"The idea of the research presented in this book arose from the constant questions I asked about how to apply my academic knowledge in a practical and accessible way, something that could actually make a difference in the community, because I was often reflecting on the fact that I was completing one of the courses considered to be the most difficult (chemistry), but at the same time not knowing how to apply all this academic knowledge in a pragmatic way. Facing these conflicts, I started to research the destinations given to the waste. This is because if I could produce something useful from something useless, that is, from leftovers, I would certainly be applying my knowledge in one of the most noble and elegant ways possible. That was how I came to know about the technology of biodigesters and, with the support of my family, I undertook the construction of a biodigester in the municipality of Iracema-CE, which is still in operation today, and whose construction I detail in this work, demonstrating its simplicity and accessibility.