4,130 research outputs found

    Application possibilities and performance of forward osmosis in industrial water management

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    Membrane filtration processes such as micro-, ultra- and nanofiltration as well as reverse osmosis are frequently used in industrial water treatment and waste water treatment. They use a high physical pressure difference as a driving force to press water through a semi-permeable membrane and produce purified water. For this reason, large amounts of energy are required. In contrast, forward osmosis is an innovative membrane filtration process that uses the naturally occurring osmotic pressure gradient between two liquids to generate the water flow through the semi-permeable membrane. In forward osmosis, one liquid with low osmotic pressure is concentrated (so-called Feed Solution) and a second liquid is diluted (so-called Draw Solution). If 'pure' water is to be obtained, a second treatment stage is necessary to regenerate the draw solution. Due to its natural driving force, forward osmosis offers the potential for energy-efficient treatment of water from various sources. This makes it a promising process for further concentration of aqueous product and waste water streams. For this reason, the application possibilities and the potential of forward osmosis in the industrial water sector were examined in more detail within the scope of this thesis. Within laboratory tests, forward osmosis treatment of different liquid streams of a dairy, an automobile production as well as a semiconductor production was examined. The core of the laboratory test set-up was a membrane test cell for flat sheet membranes with an effective membrane area of 48 cm². Special forward osmosis membranes from various manufacturers were used. The feed and draw solutions were circulated and increasingly concentrated or diluted during the course of the experiment. The permeate flow was determined by recording the change in mass. Conductivity measurements as well as analyses of the examined waters before and after the experiments allowed conclusions to be drawn about possible solute diffusion through the membrane. In addition to the laboratory tests, a model was developed and validated to simulate the experiments. Three partially adapted models from literature were used. The average permeate fluxes achieved in the laboratory experiments with real industrial water depended mainly on the osmotic pressure difference between feed and draw solution. The permeate fluxes were between 0.1 and 19.4 L/(m²⸱h) for the automotive industry, between 7.9 and 21.0 L/(m²⸱h) for the dairy industry and between 10.5 and 33.4 L/(m²⸱h) for the semiconductor industry. The reverse solute fluxes determined were between 37.7 and 21.3 g/(m²⸱h), between 4.1 and 12.2 g/(m²⸱h) and between 8.0 and 40.9 g/(m²⸱h). Within modelling, the tests with waters from automobile production were simulated. For the most part, the permeate fluxes could be well represented. The calculation of the reverse solute fluxes sometimes showed large deviations from the actual measurements. Standardized membrane performance tests were used to evaluate the development of permeate flux and to indicate fouling. Depending on the substances contained in the water, fouling occurred in the test series. In addition, deposits on the membrane surface were visible in some tests. However, the visible deposits did not always lead to a decrease in permeate flow. In an exemplary cleaning test, the membrane performance could be restored by rinsing with sodium hydroxide solution and hydrochloric acid. As a result of this thesis, different forward osmosis application scenarios in the examined industrial enterprises could be developed. For economic reasons, those scenarios in which both the feed and the draw solution are industrial waters and two liquids are treated simultaneously in one step are of particular interest. The use of an artificial Draw Solution and its treatment is unnecessary in this case. Such application scenarios could be derived for dairy and semiconductor production. No suitable Draw Solution could be identified in the investigated automobile production, which is why only applications with an artificial Draw Solution are conceivable here. In general, the critical points when using forward osmosis are the reverse solute flux through the membrane, the deterioration of the membrane performance due to fouling and the economic efficiency of the process. More in-depth investigations are required here.Membranfiltrationsverfahren wie die Mikro-, Ultra- und Nanofiltration sowie die