A state-of-the-art review (2019–2023) on constructed wetlands for greywater treatment and reuse

Faced with increasing water scarcity, the potential of greywater reuse stands out, but requires effective treatment of to remove organic matter, pathogens, surfactants, and suspended solids. Constructed Wetlands (CW) are sustainable and decentralized technologies gaining increasing prominence for this propose. They are recognized for their low-cost, simplicity, and effectiveness in wastewater treatment, producing effluents that meet quality standards for reuse. Despite their advantages, there is a need for a deeper understanding of the factors that influence their performance and efficiency. This review aims to fill this gap by systematically analyzing the current research on CW technology, identifying key variables that affect its application and potential for improvement. A systematic review considering the period 2019–2023 was carried out using Methodi Ordinatio, a multicriteria decision-making methodology. The search databases were Science direct, Web of science and Scopus. This approach involves structures process for selecting scientific articles, resulting in a bibliographic portfolio of recent studies,. The initial search yielded 291 retrieved titles, and through multicriteria selection, 48 studies were chosen for in-depth analysis. Existing studies allowed to evaluate the ways in which CW systems are applied. The review highlights how CW systems are applied, the influence of substrates type, plants, and operational criteria which emerged as the primary factors influencing the technology's performance. This review also highlights the growing use of construction waste and biochar as substrates, which have shown promise in enhancing CW efficiency. Despite the focus on greywater "reuse", for articles selection, it was observed that the topic was scarcely addressed, thus suggesting that studies on CW application for greywater water reuse remains underexplored. This review provides a state-of-the-art synthesis of CW technology, offering valuable insights into how specific design and operational choices impact system effectiveness. It serves as a worthwhile resource for enhancing the efficiency and application of CW in sustainable wastewater management.