Wido Schmidt

Relevance of intra- and extracellular cyanotoxins for drinking water treatment

Bloom-forming cyanobacteria have been observed in eutrophic waterbodies including drinking water reservoirs all over the world. In this connection investigations about the relevance of intra- and extracellular cyanotoxins for drinking water treatment were carried out in laboratory- and pilot-scale experiments. An algae growth phase depended toxin release from cyanobacteria was obtained naturally caused from cultured cyanobacteria (Microcystis aeruginosa) and in a eutrophic reservoir containing Planktothrix rubescens. Results from laboratory-scale tests using cultivated cyanobacteria and pilot-scale experiments at a eutrophic reservoir underline the induced toxin release during conventional water treatment. Additional to the known toxin release using pre-oxidation, it was obtained the first time that the application of flocculation/filtration also effects in toxin release under the conditions investigated, possibly caused by turbulences in pipes and pressure gradients in filters. Bedeutung intra- und extrazellularer Cyanotoxine fur die Trinkwasseraufbereitung Die Beeintrachtigung der Trinkwasserqualitat infolge oftmals uberraschender Algenmassenentwicklungen stellt die Wasserwerke in vielen Landern der Welt vor erhebliche Probleme. In diesem Zusammenhang wurde das Verhalten intra- und extrazellularer Cyanotoxine im Prozess der Wasseraufbereitung anhand von Laborversuchen und an einer kleintechnischen Versuchsanlage untersucht. Die naturliche Freisetzung der Cyanotoxine wurde, abhangig vom Wachstumsstadium der Cyanobakterien, sowohl an einer Microcystis aeruginosa-Kultur als auch an einer mit Planktothrix rubescens belasteten eutrophen Talsperre nachgewiesen. Im Ergebnis von Labor- und kleintechnischen Versuchen an kultivierten bzw. naturlich vorkommenden Cyanobakterien wurde festgestellt, dass im Prozess der konventionellen Aufbereitung eine induzierte Toxinfreisetzung stattfindet. Neben der bereits bekannten Freisetzung bei der Voroxidation konnte erstmals auch die Freisetzung von Cyanotoxinen im Prozess der Flockung/Filtration, wahrscheinlich hervorgerufen durch Turbulenzen im Leitungssystem und Druckgradienten in Filtern, nachgewiesen werden.

Polar nitrogen compounds and their behaviour in the drinking water treatment process.

Aliphatic and alicyclic amines as well as ethanolamines are extremely polar compounds, frequently found in the environment, and some of them have high toxicity. To address the contamination of selected German surface waters examined and the importance of bank filtration in Eastern Germany, investigations on the behaviour of polar organic nitrogen compounds during water treatment were carried out. Test conditions were designed appropriately for drinking water treatment conditions, and the tests were carried out using model water as well as bank filtrate. Test filter studies of microbial degradation of selected compounds demonstrated the following order of biodegradability: ethanolamine > dimethylamine > pyrrolidine > ethylenediamine. piperidine > diethylamine > morpholine > piperazine > cyclohexylamine. Flocculation tests using iron salts as well as aluminium salts as coagulants showed very low removal rates for the amines. The best results for the removal of the polar organic nitrogen compounds from the water were obtained using ozonation. Based on the reaction-rate constants, the order of degradation by ozone is: piperazine > morpholine > ethylenediamine > piperidine, cyclohexylamine > dimethylamine > ethanolamine > pyrrolidine > diethylamine. Disinfection by chlorine-containing agents under drinking water treatment conditions did not give effective elimination of the selected polar nitrogen compounds.

Pesticides and other organic micro pollutants in the river Elbe

The main components of organic micro pollution regularly found in the river Elbe, belong to the wide spectrum of pesticides, nitro and chloro benzenes and the chelating agents, especially ethylenediaminetetraacetic acid (EDTA). The level of organic micro pollution with pesticides and the other organic micro pollutants in the upper and middle reaches of the river Elbe between Schmilka and Wittenberge was determined over a period of nearly three years. Four sample preparation methods (SPE: solidphase extraction and LLE: liquid-liquid extraction both with and without derivatization) have been used to analyze a wide spectrum of pesticides with different polarities by GC/ECD, NPD and MS. The pesticide pollution caused by the triazines decreases significantly from 0.35 μg/l (mean value) in 1992 up to 0.15 μg/l (mean value) in 1994. The correlation with the river water flow shows the diffuse character of the triazine input. In the last year of the pesticide screening a change to the more polar substances such as phenoxyalkanoic acid and nitrophenol pesticides as well as chloralkanoic acid pesticides have been noticed. The origin of trichloroacetic acid (TCA) can be explained by the waste influence, supported by the good correlation of the TCA course with the chloroform concentrations determined.

