Application of Statistical Tool for the Optimization of Biofiltration of Toluene Using Corn Stacks as Packing Material

Abstract

In this work, statistical design was applied for the optimization of process parameters for the biofiltration of toluene using mixed microorganisms obtained from pharmaceuticals wastewater sludge in a packed bed biofilter. The effects of process parameters such as gas flow rate, initial toluene concentration, height of the packing material, and temperature on removal efficiency (RE) of toluene was studied and optimized using response surface methodology. Using Box–Behnken Design, 30 experiments were carried out for the four test variables. From the results, the optimum condition for maximum RE was found to be: gas flow rate—0.01 m3 h−1, initial toluene concentration—0.25 g m−3, packing height—0.75 m, and temperature—31 °C. At these optimized conditions, the removal efficiency of toluene was found to be 95 %. A high R 2 value of greater than 0.9 indicates the fitness of the model to predict the experimental data. Biokinetic studies led to a good fit between experimental data and mathematical equations, yielding a calculated maximum toluene degradation rate of 140.42 g m−3 h−1 with a half-velocity constant, K S, of 0.076 g m−3.