From lists of published rate constants for the direct reactions of aqueous ozone with substrates we can conclude: if, for example, 0.5 mg/l ozone is present, the following types of compounds react within less than 10 seconds: sulfite, nitrite, olefinic aliphatic hydrocarbons, phenols, polyaromatic hydrocarbons, organic amines and sulfides. Much slower to react are some chlorosubstituted olefins (chlorinated solvents). Benzene, saturated hydrocarbons, or tetrachloroethylene require days to be significantly oxidized by molecular ozone. <BR/> In bromide-containing waters (seawater, brackish waters, pool waters), the bromide is the primary reactant with ozone. It is oxidized to hypobromite or even bromate, and can destroy part of the ozone in a catalytic chain process. The hypobromite can produce bromoform. <BR/> Some of the aqueous ozone always decomposes. This decomposition is often initiated by increased pH (OH<SUP>*</SUP>-ions) and accelerated by many types of organic compounds which may act as promoters of a radical type chain reaction. This chain reaction is, however, somewhat inhibited by carbonate. Therefore, the half-life of ozone varies according to the type of water treated. For example, in typical drinking water it can be anything from 1 to 20 minutes. <BR/> Ozone decomposition leads to the formation of the OH<SUP>*</SUP>-radical. This is so reactive that, in drinking water, most of it is consumed by humics and other dissolved organic materials. The OH- radical can even be reduced by carbonate and bicarbonate ions. But a fraction of this oxidant is still available to oxidize a specific micropollutant, even when this is present in relatively low concentrations. Based on known kinetic constants, all these effects are easily predictable. <BR/> UV-irradiation of aqueous ozone produces primarily hydrogen peroxide which, under certain circumstances, may initiate decomposition of additional ozone to OH<SUP>*</SUP>-radicals. <BR/> The chemical effects of ozonation processes must also be considered with respect to combined processes, where ozonation is, e.g. followed by treatment with chlorine or microbiological treatment steps, or even by membrane filtration in the case of industrial waste water treatment.

Our global environment is on the average, with regard to a proton and electron balance, in a stationary state. Schematically, the oxidation states and the H<SUP>+</SUP> reservoirs of the weathering sources equal those of the sedimentary products. Obviously, such balances are locally and regionally upset. In addition, they have become significantly disturbed by the combustion of fossil fuels which generates a net production of H<SUP>+</SUP> ions in atmospheric deposition. <BR/> In this chapter, we intend to show how this disturbance is transferred to the terrestrial and aquatic environment and to review the major H<SUP>+</SUP> yielding and H<SUP>+</SUP> consuming processes occurring in the watersheds, paying special attention (1) to the disturbance of the H<SUP>+</SUP> balance resulting from temporal or spatial decoupling of the production and mineralization of the biomass, and (2) to the H<SUP>+</SUP> ion consumption by the weathering of rocks. The aggradation of vegetation (productive forests) may be accompanied by acidification of surrounding waters. In some instances, the acidic atmospheric deposition may be sufficient to disturb the existing H<SUP>+</SUP> balance between aggrading vegetation and weathering reactions. <BR/> Chemical weathering is shown to be a key process in neutralizing the internal production and the anthropogenic input of acids to a watershed. The lakes which have been acidified by acid precipitation are those lacking carbonate minerals and characterized by sensitive hydrological settings.

Aus der Sicht des Gewässerschutzes braucht es zur Verbesserung der Seenqualität bis zum gesetzeskonformen Zustand weitere Reduktionen der Phosphorbelastung. Den Phosphorhaushalt der Schweiz wird man nicht durch abwassertechnische Massnahmen allein unter Kontrolle bringen können. Dies wird nur möglich, wenn auch an den Quellen gesteuert wird, nämlich bei der Einfuhr von Phosphaten zur Anwendung in Düngern, Futtermitteln und Waschmitteln. Solche Steuerungsmassnahmen verlangen teilweise auch nach Ersatzstoffen oder/und neuen technischen Verfahren, deren Umweltverträglichkeit ebenfalls gründlich geprüft werden muss.

