INFLUENCE OF TEMPERATURE ON BIOLOGICAL PHOSPHORUS REMOVAL - PROCESS AND MOLECULAR ECOLOGICAL-STUDIES

This paper describes the impact of long-term (weeks) temperature chang es on stoichiometry and kinetics of the anaerobic and aerobic phases o f the biological phosphorus removal process. Steady state conversion o f relevant compounds for biological phosphorus removal was studied at 20, 30, 20, 10 and 5 degrees C, following chronological order. Integra ted in the process study, two methods (electron-microscopy and dry den aturing gradient gel electrophoresis) were applied to investigate the complexity of the bacterial community of biological phosphorus removin g sludge cultivated at different temperatures. The coefficient for met abolic conversions obtained from long-term temperature tests was simil ar to the temperature coefficient observed in short-term (hours) tests (theta = 1.085 versus theta = 1.078, respectively).-Temperature had a moderate impact on the aerobic P-uptake process rate (theta = 1.031) during long-term tests. However, a strong temperature effect on other metabolic processes of the aerobic phase, such as polyhydroxyalkanoate consumption (theta = 1.163), oxygen uptake (theta = 1.090) and growth (theta>1.110), was observed. Different temperature coefficients were obtained for the aerobic phase from long-term and short-term tests, pr obably due to a change in population structure. This change was also v isible from molecular ecological studies. The different temperature co efficient found for P-uptake compared to the other metabolic processes of the aerobic phase underlines that, in complex processes such as BP R, it is dangerous to draw conclusions from easily observable paramete rs (like phosphate) only. Such consideration can easily lead to undere stimation of the temperature dependency of other metabolic processes o f the aerobic phase of BPR. (C) 1998 Elsevier Science Ltd. All rights reserved.