Using biosorption to enrich the biomass of seaweeds from the Baltic Sea with microelements to produce mineral feed supplement for livestock

The paper discusses various aspects of biosorption of microelements by marine seaweeds to be used as mineral feed supplement for livestock. In the study, biosorptive properties of a single marine species Cladophora rupestris and mixed species of algae from the Baltic Sea (a mixture of Cladophora sp. and Enteromorpha prolifera) were investigated. The mechanism of biosorption was identified as cation-exchange with light metals. Cation-exchange capacity was determined and compared with biosorption capacity. Biosorption was carried out at different pH and temperature, to choose the best operation conditions. Biosorption was performed in single- and multi-metal system to select the best production mode. The experiments showed that the biomass can bind high quantities of microelements. The maximum biosorption capacity, a model parameter of Langmuir equation for C. rupestris was 6.46 meq g−1 for Cr(III) ions, 1.37 meq g−1 for Co(II), 1.24 meq g−1 for Cu(II), 1.16 meq g−1 for Zn(II), 0.984 meq g−1 for Mn(II) and for mixed species of seaweeds from the Baltic Sea was as follows: Cr(III) 5.20 meq g−1, Co(II) 1.68 meq g−1, Mn(II) 1.28 meq g−1, Zn(II) 1.16 meq g−1, Cu(II) 0.988 meq g−1. It was found that in single-metal system, the biomass bound more metal ions than in multi-metal system. The recommended level of supplementation to feed for laying hens and swine was discussed. Also, multielemental analysis of the biomass was carried out and compared with the composition of other representatives of Cladophora and Enteromorpha.