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UV Irradiation versus combined UV / hydrogen peroxide and UV / ozone treatment for the removal of persistent organic pollutants from water

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... Sona et al studied the removal of recalcitrant contamination in water using ultraviolet radiation. They showed that sulfamethoxazole could be removed almost 100% and fuel-derived contaminants such as MTBE 26% could be removed as well (25). In the recent years, incorrect and arbitrary consumption of drugs, especially antibiotics, have become one of the basic challenges in the field of health in Iran. ...
... Other studies also demonstrated that better removal of antibiotic occurred at lower pH. Studies conducted by Guo et al (27) and Sauna et al (25) also showed that H+ ions have an important role in the formation of radicals H°. The antibiotic initial concentration plays a major role in many photo-reaction processes. ...
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Background and purpose: Highly consumption of antibiotics and their entrance into the environment has increased concerns all over the world. These compounds enter to the environment through an incomplete metabolism and a considerable amount of them cannot be removed using usual waste filtration systems. Therefore, the present study aimed to investigate the feasibility of using ultraviolet radiation (UV-A) to remove penicillin G (PENG) from aqueous phase and determining its removal efficiency. Materials and Methods: The experiments were carried out in the batch mode. The samples were assessed in a 2-liter reactor. In order to investigate the effect of UV-A radiation on the removal rate of antibiotic penicillin G (PENG), the following parameters were studied. Three concentration levels of PENG antibiotic (10,25,and 45 mg/l) were exposed to UV-A at three pH levels (3,7,11) and were evaluated at four reaction times (30,60,90, and 120 min). Antibiotic penicillin G (PENG) was determined using HPLC instrument (Waters YL9100,USA) and results analyzed using factorial design software. Results: The finding demonstrated that antibiotic removal rate increased by decreasing pH and decreasing the initial concentration of antibiotic and increasing contact time. The maximum rate of penicillin G removal occurred in acidic pH (pH=3) is as much as 38%. All of the variables in the process have been statistically significant effect (p
... In experiments of Echigo et al. (1999), Yamada and Tsuno (2000), and Sona et al. (2006) with VUV/O 3 no nitrite was detected when high ozone concentrations (>1 mg/L) were used in the experiments. For the technical implementation of the VUV/O 3 process the internal generation of ozone by VUV light is a promising technology. ...
... For the diminution of trace organic compounds, the EE/O values are much lower and EE/O values of 2.5 kWh/m 3 are considered suitable for practical applications (Andreozzi et al., 1999). Sona et al. (2006) The results showed that VUV yielded the lowest EE/O values in pure water. Additionally, the combination of VUV with ozone produced by a VUV lamp was evaluated. ...
Article
The vacuum-UV radiation of water results in the in situ generation of hydroxyl radicals. Low-pressure mercury vapor lamps which emit at 185 nm are potential sources of VUV radiation. The scope of this article is to give an overview of the application of VUV radiation at 185 nm for water treatment including the transformation of inorganic and organic water constituents, and the disinfection efficiency. Another focus is on the generation of ozone by VUV radiation from oxygen or air and the application of the produced ozone in combination with VUV irradiation of water in the VUV/O3 process. The advantages and limitation of the VUV process at 185 nm as well as possible applications in water treatment are outlined.
... The higher the concentration of H2O2, the better the performance of the water treatment system. [12] It was observed that the oxidation rate of nanomolar Fe(II) with H2O2 is a function of pH, temperature and the concentration of HCO3and H2O2. And FeOH + is the most important iron species controlling the Fe(II) oxidation with H2O2 in the pH range of natural seawater systems. ...
... Different from hydroxyl radicals, sulfate radicals are more selective for oxidizing unsaturated bond and aromatic constituents. In terms of ICM removal, the use of UV/H 2 O 2 [12], UV/S 2 O 8 2− [13] and O 3 /H 2 O 2 [10] has been investigated. However, these processes solely employed hydroxyl or sulfate radicals as the oxidizing species, while the potential of utilizing both radicals simultaneously is rarely investigated. ...
