Phenols are compounds found in agricultural products and by-products, with high antioxidant activity and positive impact on human health. As a result, their isolation and purification are of high interest and these compounds can be used in cosmetics, nutritional and pharmaceutical supplements. Recently, a preliminary design of a treatment plant was presented by the researchers of our laboratory, based on experiments carried out with three materials rich in phenolic compounds (olive leaves, grape marcs, and espresso coffee residuals).