Effect of temperature on storage polymers and settleability of activated sludge

This paper describes the effect of tropical temperatures on substrate stora ge and settleability in an activated sludge sequencing batch reactor (SBR). Substrate uptake, ammonium consumption, oxygen uptake, CO2 production and poly-beta-hydroxyalkanoate formation and consumption were measured at diffe rent temperatures (15. 20, 25, 30 and 35 degrees C). Kinetics of the proces ses were strongly influenced by temperature. All the observable rates excep t the PHB and NH4 consumption increased with an increase in temperature. Th e accumulation of storage polymers strongly depended on temperature. The ro le of substrate storage for microbial population dynamics and resulting SVI is discussed. The SVI strongly increased with an increased temperature. Th e results are discussed in the context of the kinetic selection theory of C hudoba et al. [Chudoba, J., Grau, P. and Ottava, V. (1973) Control of activ ated sludge filamentous bulking. II. Selection of microorganism by means of a selector. Water Res. 7, 1389-1406.]. From this it becomes evident that t he formation of storage polymers should be considered as equally important as the direct competition for substrate based on affinity constants. (C) 19 99 Elsevier Science Ltd. All rights reserved.