Article
The degradation of iodinated X-ray contrast medium, iopromide, by UV irradiation with the assistance of combined oxidants of S2O82− and H2O2 has been investigated. The effects of various parameters, including different wavelengths of UV irradiation, UV intensities, initial solution pH levels, dosages of oxidants, dosing sequence, and the presence of non-target organic matters, have been evaluated. The iopromide decay follows pseudo-first-order kinetics. The UV at 254nm exhibits higher decay rate of iopromide than the others (300 and 350nm) due to stronger photon energy of 254nm and the relatively higher absorptivity of S2O82−, H2O2 and iopromide nearby this wavelength. Optimum pH level was determined to be around 4.34. The mechanism is complicated because of the involvement of the scavenging, recombination, self-decomposition and/or stability of the involved oxidant (S2O82− and H2O2) and radicals (SO4− and HO) as discussed in the paper. Iopromide decay rate is linearly proportional to the [S2O82−], however a nonlinear-optimal rate was observed by varying [H2O2] due to the formation of weaker radicals via overdosing of H2O2. Additionally, the sequential addition of S2O82− to UV/H2O2 or H2O2 to UV/S2O82− was found no better than the UV/S2O82−/H2O2. This is because the quenching of already formed SO4− by newly added H2O2 (or vice versa the quenching of HO by S2O82−). The simultaneous addition of S2O82− and H2O2, however, will slightly delay the generation rates of SO4− and OH due to the competition of photons between S2O82− and H2O2, which can reduce both the radical-scavenging reactions and the peak radical concentration in the solution, thus maximizing the utilization of precious radicals. The presence of non-target organics, especially the humic acid, in the UV/S2O82−/H2O2 process will quench the radicals, a pre-treatment is recommended to lessen this problem in real application.
... These first results support the presumption that the formation of nitrite can be avoided in the UV/ozone AOP. Sona et al. (2006) observed the same effect and explain it by the oxidization of the formed nitrite with ozone. Additionally, nitrite could also be oxidized back to nitrate by hydroxyl radicals (Gonzalez and Braun, 1995). ...
Article
The degradation of geosmin and 2-methylisoborneol (2-MIB) by UV irradiation at different wavelengths was investigated under varying boundary conditions. The results showed that conventional UV radiation (254 nm) is ineffective in removing these compounds from water. In contrast to the usual UV radiation UV/VUV radiation (254+185 nm) was more effective in the removal of the taste and odour compounds. The degradation could be described by a simple pseudo first-order rate law with rate constants of about 1.2 x 10(-3) m(2)J(-1) for geosmin and 2-MIB in ultrapure water. In natural water used for drinking water abstraction the rate constants decreased to 2.7 x 10(-4) m(2)J(-1) for geosmin and 2.5 x 10(-4) m(2)J(-1) for 2-MIB due to the presence of NOM. Additionally, the formation of the by-product nitrite was studied. In the UV/VUV irradiation process up to 0.6 mg L(-1) nitrite was formed during the complete photoinitiated oxidation of the odour compounds. However, the addition of low ozone doses could prevent the formation of nitrite in the UV/VUV irradiation experiments.
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The previously not studied photochemical degradation of sulfamethoxazole (SMX) to the isomer of SMX (ISO) was measured via a polychromatic (Xe) and a monochromatic (Hg) light source and accompanied by quantum chemical DFT calculations. In addition to the $$\mathrm{p}K_\mathrm{a} = \;7.0 \pm 0.1$$ p K a = 7.0 ± 0.1 of ISO, tautomer-dependent properties such as the $$K_\mathrm{OW}$$ K OW were measured and theoretically confirmed by DFT. The kinetics in solutions below and above the $$\mathrm{p}K_\mathrm{a} = 5.6$$ p K a = 5.6 of SMX were studied for the available and quantifiable products SMX, ISO, 3-amino-5-methylisoxazole (AMI), 2-amino-5-methyloxazole (AMO), and sulfanilic acid (SUA). The quantum yields of the neutral ( $$\Phi _\mathrm{N}$$ Φ N ) and anionic $$\Phi _\mathrm{A}$$ Φ A ) forms of SMX ( $$\Phi _\mathrm{A} = 0.03 \pm 0.001$$ Φ A = 0.03 ± 0.001 , $$\Phi _\mathrm{N} = 0.15 \pm 0.01$$ Φ N = 0.15 ± 0.01 ) and ISO ( $$\Phi _\mathrm{A} = 0.05 \pm 0.01$$ Φ A = 0.05 ± 0.01 and $$\Phi _\mathrm{N} = 0.06 \pm 0.02$$ Φ N = 0.06 ± 0.02 ) were found to be wavelength-independent. In a competitive reaction to the formation of ISO from SMX, the degradation product TP271 is formed. Various proposed structures for TP271 described in the literature have been studied quantum mechanically and can be excluded for thermodynamic reasons. In real samples in a northern German surface water in summer 2021 mean concentrations of SMX were found in the range of 120 ng/L. In agreement with the pH-dependent yields, concentrations of ISO were low in the range of 8 ng/L. Graphical abstract
