Environmental applications of tomato processing by-products

Sustainable management of large amounts of tomato wastes generated during industrial processing is nowadays considered as an urgent challenge. In this chapter, recent investigations on the environmental application of tomato wastes and their derived carbonaceous materials for wastewater treatment are reviewed and summarized. The effect of tomato waste properties as well as the operating conditions (including the temperature, residence time, heating gradient, and activation process) on the derived chars/activated carbons physicochemical properties are analyzed. The efficiency of nonactivated and activated chars along with the involved mechanisms during inorganic and organic pollutants removal from aqueous solutions is also reviewed. This work points out that the characteristics of tomato-derived adsorbents depend mainly on the raw precursor nature and properties, and especially on the used modification method. The highest adsorption capacities for both organics and inorganics pollutants have been obtained for activated carbons produced from the impregnation of tomato wastes with specific chemicals such as ZnCl2, FeCl2, and H3PO4. The preparation of these activated carbons should, however, occur for impregnating mass ratios (chemical/biomass) higher than 2:1, thermal treatment at temperatures lower than 650 to 700°C, and a residence time of at least 60 min. On the other hand, the optimization of the activation procedure, the use of real effluents for dynamic adsorption and the reuse of loaded tomato-derived-adsorbents in a context of circular economy and sustainable development manner are the main research and development challenges.