Development of an Integrated Process for Eggshell Valorization

The current global trend towards more stringent environmental standards, technical applicability and cost-effectiveness, became key factors in the selection of adsorbents. After demonstrating the performance of eggshell-derived adsorbent under a range of lab operating conditions, this work focused the adsorption efficiency of calcined eggshell powder (CEP), in the treatment of wastewaters from different industrial units. In order to do it, the removal of organic material, expressed as chemically oxygen demand (COD), was monitored in leachate wastewaters from sanitary landfill (LLWW) and in municipal residual wastewaters (MWW). Furthermore, the efficiency of alkaline metals removal, specifically from effluents of industrial unites from superficial treatments, was also assessed. A detailed study of the eggshell characteristics, before and after the adsorption process, was carried out, aiming at investigate the adsorption mechanism underlying the removal of different pollutants. Results demonstrate that adsorption of organic material and metals in the CEP, go around 84% of organic material removal in MWW and 81% in LLWW. Finally, a removal of 95% of aluminium (Al) from MWW, deriving from anodizing industrial plant, and a removal of 88% copper (Cu), 95% chromium (Cr) and 30% nickel (Ni) from effluents of superficial treatments produced in Ni/Cr plating plants, were also determined This suggests that CEP adsorbent is appropriated to wastewaters treatment with high contents of organic matter and heavy metals, from different aqueous systems or different industries. The application of this adsorbent in this methodology showed good cost-benefits ratio, proving that it can be an effective alternative to activated carbon. However, aiming the progress and sustainability of the whole eggshell valorisation, we are further optimizing, testing and developing new techniques and products to recover the organic fraction of the eggshell through the reclamation of several bioactive peptides derived from hydrolysis of different proteins that constitute these residues. These products are intended to be introduced in the food, cosmetic and pharmaceutical markets.