Sustainable wastewater treatment via hydroponic Cultivation of stinging nettle: a phytoremediation approach

Water pollution from textile industries poses severe ecological risks due to the presence of toxic dyes, heavy metals, and persistent organic pollutants. This study evaluates the phytoremediation potential of <i>Urtica dioica</i> (stinging nettle), a locally abundant species in Himachal Pradesh, for treating textile wastewater using a coconut-coir-based hydroponic system. Untreated effluent from India textile industry, was subjected to a 40-day treatment under controlled conditions, followed by physicochemical and biological analyses in accordance with American Public Health Association (APHA) and Indian standards (IS). The system achieved substantial reductions in cadmium (84.62%), zinc (92.31%), lead (93.33%), Biochemical oxygen demand (BOD 89.32%), Chemical oxygen demand (COD 79.2%), phenolic compounds (81.81%), and ammonical nitrogen (98.36%), alongside notable improvements in water clarity, color, and odor. Post-harvest biomass management through pyrolysis or phytomining supports circular economy applications and safe disposal. Compared to conventional methods, this hydroponic phytoremediation approach is cost-effective, energy-efficient, and produces minimal sludge or hazardous by-products. The findings highlight the potential of hydroponically cultivated <i>Urtica dioica</i> as a scalable, low-cost, and sustainable solution for decentralized wastewater treatment, advancing green engineering practices.