Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe.

Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200.

Evaluation of natural organic matter changes from Lake Hohloh by three-dimensional excitation-emission matrix fluorescence spectroscopy during TiO(2)/UV process.

This study shows the changes of natural organic matter (NOM) from Lake Hohloh, (Black Forest, Germany) during heterogeneous photocatalysis with TiO2 (TiO2/UV). The effect of pH on the adsorption of NOM onto TiO2 in the dark and TiO2/UV degradation of NOM was followed using three-dimensional excitation-emission matrix (EEM) fluorescence. At pH values between 4 and 9, the NOM was adsorbed onto TiO2 in the dark with a greater decrease in the fluorescence intensity and in the spectral shapes, especially under acidic pH conditions.

[Hydraulic fracturing - a hazard for drinking water?].

Hydraulic fracturing (fracking) is a technique used to release and promote the extraction of natural gas (including shale gas, tight gas, and coal bed methane) from deep natural gas deposits. Among the German public there is great concern with regard to the potential environmental impacts of fracking including the contamination of ground water, the most important source of drinking water in Germany. In the present article the risks of ground water contamination through fracking are discussed.

Evaluations of the TiO2/simulated solar UV degradations of XAD fractions of natural organic matter from a bog lake using size-exclusion chromatography.

This work reports on the changes in compositions of humic acids (HAs) and fulvic acids (FAs) during photocatalytic degradation. The HAs and FAs were obtained from the XAD-resin fractionation of natural-organic matter (NOM) from a bog lake (Lake Hohloh, Black Forest, Germany). Degussa P-25 titanium dioxide (TiO2) in a suspension and a solar UV simulator (batch reactor) were used in the experiments.

Influence of the pH-value on the photocatalytic disinfection of bacteria with TiO2--explanation by DLVO and XDLVO theory.

A photocatalytic disinfection with P25 TiO(2) was conducted at three pH-values (4, 7 and 10) in NaCl solution (c = 10 mmol L(-1)). Neither the osmotic stress nor solely the pH-value had a significant impact on the survival of the Escherichia coli cells. The cells were more damaged at pH 4 than at pH 7 and 10 in irradiation experiments with TiO(2).

Application of excitation-emission fluorescence matrices and UV/Vis absorption to monitoring the photocatalytic degradation of commercial humic acid.

This study reports the use of excitation-emission matrix (EEM) fluorescence and UV/Vis spectroscopy to monitor the changes in the composition and reactivity of Aldrich humic acids (Aldrich HA) as a model compound for natural organic matter (NOM) during photocatalytic degradation. Degussa P-25 titanium dioxide (TiO(2)) and a solar UV-light simulator (a batch reactor) were used. The photocatalysis shifted the fluorescence maxima of EEMs of Aldrich HA toward shorter wavelengths, which implied that the photocatalytic degradation of commercial Aldrich HA caused the breakdown of high molecular weight components and the formation of lower molecular weight fractions.

Study of pH effects on the evolution of properties of brown-water natural organic matter as revealed by size-exclusion chromatography during photocatalytic degradation.

This study shows the effect of pH on the photocatalytic degradation of natural organic matter (NOM). The experiments were carried out in batch reactor (a solar UV-light simulator) with Degussa P-25 titanium dioxide (TiO2). The NOM degradation was followed by size-exclusion chromatography for dissolved organic carbon (DOC), ultraviolet absorption and fluorescence-detection (SEC-DOC, SEC-UV254 and SEC-Fl254/450).

Nanoparticles in aquatic systems.

Nanoparticles (NP) are ubiquitous in environmental and technical aquatic systems. Understanding the role and the fate of NP in these systems is an interdisciplinary challenge requiring innovative experimental, theoretical and analytical approaches and critical reflection of classical concepts. This contribution critically reviews the outstanding properties of NP and the resulting consequences for their behaviour in environmental and technical aquatic systems considering natural NP which are mostly geogenic or biogeogenic, and engineered NP.

Application of an optimized system for the well-defined exposure of human lung cells to trichloramine and indoor pool air.

In this study an in vitro exposure test to investigate toxicological effects of the volatile disinfection by-product trichloramine and of real indoor pool air was established. For this purpose a set-up to generate a well-defined, clean gas stream of trichloramine was combined with biotests. Human alveolar epithelial lung cells of the cell line A-549 were exposed in a CULTEX(®) device with trichloramine concentrations between 0.

Nanofiltration for enhanced removal of disinfection by-product (DBP) precursors in swimming pool water-retention and water quality estimation.

Three nanofiltration (NF) membranes with a chlorine tolerance > or = 1 mg L-1 were applied to reduce DBPs and their precursors in swimming pool water. A lab scale plant with crossflow modules was installed in by-pass at the sand filter outlet of a swimming pool for a period of several weeks. The chlorine tolerances of the membranes SB90 and NP030 were found to be adequate for filtration under swimming pool water conditions over the given experimental period.

Interactions and stability of silver nanoparticles in the aqueous phase: Influence of natural organic matter (NOM) and ionic strength.

The rapid development of nanotechnology and the related production and application of nanosized materials such as engineered nanoparticles (ENP) inevitably lead to the emission of these products into environmental systems. So far, little is known about the occurrence and the behaviour of ENP in environmental aquatic systems. In this contribution, the influence of natural organic matter (NOM) and ionic strength on the stability and the interactions of silver nanoparticles (n-Ag) in aqueous suspensions was investigated using UV-vis spectroscopy and asymmetrical flow field-flow fractionation (AF⁴) coupled with UV-vis detection and mass spectrometry (ICP-MS).