Minimization Of Disinfection By-Products Formation In Water Purification Process Using Chlorine Dioxide — Case Studies

Abstract The formation of the by-product chlorite after using chlorine dioxide for the disinfection of drinking water depends on the quantity of the organic matter dissolved in the water. A further decisive factor for the chlorite formation is the level of residual free chlorine dioxide. The chlorine dioxide demand decreases by application of activated carbon filtration, especially after the use of a combination of ozone and activated carbon treatment of the water. Nevertheless, higher chlorine dioxide residuals are a source of chlorite and chlorate formation. The concept of the “Minimum Chlorine Dioxide Dosage (MCDD)” is developed in order to give a clue to the water companies for an optimized chlorine dioxide dose without compromising the disinfection efficiency. By application of the MCDD, the residual level of chlorine dioxide is focused to 0.05 mg/L after 0.5 h contact time. In the range of the MCDD the ratio of the chlorite formation and the chlorine dioxide demand is nearly independent of the level of DOC.

Trace analysis of bromate and bromide with ion chromatography on coated reversed phase materials

Abstract The ion-chromatographic method for trace analysis of bromate and bromide presented in this paper is based on coating of reversed phase (RP) material with an ionogenic agent, tetrakisdecylammonium bromide, to obtain a pseudo ion-exchange column. The analysis is carried out with usual HPLC pump and UV-detection near 200 nm. Some commercially available RP materials were tested for the coating procedure. The differences between the reversed phases are not significant. All HETP values are calculated between 0.02 and 0.14 mm. The calibration, the sensitivity of the method and the long-time stability of the coated column were tested with one selected RP material. It is shown that the simultaneous trace analysis of bromate and bromide in surface and drinking waters with chloride concentrations up to 50 mg/L is possible without any clean-up on Ag precolumns. A comparison of performance data with a determination method for bromate and bromide employing a commercially available equipment demonstrates the efficiency of the new technique.

Assessing drinking water treatment systems for safety against cyanotoxin breakthrough using maximum tolerable values.

For assessing the safety of drinking water supplies suffering cyanobacterial blooms in their water source, a methodology is proposed which relates the performance of their current treatment train to the quality of the raw water. The approach considers that different treatment trains can remove algal toxins with different efficiency. Maximum Tolerable (MT‐) values of the raw water expressed by cell counts or by biovolumes of cyanobacteria were calculated. Three MT‐categories were identified by colours; high risk (red), moderate risk (yellow) and no risk (green). Two treatment facilities using a conventional (1) and polishing train (2) were assessed using this methodology. For most of the time during an algal bloom the water quality could be classified as yellow which means short term higher toxin levels in comparison to the guide line in clear water were found. However, the red classification, indicating a high risk for drinking water quality was never reached. The model proposed can be understood as supplement of the common alert level framework, ALF‐concept (Chorus and Bartram, Situation Assessment, Planning and Management. London and New York: E & FN Spon. 1999; House et al., Management Strategies for Toxic Blue Green Algae: Literature Review. Australia: CRC for Water Quality and Treatment. 2004).

Kinetic and Mechanistic Studies of the Ozonation of Alicyclic Amines

Abstract Studies about the ozonation of the polar and mobile alicyclic amines pyrrolidine, piperidine, morpholine and piperazine were carried out in model water at pH 7.0. According to a pseudo-first order rate law the reaction-rate constants were determined from the decrease of the amine concentration vs. the reaction time. The order of degradation of the alicyclic amines by ozone, resulting from the kinetic constants obtained, is piperazine > morpholine ⋙ piperidine > pyrrolidine. The pH value of the water, the chemical structure of the amines and their pKA values are recognized to be parameters influencing the reactionrates of the amines.

Characterization and quantification of humic substances 2D-Fluorescence by usage of extended size exclusion chromatography.

In this article, two methods for in-depth analysis of humic substances fluorescence are presented. The first one allows the combined analysis of fluorescence excitation-emission matrix (EEM) with chromatography technique. The main issue is the coupling of size exclusion chromatography (SEC) with spectroscopy by the use of an absorption and a fluorescence spectrometer as additional detectors. These allow a detailed characterization of humic substances depending on their molecular size, concentration and optical properties. For the evaluation of the resulting complex data, a model based on non-negative matrix factorization, which is also presented in this article, was developed. From the results of the examined humic substances standards, the second method was developed. It allows the characterization and quantification of humic substances fluorescence of a natural water sample solely on the basis of an excitation-emission matrix. The validation of the model is carried out within the framework of extensive analysis of real water samples.

Monitoring auf Arzneimittelwirkstoffe im Elbeeinzugsgebiet

Pharmazeutische Wirkstoffe, deren jahrliche Produktionsmengen bis zu einigen 100 Tonnen betragen konnen, gelangen in der Regel durch menschliche Ausscheidungen bzw. durch unsachgemase Entsorgung in kommunale Klaranlagen, wo sie nicht in allen Fallen vollstandig eliminiert werden. Mit Hilfe eines neuentwickelten Analysenverfahrens wurden im Jahr 1997 umfangreiche Untersuchungen zum Vorkommen von Arzneimittelruckstanden im Elbeeinzugsgebiet durchgefuhrt (Sacher et al. 1998).

Länderübergreifende Erfassung polarer organischer Mikroverunreinigungen in der Elbe (Labe) auf tschechischem und deutschem Gebiet

In Anbetracht der landerubergreifenden Nutzung der Gewasser ist fur einen Flus wie die Elbe (Labe) die bilaterale Zusammenarbeit tschechischer und deutscher Einrichtungen auf dem Gebiet des Gewasserschutzes von groser Bedeutung.