Fritz H. Frimmel

Fate of pharmaceuticals-photodegradation by simulated solar UV-light

The fate of pharmaceuticals in surface waters under solar irradiation was investigated. Photodegradation of pharmaceuticals caused by sun irradiation may be of major significance in the natural elimination process. Based on a data compilation from the literature, the lipid lowering agent metabolite clofibric acid, the iodinated X-ray contrast media iomeprol, which contribute to the adsorbable organic halogen compounds, and the antiepileptic drug carbamazepine were selected. The irradiation experiments were carried out in batch experiments with simulated UV-sunlight. The photodegradation of the pharmaceuticals showed a pseudo-first-order kinetics. The objective of this investigation was to demonstrate that the extent of photoinduced degradation of pharmaceuticals can vary significantly for the different pharmaceuticals and it strongly depends on the water constituents present in solution. The influences of different initial pharmaceutical concentrations, the presence of other pharmaceuticals like carbamazepine or clofibric acid and the presence of natural organic matter on the photochemical degradation rate of pharmaceuticals in aqueous solutions were investigated. Analyses of the pharmaceuticals and their photodegradation products were carried out by high performance liquid chromatography with diode-array and fluorescence detection.

Short-term tests with a pilot sewage plant and biofilm reactors for the biological degradation of the pharmaceutical compounds clofibric acid, ibuprofen, and diclofenac

The biodegradation of three active compounds of pharmaceuticals clofibric acid, ibuprofen, and diclofenac was investigated in short-term tests with a pilot sewage plant (PSP) and biofilm reactors (BFR, oxic and anoxic) as model systems for municipal sewage treatment. The PSP was characterized with respect to mixing behavior, the BFR with respect to biofilm content and sorption of the pharmaceutical compounds. The short-term experiments were carried out for 55 h in the PSP and for 48 h in the BFR. The concentration of the pharmaceuticals was in the microgram per liter range in presence of readily biodegradable substances in the milligram per liter range. Therefore, a too short time period and too low concentration to promote adaption of the microorganisms were applied. Under the operating conditions applied the biodegradation of the lipid lowering agent clofibric acid and the analgesic agents ibuprofen and diclofenac in the oxic BFR resembled that in the PSP. Clofibric acid and diclofenac were not eliminated and reached a level of approximately 95% of their initial concentration, whereas the concentration of ibuprofen was decreased to approximately 40% in the PSP and to approximately 35% in the oxic BFR. Both systems showed, therefore, an inherent ability for ibuprofen biodegradation. Elimination in the anoxic BFR resulted in a decrease of the concentration of all three substances to values between 60 and 80% of their initial concentration. In contrast to the PSP acetone revealed as inhibitor in the BFR. In both systems acetone was not degraded in the short-term tests.

Degradation of phenol and salicylic acid by ultraviolet radiation/hydrogen peroxide/oxygen

Abstract Based on the oxidation reactions of u.v. radiation/hydrogen peroxide/oxygen with either phenol or salicylic acid a spectra library was established. The reaction products contain hydroxylated phenols, benzoquinone and aliphatic acids with up to six carbon atoms. Many of the substances have been identified by means of chromatography and spectra comparison. From the observed concentrations of the substances and the known reaction mechanisms the following course of reaction has been postulated. The first reaction step is the hydroxylation of the aromatic ring. Further oxidation occurs via abstraction of a hydrogen atom to form 1,2-benzoquinone which is cleaved to form muconic acid. The cleavage of the muconic acid by u.v. radiation/hydrogen peroxide/oxygen leads to maleic acid, fumaric acid and oxalic acid. The degradation of oxalic acid leads to formic acid and finally to carbon dioxide. The hydroxylation of the double bond of the maleic or fumaric acid and the abstraction of a hydrogen atom produces malic acid. The reactions can be seen as essential step in the photochemical transformation of refractory substances into biodegradable ones.

Characterization of natural organic matter as major constituents in aquatic systems

Abstract Natural organic matter (NOM) is ubiquitous in global aquatic systems, the mass concentrations ranging from 0.5 to 100 mg/l of organic carbon. The polydispersity of molar masses and the chemical structures comprising NOM give it a multifunctional role in natural environment and in water treatment processes. Important functions include serving as an electron donor in metal complexation, sorption of xenobiotics and adsorption onto mineral phases and onto activated carbon. NOM is partially oxidized during microbial utilization and during water treatment in which it may also become substituted with chlorine leading to a suite of products with toxic relevance. Meaningful methods of NOM characterization would be useful for the development of a predictive capacity for NOM behaviour in different water sources. Among analytical characterization methods, those directly applicable to aqueous samples are most useful and in addition to classical spectroscopic methods, more advanced methods have become available within the last decade. High pressure liquid chromatography using gels have proved useful in combination with UV/vis, fluorescence, light scattering and sensitive dissolved organic carbon detection techniques, yielding information on molecular absorbance, size distribution, molar mass and reactivity. Information on biodegradability of NOM can be deduced from experimental measurement of bacterial growth under defined conditions. The nature and amount of biologically assimilable organic carbon (AOC) in combination with the bacterial cell number and growth rate constants can provide a meaningful characterization of microbial stability in aquatic systems. In addition, determination of directly available and acid or enzymatically hydrolysable amino acids and carbohydrates can add to the understanding of NOM biodegradability over different time scales. The paper gives the results obtained by the application of the different methods for the characterization of aquatic NOM and its fractions of different origin. It can be shown that the availability of advanced characterization techniques offers the potential for predicting the functionality of aquatic NOM without precise knowledge of the chemical structures present in the macromolecular complex.

