Constructed wetlands for water treatment

Abstract

This paper gives an introduction to constructed wetland technology. The term constructed wetland as used in this paper describes an artificial wetland designed to improve water quality. Constructed wetlands provide the optimal treatment conditions found in natural wetlands but have the flexibility of being constructed. The two main types of constructed wetlands are described: surface flow and subsurface flow constructed wetlands (subsurface flow constructed wetlands are further subdivided into horizontal and vertical flow constructed wetlands). The removal mechanisms for main constituents of wastewater (organic matter, nitrogen, and phosphorus) and for additional pollutants (heavy metals, special organic compounds, and pathogens) are discussed as well as the role of plants in the treatment process. The treatment efficiency for heavy metal removal with constructed wetlands is shown as an example. A simulation tool for subsurface flow constructed wetlands is presented that is capable to model the transformation and elimination processes for the main constituents of wastewater (organic matter, nitrogen, and phosphorus). Simulation results for a pilot-scale constructed wetland for wastewater treatment are shown.