Temperature effects in bio-P removal

This paper discusses the temperature influence in biological phosphorus removal through literature review and experimental evidence. An SBR (Sequencing Batch Reactor) was operated in an anaerobic-aerobic sequence to cultivate an enriched biological phosphorus removing sludge. The impact of long term temperature changes on the stoichiometry and kinetics of the different processes involved was studied at 20, 15, 10 and 5°C. At 5°C breakthrough of acetate to the aerobic period occurred. It was shown that the stoichiometry of the anaerobic processes was insensitive to long-term temperature changes, whereas the kinetics of the aerobic and anaerobic processes were clearly affected. The aerobic phosphorus uptake rate showed a maximum in the interval between 15 and 20°C. All other anaerobic and aerobic conversion rates increased with increasing temperature. A simplified Arrhenius equation was used to describe the effect of temperature on the reaction rates. It was shown that a prediction of the temperature effect on a full scale biological nutrient removal plant is not a straight forward case because of the different influence of temperature on the subprocesses. All these influences should be accounted for.