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Optimierung des Membranhybridverfahrens Flockung-Ultrafiltration zur Huminstoffentfernung bei der Trinkwasseraufbereitung
Citation Link: https://doi.org/10.15480/882.1317
Publikationstyp
Master Thesis
Date Issued
2016
Sprache
German
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2016-02-24
TORE-DOI
Over the past three decades increasing concentrations of natural organic matter, which is in large part composed of humic substances, in drinking water reservoirs have been obeserved. High contents of humic substances in drinking water are undesirable for practical and aesthetical resaons as well as due to statutory limits. As their removal by common processes in drinking water treatment, such as aeration and rapid filtration, is low, research into efficient methods for the reduction of the humic content is important to ensure the supply of high quality drinking water in the future.
This thesis is aimed at exploring the potential of the hybrid process in-line coagulation-ultrafiltration for the reduction of colour caused by humic substances as an additional treatment step in a Northern German water supply facility. In pilot-scale experiments on site the influence of several operational parameters and of a stepwise decrease of coagulant dosing (ferric chloride) was investigated.
Overall, the membrane hybrid process proved to be suitable to reduce the content of humic substances and hence the colour of the treated water. The resulting UV absorption and colour in the permeate could be described as a function of coagulant concentration and raw water quality by a simple empirical model. A loss of permeability, which was only partly reversible by hydraulic backwashing, occured already during the first 21 hours of filtration. Total fouling was dominated by the compressible cake layer deposited on the membrane. The associated pressure drop could be estimated by Darcy’s law inspite of the inhomogenous distribution of the cake layer along the length of the capillary membrane. Main influences on the hydraulically irreversible fouling turned out to be the concentration of uncoagulated natural organic matter as well as the dosed amount of coagulant and the operational parameters of the ultrafiltration. It seems that beyond a certain mass of coagulant, which depends on the operating conditions, the removal of the cake layer by hydraulic backwashing is incomplete. Below this critical value the extent of hydraulically irreversible fouling was presumably determined by the concentration of organic substances. The stepwise decrease of coagulant dosing provided no signicant advantage in terms of the removal of colour and the mitigation of membrane fouling for the investigated application. Based on the insights gained during the ten weeks of pilot plant operation recommendations were given and approaches for further optimization developed.
This thesis is aimed at exploring the potential of the hybrid process in-line coagulation-ultrafiltration for the reduction of colour caused by humic substances as an additional treatment step in a Northern German water supply facility. In pilot-scale experiments on site the influence of several operational parameters and of a stepwise decrease of coagulant dosing (ferric chloride) was investigated.
Overall, the membrane hybrid process proved to be suitable to reduce the content of humic substances and hence the colour of the treated water. The resulting UV absorption and colour in the permeate could be described as a function of coagulant concentration and raw water quality by a simple empirical model. A loss of permeability, which was only partly reversible by hydraulic backwashing, occured already during the first 21 hours of filtration. Total fouling was dominated by the compressible cake layer deposited on the membrane. The associated pressure drop could be estimated by Darcy’s law inspite of the inhomogenous distribution of the cake layer along the length of the capillary membrane. Main influences on the hydraulically irreversible fouling turned out to be the concentration of uncoagulated natural organic matter as well as the dosed amount of coagulant and the operational parameters of the ultrafiltration. It seems that beyond a certain mass of coagulant, which depends on the operating conditions, the removal of the cake layer by hydraulic backwashing is incomplete. Below this critical value the extent of hydraulically irreversible fouling was presumably determined by the concentration of organic substances. The stepwise decrease of coagulant dosing provided no signicant advantage in terms of the removal of colour and the mitigation of membrane fouling for the investigated application. Based on the insights gained during the ten weeks of pilot plant operation recommendations were given and approaches for further optimization developed.
Subjects
Ultrafiltration
Flockung
Huminstoffe
Kapillarmembran
stufenweise Dosierung
hydraulisch irreversibles Fouling
DDC Class
600: Technik
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