TiO2-catalyzed photooxidation of arsenite to arsenate in aqueous samples

The TiO2-catalyzed photooxidation of arsenite (As(III)) to arsenate (As(V)) was studied in aqueous TiO2 suspensions using a solar simulator which emitted ultraviolet and visible radiations. The concentration of As(III) was varied between 50 microg l(-1) and 10 mg l(-1), and the concentration of TiO2 between 1 mg l(-1) and 50 mg l(-1). Total oxidation of As(III) to As(V) occurred within minutes. The concentration of As(III) declined exponentially which indicates first-order kinetics. In the pH range between 5 and 9 there was no significant influence of the pH of the suspension on the reaction rate. Batch experiments without irradiation showed that part of the arsenic was adsorbed on the TiO2 surface. When using 100 microg l(-1) As and between 1 mg l(-1) and 50 mg l(-1) TiO2, 8-39% of As(III) and up to 73% of As(V) were adsorbed by TiO2. As(III) was also oxidized by UV radiation in the absence of TiO2, but the reaction was slower than in the presence of TiO2 resulting in an irradiation time too long for practical use. In addition, oxidation of As(III) in the presence of TiO2 was also observed under solar irradiation within a few minutes.

Structural characterization of aquatic humic substances: The need for a multiple method approach

Abstract.An overview of different characterization methods and the possibilities for describing structural elements of humic substances from aqueous environments (HS, or refractory organic substances (ROS)) is given within this review. The application of different analytical methods for the qualitative and quantitative characterization of HS, including physical/chemical analysis (elemental analysis, acid/base titration), spectroscopic methods (UV/VIS, NMR, fluorescence, mass spectrometry), fractionation methods (gel chromatography, flow-field-flow-fractionation), and degradation methods (oxidation, pyrolysis, hydrolysis) are discussed. The paper focuses on the most commonly used chemical, spectroscopic and chromatographic methods used in the last few years. Aspects concerning information related to newer procedures are considered. Case studies representing results gained from reference samples isolated from brown water and wastewater effluents are given to cross-check results gained from several methods. The influence of different isolation procedures on the specific character of the fractions is also discussed.

Refractory organic substances in the environment

Preface. List of Authors. List of Abbreviations. Setting the Scene. The Relevance of Reference Materials Isolation and General Characterization. Element Determination and its Quality Control in Fractions of Refractory Organic Substances and the Corresponding Original Water Samples. Structural Investigations. Heavy Metal and Halogen Interactions with Fractions of Refractory Organic Substances Separated by Size exclusion Chromatography. Characterization of Refractory Organic Substances and Their Metal Species by Combined Analytical Procedures. Application of Nuclear Magnetic Resonance Spectroscopy to Structural Investigations of Refractory Organic Substances Principles and Definitions. Structural Characterization of Refractory Organic Substances by Solid state High resolution 13C and 15N Nuclear Magnetic Resonance. Quantification of Substructures of Refractory Organic Substances by Means of Nuclear Magnetic Resonance. Nuclear Magnetic Resonance Spectroscopy Investigations of Silylated Refractory Organic Substances. Isotopic Evidence for the Origin and Formation of Refractory Organic Substances. Analytical Pyrolysis of Humic Substances and Dissolved Organic Matter in Water. Charaacterization of Refractory Organic Substances by HPLC/MS. UV Visible Spectroscopy and the Potential of Fluroscent Probes. Stationary and Time resolved Fluorescence for Refractory Organic Substances Characterization. Structural Characterization of Refractory Organic Substances by Pyrolysis GC/FTIR. X ray Microscopy Studies of Refractory Organic Substances. Fractionation of Refractory Organic Substances by Electrophoresis. Occurence of Amino Acids, Carbohydrates, and Low molecular weight Organic Acids in Refractory Organic Substances. Serological Characteization of Refractory Organic Substances. Biochemical and Biological Characterization. Formation, Utilization and Transformation of Some Refractory Organic Substances by Aquatic Microorganisms. Effect of Microorganisms on the Formation and Transformation of Iodine Species of Refractory Organic Substances. The Influence of Refractory Organic Substances on Bacterial Colonization and Diversity Patterns. Influence of Refractory Organic Substances on Enzyme Activity in vivo and DNA Damage of Aquatic Microorganisms. Effects of Dissolved Organic Matter on the Bioconcentration of Organic Contaminants and on Reproduction in Aquatic Invertebrates. Molecular Interactions. Sorption of Dissolved Organic Matter on Soil Particles and its Dependence on their Surface charge Properties. Dissolved Organic Carbon in Seepage Water Production and Transformation During Soil Passage. Refractory Organic Substances in Aggregated Forest Soils Retention versus Translocation. Refractory Organic Substances Derived from Organic Amendments in Soil Formation, Translocation, and Interaction with Xenobiotics. Analysis of the Binding Amitrole and Anilazine to Aquatic and Terrestrial Refractory Organic Substances. Sorption and Chemical Reactions of Polycyclic Aromatic Hydrocarbons with Dissolved Refractory Organic Substances and Related Model Polymers. Investigation of the Interactions between Polycyclic Aromatic Compounds and Refractory Organic Substances with Stationary and Time resolved Fluorescence and Absorption Spectroscopy. Index. Author Index.

