Bio-composite of Fe-sludge biochar immobilized with Bacillus Sp. in packed column for bio-adsorption of Methylene blue in a hybrid treatment system: Isotherm and kinetic evaluation

Abstract The present study highlights the potential of bio-composite of Fe-sludge biochar and Bacillus sp for decolorization of Methylene blue (MB) dye. The Packed Bed Continuous Reactor (PBCR) hybrid system was containing bio-composite of Fe-sludge biochar with an ultraviolet system containing 600 mg ⋅ L−1 MB dye. PBCR treated effluent was passed through the immobilized Bacillus sp. cells for biodegradation. The adsorption capacity of Fe-sludge biochar was 29.13 mg/g after 5 treatment cycles in PBCR. The kinetics parameters for pseudo-first-order, K 1 and R2 were found to be 0.007 min −1 and 0.95; pseudo-second-order K 2 and R2 were 1.69 g/mg/min and 1.0, respectively for bio-composite of Fe-sludge biochar Adsorption isotherm parameters values for Langmuir ( K L ), Freundlich ( K F ), and R2 were found to be 0.0366 L mg −1, 0.685 mg g-1 and 0.37 and 0.79, respectively. The Monod growth kinetic parameters Ks, μ max/Ks and μ max were found 41.3 mg day −1, 0.0103 mg day −1, and 0.426 day −1 respectively. Fe-sludge biochar immobilized with bacteria cell shows higher removal efficiency of MB dye in comparison to free bacterial cells system. Adsorption using the hybrid process (engineered biochar + bacteria) could be more effective and low-cost green approach for the organic pollutants removal from the industrial effluent.