Optimization and application of bacterial consortia for enhanced bioremediation of dairy industry effluent using Box-Behnken design

Abstract

This study optimized and evaluated a bacterial consortium for treating dairy industry effluent. Effluent samples collected from a dairy processing facility in Nigeria were analyzed for physicochemical parameters and heavy metal concentrations. Bacterial isolates were screened, identified and tested for compatibility before developing a consortium. Bioremediation conditions were optimized using experimental design, focusing on molasses concentration, temperature, pH and inoculum size. The optimal conditions for total organic carbon degradation were a molasses concentration of 0.60 mg/L, a temperature of 32°C, pH 7.7, and an inoculum size of 17 mL. Under these conditions, total organic carbon decreased from 520 mg/L to 43.6 mg/L, chemical oxygen demand reduced from 1,480 mg/L to 120 mg/L, and biochemical oxygen demand declined from 780 mg/L to 65 mg/L, demonstrating significant pollutant removal. Carbon dioxide evolution increased steadily, reflecting active microbial metabolism, while enzyme activities peaked around day 10, correlating with enhanced bacterial proliferation and subsequent nutrient depletion. The regression model exhibited a high predictive accuracy, with an R² value of 0.9997, confirming the reliability of the bioremediation process. These findings underscore the effectiveness of the optimized bacterial consortium in degrading organic pollutants in dairy effluent. The study highlights the potential application of microbial consortia in industrial wastewater treatment, providing a sustainable and efficient approach to reducing environmental pollution.