Sustainable wastewater treatment using Canna indica in constructed wetlands: A green technology review

Constructed wetlands (CWs) are eco-friendly, low-cost systems increasingly used for wastewater treatment and among the various macrophytes utilized, Canna indica has shown significant potential due to its high adaptability, attractive growth and pollutant removal capabilities. This plant contributes to the treatment process through direct nutrient uptake and by supporting microbial activity in its rhizosphere, enhancing the degradation of organic matter and removal of nutrients and heavy metals. Studies across different CW configurations—including vertical flow, horizontal subsurface flow and hybrid systems—demonstrate effective removal of Biological Oxygen Demand (BOD) 59-98%, Chemical Oxygen Demand (COD) 47-99%, Total Suspended Solids (TSS) 97%, Total Nitrogen (TN) 45-98%, Total Phosphorus (TP) 50-96% and FCB 95-97%. Its application not only improves the functional efficiency of CWs but also adds landscape value, contributing to the ecological and aesthetic benefits of treatment sites. This review highlights the plant’s phytoremediation capacity, operational advantages and potential for integration into sustainable wastewater management systems, while also suggesting future direction for research focused on large-scale implementation, hybrid system design and long-term monitoring. However, despite encouraging research outcomes, critical knowledge gaps persist, including limited long-term field trials, inadequate understanding of plant–substrate–microbe interactions and the need for optimized or hybrid CW configurations to achieve higher efficiency and broader real-world applicability.