Modifications to aerobic digestor design

Abstract Generally, aerobic digestion of biological sludges is conducted in completely-mixed aeration basins. Although first-order kinetics have classically been used to predict and design aerobic digestors, it is shown that these models will result in underdesign and that a model based on a mass balance around the digestor more accurately predicts digestor performance. The experimental work discussed herein demonstrates that a first-order rate coefficient, determined under batch conditions, can be employed in the completely-mixed model for design purposes. Certain design constraints are discussed, such as laboratory scale-up, temperature, etc. A design example is illustrated using the approach presented herein.