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Ozonation has been applied to treat the actual pharmaceutical wastewater samples for the removal of chemical oxygen demand. Ozonation can generally achieve higher pharmaceuticals removal rates as compared to conventional processes as ozone reacts with a variety of complex compounds, intermediates and breaks them into simpler ones. Chemical oxygen demand removal study can be useful to elucidate the effect of pH on ozonation. In this study, an attempt has been made to assess the impact of ozonation on the removal of persistent chemical oxygen demand from actual pharmaceutical wastewater samples under varying conditions of pH from 4 to 10. Lower chemical oxygen demand removal efficiency was observed under an acidic medium (pH 4.0) as compared to those at pH 6.9 and 10.0. Treatment at alkaline pH 10.0 using 30.0 mg L−1 ozone for a treatment time of 10 min resulted in 66.67% chemical oxygen demand removal from the sample. It was reported that ozonation at higher pH favored chemical oxygen demand removal from the sample. At elevated pH, indirect reactions are the main means of ozonation, and also as the rate of formation of hydroxyl radicals substantially increases, it can be said that the percentage of chemical oxygen demand removal was significant in the alkaline medium. Improved biodegradability (ratio of biochemical oxygen demand to chemical oxygen demand = 0.455) after 10 min of treatment showed the effect of ozonation on the actual sample. It was concluded that ozone treatment alone can remove pharmaceuticals from the actual wastewater sample.
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Iodinated disinfection byproducts (I-DBPs) formed in water treatment are of emerging concern due to their high toxicity and the tase-and-odor problems associated with iodinated trihalomethanes (I-THMs). Iodoacetic acid and dichloroiodomethane are currently regulated in Shenzhen, China and the Ministry of Health of the People's Republic of China has also been considering regulating I-DBPs. Iodide (I–), organoiodine compounds (e.g., iodinated X-ray contrast media [ICM]), and iodate () are the three common iodine sources in aquatic environment that lead to I-DBP formation. While UV irradiation effectively inactivate a wide range of microorganisms in water, it induces the transformation of these iodine sources, enabling the formation of I-DBPs. This review focuses on the fate and transformation of these iodine sources in UV-based water treatment (i.e., UV irradiation and UV-based advanced oxidation processes [UV-AOPs]) and the formation of I-DBPs in post-disinfection. I– released in UV-based treatments of ICM and can be oxidized in subsequent disinfection to hypoiodous acid (HOI), which reacts with natural organic matter (NOM) to produce I-DBPs. Both UV and UV-AOPs are not able to fully mineralize ICM and completely oxidize the released I– to (except UV/O3). Results reveal that UV and UV-AOPs are adequate for I-DBP degradation but require high UV doses. While the ideal I-DBP mitigation strategy awaits to be developed, understanding their sources and formation pathways aids in informed selections of water treatment processes, empowers water suppliers to meet drinking water standards, and minimizes consumers’ exposure to I-DBPs.
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This article aims to discuss relevant aspects related to photolysis and its relation to the food area. For this purpose, topics relating to different types of radiation are shown, the use of radiation incidence on the preparation and pretreatment of analytical samples, the application of photolysis studies stability of foods and beverages (wine for example), and the use of photochemistry in wastewater treatment, specially effluent from the food industry.