Umkehrosmose werden häufig in der industriellen Wasseraufbereitung sowie Abwasserbehandlung eingesetzt. Sie nutzen einen hohen physikalischen Druck-unterschied als Triebkraft, um Wasser durch eine semipermeable Membran zu pressen und gereinigtes Wasser zu erzeugen. Dafür sind große Energiemengen nötig. Im Gegensatz dazu ist die Vorwärtsosmose ein innovatives Membranfiltrationsverfahren, welches den natürlich vorkommenden osmotischen Druckgradienten zwischen zwei Flüssigkeiten nutzt, um einen Wasserfluss durch die semipermeable Membran zu erzeugen. Dabei wird eine Flüssigkeit mit niedrigem osmotischen Druck aufkonzentriert (sog. Feed Solution) und eine zweite Flüssigkeit verdünnt (sog. Draw Solution). Soll „reines“ Wasser gewonnen werden, ist eine zweite Aufbereitungsstufe zur Regeneration der Draw Solution notwendig. Durch die natürliche Triebkraft bietet die Vorwärtsosmose das Potenzial zur energieeffizienten Behandlung von Wässern verschiedener Herkunft. Damit ist sie ein vielversprechendes Verfahren zur weitergehenden Aufkonzentrierung von wässrigen Produkt- und Abwasserströmen. Aus diesem Grund wurden die Einsatzmöglichkeiten und das Potenzial der Vorwärtsosmose im industriewasser-wirtschaftlichen Bereich im Rahmen dieser Arbeit näher untersucht. Im Rahmen von Laborversuchen wurde die Aufbereitung von verschiedenen Flüssigkeitsströmen einer Molkerei, einer Automobilproduktion sowie einer Halbleiter-fertigung mittels Vorwärtsosmose untersucht. Kernstück der Laborversuchsanlage war eine Membrantestzelle für Flachmembranen mit einer wirksamen Membranfläche von 48 cm². Zum Einsatz kamen spezielle Vorwärtsosmosemembranen verschiedener Hersteller. Die genutzten Feed und Draw Solutions wurden im Kreislauf geführt und im Versuchsverlauf zunehmend aufkonzentriert bzw. verdünnt. Über die Erfassung der Masseänderung wurde der Permeatfluss bestimmt. Leitfähigkeitsmessungen sowie Analysen der untersuchten Wässer vor und nach den Versuchen ließen Schlussfolgerungen über eventuell auftretende Stoffdiffusion durch die Membran zu. Zusätzlich zu den Laborversuchen wurde ein Modell zur Simulation der Experimente erstellt und validiert. Dabei wurden drei, teilweise adaptierte, Modellansätze aus der Literatur verwendet. Die durchschnittlichen Permeatflüsse, welche bei den Laborversuchen mit reellen industriellen Wässern erreicht wurden, hingen vorrangig von der osmotischen Druckdifferenz zwischen Feed und Draw Solution ab. Die Permeatflüsse lagen für die Automobilindustrie zwischen 0,1 und 19,4 L/(m²⸱h), für die Molkerei zwischen 7,9 und 21,0 L/(m²⸱h) und für die Halbleiterindustrie zwischen 10,5 und 33,4 L/(m²⸱h). Die ermittelten Salzrückflüsse betrugen zwischen 37,7 und 21,3 g/(m²⸱h), zwischen 4,1 und 12,2 g/(m²⸱h) sowie zwischen 8,0 und 40,9 g/(m²⸱h). Im Rahmen der Modellierung wurden die Versuche mit Wässern der Automobilproduktion nachgebildet. Dabei konnten die Permeatflüsse größtenteils gut dargestellt werden. Die Berechnung der Salzrückflüsse wies gegenüber den tatsächlichen Messungen mitunter große Abweichungen auf. Durch standardisierte Membranleistungstests konnte die Entwicklung des Permeatflusses evaluiert und Fouling nachgewiesen werden. In Abhängigkeit der Wasserinhaltsstoffe trat Fouling in den Versuchsreihen auf. Zusätzlich waren bei einigen Versuchen Ablagerungen auf der Membranoberfläche sichtbar. Jedoch führten die sichtbaren Ablagerungen nicht in allen Fällen zu einem Rückgang des Permeatflusses. In einem exemplarisch durchgeführten Reinigungsversuch konnte die Membranleistung durch Spülprozesse mit Natronlauge und Salzsäure wiederhergestellt werden. Als Ergebnis der Arbeit konnten verschiedene Anwendungsszenarien für den Einsatz der Vorwärtsosmose in den untersuchten Industriebetrieben entwickelt werden. Hierbei sind aus wirtschaftlichen Gründen vor allem jene Szenarien interessant, bei denen sowohl die Feed als auch die Draw Solution industrielle Wässer sind und zwei Flüssigkeiten simultan in einem Schritt aufbereitet werden. Der Einsatz einer künstlichen Draw Solution und deren Aufbereitung ist in diesem Fall unnötig. Solche Anwendungsszenarien konnten für die Molkerei sowie die Halbleiterherstellung abgeleitet werden. In der untersuchten Automobilproduktion konnte keine geeignete Draw Solution identifiziert werden, weshalb hier lediglich Anwendungen mit einer künstlichen Draw Solution denkbar sind. Als kritische Punkte beim Einsatz der Vorwärtsosmose stellten sich der auftretende Salzrückfluss durch die Membran, die Verschlechterung der Membranleistung durch Fouling sowie die Wirtschaftlichkeit des Verfahrens heraus. Hier besteht weitergehender Forschungsbedarf

