Monitoring and assessment of ecological systems used for iron and environmental pollutants remediation from aqueous medium

The study assessed the efficiency of three distinct ecological system configurations for removing iron from an aqueous medium. Three systems were designed for the treatment of Fe at concentration of 3 mg/l: TS-1 (using graphite electrode with an applied electric potential of 12 V), TS-2 (using Eichhornia crassipes, an aquatic plant species), and TS-3 (using both Eichhornia crassipes and graphite electrode). During the treatment period of 96 h, TS-1 performed the best in pollutant removal, followed by TS-2 and TS-3. Fe removal ranged from 14 to 99%, NH₄⁺-N reduction ranged from 83 to 100%, COD reduction ranged from 19 to 55%, and PO₄³⁻-P removal ranged from 55 to 60%. pH and ORP were found to have an inverse relationship in all systems. Using correlation and PCA, the outcomes were statistically validated. The SEM image showed that TS-2 had 4.61 times higher Fe deposition on its roots, whereas no deposits were observed in TS-3. Plant chlorophyll and ash content increased in TS-2 but reduced in TS-3, indicating electric potential-induced stress in plants. SEM-EDX examination of electrodes shows O buildup at TS-1 and TS-3 cathodes, indicating O reduction. P, N, and Fe also accumulated on electrodes. More precipitation occurred on cathodes than on anodes. The pollutant reaction order followed first-order kinetics for all systems; and the rate constants K_A were calculated for Fe and COD. The study highlighted the use of coupled electrochemical and ecological systems to remediate Fe from aqueous solutions.