A Review of Treatment Wetland Typologies for Wastewater Treatment in Mitigating Freshwater Scarcity

The demand for freshwater continues to increase due to expanding agricultural activities, population growth, industrialization, and climate change-induced droughts. These challenges are further exacerbated by the indiscriminate discharge of untreated wastewater into surface water bodies, leading to the degradation of freshwater resources. Wastewater reuse for irrigation and environmental applications represents a sustainable approach to alleviating freshwater scarcity. However, its implementation is constrained by technical, regulatory, and safety considerations. This review synthesizes current research on wastewater treatment strategies, with a particular focus on treatment wetland systems integrated with complementary technologies such as biofilters, bioreactors, filtration processes, and trophic ponds. The performance of these combined systems in improving effluent quality and enabling safe reuse is critically evaluated. The findings indicate that hybrid treatment approaches can substantially enhance contaminant removal efficiency and improve water quality for reuse. Among the examined methods, the combination of ultraviolet (UV) irradiation with the highlighted disinfection techniques is identified as a promising step for achieving high levels of wastewater decontamination.