A review on constructed wetlands for environmental and emerging contaminants removal from wastewater: traditional and recent developments

The water crisis is a global problem. According to estimates, at least one month of significant water scarcity impacts four billion people, or over two-thirds of the world's population, each year. Thus, the world is looking for sustainable technology to maintain water pollution eradication, wastewater management, and water security. Constructed wetlands (CWs) are the sustainable systems that have demonstrated the potential to remediate several types of wastewater. This review paper covers the details of the constructed wetlands like components, types, design, factors that affect the performance of the CW, life cycle assessment of the CW, circular economy generation, total expenditure, and removal efficiency for various wastewaters. This paper has also discussed the kinetics of the pollutants removal and model used for designing the constructed wetlands, along with newly evolved constructed wetlands. However, the overall performance of all types of CW is remarkable. But the version of the hybrid CW is incredible. It maintains suitability regarding energy consumption, pocket-friendliness, and scalability in every aspect and is applied to various types of wastewaters. The remaining newly engineered CWs are on the way to their progression and acceptance socially, economically, and environmentally. The new generation of constructed wetland technologies is emerging to expand on the achievements of previous (traditional) wetland technologies. They aim to fulfill present market needs or open new market niches.