Constructed Wetland, Challenge-Approach-Design

Wastewater/runoff reuse is one of the strategies for sustainable water resource management which, based on the consumption type, requires supplementary treatment and standardization due to a wide range of environmental contaminations. Wastewater recycling not only reduces the pressure on fresh water resources but also is so frugal in comparison to the huge costs and the environmental and socioeconomic impacts of water transfer projects, especially between the basins. Nowadays, the application of bio-methods such as constructed wetlands has increased significantly due to the high cost of conventional wastewater treatment approaches. Constructed wetland systems have different design methods depending on the desired outlook (wastewater or runoff treatment). With regards to the flow patern, the system classifies into free water surface flow, and horizontal and vertical subsurface flow. Design configurations of the constructed wetlands depend on the kinematic description of biological reaction as well as the designer’s knowledge of the flow pattern. In this paper, the related literature is reviewed and the required supplementary treatment of secondary effluent of the treatment plant is presented. Then the performance of different types of constructed wetlands in removal of pollutants is investigated. Finally the principles of constructed wetlands design with the aim of harvesting and treating runoff and wastewater have been thoroughly described. The design criteria are presented based on the observed obstacles for such evolution in the field of water recycling. The feasibility of constructed wetlands is then investigated, especially in arid and semi-arid regions. By presenting the justified plan for the system application, the required measures for site selection of such constructed wetland systems are expressed.