The environmental crisis and the growing need to reduce solid waste make it imperative to adopt integrated, scientifically sound, and environmentally friendly solid waste management practices in order to ensure a sustainable future. This study presents an alternative waste management proposal in accordance with the standards set out in the European Waste Directive (Directive 2018/850/EC) in order to lessen greenhouse gas emissions. The primary objective is to develop a circular waste management system that uses waste as feedstock for the production of biofuel in order to meet Catalonia’s energy needs and, at the same time, reduce its environmental footprint. Waste that is highly biodegradable and rich in organic matter cannot be disposed of in landfills, according to order TED/834/2023, and is therefore used to produce biogas through anaerobic digestion (AD) or to produce compost. In addition, gas emissions from landfills, which are rich in methane, are also collected and used for biogas production. Plans for biogas production at landfills and at an anaerobic digestion biogas plant, and for compost production from organic waste, were implemented using SuperPro Designer simulation software. The research has shown that this approach to solid waste management offers positive results in terms of energy due to biogas production, in terms of the environment due to waste reduction and compost production, and in terms of the economy due to a 25% increase in the efficiency of the biogas plant.