Trichloramine in swimming pools--formation and mass transfer.

Trichloramine is a volatile, irritant compound of penetrating odor, which is found as a disinfection by-product in the air of chlorinated indoor swimming pools from reactions of nitrogenous compounds with chlorine. Acid amides, especially urea, ammonium ions and α-amino acids have been found as most efficient trichloramine precursors at acidic and neutral pH. For urea a relative NCl(3) formation of 96% at pH 2.

Metabolites indicate hot spots of biodegradation and biogeochemical gradients in a high-resolution monitoring well.

Anaerobic degradation processes play an important role in contaminated aquifers. To indicate active biodegradation processes signature metabolites can be used. In this study field samples from a high-resolution multilevel well in a tar oil-contaminated, anoxic aquifer were analyzed for metabolites by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry.

Effect of selected metal ions on the photocatalytic degradation of bog lake water natural organic matter.

Herein we report the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) in the presence of 0, 5, and 10 μmol L(-1) of added Cu(2+), Mn(2+), Zn(2+) and Fe(3+). The reactions were followed by size exclusion chromatography with organic carbon detection (SEC-DOC) and by measurements of low molecular weight organic acids. Addition of Cu(2+) had the largest effect of all four studied metals, leading to a retardation in the molecular size changes in NOM: degradation of the larger molecular weight fraction was inhibited leading to reduced production of smaller molecular weight metabolites.

The hybrid process TiO(2)/PAC: performance of membrane filtration.

In investigations concerning the photocatalytic degradation by TiO(2) usually filter discs with a pore size of 0.22 mum and 0.45 mum are used for the removal of photocatalyst particles in aqueous suspensions.

Influence of the zeta potential on the sorption and toxicity of iron oxide nanoparticles on S. cerevisiae and E. coli.

The influence of the zeta potential on the sorption between microorganisms (Saccharomyces cerevisiae and Escherichia coli) and iron oxide nanoparticles is demonstrated in a model salt solution at two different pH-values. There was only a 1% survival rate of E. coli (4.

Photocatalytic degradation of clofibric acid, carbamazepine and iomeprol using conglomerated TiO2 and activated carbon in aqueous suspension.

The combination of powdered activated carbon (PAC) and TiO(2) has been tested for synergistic/antagonistic effects in the photocatalytic degradation of carbamazepine, clofibric acid and iomeprol. Synergistic effects are thought to be caused by rapid adsorption on the PAC surface followed by diffusion to the TiO(2) surface and photocatalytic degradation. The Freundlich constant K(F) was used for comparing the sorption properties of the three substances and it was found that K(F) for clofibric acid was 3 times lower than for carbamazepine and iomeprol, regardless of the kind of PAC used.

Nitrifying microorganisms in fixed-bed biofilm reactors fed with different nitrite and ammonia concentrations.

Nitrifying bacteria and archaea were fed in fixed-bed biofilm reactors with different nitrite and ammonia concentrations in synthetic and real wastewater. During high nitrite concentrations (rho(NO(2)(-))=5-10mg/L), an increase in the abundance of Nitrobacter species was detected with fluorescence in situ hybridization (FISH), while Nitrospira species disappeared to a large extent. During high ammonia concentrations (rho(NH(4)(+))=60-80 mg/L), a slight increase in ammonia-oxidizing bacteria was obtained, while the abundance of archaebacteria remained unchanged.

Use of fluorescence fingerprints for the estimation of bloom formation and toxin production of Microcystis aeruginosa.

The development of methods facilitating the detection of cyanobacterial blooms in drinking water reservoirs at an early stage is of great importance. Fluorescence spectroscopy could meet these requirements. The study contains the examination of possible correlations between the different maxima of a fluorescence excitation-emission matrix and the amount of produced and excreted toxins of a lab culture of Microcystis aeruginosa at different stages of growth.

The concentration of polysaccharides and proteins in EPS of Pseudomonas putida and Aureobasidum pullulans as revealed by 13C CPMAS NMR spectroscopy.

Extracellular polymeric substances were extracted from the bacterial strain Pseudomonas putida and the fungal species Aureobasidium pullulans using three different methods (formaldehyde-NaOH, ethylenediaminetetraacetic acid (EDTA) and cation-exchange-resin). The composition of the extracellular polymeric substances (EPS) was analysed by biochemical and high-resolution solid state 13C nuclear magnetic resonance (NMR) spectroscopic methods. The EPS yield was strongly dependent on the extraction method, with the formaldehyde-NaOH method showing the best extraction efficiency.

Electrochemical reduction of the iodinated contrast medium iomeprol: iodine mass balance and identification of transformation products.

Potentiostatic-controlled electrochemical reduction of iomeprol was used to deiodinate iomeprol (IMP), a representative of the iodinated X-ray contrast media. The reduction process was followed by product analysis with liquid chromatography-electrospray ionization-tandem mass spectrometry and ion chromatography-inductively coupled plasma-mass spectrometry. The identification is mainly based on the interpretation of the mass fragmentation.

Formation of bromoform in irradiated titanium dioxide suspensions with varying photocatalyst, dissolved organic carbon and bromide concentrations.

We report the formation of bromoform in TiO(2) suspensions (P25) under simulated solar UV irradiation at different concentrations of photocatalyst (0.5-1.5 g L(-1)) as well as initial concentrations of bromide ions (1-3mg L(-1)) and 2,4-dihydroxybenzoic acid (2-10mg L(-1)).