From past to present: Tracing the evolution of treatment wetlands and prospects ahead

Constructed wetlands (CWs) have played a vital role in mitigating water pollution as a significant technology employed by over 80 countries worldwide since its inception in 1950s. It has witnessed a huge transformation from a series of experiments into an established technology successfully applied in various wastewater treatments. Since its introduction, CW has seen significant advancements and improvements. Over time, this change has been reflected in the design incorporation of hybrid and specialized systems. Also, the addition of operational improvements, such as tidal flow, effluent circulation, and aeration etc., has expanded the technology. Additionally, currently large-scale operations are witnessed in the USA, the Middle East, Asia, and Europe. Together with recent investigations into the removal of new pollutants, substrate optimization for increased pollutant removal reflects the growth in CW research and development. This review assesses the growth of this field by taking a retrospective look at its developmental process from the genesis, highlighting its current state and estimating its expected future technological advancements. CW has had a significant impact on wastewater treatment since its inception, as we look ahead, it offers potential opportunities for future water sustainability due to its versatility and effectiveness in addressing numerous water-related challenges.