Removal of precursors for disinfection by-products (DBPs) — differences between ozone- and OH-radical-induced oxidation

Pre-oxidation is often applied to reduce the formation of disinfection by-products (DBPs). The aim of pre-oxidation is to remove the centers of natural organic matter (NOM) which are responsible for the formation of DBPs. In this paper, the differences between ozone- and OH-radical-induced oxidation to remove DBP-precursors are compared. The experiments were done with water of the River Ruhr (Germany) with a concentration of dissolved organic carbon (DOC) of 2 mg/l. Ozonation was able to remove DBP precursors selectively. After application of an absorbed ozone mass of 1.5 mg/mg DOC, a reduction in the formation potential for (THM-FP) and in the formation potential for organic halogen adsorbable on activated carbon (AOX-FP) down to 68 and 73% of the initial concentration was achieved, respectively. A removal of NOM was not achieved using absorbed ozone masses between 0.5 and 1.5 mg/mg DOC. In the hydrogen peroxide/UV process, in which OH-radicals are the reactive species, an increase in the THM concentration was measured after application of this process with short irradiation times. The maximum value of the THM-FP was 20% higher than the initial THM-FP. After an irradiation time of 1,050 min and a hydrogen peroxide consumption of 5.6 mg/l, the THM-FP and AOX-FP decreased to 75 and 71% of the initial formation potential, respectively. There was no selective removal of DBP precursors because the DOC concentration decreased also to 75% of the initial DOC-concentration after 1,050 min of irradiation.

Sorption of phenols to dissolved organic matter investigated by solid phase microextraction

The sorption of phenol and different halogenated phenols to natural organic matter of a brown water lake (HO14), of a compost extract, of Aldrich humic acid (Aldrich-HA), and to the protein bovine serum albumin (BSA) was investigated using solid phase microextraction (SPME). The limit of determination for the SPME analysis was < 15 microg/l for all phenols investigated. The extraction coefficients K(F) were calculated according to a first-order extraction kinetics. In general, the extraction equilibrium was established faster due to the presence of dissolved organic matter (DOM). The highest sorption capacity of phenols was observed for BSA with log K(OC) values in the range between 2 and 6. For the compost extract and HO14 only a small sorption of the investigated phenols was determined. On the other hand, Aldrich humic acid showed a reasonable sorption of phenols with log K(OC) values between 2 and 3. The sorption to DOM decreased when the pH of the solution was increased.

Childhood asthma and environmental exposures at swimming pools: state of the science and research recommendations.

Objectives Recent studies have explored the potential for swimming pool disinfection by-products (DBPs), which are respiratory irritants, to cause asthma in young children. Here we describe the state of the science on methods for understanding children’s exposure to DBPs and biologics at swimming pools and associations with new-onset childhood asthma and recommend a research agenda to improve our understanding of this issue. Data sources A workshop was held in Leuven, Belgium, 21–23 August 2007, to evaluate the literature and to develop a research agenda to better understand children’s exposures in the swimming pool environment and their potential associations with new-onset asthma. Participants, including clinicians, epidemiologists, exposure scientists, pool operations experts, and chemists, reviewed the literature, prepared background summaries, and held extensive discussions on the relevant published studies, knowledge of asthma characterization and exposures at swimming pools, and epidemiologic study designs. Synthesis Childhood swimming and new-onset childhood asthma have clear implications for public health. If attendance at indoor pools increases risk of childhood asthma, then concerns are warranted and action is necessary. If there is no such relationship, these concerns could unnecessarily deter children from indoor swimming and/or compromise water disinfection. Conclusions Current evidence of an association between childhood swimming and new-onset asthma is suggestive but not conclusive. Important data gaps need to be filled, particularly in exposure assessment and characterization of asthma in the very young. Participants recommended that additional evaluations using a multidisciplinary approach are needed to determine whether a clear association exists.