Development and application of modified biocarrier immobilized with Bacillus sp. for azo dye degradation: batch and continuous study

Abstract

The rapid growth of the industry and urbanization induces the consumption of large amounts of freshwater. In the meantime, untreated or partial treatment of industrial (especially textile) wastewater creates a threat to the living system. Azo dyes are generally used in textile industries and cause hazardous effects due to their recalcitrant and toxic nature. The present work emphasized the synergetic effect of adsorption and biodegradation of a modified biocarrier on Congo red (CR) dye removal. The modified biocarrier was developed by entrapping the polyurethane foam and activated carbon with sodium alginate. The adsorption effect was better explained by the Langmuir isotherm than Freundlich isotherm. Various independent factors, including pH, dissolved oxygen (DO), and dye concentration, were optimized in a fixed bed bioreactor (FBBR) filled with Bacillus sp. immobilized modified biocarrier. The highest removal of 95.43% was evaluated at a pH of 7.0, DO of 5.0 mg O2/L, and inlet CR dye concentration of 100 mg/L. Moreover, the continuous operation of FBBR achieved a 91.13% dye removal at an inlet loading rate of 216 mg/L. d at an initial dye concentration of 300 mg/L. The present approach could be an efficient technology for azo dye treatment.