Synergistic impact of tannery solid waste derived biochar and autochthonous microbes on metals phytoextraction and stress alleviation in sunflower

The high content of toxic metals (TMs) in tannery solid waste (TSW) necessitates a synergistic approach for its remediation. The research focused on the derivation of TSW biochar and its autochthonous microbes as an integrated approach for phytoextraction of TMs. For this, TSW autochthonous strains of <i>Bacillus</i> and <i>Trichoderma viride</i> were used alone and in combination with TSW biochar treatments of 2.5, 5, and 10% (w/w), namely; BC1, BC2, BC3. Surface analyses of TSW biochar through SEM and FTIR demonstrated the agglomeration and deposition of inorganic moieties and exchangeable functional sites on the biochar surface. The combined treatment of TSW biochar along with <i>Bacillus</i> and <i>T. viride</i> revealed significantly improved TMs uptake (Cr 540.01 mg kg^-1 > Cd 380.44 mg kg^-1 > Pb 224.44 mg kg^-1) and plant biomass at 10% TSW biochar amendment. However, TMs content was found below the limit of detection (LOD) in seeds of sunflower. Biochemical responses such as total soluble protein content (73.61%), total chlorophyll content (12.69%), catalase (80.66%), and superoxide dismutase (82.31%) were improved under treatment assisted with microbial inoculum as compared to control. This integrated method promotes environmental sustainability and agricultural production by addressing the challenges associated with handling of TSW.