Highlights 2019
Outlet ci/c0 [%]
Complete elimination [%]
Sampling point discharge
Experiment duration [h] SAK254
DOC
TOC
Arzneimittelrückstände
Complete elimination
Fig. 9: Relative concentration and total elimination in the adsorber discharge
The complete elimination of pharmaceutical residues over the test duration at different sampling points is shown in Fig. 8. It can be seen at the lowest sampling point that complete elimination of only 65% was realised at the first sampling when the experiment was started. One explanation for this is the high empty tube speed and the resulting short contact time. It is probable that the adsorbents were not fully loaded in the first layer. A continuous increase in the sum parameters and the concentration of pharmaceutical residues was determined in the outlet over an experimental period of 14 h. A 91% total elimination of trace substances had been realised by the end of the experiment. This is clearly well above the 80% value that was specified as the cleaning target [6]. The results are shown in Fig. 9. The results show that the required elimination rates in the adsorber outlet can be realised using this process. The adsorbent volume to be discharged and the cycle time can be determined using the breakthrough curve and the loading progress in the adsorber-bed. The other components needed for wetting, water separation, drying and reactivation can be selected and dimensioned based on this. Furthermore, the results also show that the adsorption capacity in the lower layers is not fully utilised at high empty tube speeds. Frequent adsorbent discharging, even with high empty tube speeds and large volumetric flows, means that the treatment process can take place with reduced area requirements. However, this form of process controlling would reduce the regeneration frequency as well as the overall lifetime of the adsorbents and the process efficiency. The parameters can be varied and optimisation between the area F & S International Edition No. 20/2020
being used and process efficiency can be realised, but this will depend on the general conditions of the relevant application. 7. Summary and conclusions An adsorption process was developed to combine the advantages of a fixed-bed process with those of a continuous process by implementing a so-called moving-bed. The relevant process parameters, especially the adsorbent volume to be discharged and the discharge cycles, must be specifically determined for each application in order to ensure energy-efficiency and economical process utilisation. By increasing the discharge frequency, high empty tube speeds can also be achieved, thus reducing space requirements. This is particularly important in applications where area requirements are a limiting factor in selecting the process to be used. Reference literature: [1] Türk, et.al.; Volkswirtschaftlicher Nutzen der Ertüchtigung kommunaler Kläranlagen zur Elimination von organischen Spurenstoffen, Arzneimitteln, Industriechemikalien, bakteriologisch relevanten Keimen und Viren, Abschlussbericht im Auftrag des Ministeriums für Klimaschutz, Umwelt, Landwirtschaft, Natur- und Verbraucherschutz Nordrhein-Westfalen (MKULNV), Duisburg; 2013 [2] UBA, Positionspapier organische Mikroverunreinigungen von Gewässern, vierte Reinigungsstufe für weniger Einträge, 2015 [3] Bornemann, „Der Einsatz von Pulveraktivkohle in Flockungsfiltrationsanlagen von Kläranlagen zur Elimination von Spurenstoffen“, 5. Symposium Flussgebietsmanagement beim Wupperverband und Gebietsforum „Wupper“ der Bezirksregierung Düsseldorf, 2012 [4] Bathen, Dieter; Gasphasen-Adsorption in der Umwelttechnik – Stand der Technik und Perspektiven, 2002 [5] Sielemann, Heinrich; Adsorption in flüssigfluidisierten mehrstufigen Rieselbodenwirbelschichten, Dissertation, Dortmund, 1996 [6] Kompetenzzentrum Mikroschadstoffe.NWR, Anleitung zur Planung und Dimensionierung von Anlagen zur Mikroschadstoffelimination, Stand 20.03.2015, Köln
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