Abstract
River pollution has become a growing concern in developing countries. It can affect food supplies, drinking water, and environment hence impacting animal and human health. The present study was designed to explore the potential of floating wetlands (FWs) in partnership with pollutant-degrading bacteria for the clean-up of heavily contaminated water of river Ravi at microcosm scale. River Ravi receives excessive discharges of untreated sewage and industrial wastewater from the Lahore city. To this end, FWs are sustainable alternatives to treat wastewater because of their high efficiency and simplicity in the design and structure. Thus, remediation potential of FWs planted with two macrophytes namely Phragmites australis and Brachia mutica was evaluated in the presence of a consortium five different rhizospheric and endophytic bacteria. We found a significant reduction of organic and inorganic pollutants by the application of FWs, whose potential was further boosted by bacterial inoculation. The performance of P. australis was better than B. mutica. Briefly, plant-bacterial synergism for P. australis reduced COD, BOD5, and TOC up to 85.9%, 83.3%, and 86.6% in 96 h, respectively. Total nitrogen was reduced from 37.5 to 2.07 mg l−1, nitrate from 33.3 to 1.23 mg l−1, and phosphorus from 2.63 to 0.53 mg l−1. Trace metals were also reduced up to 79.5% for iron, 91.4% for nickel, 91.8% for manganese, 36.14% for lead, and 85.19% for chromium. The better persistence of inoculated bacteria was tracked in the root/shoot interior of P. australis, which suggest their potential role in improved pollutant reduction. It is thus concluded that bacterial-assisted FWs may be a suitable choice for the remediation of heavily polluted river water. Furthermore, a field-scale application of FWs for the on-site treatment of contaminated water on the Ravi river is recommended.