Methyl tert-butylether (MTBE) used as fuel oxygenate poses problems for water suppliers since it is persistent in the aquatic environment and the removal efficiency by conventional water treatment methods (aeration or activated carbon filtration) is rather low. Substitution by other ether compounds such as ethyl tert-butylether (ETBE), tert-amylmethylether (TAME) or di-isopropylether (DIPE) is discussed, however, their environmental behaviour is similar to that of MTBE. Experiments investigating the elimination efficiency of AOP were carried out in tap water and water from Lake Constance. The elimination efficiency for all treatment processes was found to follow the order: MTBE << TAME approximately equal ETBE < DIPE For all compounds under investigation, neither pure ozonation nor UV irradiation yield a considerable concentration decline. Only the formation of highly reactive OH radicals shows a potential for removing the ethers from water. Therefore the addition of H2O2 in equimolar ratio prior to ozone admixing proved to be quite efficient. The application of combined UV/H2O2 showed good results in all cases; the best concentration decline was achieved with UV/ozone. The rate of elimination of the three substitutes for MTBE (ETBE, TAME and DIPE) is higher in all processes; nevertheless, no complete removal could be achieved. Therefore, from the point of view of water suppliers, the use of other ethers as substitute for MTBE is posing the same problems as MTBE.

Chemie Ingenieur TechnikVolume 78, Issue 9 p. 1181-1181 VortragFree Access Auswirkungen des zunehmenden Einsatzes von Biokraftstoffen auf die Trinkwasserversorgung C. Baus Dr.-Ing., C. Baus Dr.-Ing. baus@tzw.de DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this authorJ. Kiefer Dipl.-Geol., J. Kiefer Dipl.-Geol. DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this authorH.-J. Brauch Prof. Dr.-Ing., H.-J. Brauch Prof. Dr.-Ing. DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this author C. Baus Dr.-Ing., C. Baus Dr.-Ing. baus@tzw.de DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this authorJ. Kiefer Dipl.-Geol., J. Kiefer Dipl.-Geol. DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this authorH.-J. Brauch Prof. Dr.-Ing., H.-J. Brauch Prof. Dr.-Ing. DVGW-Technologiezentrum Wasser (TZW), Karlsruher Straße 84, D-76139 KarlsruheSearch for more papers by this author First published: 06 September 2006 https://doi.org/10.1002/cite.200650215AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume78, Issue9Special Issue: GVC/DECHEMA-Jahrestagungen 2006 mit 24. DECHEMA-Jahrestagung der BiotechnologenSeptember, 2006Pages 1181-1181 RelatedInformation

Most often, conventional drinking water treatment technologies such as aeration, filtration or adsorption on activated carbon are not able to remove persistent organic pollutants completely. Therefore new technologies have to be evaluated with regard to their removal efficiency. Chemical oxidation is a promising option and with ozonation a wide range of substances can already be eliminated. However, even this treatment proves to be inefficient for a number of emerging contaminants. Therefore more advanced oxidation technologies are investigated, which are able to produce highly reactive OH radicals to accelerate the degradation of persistent substances. In this study the elimination potential of UV-irradiation and advanced oxidation processes, namely UV / hydrogen peroxide and UV / ozone, for four emerging contaminants were investigated.

Methyl-tert-butylether (MTBE) is attracting more and more attention since it was discovered in groundwater and other raw water sources for waterworks and proved to difficult to remove during conventional treatment steps in drinking water production. Then fore advanced treatment processes have to be evaluated in addition to established treatment technologies. Laboratory based experiments were carried out studying ozonation with varying ozone concentrations at different pH values. For the elimination of MTBE the degradation through hydroxyl radicals was identified as the main degradation pathway. No decline of MTBE concentration occurred in experiments with molecular ozone, but AOP (Advanced Oxidation Processes) experiments where hydrogen peroxide (H2O2) was added showed a more efficient elimination. However, no complete mineralization was achieved, - tert-butyl alcohol (tBA) and tert-butyl formate (tBF) were identified as metabolites. In natural waters (i.e., groundwater, bank filtrated water, and drinking water) the efficiency of MTBE removal was strongly dependent on the efficiency content of natural organic matter and alkalinity because of their scavenging characteristics. However, bromate formation was observed as well and could cause problems for drinking water production. Comparison with data gained from waterworks orks showed that conventional ozonation techniques as applied in waterworks are not able to remove MTBE efficiently.

In Germany, the gasoline additive methyl tert-butyl ether (MTBE) is almost constantly detected in measurable concentrations in surface waters and is not significantly removed during riverbank filtration. The removal of MTBE from water has been the focus of many studies that mostly were performed at high concentration levels and centred in understanding the mechanisms of elimination. In order to assess the performance of conventional and advanced water treatment technologies for MTBE removal in the low concentration range further studies were undertaken. Laboratory experiments included aeration, granulated activated carbon (GAC) adsorption, ozonation and advanced oxidation processes (AOP). The results show that the removal of MTBE by conventional technologies is not easily achieved. MTBE is only removed by aeration at high expense. Ozonation at neutral pH values did not prove to be effective in eliminating MTBE at all. The use of ozone/H2O2 (AOP) may lead to a partly elimination of MTBE. However, the ozone/H2O2 concentrations required for a complete removal of MTBE from natural waters is much higher than the ozone levels applied nowadays in waterworks. MTBE is only poorly adsorbed on activated carbon, thus GAC filtration is not efficient in eliminating MTBE. A comparison with real-life data from German waterworks reveals that if MTBE is detected in the raw water it is most often found in the corresponding drinking water as well due to the poor removal efficiency of conventional treatment steps.

Equilibrium and kinetic adsorption of methyl tert-butyl ether (MTBE) onto three coal-based activated carbons, one coconut-based activated carbon, and two zeolites are elucidated in this study. Natural organic matter (NOM) and MTBE competed for the adsorption of activated carbons to different extents. The ideal adsorbed solution theory (IAST) combined with the equivalent background compound (EBC) model can adequately describe the NOM competition and predict the isotherms of MTBE onto the activated carbons. No competitive adsorption was observed for one of the zeolites, mordenite, due to the molecular effect. Besides, the aperture size, and the SiO2/Al2O3 ratio of the zeolite may also play an important role in the adsorption of MTBE from the aqueous phase. The surface diffusion model accurately simulated the transport of MTBE within the adsorbents employed in different water matrices. For all the activated carbons tested, the surface diffusivity of MTBE in natural water was nearly equal to that in deionized water, indicating that no apparently hindering effect occurs. A much slower adsorption kinetic of mordenite in natural water was observed since the opening apertures on mordenite may be appreciably hindered and blocked by NOM.

Persistent organic pollutants may pose a great threat to drinking water sources since they are most often not eliminated during treatment. Many substances are, however, subject to photodegradation, thus providing an efficient tool for water purification. Quantum yield measurements for several pharmaceuticals such as diclofenac, clofibric acid and iodinated X-ray contrast media (X-RCM), namely amidotrizoic acid and iopromide, showed quantum yields in the range of 0.32 for the first two and 0.025 and 0.016 for the X-RCM, respectively. A comparison of the figure-of-merit EEO for the UV photodegradation of the pharmaceuticals and the UV induced AOP UV/H2O2 for the elimination of MTBE and ETBE yields a significant increase in required energy for the AOP, indicating the lower efficiency of the combined process. UV oxidation experiments in natural waters showed both, enhancing and inhibiting effects on the photodegradation of amidotrizoic acid and iopromide.