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water research

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Project log

Andreas Nahrstedt
added 2 research items
Zusammenfassung Zwei Filter der Flockungsfiltration in Wuppertal-Buchenhofen wurden über einen Zeitraum von etwa sechs Jahren mit granu-lierter Aktivkohle (GAK) betrieben, und zwar beide mit dynami-schen Filtergeschwindigkeiten analog zu den konventionellen Sand/Anthrazit-Filterkammern. Einer der GAK-Filter wurde über ein Pumpwerk mit Filtrat der Flockungsfiltration beschickt, um den Einfluss einer Vorfiltration zu untersuchen. Es wurden jeweils etwa 70 000 Bettvolumina behandelt und über den ge-samten Zeitraum mindestens monatlich DOC/CSB und neun unterschiedliche Spurenstoffe analysiert. Die Langzeituntersu-chung liefert Durchbruchskurven im technischen Maßstab sowie Betriebserfahrungen zum Filterverhalten. Für die Übertragung der Ergebnisse der Einzelfilter auf einen theoretischen Parallel-betrieb mehrerer Filter wurde ein zeitgewichteter fortlaufender Mittelwert berechnet. Zusätzlich wurde über Massenbilanzen die stoffspezifische Beladung der Aktivkohle bestimmt. Abstract Long-term experience with the use of GAC filters to eliminate micropollutants Over a period of around six years, two flocculation filtration filters with granulated activated carbon (GAC) were operated in Wuppertal-Buchenhofen. These filters ran at dynamic filter speeds equivalent to those of conventional dual media (anthra-cite and quartz sand) chambers. One GAC filter was fed with fil-trate from the flocculation filtration via a pumping station in order to test the influence of prefiltration. About 70,000 bed volumes were treated, with DOC/COD and nine different micropo-llutants analysed at least monthly during the entire period. The long-term study depicts breakthrough curves on a large scale as well as operational experience regarding filter behaviour. A time-weighted continuous mean was calculated in order to translate the findings for individual filters to a theoretical situation in which several filters operate in parallel. In addition, activated carbon's substance-specific loading was identified using mass balances.
Pilotation of Ozonation + BAC Filtration for the Removal of Micropollutants
Elke Dopp
added a research item
The aim of this interdisciplinary research project in North Rhine-Westphalia (NRW), Germany, entitled “Elimination of pharmaceuticals and organic micropollutants from waste water” involved the conception of cost-effective and innovative waste-water cleaning methods. In this project in vitro assays, in vivo assays and chemical analyses were performed on three municipal waste-water treatment plants (WWTP). This publication focuses on the study of the in vitro bioassays. Cytotoxic, estrogenic, genotoxic and mutagenic effects of the original as well as enriched water samples were monitored before and after wastewater treatment steps using MTT and PAN I, ER Calux and A-YES, micronucleus and Comet assays as well as AMES test. In most cases, the measured effects were reduced after ozonation, but in general, the biological response depended upon the water composition of the WWTP, in particular on the formed by-products and concentration of micropollutants. In order to be able to assess the genotoxic and/or mutagenic potential of waste-water samples using bioassays like Ames test, Comet assay or micronucleus test an enrichment of the water sample via solid-phase extraction is recommended. This is in agreement with previous studies such as the “ToxBox”-Project of the Environmental Agency in Germany.
Elke Dopp
added a research item
Complex mixtures of chemicals in waste and finally in surface water may pose a risk to the environment and also to human health. This contamination of surface water cannot be addressed with chemical analysis alone. Tools are required to detect and assess these micropollutants which might cause adverse effects. Effect-directed analysis (EDA) with effect-based methods in combination with state-of-the-art chemical analysis can meet this challenge. The present paper summarizes and outlines current experiences with analytical tools and bioassays as integrated approach for assessment of water quality. The need for a holistic and solution-oriented procedure of water quality monitoring is described. To integrate and evaluate existing information about toxicity pathways, which are essential for the EDA approach, the adverse outcome pathway (AOP) concept is useful and recommended. An integration of AOP concept in water quality assessment and further requirements are discussed.
Elke Dopp
added 3 research items
Increased concentrations of industrial chemicals, pharmaceuticals and personal care products can be detected in effluents of waste water treatment plants. These could be contrary to regulations of the European Water Framework Directive (WFD), which requires a “good” chemical and biological status for all water bodies until 2015. Various organic substances can be removed from waste water by advanced oxidation processes (AOP). However, a complete mineralization of the total organic carbon (TOC) in waste water (WW) is not economical. Hence, development of transformation products is assumable. Only few is know about oxidation by-products. Especially toxicological relevant information on these to some extend stable intermediates are insufficient. In order to evaluate how oxidation processes can be used in waste water treatment, without the formation of critical oxidation by-products and to ensure the conformance of the treated WW to the European WFD, this project is conducted in co-operation with the University of Duisburg-Essen (separation and identification of oxidation by-products) and the University Hospital in Essen (toxicological tests). Performance of the oxidation experiments in laboratory scale, pilot plant scale and in authentic waste water are contributed by the Institute of Energy and Environmental Technology (IUTA) including determination of the substances and characterization of potential oxidation by-products.
