**3. Biomass bioconversion technologies**

Waste valorization is a process that converts waste materials into valuable products, such as chemicals, materials, and fuels. The transformation of biomass into valueadded products is increasing worldwide due to the following characteristics [6–9]:


Certain types of biomass can be used directly, without any or almost no treatment, such as wood residues, such as sawmill residues, logging residues, and municipal wood residues from plants and crops, which are used as fertilizer; in other cases, pretreatment is required to condition the biomass before it is subjected to processes to obtain a product of industrial interest [8]. The most common pretreatment methods are mechanical shredding, acid or alkaline hydrolysis, extraction of the components by organic solvents or ionic liquids, and steam explosion treatment, as some examples [10, 11].

The technologies applied to modify biomass properties are grouped into 4:


**Figure 6** illustrates a graphic representation of the most common technologies used in biomass valorization.
