Oxygenation conducted in low temperature clean water

Sammanfattning: Aeration tests were conducted under non-standard conditions with clean tap water in various temperatures below 20 °C, with the aim of studying changes that may occur. An initial deoxygenation of 0.8 litre water was performed with sodium sulfite and a cobalt catalyst pre-dissolved in water, in order to bind already present dissolved oxygen. The resulting dissolved oxygen concentration after 20 minutes did not decrease below 2 mg/L, despite increasing the sodium sulfite concentrations. Thereafter, a reoxygenation with the same time interval was conducted by using an aeration system, which resulted in an increase of saturated oxygen concentration with lower temperatures. pH-measurements were carried out during the whole experiment in order to follow the conversion of sulfite to sulfate. The pH-data obtained confirmed that sulfite had been converted to sulfate, although, a few deviations could be observed for most of the experiments. The conductivity was also measured to ensure that the sulfite had been properly dissolved when added to the water tank. In general, the conductivity never deviated and held a constant trend throughout the tests. The collected data could not be made of use in order to properly determine how the aeration, for temperatures below 20 °C, could be evaluated. Further tests have to be performed in order for a definite conclusion to be drawn.