Surface-Flow Constructed Treatment Wetlands for Pollutant Removal: Applications and Perspectives

Abstract

I review the technology and application of free-water surface flow (FWS), macrophyte-dominated constructed treatment wetlands (CTWs) for pollutant removal. FWS-CTWs are used to remove a wide range of pollutants from various wastewaters. In FWS-CTWs, hydrologic conditions have a key influence on the biotic community, biogeochemical processes, and the fate of pollutants. Therefore, understanding the interactive effects of hydrology and biotic communities is critical to pollutant removal. In the past two decades, studies and applications of FWS-CTWs have increasingly focused on four wetland technologies: 1) tertiary treatment wetlands, 2) submerged aquatic vegetation (SAV) dominated systems, 3) FWS constructed wetlands for watershed management, and 4) hybrid systems. Managing FWSCTWs, including adjustment of flow and water depth is crucial to the sustainability of effective treatment. Multiple functions and services of FWS-CTWs such as biological conservation and other ancillary benefits can be added while FWS-CTWs are applied to wastewater treatment. To reduce the acreage necessary for pollutant removal, coupling FWS-CTWs with other technologies has an application perspective for water quality improvement. Using FWS-CTWs is cost effective and environmentally sound for water sanitation, reuse, and conservation and supports sustainable resource management.

Long-term phosphorus removal in the Everglades stormwater treatment areas of South Florida in the United States

“…Stormwater CWs have a wide range of P removal efficiencies, 30-90% (Coveney et al, 2002;Kadlec, 2006;Chen and Vaughan, 2014). Mechanisms for P removal from the water column include sedimentation, soil adsorption, chemical precipitation, biotic uptake, and peat accumulation (Reddy et al, 2011;Chen, 2011). Chemical precipitation of P with metals, such as calcium, is pH-related and particularly important in SAV dominated wetlands (Dierberg et al, 2002;Chen, 2011).…”

“…Mechanisms for P removal from the water column include sedimentation, soil adsorption, chemical precipitation, biotic uptake, and peat accumulation (Reddy et al, 2011;Chen, 2011). Chemical precipitation of P with metals, such as calcium, is pH-related and particularly important in SAV dominated wetlands (Dierberg et al, 2002;Chen, 2011). Due to the potential to return to the water column that depend on the hydrologic regime or soil redox conditions, the chemically precipitated and adsorbed P in sediments is short-term P sequestration (Patrick and Khalid, 1974;Reddy et al, 1999).…”

Role of Wetlands

“…Emergent, submerged and/or free-floating aquatic species form a part of both natural and constructed wetlands (Brix 1994(Brix , 1997 nuttallii, Potamogeton pusillus and Najas guadalupensis are present in many natural and constructed wetlands (Chen 2011).…”

Sustainability of the constructed wetland based on the characteristics in effluent

“…N and P) from various wastewaters including storm water runoff and municipal wastewater (Ghermandi et al 2007;Vymazal 2007;Snow et al 2008;Cooper 2009;Kadlec 2009;Chen 2011). Because of high removal efficiency, low cost, water and nutrient reuse, and other ancillary benefits, CWs have become a popular option for wastewater treatment (Ghermandi et al 2007;Rousseau et al 2008;Kadlec 2009;Llorens et al 2009).…”