The Effects of Temperature on the Biochemical Reaction Rates of the Activated Sludge Process

Experimental results and literature information were analyzed to define the effects of temperature change on the fundamental biochemical reactions that take place in the activated sludge wastewater treatment process. The reactions that were investigated were: organic substrate stabilization, production of cellular material, maintenance energy requirements, oxygen utilization, autooxidation of cellular mass and nitrification. Classic kinetic parameters and concepts were used in the analysis of the information. The variation of these parameters with temperature was compared to the variation predicted by the classic Arrhenius relationship for chemical reactions. The results were interpreted in terms of microbial population dynamics in the highly diverse mixed-culture system of activated sludge. It was found that all classically defined parameters follow the Arrhenius relationship over the 5 to 20°C range, but, except for substrate stabilization rate, do not follow it above 25°C.