Kinetic studies of biogas generation using municipal waste as feed stock

A comprehensive study has been made on biogas kinetics from municipal waste. A 10 dm3 anaerobic batch digester equipped with a mechanical agitator has been used under controlled environment (pH 6.8, temperature = 40 °C) for this purpose. Influent slurry concentration varied from 20 to 56 kg/m3. At 20 kg/m3 the concentration of carbohydrate, protein and fat varied from 0.83 to 2.0 kg/m3, 0.25 to 0.70 kg/m3 and 0.26 to 0.56 kg/m3, respectively. The biogas generated from the digester had the methane concentration as high as 80% (v/v) at an influent slurry concentration of 20 kg/m3 on the 15th operating day of the digester. The calorific value of biogas obtained from the digester is in the range of 27.98–31.46 MJ/(N m3). An attempt has been made to separate both acidogenic and methanogenic bacterial consortia. It has been noted that classical Monod-type substrate uninhibited model equation can be used to predict the growth kinetics of separated bacterial consortia of both types. Biogas generation kinetics was studied using initial influent slurry, carbohydrate, protein and fat concentrations as parameters. By judiciously coupling differential mass balance equations, mathematical model equations were obtained.