Abstract: Inventive process consisting of the inserting in any industrial PELLET production plant and at any point of the same plant of a technological system called a “control chamber” that can evaluate the biomass that will form the pellets, detecting the presence of toxic materials deriving from processing scrap and waste, with the presence of substances such as lacquers, paints, and sprays, or wood coming from trees contaminated by radioactive, toxic or other environmental factors. The “control chamber” consists of a pellet transport system, a series of sensors, optical devices, weighing and control systems that can continuously monitor, analyze and grade all the pellets. It also has a system for the selecting and storage of pellets according to the quality detected.