Comparative Performance of Canna indica and Saccharum spontaneum in nature-based Systems for treatment of antibiotic-laden wastewater

Cattle feedlot wastewater contains high organic and nutrient loads along with residual veterinary antibiotics, posing risks to downstream soil and groundwater quality. This study evaluates Macrophyte-Assisted Vermifiltration (MaVF) as a sustainable, low-energy, nature-based treatment system for such antibiotic-rich wastewater. A comparative assessment was conducted using two macrophyte species, Canna indica and Saccharum spontaneum, integrated into vermifiltration units and monitored for 126 days. Weekly analyses included COD, nutrients (TN, TP, NH₄⁺–N, PO₄³⁻–P), and commonly occurring antibiotics. MaVF–Canna demonstrated the highest treatment efficiency, achieving 56.1 ± 1.6 % COD removal, 43.4 ± 1.7 % TN removal, and 50 ± 5.4 % TP removal. Antibiotic removal across the MaVF systems ranged from 36–54 % for most compounds, with Canna indica consistently outperforming Saccharum spontaneum. MaVF–Canna exhibited superior performance compared to MaVF–Saccharum, which can be attributed to the higher root density, faster growth rate, and greater rhizosphere oxygenation capacity of Canna indica. These traits enhance plant–microbe–earthworm interactions, leading to improved degradation of organics, nutrients, and antibiotics. Ampicillin showed limited removal (2–4 %) across all systems, reflecting its known recalcitrance. A life cycle cost (LCC) assessment revealed that MaVF provides an economically viable and resource-efficient alternative to conventional systems, with a total treatment cost of 261 ₹ m⁻³. The low operational energy demand and use of locally available materials further support its suitability for decentralized rural applications. Overall, the findings underscore the potential of MaVF particularly with Canna indica as a climate-resilient, cost-effective, and environmentally sound nature-based solution for mitigating antibiotics and co-occurring pollutants in livestock wastewater.