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UV/H2O2 advanced oxidation is an effective barrier against organic micro pollutants. Several studies have focused on the degradation of a wide range of pollutants, but regarding the comparison of low-pressure mercury lamps (LP) with medium-pressure mercury lamps (MP) with respect to energy consumption by the UV/H2O2 process, little is known so far. Although the absorbance of H2O2 at 254 nm is low, the results of this research show that the yield of hydroxyl radical formation (OHCT) with LP lamps is comparable or higher than with MP lamps. In a water matrix with a background absorbance due to organics and nitrate, H2O2 absorbs UV light very effectively at 254 nm. Generally, due to the contribution of direct photolysis, the degradation of pollutants is better with MP-UV/H2O2 than with LP-UV/H2O2 at the same UV fluence. Therefore, with LP-UV/H2O2 micro pollutants are predominantly degraded through reaction with OH radicals. However, due to the much higher efficiency of LP lamps in converting electrical energy to UV-C light, the energy required to achieve 90% degradation (EEO) of pesticides and pharmaceuticals can be significantly lower with LP-UV/H2O2 than with MP-UV/H2O2. Results of bench-scale tests show EEO data of the LP-UV/H2O2 process to be 30%–50% lower than for the MP-UV/H2O2 process. At these process conditions MS2 phage inactivation was found to be more than 8 logs for both MP-UV/H2O2 and LP-UV/H2O2.
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The occurrence of the taste and odour compounds geosmin and 2-methyl isoborneol (2-MIB) affects the organoleptic quality of raw waters from drinking water reservoirs worldwide. UV-based oxidation processes for the removal of these substances are an alternative to adsorption and biological processes, since they additionally provide disinfection of the raw water. We could show that the concentration of geosmin and 2-MIB could be reduced by VUV irradiation and the combination of UV irradiation with ozone and hydrogen peroxide in pure water and water from a drinking water reservoir. The figure of merit EE/O is an appropriate tool to compare the AOPs and showed that VUV and UV/O(3) yielded the lowest treatment costs for the odour compounds in pure and raw water, respectively. Additionally, VUV irradiation with addition of ozone, generated by the VUV lamp, was evaluated. The generation of ozone and the irradiation were performed in a single reactor system using the same low-pressure mercury lamp, thereby reducing the energy consumption of the treatment process. The formation of the undesired by-products nitrite and bromate was investigated. The combination of VUV irradiation with ozone produced by a VUV lamp avoided the formation of relevant concentrations of the by-products. The internal generation of ozone is capable to produce ozone concentrations sufficient to reduce EE/O below 1 kWh m(-3) and without the risk of the formation of nitrite or bromate above the maximum contaminant level.
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The applicability of O(3), UV/H(2)O(2) and O(3)/UV treatment processes as technologies for water reuse considering pharmaceuticals and personal care products (PPCPs) removal was investigated. Electrical energies required for the effective removal of various PPCPs in secondary effluent were 0.09 kWh/m(3), 0.54 kWh/m(3) and 1.09 kWh/m(3) for O(3), UV/H(2)O(2) and O(3)/UV treatments, respectively, showing that O(3) treatment is the most cost-effective treatment option for the PPCPs removal. O(3) treatment showed the effective PPCPs removal at O(3) dose of 6 mg/L; however, the formation of bromate is expected for O(3) treatment using O(3) dose of more than 4 mg/L. In particular, bromate formation will be a critical issue when the reclaimed water is used for direct/indirect potable reuses. Therefore, in order to suppress the bromate formation as well as achieve the effective PPCPs removal, O(3)/UV treatment will be recommended. UV/H(2)O(2) treatment will be also a profitable treatment method because no bromate will be formed during the process. The evaluation for ecological risk of PPCPs by the applied processes showed that all the processes could decrease the ecological risk caused by parent PPCPs considerably. This means that the investigated treatment processes can play an important role in reducing unpredictable side effects caused by PPCPs in the aquatic environment.
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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.
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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. Therefore 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 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 showed that conventional ozonation techniques as applied in waterworks are not able to remove MTBE efficiently.
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Water homolyses upon vacuum-uv excitation into HO* radicals, hydrogen atoms and with lower efficiency, hydrated electrons. These primary species induce a series of reactions partially depleting nitrate and nitrite from aqueous solutions. Depletion rates depend on the presence of dissolved oxygen and temperature. Nitrate, nitrite, peroxynitrite and N2O were identified as reaction products after irradiation of, either, nitrite and nitrate in aqueous solutions. A reaction mechanism is proposed in accord with the experimental facts and with the evidence given in the literature, where NO2 * and NO* are key intermediates. NO3 −, NO2 −, NO2 *, NO* O2NO2 −, ONO2 − and N2O, seem to be interrelated by many redox reactions and reaction equilibria where pH and the availability of electrons determine their occurrence. The proposed mechanism is supported by a computer program with which the observed experimental behavior could be simulated.
