An Efficient Biological Treatment on Dairy Wastewater by Lactobacillus plantarum: Mathematical Modeling and Process Parameters Optimization

The ability of Lactobacillus plantarum for biological treatment of dairy wastewater was investigated using a response surface method. The effects of three culture condition parameters of temperature (24.93-40.07 degrees C), pH (4.3-6.7), and agitation rate (99.5-200.5 rpm) on the removal efficiency of sugar, total protein content (TPC), and chemical oxygen demand (COD) of the wastewater were studied. For each response parameter, a second-order polynomial model versus independent variables (p < 0.0001) was determined and statistically obtained with high coefficient of determination values (R-2 > 0.95). Numerical optimization defined the optimum treatment conditions for achieving the highest removal efficiency was temperature of 28 degrees C, pH of 5.03, and agitation rate of 147.51 rpm. Under the optimum condition, the removal efficiency values for sugar, TPC, and COD were predicted to be 72.18%, 54.51%, and 78.99%, respectively.