Industrial wastewater treatment by downflow hanging sponge system: Techno-economic analysis, life cycle assessment, and sustainable development goals fulfillment

Abstract

While several studies have discussed the performance of downflow hanging sponge (DHS) systems toward industrial wastewater treatment (IWWT), there is still a research gap in exploring the associated profitability scenarios, environmental aspects, and sustainability criteria. The current study elucidated the principles, advantages, and limitations of IWWT by the DHS-based system, giving detailed explanations on the removal mechanisms of heavy metals, dyes, emerging contaminants, and nutrients. The techno-economic analysis revealed profitability indicators of 6.4-year payback period, 819 USD net present value, and 8.9 % internal rate of return from pollutant shadow price, carbon credits, and biogas selling. The life cycle assessment (LCA) observations exhibited minimal impacts on toxicity, eutrophication, acidification, human health, and ecosystem quality at the midpoint/endpoint hierarchy levels. The proposed DHS-based plant could fulfil sustainable development goals (SDGs), primarily SDG#3 by reducing water-borne disease, SDG#6 by enhancing water availability, SDG#13 by minimizing the carbon footprint issue, and SDG#14 by conserving aquatic environment. This study depicted that the techno-financial analysis and LCA tools could be integrated with the design and optimization strategies of DHS, offering insights into profitability and holistic management approaches in sustainable wastewater treatment. Because energy utilization for pumps’ operation emerged as a critical factor influencing the overall LCA score, future investigations should employ biogenic sources for electricity supply and apply artificial intelligence techniques to optimize the equipment operation mode that could reduce the expected CO₂ emissions. Further studies would also consider expanding the inventory data size, incorporating additional operating factors, and validating the LCA outputs experimentally.