HYDRO-FILTER: an experimental pilot integrating phytoremediation and adsorption for sustainable wastewater treatment

In arid regions facing severe water scarcity, phytoremediation coupled with efficient treatment and reuse of non-conventional water resources is vital for sustainable development and environmental preservation. This study evaluates the PV-Hydro Filter, an integrated technology that synergizes mechanical filtration, chemical adsorption, and phytoremediation. The system utilizes a multi-layered sand and coal residue filter as a primary stage, followed by a secondary hydroponic phytoremediation unit featuring two plant species Cyperus papyrus and Nerium oleander. To evaluate the efficiency of this multi-stage system, comprehensive physical, chemical, and microbiological analyses were performed on water samples, alongside physiological assessments of the plants and seed germination assays. Results demonstrate that this dual-treatment approach is highly effective, achieving removal rates of 79% for nitrates, 87% for nitrites, and 85% for phosphates, while simultaneously reducing the organic load with biological oxygen demand and chemical oxygen demand removal between 75% and 85%. Microbiological analysis confirmed the system's superior disinfection capacity, achieving a total elimination of Escherichia coli in the final stage. Plant physiological assessments revealed high adaptation to the wastewater environment. While C. papyrus exhibited higher chlorophyll a levels, N. oleander showed a substantially higher concentration of chlorophyll b at 59.02 mg. g^-1 and higher total chlorophyll concentrations, indicating robust photosynthetic health. Furthermore, the phytotoxicity of the treated water was validated through seed germination tests, where experimental groups irrigated with treated effluent showed a superior germination rate of 100% compared to the 73.3% observed in the control group, confirming the water's safety and nutrient-rich quality for irrigation.