Phytoremediation in constructed wetlands

Contamination of water by toxic pollutants through the discharge of municipal, domestic, hospital, and industrial wastewater has become a worldwide environmental problem due to its serious consequences on human health, agricultural crop productivity, and aquatic ecosystems. Phytoremediation using constructed wetlands (CWs) has become a logical solution to improve the quality of contaminated waters by acting as a sink for various contaminants. Hence, the present chapter is aimed to provide a concise discussion of the CWs and its phytoremediation attributes as a plant-based cleanup technology for the remediation of wastewaters. The CWs are complex ecosystems due to variable conditions of hydrology, soil and sediment types, plant species diversity, growing season, and water chemistry. Macrophytes play a vital role bringing necessary physical effects in order to remove and retain pollutants. The hydrology is the key of CWs which defines the species diversity, productivity, and nutrient cycling. The classification of CWs is based on vegetation type, hydrology, and flow direction. Various types of CWs are now being combined into hybrid systems, in order to achieve better treatment performance. Hence, phytoremediation in CWs is being of increasing interest to remediate metals and metalloids, nutrients, volatile organic compounds (VOCs), hydrocarbons, pesticides, pharmaceuticals, explosives, polycyclic aromatic hydrocarbons (PAHs), and pathogens. The relatively brief history of phytoremediation using constructed wetlands has been endeavored for most field applications in order to remediate hazardous pollutants in wastewater and thereby healing the Earth.