ABSTRACT
53This chapter describes the impact of long-term (weeks) temperature changes on stoichiometry and kinetics of the anaerobic and aerobic phases of BPR processes. Steady state conversion of relevant compounds for BPR was studied by adapting reactors in subsequent periods to 20, 30, 20, 10 and 5°C. Integrated in the process study, two methods (electron-microscopy and dry denaturing gradient gel electrophoresis) were applied to investigate the composition of the bacterial community of biological phosphorus removing sludge developing at those different temperatures. The temperature coefficient for metabolic conversions obtained from long-term temperature tests was similar to the temperature coefficient observed in short-term (hours) tests (θ=1.085 and θ=1.078, respectively).Temperature had a moderate impact on the aerobic P-uptake process rate (θ =1.031) during long-term tests. However, a strong temperature effect on other metabolic processes of the aerobic phase, such as PHA consumption (θ=1.163), oxygen uptake (θ =1.090) and growth (θ>1.110), was observed. Different temperature coefficients were obtained for the aerobic phase from long-term and short-term tests, probably due to a change in population structure. This change was also visible from molecular ecological studies. The different temperature coefficient found for P-uptake compared to the other metabolic processes of the aerobic phase underlines that in complex processes such as BPR, it is dangerous to draw conclusions from easily observable parameters (like phosphate) only. Such consideration can easily lead to underestimation of the temperature dependency of other metabolic processes of the aerobic phase of BPR..
