13 research outputs found

    Zur Bildung und Vermeidung schwer entfernbarer Partikelablagerungen in Kapillarmembranen bei der Dead-End Filtration

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    SIGLEAvailable from TIB Hannover: RO 7208(34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

    The impact of optimised coagulation on membrane fouling for coagulation/ultrafiltration process

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    This work aimed to demonstrate the effect of optimised coagulation on minimise fouling for coagulationÔÇôultrafiltration process. Coagulation as pretreatment has the potential to mitigate fouling and enhance flux. Operating parameters were tested by a matrix of experiments for various mixing conditions and coagulant doses. In coagulation experiments, varied shear forces were applied to generate different floc characteristics in order to assess the effect on membrane fouling. Floc properties were investigated with an optical monitoring technique to identify structure, size and growth of flocs. It was shown that stronger flocs are of advantage for fouling mitigation and that the coagulant dosage is crucial for the performance of filtration. The impact of water quality was assessed using general water quality parameters and organic characterisation techniques to investigate the performance of each treatment step. The treatment efficiency was further assessed based on comparing the molecular size fractions of the organic matter before and after coagulation using a size exclusion chromatography technique. The result confirmed the significance of organic character on treatment performance.Mike Dixon, Christian Staaks, Rolando Fabris, Vipasiri Vimonses, Christopher W.K. Chow, Stefan Panglisch, John A. van Leeuwen, Mary Drika

    Weiterentwicklung und Validierung eines Verfahrens zur direkten Aufbereitung von Flusswasser mittels Ultrafiltration Abschlussbericht

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    Eine direkte Aufbereitung eines Wassers aus der fliessenden Welle mit der Ultrafiltration ist bisher nicht realisiert worden, da sich Wasserinhaltsstoffe, wie z.B. Huminstoffe, in erheblichem Masse auf der Membran ablagern und durch eine Rueckspuelung nicht sehr weitgehend entfernt werden koennen. Dies fuehrt zu einer schnellen Verringerung des Permeatflusses, so dass das Verfahren nicht mehr wirtschaftlich betrieben werden kann. Es gibt Hinweise darauf, dass nach Zugabe eines Flockungsmittels stoerende Wasserinhaltsstoffe zum Teil in die Flocken eingebunden werden koennen. Vermutlich koennen sich dadurch Wasserinhaltsstoffe nicht mehr adsorptiv auf der Membranoberflaeche anlagern und werden bei einer Rueckspuelung weitgehend mit den Flocken von der Membranoberflaeche entfernt. Ziel ist es, durch Zugabe von Flockungsmittel den Betrieb einer UF-Anlage zu stabilisieren. Weiter ist zu beachten, dass Aenderungen der Wasserqualitaet bei einem Fliessgewaeser nach Regenfaellen sehr schnell erfolgen und ebenso sehr weitgehend sein koennen. Um hier einen optimalen Einsatz des Flockungsmittels zu erreichen, muessen die betriebsrelevanten Einflussgroessen ermittel werden, die zu einer Verminderung des Membranfoulings fuehren. Diese Untersuchungen wurden sowohl im Labormassstab am IWW als auch im Pilotmassstab in der Wassergewinnung Martinlamitz der HEW HofEnergie+Wasser GmbH durchgefuehrt und konnten die prinzipielle Eignung der Kombination Flockung/UF nachweisen. Die erreichte Wasserqualitaet nach Aufbereitung durch die konventionelle Anlage mit Flockungsfiltration konnte ebenso durch eine Aufbereitung mittels Flockung/UF erreicht und insbesondere im Hinblick auf die mikrobiologischen Parameter verbessert werden. Dies geschah i.d.R. mit wesentlich niedrigeren Flockungsmitteldosiermengen als in der konventionellen Flockungsfiltration des WW. Die Ergebnisse zeigen die Anwendbarkeit und Wirtschaftlichkeit des Verfahrens bei Einsatz in der Trinkwasseraufbereitung. (orig.)A direct treatment of river water with ultrafiltration is not yet realised in larger scales due to the considerable fouling and scaling effects caused by water contaminants on the membranes surface under those circumstances. Therefore, the deposits on the membrane cannot be eliminated extensively by conventional backwashing. This will lead to a fast decrease in membrane performance, so that the process cannot be driven economically. Indications are given that dosing coagulants into the raw water stream can be of high advantage for the ultrafiltration process, because the undesired water contaminants, e.g. humic substances, can be partly embedded into the formed flocs and therefore it is assumed that they cannot adsorb onto the membranes surface. The undesired water contaminants should than be able to be eliminated extensively from the membranes surface together with the flocs using an optimised backwashing procedure. Furthermore, the raw water can vary very fast and to high extend, i.e. it can temporally be contaminated with much higher amounts of turbidity and natural organic matter, due to rainfalls or snow melts. To achieve an optimised use of the coagulant, the process parameters leading to a decrease of the fouling and scaling effects have to be examined. The investigations were performed on laboratory scale at the IWW and on pilot scale at the water works of the HEW Hof Energie und Wasser GmbH in Martinlamitz. The results proofed the fundamental applicability of the process combination flocculation/ultrafiltration. The water quality after conventional treatment with flocculation/sand filtration could be likewise achieved with the combination flocculation/ultrafiltration and with regards to microbiological parameters it could be improved, was equal to the water quality. These results could be usually achieved by less coagulant dosages as used in the conventional treatment step. The research could show the applicability and the economic efficiency when used in drinking water treatment. (orig.)Available from TIB Hannover: F02B1861 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

