Constructed Wetlands, Surface Flow

Abstract

Constructed wetland (CW) treatment systems are engineered systems that have been designed and constructed to utilize the natural processes involving wetland vegetation, soils, and their associated microbial assemblages to assist in treating wastewater. They are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. CWs for wastewater treatment may be classified according to the flow regime into surface flow (SF or free water surface (FWS)) and subsurface flow (SSF) systems. The FWS CWs could be further categorized according to the life-form of the dominating macrophyte into systems with free-floating, floating-leaved, emergent, and submerged macrophytes. CWs with emergent macrophytes are the most commonly used FWS systems. FWS CWs are found in all continents with majority being in Europe and North America. They have been used around the world for various wastewaters including municipal and domestic sewage, wastewaters from livestock operations, industrial wastewaters including those from agroindustry and landfill leachates. During the last four decades thousands of applications have proved that FWS CWs are viable alternative to conventional treatment technologies.