Development of a process for waste eggshell valorisation

Abstract

In this work it was evaluated the adsorption efficiency of calcined eggshell from the egg-breaking operations in the treatment of wastewaters from different industrial units. It was evaluated the removal of organic material, expressed as chemically oxygen demand (COD), in leachate wastewaters from sanitary landfill (LLWW) and the municipal residual wastewaters (NWW). It was also assessed the efficiency of alkaline metals removal, specifically aluminum, copper, chromium and nickel from effluents from industrial units from superficial treatments. A detailed study of the eggshell characteristics, before and after the absorption 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 calcined eggshell achieved 89% of organic material (COD) removal in municipal wastewaters and 81% in landfill leachates wastewaters. It was also verified a removal of 95,4% aluminum from residual wastewaters from anodizing industrial plant and a removal of 88% copper, 95% chromium and 30% nickel, in effluents from superficial treatments produced in Ni/Cr plating plants. This evidence demonstrates that calcined eggshell-based adsorbent proved to be 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, which proves that it can be an effective alternative to activated carbon.