Testfilter experiments for defining dissolved organic carbon biodegradation during riverbank filtration at different temperatures

Abstract The aims of this study are to (1) determine the BDOC in Elbe River water to compare with data from former studies, (2) to check the impact of changes in river water temperature (10, 20, and 25 °C). Four columns were filled with vulcanite pumice stone (for minimizing adsorption capacity), each of them having a separate reservoir feed with filtered Elbe River water. The ultraviolet absorption at 254 nm (UV254) was determined. DOC concentration was measured after 7, 10, and 14 days. Results represent that the main DOC degradation happens within an effective contact time of 5–7 days. Temperature increasing from 10 to 20 °C, raised the DOC degradation from 19 to 23%. By increasing the temperature to 25 °C, a higher DOC removal was observed than at 10 and 20 °C. This was expected due to higher biological activity at higher temperatures (BDOC increased from 23 to 26%). An increase in temperature by 15 Kelvin signified 30% more UV254 removal, expressing the effect of temperature variation on the attenuation of organic compounds. The difference in UV254 reduction at 25 °C compared to 20 °C was lower. A comparison with old data sets of last 22 years for Elbe River water at 20 °C shows that UV254 reduction (~ 27%) slightly increased but DOC biodegradation rate slightly decreased from ~ 27 to ~ 23%.