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The fuel oxygenate methyl tert-butyl ether (MTBE) is one of the most frequently detected volatile organic compounds in groundwater and, thus, has become a priority groundwater pollutant over the last decade. Methods for the quantitative determination and for compound-specific isotope analysis (CSIA) of MTBE and its key degradation intermediate, tert-butyl alcohol (TBA), in ground and surface water are reviewed. These compounds are exclusively analyzed by gas chromatography (GC), mainly with mass spectrometric (MS) detection because of the requirements for selectivity and sensitivity. Sample introduction/enrichment based on direct aqueous injection, headspace analysis, solid-phase microextraction (direct immersion and headspace), and purge-and-trap is discussed. Specific advantages and disadvantages of these techniques are compared and criteria are given for choosing an appropriate method. Furthermore, it is shown that CSIA can be used to determine the isotopic composition of MTBE and related compounds in the low μg/L range and will therefore become an invaluable tool in the characterization of the environmental fate of such pollutants.
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High concentrations of adsorbable organic iodine (AOI) are found in municipal treatment plant effluents and surface waters by specific organic halogen determination. The high AOI is caused by widely used triiodinated X-ray contrast agents, which are very stable and hydrophilic. We have analysed specifically surface water influenced by a municipal treatment plant effluent, the surface water after bank filtration and raw drinking water. The X-ray contrast agents were determined by liquid chromatography-mass spectrometry with positive electrospray ionization after enrichment by solid phase extraction. Diatrizoate and iopromide, two triiodinated contrast agents are detectable in all samples, whereby the less polar component iopromide seems to be reduced during bank filtration. Just a trace of iopromide is identified in surface water after bank filtration and in the raw drinking water. Approximately 60% of the initial AOI is extractable and approximately 25% of the extractable AOI can be identified as specific triiodinated contrast agents.
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Kinetic simulations have been tested by laboratory experiments to evaluate the major factors controlling bromate formation during ozonation of waters containing bromide. In the presence of an organic scavenger for OH radicals, bromate formation can be accurately predicted by the molecular ozone mechanism using published reaction rate data, even for waters containing ammonium. In the absence of scavengers, OH radical reactions contribute significantly to bromate formation. Carbonate radicals, produced by the oxidation of bicarbonate with OH radicals, oxidize the intermediate hypobromite to bromite, which is further oxidized by ozone to bromate. During drinking water ozonation, molecular ozone controls both the initial oxidation of bromide and the final oxidation of bromite. OH radical reactions contribute to the oxidation of the intermediate oxybromine species. Bromate formation in advanced oxidation processes can be explained by a synergism of ozone and OH radicals.
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In this paper, analytical methods for the trace-level determination of 60 pharmaceuticals in aqueous samples are presented. The list of compounds amenable to the methods comprises analgesics, antiphlogistics, antirheumatics, beta-blockers, broncholytics, lipid-lowering agents (or their metabolites), antiepileptics, vasodilators, tranquillizers, antineoplastic drugs, iodinated X-ray contrast media, and antibiotics of different kind, mainly sulfonamides, macrolides, and penicillins. All methods are based on automated solid-phase extraction followed by GC-MS (after derivatization of the acid compounds) or HPLC-electrospray ionization MS-MS. After an intense validation, which included the determination of performance data according to the German standard method DIN 32645 (limit of detection, limit of identification, limit of determination), the determination of linearity, recovery, and repeatability and the study of matrix effects, the analytical methods were applied within a monitoring program on the occurrence of pharmaceuticals in groundwaters of Baden-Württemberg. During this monitoring program, it was found that several of the compounds under investigation could be detected in groundwaters and their occurrence could be traced back to an impact of municipal or industrial waste water.
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In Germany information on the occurrence of MTBE in groundwaters is scarce. In order to assess the German situation, in 1999 a monitoring programme on MTBE in groundwater was set up. Within this survey 170 wells were examined, which are used as groundwater monitoring points or which are foreseen for drinking water extraction in emergency cases or for irrigation purposes. In rural areas MTBE was found only in 9% of all samples in concentrations above the limit of determination (LOD) of 0.05 microg L(-1). In urban areas MTBE was detected in 49% of all wells under investigation and the median concentration was calculated to 0.17 microg L(-1). In one case a maximum MTBE concentration of almost 700 microg L(-1) was detected. As a first result of this survey one can conclude, that MTBE is regularly present in German groundwaters under urban areas. Although investigations about the occurrence of MTBE in German groundwaters have to be extended in future, this first snapshot can lead to the assumption, that MTBE concentrations due to diffuse sources are lower than the ones found in the USA. Nevertheless, e.g. accidental spills can lead to elevated MTBE concentrations.
