PH CONTROL IN ANAEROBIC TREATMENT OF INDUSTRIAL WASTE-WATER

Based on a comprehensive analysis of four groups of chemical and biological reactions, a general pseudo-steady-state mathematical model of the anaerobic-digeston buffer system was developed. According to the characteristics of the wastewater being treated and the biological efficiencies of the reactors, this model was able to predict the pH, the concentration of bicarbonate in the effluent, and the percentages of methane, carbon dioxide, and hydrogen sulfide in the biogas from several laboratory-scale reactors of different configurations treating different types of influent. The model showed that the composition of the wastewater, such as the concentration of volatile fatty acids (VFA), sulfate, nitrogenous compounds, and chemical oxygen demand (COD), has a profound effect on the chemical demands for pH control in anaerobic digestion. By means of simulation, some operational factors, such as the flow pattern in the reactors, recirculation and the effectiveness of different chemicals for PH adjustment are also discussed.