Temperature effects on the oxygen transfer rate between 20 and 55°C

The influence of temperature on the oxygen transfer rate (OTR) was studied in a bubble column. Aeration took place in three different liquids: tapwater, anaerobically pretreated paper process water and thermophilic sludge grown on a mineral medium and volatile fatty acids as carbon source. The OTR was measured in a temperature range of 20–55°C in case of tap- and process water. The OTR in the thermophilic sludge was determined at 55°C.The OTR remained constant over the specified temperature range in case of tapwater and showed a slight increase in case of process water. The constant OTR in case of tapwater was due to the counteracting effect of an increased overall oxygen transfer coefficient versus the decreased oxygen saturation concentration at higher temperatures. At 55°C the OTR in the thermophilic sludge was comparable to both other liquids at this temperature.