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An overview of methyl tert butyl ether (MTBE) concentrations in German river water (315 samples) and wastewater (82 samples) is given In the agglomerated area of Frankfurt/M several samples of surface water wastewater and industrial effluents were analyzed for its MTBE content from 1999 to 2001 MTBE was analyzed by a combination of headspace solid phase microextraction and gas chromatography mass spectrometry (HS SPME/GC MS) Rhine and Main water concentrations of MTBE in the lower parts of the rivers were approximately 250 ng/L and 200 ng/L respectively The concentrations increased from the upper parts of the rivers to its mouths Water from the Elbe Neckar and Weser rivers showed lower MTBE concentrations and the ether was not detected in the Danube river Generally higher MTBE concentrations were detected at urban agglomerations compared to rural areas Small urban creeks without significant industrial input showed MTBE concentrations of approximately 50 ng/L and it was hardly detectable in small rural creeks Higher MTBE concentrations in river water were correlated with increased concentrations of the oxygenate measured in precipitation Most MTBE concentrations in river water fell in the range of 50-200 ng/L (32%) 10-50 ng/L (28%) and 2001000 ng/L (26%) MTBE concentrations in German surface water and air are 3-17 times lower compared to Californian data Wastewater samples from influents of two sewage plants showed MTBE concentrations of approximately 100300 ng/L and a loading of 2-37 kg/a was calculated An eliminated MTBE percentage of roughly 30-35% of MTBE in the plants was estimated Industrially influenced samples of river water or public wastewater and industrial effluents showed MTBE concentrations of up to 2267 ng/L and 28 mug/L respectively This input has not been considered before because only 15% of the produced amount of MTBE in Germany is used for industrial processes but it should not be neglected because MTBE is very persistent in water.
Article
In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), a gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking storage tanks. In this paper, we investigate ozonation and UV-ozonation for treatment of MTBE in contaminated drinking water sources. We report the test protocol and results of using solid-phase microextraction (SPME) to determine the level of MTBE and its oxidation byproducts in samples drawn from laboratory-scale ozone and UV-ozone reactors being evaluated at a US EPA research facility. Analysis of a prepared MTBE standard indicated a detection limit on the order of 0.1 microgl(-1) with a repeatability of +/-0.4%. Results show that the overall rate of removal of MTBE via UV-ozonation in a relatively turbid surface water (15 ntu) is twice that of ozonation alone. In addition, GC-MS analysis of decomposition products showed that tert-butyl formate (TBF), methyl acetate, butene, acetone, and acetaldehyde were produced by both processes. TBF and butene reach similar maximum yields from the two processes, but are more efficiently degraded by UV-ozonation treatment. This indicates that these treatment processes also degrade these byproducts. In contrast, the remaining byproducts (methyl acetate, acetone, and acetaldehyde) are formed at similar levels during treatment, but are not degraded once formed. These byproducts may be resistant to hydrogen abstraction by hydroxyl radical.
Article
In this paper, an analytical method for the determination of six iodinated X-ray contrast agents (amidotrizoic acid, iohexol, iomeprol, iopamidol, iopromide, and ioxitalamic acid), iodide, and iodate in water samples is presented. The method is based on a separation of the analytes by ion chromatography (IC) and a subsequent detection by inductively-coupled plasma mass spectrometry (ICP-MS). The method was optimised with respect to separation conditions (column type and eluent composition) and extensively validated. Without pre-concentration of the samples, limits of detection below 0.2 microg/l could be achieved whereby reproducibility was below 6% for all compounds under investigation.
Abbauverhalten und Vorkommen organischer Jodverbindungen im Raum Berlin
  • S Wischnack
  • J Oleksy-Frenzel
  • M Jekel
Wischnack S, Oleksy-Frenzel J, Jekel M. Abbauverhalten und Vorkommen organischer Jodverbindungen im Raum Berlin. GdCH Fachgruppentagung Wasserchemie 1998;96-99.