The application of Scoria-based horizontal subsurface flow constructed wetland for efficient textile wastewater treatment

• Textile wastewater contains excessive pollutants exceeding discharge limits. • A scoria-based wetland with vetiver grass was used for treatment. • The planted system reduced COD to 61.80 mg/L and dye to 27.30 mg/L. • DO increased to 5.80 mg/L, and EC dropped to 440.60 µS/cm post-treatment. • Vetiver-planted wetlands showed superior pollutant removal efficiency. Textile wastewater pollution, primarily caused by synthetic dyes, poses significant threats to aquatic ecosystems and human health. Therefore, this study aimed to treat textile wastewater using a horizontal subsurface flow constructed wetland. The system was developed with scoria as a filter medium and planted with vetiver grass. Various physicochemical parameters of the wastewater were analyzed before treatment. The results showed that wastewater from the Ketema Kebede (KK) textile industry had a chemical oxygen demand (COD) of 995.1 mg/L ± 14.85, a dye concentration of 377.63 mg/L ± 34.71, a temperature of 79.17°C ± 0.35, a dissolved oxygen (DO) level of 1.17 mg/L ± 0.25, and an electrical conductivity (EC) of 1850.07 µS/cm ± 132.40, all exceeding permissible discharge limits, necessitating treatment before discharge. After treatment, the planted constructed wetland significantly improved water quality by increasing DO (5.80 mg/L), slightly lowering pH (7.90), and reducing EC (440.60 µS/cm), COD (61.80 mg/L), and dye concentration (27.30 mg/L). The unplanted system also improved water quality but with lower efficiency, achieving DO (3.80 mg/L), stable pH (8.10), EC (490.30 µS/cm), COD (76.30 mg/L), and dye concentration (38.40 mg/L). Overall, the vetiver-planted constructed wetland exhibited superior pollutant removal efficiency, demonstrating its potential for large-scale industrial textile wastewater treatment.