Municipal wastewater treatment using constructed wetlands

The aim of the paper is to present alternative to conventional (i.e., the commonly used biological treatment plants) wastewater treatment systems, appropriate for small communities and settlements. These systems are the natural treatment systems. The emphasis here is given on constructed wetlands (CWs). First, advantages and disadvantages of these systems are presented compared to conventional systems. Design guidelines from various EU countries for CW systems used in municipal wastewater treatment, and data on the operation of such systems in Greece are presented. Finally, the wastewater treatment facility in Korestia municipality, Kastoria prefecture, Northern Greece, is described, where this technology was employed. The system was designed as a hybrid system, consisting in series of vertical flow CW beds (1 and 2 stage) and a horizontal subsurface flow bed (3 stage) to serve 600 population equivalent (p.e.). The first stage consists of 3 identical beds, with a total surface area of 891 m or 1.5 m/p.e.; the second stage comprises two identical beds, with a total surface area of 594 m or 1.0 m/p.e., and the third stage of one bed with a surface area of 903 m or 1.5 m/p.e. The total construction cost was 286,282 € or 477 €/p.e. The expected operating cost was estimated at 7,121 €/year, or 11.87 €/p.e./year. The use of constructed wetlands, as appropriate wastewater treatment method in small settlements, is proposed.