Valorization of Biomass Residues by Biosorption of Microelements in a Closed-Loop Cycle

Abstract

The concept of the research data presented assumes the valorization of goldenrod residues from supercritical CO2 extraction following the circular economy principles. The biomass was enriched with microelements (Cr, Zn, Cu) by biosorption from single and multielemental solutions in batch and packed bed reactors. Modeling of biosorption equilibrium supported by instrumental analysis (SEM and FTIR) of material properties was employed to explain the metal ions binding mechanism. The preferential biosorption of Cr(III) over the divalent ions, allows the possibility of valorization of goldenrod residue in a garden-scale biosorption tank acting as a fixed-bed reactor working in an open circulation run and fed with microelements diluted in rainwater. The use of fertigation solution in optimal doses of micronutrients did not show any phytotoxic effect. Using the post-sorptive solution as a source of micronutrients for plants showed significant effects on growth parameters (increased chlorophyll content by 54%) compared to groups fertilized with commercial formulation (13% higher sprout mass). Additionally, fertigation with the post-sorption solution leads to the biofortification of cucumber sprouts. The recycling process results in two products: enriched biomass as a potential feed additive (with Cr(III), Cu(II), and Zn(II)) and a post-sorption solution (with Zn(II) and Cu(II) only) used in the fertigation of plants. Graphical Abstract