**2. WtL and WtE technologies: historical and technological overview**

Biorefineries are a way to achieve sustainable waste management with many environmental and economic benefits. However, waste streams are often very selective in terms of the technological option most suitable for their valorization. As such, a complete understanding of each technology is a fundamental resource to determine if the different wastes available can be viewed as a raw material for valuable products. **Tables 1–3** summarize the different thermochemical, biological, and chemical processes discussed. A brief description of each technology follows.