Apart from UV oxidation with and without H2O2, ozone is nowadays one of the most used oxidants in water treatment processes worldwide. These oxidants might easily undergo reactions with compounds still present in the water after advanced oxidation processes resulting in the formation of oxidation byproducts. Therefore this study was designed to evaluate possible toxic effects of water contaminants comparing the unchanged molecule and its oxidation by-products applying different advanced oxidation methods mainly used in waste water treatment. Toxicty testing will be done as shown in Fig. 1. All substances will be tested for cytotoxicty and genotoxicity. In case of toxic effects futher tests will be performed. Triclosan and 2,4-Dichlorophenol were chosen as an example for a water pollutant before and after ozonisation and were tested for toxicity.
-Distribution of invasive aquatic organisms through ballast water uptake and release -Increasing amounts of drug residues and biocides in surface waters •Are advanced oxidation processes (AOP) sufficient in the disinfection of ballast water? -Are drugs and biocides in the water a possible source for toxic by-products formed during oxidative treatment?
Elke Dopp
added 10 research items
Copper plumbing materials can be the source of copper ions in drinking water supplies. The aim of the current study was to investigate the influence of copper ions on the viability and cytotoxicity of the potential pathogen Pseudomonas aeruginosa that presents a health hazard when occurring in building plumbing systems. In batch experiments, exposure of P. aeruginosa (10(6)cells/mL) for 24h at 20°C to copper-containing drinking water from domestic plumbing systems resulted in a loss of culturability, while total cell numbers determined microscopically did not decrease. Addition of the chelator diethyldithiocarbamate (DDTC) to copper-containing water prevented the loss of culturability. When suspended in deionized water with added copper sulfate (10 μM), the culturability of P. aeruginosa decreased by more than 6 log units, while total cell counts, the concentration of cells with intact cytoplasmic membranes, determined with the LIVE/DEAD BacLight kit, and the number of cells with intact 16S ribosomal RNA, determined by fluorescent in situ hybridization, remained unchanged. When the chelator DDTC was added to copper-stressed bacteria, complete restoration of culturability was observed to occur within 14 d. Copper-stressed bacteria were not cytotoxic towards Chinese hamster ovary (CHO-9) cells, while untreated and resuscitated bacteria caused an almost complete decrease of the concentration of viable CHO-9 cells within 24 h. Thus, copper ions in concentrations relevant to drinking water in plumbing systems seem to induce a viable but non-culturable (VBNC) state in P. aeruginosa accompanied by a loss of culturability and cytotoxicity, and VBNC cells can regain both culturability and cytotoxicity, when copper stress is abolished.
The fate in wastewater treatment of gadolinium chelates used in increasing amounts as contrast agents in magnetic resonance imaging recently got into the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd DTPA, Gd DTPA BMA and Gd BT DO3A, which were 4.8 ± 0.88, 46 ± 2.5 and 24 ± 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of (•)OH. Different methods have been applied and compared for determination of k(•OH + Gd chelate). From rate constants determined by pulse radiolysis experiments (k((•)OH + Gd DTPA) = 2.6 ± 0.2 × 10(9) M(-1) s(-1), k((•)OH + Gd DTPA BMA) = 1.9 ± 0.7 × 10(9) M(-1) s(-1), k((•)OH + Gd BT DO3A) = 4.3 ± 0.2 × 10(9) M(-1) s(-1)), it is concluded, that a reaction in wastewater via (•)OH radicals is feasible. Toxicity has been tested for the transformation products mixture of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable.
Elke Dopp
added 9 research items
The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors.
Triclosan is an antimicrobial agent widely used in many household and personal care products. Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater, wastewater treatment plants and receiving waters. In this study removal of triclosan by aqueous ozone was investigated and the degradation products formed during ozonation of an aqueous solution of triclosan were analyzed by GC-MS and HPLC-MS/MS. The following transformation products have been identified: 2,4-dichlorophenol, chloro-catecol, mono-hydroxy-triclosan and di-hydroxy-triclosan during treatment process. Cytotoxicity and genotoxicity of pure triclosan and 2,4-dichlorophenol have been investigated and the results showed reduced genotoxic effects after ozonation, though the respective chlorophenol is harmful to aquatic organisms.
The entry of pharmaceuticals into the water cycle from sewage treatment plants is of growing concern because environmental effects are evident at trace levels. Ozonation, UV- and UV/H2O2-treatment were tested as an additional step in waste water treatment because they have been proven to be effective in eliminating aqueous organic contaminants. The pharmaceuticals carbamazepine, ciprofloxacin, diclofenac, metoprolol and sulfamethoxazole as well as the personal care products galaxolide and tonalide were investigated in terms of degradation efficiency and by-product formation in consideration of toxic effects. The substances were largely removed from treatment plant effluent by ozonation, UV- and UV/H2O2-treatment. Transformation products were detected in all tested treatment processes. Accompanying analysis showed no genotoxic, cytotoxic or estrogenic potential for the investigated compounds after oxidative treatment of real waste waters. The results indicate that by-product formation from ozonation and advanced oxidation processes does not have any negative environmental impact.
Elke Dopp
added a research item
Moderne Kläranlagen reinigen Abwasser effizient von leicht abbaubaren organischen Stoffen und Nährstoffen. Sie sind aber nicht für die Eliminierung von Mikroschadstoffen konzipiert, so dass viele dieser Stoffe im Abwasser kaum abgebaut werden und somit über die Vorflut in Oberflächengewässer gelangen. Dieser Artikel geht unter anderem der Frage nach, wie überhaupt Auswirkungen von Gemischen unzähliger Verbindungen im niedrigen Konzentrationsbereich auf Organismen messbar sind.