Evaluation of Odomin and potential factors reducing the hydrogen sulphide levels in sewage systems

Sammanfattning: Xylem Inc. develops pumps and integrated solutions for sewages systems. A new concept has been designed to reduce the levels of hydrogen sulphide, H2S, in wastewater. H2S is a toxic, stinking gas that smells at levels above 0.002-0.2 ppm. Recommended exposure level is 15 ppm for 15 minutes. The gas is soluble in water and arises with both increasing temperatures and long retention times. Levels of H2S normally differ between 0-1000 ppm, depending on the time of year. The new concept, a pre-chamber installed upstream a pump station, is called Odomin. Inside Odomin H2S is oxidized to sulphuric acid, H2SO4, on moist surfaces. A plate is used to splash thewastewater onto the moist surfaces surrounding the plate. This master thesis aims to find the reduction rate, in terms of H2S, between Odomin 65 and the pump sump and to evaluate three factors that have possibility to improve the performance of Odomin 65. The investigated factors are 1) a sacrificial anode made from carbon steel 2) a reduced area of the inlet which increases the splash effect and 3) an increased inner area to increase themoist surfaces inside Odomin. The evaluation is made with 23 factorial design. The analysis indicates that no factor affect the daily mean value with a significance at 5%. The sacrificial anode is the one factor showing a reduction by the levels of H2S in the pump sump for both mean and extreme values. The general reduction rate is 5.33 and this can be increased with 55% by using the splash. The tests were affected by several influences that impact the trustworthiness of the results. Therefore this analysis needs additional investigations in order to be verified.