Removal of pharmaceuticals during river bank filtration - LEESU

II- Overview of previous studiesAs river bank filtration is not a new research topic, it seemed important to me to do somereading of previous studies in order to acquire a general understanding on the subject.The detail of the overview is given in Appendix 1.1) Subject of the studiesThere is a large variety of studies on the theme of river bank filtration. Some describe thegeneral results obtained for a broad range of pollutants; others focus on the elimination of agroup of molecules during on-site or lab-scale experiments. Oxic or aerobic conditions andtheir influence on the removal efficiency have been investigated. For the most part, theresearch consisted of a series of observations on the molecules behavior during soil passage.2) Investigated chemicalsSome works expose the results obtained for all OMPs found on the sites of the experiments,others focus on some groups of chemicals such as antibiotics, flame retardants, or pesticides.The distinction between bulk organic matter and trace organic compounds is done in somecases.3) Experimental set-upsEach study provides experimental results to confirm or contradict theoretical hypothesis anddraw conclusions. Some experiments are done directly on the field and consist of a series ofmeasurements at different places. Others consist of the study of lab-scale or pilot-scale sandcolumns reproducing the river bed. These artificial set-ups enable a wider range ofmeasurements and tests while having the possibility to change redox, aerobic or temperatureconditions in order to have a better understanding of the mechanisms responsible for theremoval. The columns are often filled with artificial sand because it is easier to manipulateand more ―universal‖ than some natural ground samples. Then the columns are fed with waterspiked with the investigated compounds.4) Analytical methodsBulk organic matter is quantified with DOC (Dissolved Organic Carbon) or TOC (TotalOrganic Carbon) measurements. UV 254 measurements can also quantify and characterize theorganic content while ATP tests can assess the biological activity. More specificmeasurements such as chromatography and mass spectroscopy are needed to characterize thetrace organic compounds. The adsorption capacity of the ground can be tested with batchexperiments. Retardation factors can then be calculated.5) ResultsRiver bank filtration is a reliable cleaning process regarding organic micro pollutants as longas the residence time and travel path are long enough. However, some compounds such asSulfamethoxazole are persistent and need other barriers to be totally eliminated. I gathered the23