Im Kehricht liegt über 95 % des Elements Eisen in metallischer Form vor. In dieser Arbeit wurde analysiert, wie die Prozesse Kehrichtverbrennung und Deponierung das Eisen verändern.<br /> Die Untersuchungen wurden an KVA-Schlacken mit verschiedener Vorgeschichte durchgeführt. Da das Eisen in der Schlacke in den verschiedensten Formen auftritt, musste für eine gute Erfassung ein aufwendiges Probenaufbereitungsverfahren verwendet werden. Die Eisengehalte der anfallenden Pulverfraktionen wurden nach nasschemischem Aufschluss mit AAS ermittelt. Mit Röntgendiffraktometrie konnte halbquantitativ die Phasenzusammensetzungen dieser Pulver bestimmt werden. Aus in Araldit eingebetteten Schlackenproben wurden An- und Dünnschliffe hergestellt, die mit Auflicht-, Durchlichtund Rasterelektronenmikroskopie analysiert wurden. Dadurch konnte die Morphologie der eisenhaltigen Phasen und ihre Vergesellschaftung mit andern Schlackenphasen ennittelt werden. In der Auswertung wurden die Resultate der verschiedenen Analysemethoden miteinander verknüpft.<br /> Die untersuchten Schlacken haben Eisengehalte von 13 bis 17 Gew% der Trockensubstanz. [...]

During 48 hours in Winter and 36 hours in Summer, the behaviour and diurnal load variations of nitrilotriacetate (NTA) and ethylenediamintetraacetate (EDTA) were investigated in the sewage treatment plant Glatt (waste water discharge: Q = 55 - 60000 m³/d, 110000 inhabitants) of the city of Zurich. The measurements were made on one lane (volume = 1812 m³, Q = 14700 m³/d) of the four parallel lanes of the secondary treatment. For the discussion of the results we used the activated sludge model of the IAWPRC task group, which was extended by the kinetics of biological degradation of NTA and of its adsorption onto activated sludge.<br/> The plant had a sludge age of 3.6 days in Winter and 4.8 days in Summer and was in Winter partly nitrifying (waste water temperatures: 10-11°C and 20 °C, respectively). In the investigated lane the average daily loads of NTA and EDTA were during both investigated periods 13 ± 7 kg NTA/d (0.5 ± 0.3 g NTA/person·d) and 1.3±0.6 kg EDTA/d, respectively. The influent concentration varied from 300 to 1500 μg NTA/l and from 30 to 150 μg EDTA/l. NTA was in winter and in summer up to 97% biologically degraded. No elimination was observed for EDTA within the analytical precision. Between 12 a.m. and 2 p.m. of the second day in the winter period additional 17 kg of NTA (120% of a daily load) were added to the effluent of the primary clarifier. During 4 to 5 hours the biological NTA degradation was not limited by low NTA concentrations and four times more than the daily average of NTA was degraded. Due to the increased NTA concentration (up to 2000 μg NTA/l in the effluent of the secondary clarifier) zinc and lead were redissolved from the activated sludge, and their effluent concentration in the secondary clarifier increased by 200% and 50%, respectively. The concentration of copper did not increase during the NTA shock loading.

Genetic mechanisms in bacteria provide a continuous source of alterations in DNA sequences that may lead to favourable adaptations. Bacteria that use chlorinated aromatics as sole carbon and energy sources show evidence of these different genetic alterations. The distinct effects of single base-pair mutations on adaptation of bacterial strains (e.g. by changing the substrate specificity of a key metabolic enzyme or regulator protein) have been demonstrated in various studies. In addition to these small sequence modifications, intermolecular or intercellular gene exchange mechanisms can result in new strains with altered metabolic capabilities. The details of these evolutionary processes with respect to the metabolism of chlorobenzenes and chlorocatechols are reviewed in this manuscript.

The dynamic behavior of tetrachloroethene (PER), atrazine, and nitrilotriacetate (NTA) in a small lake in Switzerland has been evaluated quantitatively using field data and a simulation software (MASAS) for modeling organic pollutants in lakes. For PER, atrazine and NTA, the input and the seasonal variation in the vertical distribution could be described successfully by applying simple box models as well as a one-dimensional vertical model. In the case of PER, it was possible to reconstruct the input history for a long time period (9 years), and it was found that the stagnant boundary layer model was well suited for estimating the average gas exchange rate of this volatile compound between the lake and the atmosphere. Atrazine showed, except for a short time period during the summer, a very conservative behavior in the lake. For NTA, an average <I>in situ</I> rate constant of 0.035 d^-1 was determined for its elimination from the water column. The elimination was attributed primarily to biodegradation. The results of this study demonstrate nicely the power of the combined use of mathematical models, including computer simulations, and field measurements for assessing the environmental behavior of organic pollutants.