The comparison of biosorption of nutritionally significant minerals in single‐ and multi‐mineral systems by the edible microalga Spirulina sp.

BACKGROUND: This paper deals with the biosorption process as a method of enrichment of natural biomass of the edible microalga Spirulina sp. with microelement metal ions, which is of significance in terms of animal nutrition. The influence of the following process parameters was studied for the biosorption of Cr(III): pH and biomass concentration on kinetics and equilibrium of biosorption. The enrichment process were performed in single‐ and multi‐mineral systems for nutritionally significant minerals such as Cu(II), Mn(II), Co(II), Zn(II) and Cr(III) under the conditions that were determined for Cr(III). RESULTS: The best operational parameters for the process were selected as pH 5 and Cs 1 g L−1. The maximum biosorption capacity 71.2 mg g−1, 18.4 mg g−1, 83.9 mg g−1, 31. 8 mg g−1 and 26.5 mg g−1, were reached for Cu(II), Mn(II), Co(II), Zn(II) and Cr(III), respectively. To cover 100% of animal demand on microelements, 4.91 g of the preparation for laying hens and 9 g for swine of enriched microalgae in the single‐metal system should be added to 1 kg of fodder. In the multi‐metal system the competition between microelements was high enough to make it impossible to reach a suitable ratio between bound metal ions. CONCLUSIONS: Two methods of production of mineral feed additives were proposed: a single‐metal system and a multi‐metal system. Performing the biosorption process in the single‐metal system enabled the preparation of additives with the desired composition. Carrying out biosorption in the multi‐metal system is easier, technologically, but the ratio of bound microelements is difficult to predict.