    Ueberpruefung der Einsatzmoeglichkeit der Membranfiltration zur grosstechnischen Talsperrenwasseraufbereitung mit Pilotanlagen Abschlussbericht

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    In this project was investigated how extensive micro (MF)- and ultrafiltration (UF) can enhance the particle removal efficiency of an existing drinking water treatment plant in Roetgen (6.000 m"3/h) and what are the conditions for the enhancement. Since the end of 1996 three pilot plants with a capacity of approx. 6 to 10 m"3/h, one MF (Memtec) and two UF (Aquasource and X-Flow) plants, have been compared by operating in dead-end mode. Four different feed qualities were tested: 1. the effluent of the existing treatment plant (flocculation, first filtration stage, removal of iron and manganese by a second filtration stage); 2. the effluent of the first filtration stage with additional dosing of an oxidizing agent; 3. like 2. but with additional filtration by a CaCO_3-filter; 4. the effluent of the flocculation stage. The turbidity of permeate of all pilot plants was beneath the detection limit of 0.02 NTU for all tested feed water qualities. Particles >0.5 #mu#m were removed to the background noise (2 particles/mL). With UF the removal of microbiological relevant parameters was practically complete. With MF the removal of spiked viruses was not complete. It was possible to replace the conventional treatment step for the removal of manganese by UF. However, in this case oxidizing agents (NaOCl for Aquasource or H_2O_2 for X-Flow) have to be added to the backwash water each time. It was also amazing that UF was able to treat the effluent of the flocculation stage with a high performance. In this case UF has even reached better results as in case of operating with effluent of the existing treatment plant. Chrashtests showed, that the lifetime of all tested membrane is likely not limited by the backwash stress. Concluding we can say, that in case of adjusting the conditions founded as the most suitable, all tested membranes can be operated very stable for a long term. These positive experiences made with membrane filtration were taken as occasion to start a further investigation programme with a pilot plant in a larger technical scale (150 m"3/h). (orig.)SIGLEAvailable from TIB Hannover: F99B270+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

    Ultrafiltration zur Abtrennung von Algen und algenbuertigen Substanzen mit verschiedenen Vorbehandlungen Abschlussbericht

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    Ultrafiltration of reservoir water to give drinking water has been studied in the laboratory and in the pilot plant scale. Theoretical and experimental investigations have been directed on the formation of surface layers and on membrane fouling in ultrafiltration to provide a basis for process modeling, and operation parameters of a pilot plant have been optimized. Pilot plant test proved that ultrafiltration in cross-flow mode is suited for the treatment of entrophic reservoir water. Quality of the resulting water is comparable and even higher than that produced by the PEA process, a combined flocculation/direct filtration process. Efficiency of the ultrafiltration process is substantially increased by using the PEA process or by applying permeable collectors in deep bed filtration as pretreatment methods. Ultrafiltration does not lead to additional damages of cyanobacteria, and an increase in mycrocystine concentration has not been detected. (WEN)SIGLEAvailable from TIB Hannover: F96B1208+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman