A techno-economic assessment for the water-energy-carbon nexus based on the development of a mathematical model: In the iron and steel industry

Abstract

In the steel industry, due to its high dependence on water and energy resources, it is possible to achieve the goal of sustainable development with energy and water production based on renewable energies and urban wastewater treatment (WWT) and reducing CO2 emissions. The use of municipal wastewater as a renewable resource in the resource supply chain necessitates the application of water-energy-carbon nexus (WECN). The new framework uses an integrated multi-criteria decision-making (MCDM) analysis based on the weighting and ε-constraint methods. This study utilizes Pareto optimization to identify an optimal set of technological solutions to achieve techno-economic and environmental objectives. In the default scenario, the combination of Moving Bed Biological Reactor, Ultrafiltration, and Reverse Osmosis (MBBR-UF-RO) is the optimal option for urban WWT. The obtained optimal solution has a capital cost of 71.7 million USD, and the annual production capacity of water, fertilizer and renewable energy is 8.73 million m3, 20.8 Mt and 1.6 MW, respectively. The supply water price, urban sewage inlet flow rate, government facilities, and discount rate are critical factors that affect the project's economics and investigate the effect of weights on the ranking of alternatives. This study provides insights into how a tripartite nexus can be integrated symbiotically to improve resource production and elevate the annual income.