertical and horizontal flow stages have been used separately as well.