    Chitosan as natural coagulant in hybrid coagulation-nanofiltration membrane process for water treatment

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    Water treatment industries are exploring the possibility to use environmental friendly chemicals and to discover the potential of advanced treatment technology in order to achieve sustainable development. Hybrid coagulation-membrane process has been introduced and proven to be a reliable water treatment process. In this study, the potential of chitosan as natural coagulant in hybrid coagulation-NF membrane process was studied. Three synthetic humic acid (HA) solutions with different ionic strength and composition will be used; without salt (Set 1), with NaCl only (Set 2), and with NaCl, CaCl2, and NaHCO3 (Set 3). Our findings indicated that gradual flux decline for Set 1 can be related to the continuous accumulation of neutral charged particles (pH 4.2) on the membrane surface. Formation of compact foulant layer due to further charge suppression of the foulants by dissolved ions (Set 2) resulted in severe membrane flux decline. When the pH of Set 1 and Set 2 supernatant solutions were increased to 7, fouling has been resolved due to the presence of strong electrostatic repulsion between the foulants and membrane. During the initial filtration process for Set 3, the flux has remained constant due to the strong repulsion between negatively charged foulants and membrane (pH 7). It was followed by severe flux decline which could be attributed to the effect of concentration polarization. Hence, this study highlighted that the impact of natural coagulant on the membrane process should be systematically studied in order to prevent unnecessary loss due to the incompatibility between both processes.This paper was made possible by NPRP grant #[5-1425-2-607] from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the author[s]. The authors also wish to acknowledge the Ministry of Education Malaysia for sponsoring W.L. Ang?s postgraduate study via MyBrain.Scopu

    Design of Multiregional Supervisory Fuzzy PID Control of pH Reactors

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    This work concerns designing multiregional supervisory fuzzy PID (Proportional-Integral-Derivative) control for pH reactors. The proposed work focuses, mainly, on two themes. The first one is to propose a multiregional supervisory fuzzy-based cascade control structure. It would enable modifying dynamics and enhance system’s stability. The fuzzy system (master loop) has been chosen as a tuner for PID controller (slave loop). It takes into consideration parameters uncertainties and reference tracking. The second theme concerns designing a hybrid neural network-based pH estimator. The proposed estimator would overcome the industrial drawbacks, that is, cost and size, found with conventional methods for pH measurement. The final end-user-interface (EUI) front panel and the results that evaluate the performance of the supervisory fuzzy PID-based control system and hybrid NN-based estimator have been presented using the compatibility found between LabView and MatLab. They lead to conclude that the proposed algorithms are appropriate to systems nonlinearities encountered with pH reactors

    Utilization of Papaya Seeds as Natural Coagulant for Synthetic Textile Coloring Agent Wastewater Treatment

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    Textile wastewater contains a lot of pollutants which is hazardous if directly discharged. Coagulation and flocculation using inorganic salts were widely used to treat textile wastewater. However this method pose some drawbacks, such as high coagulant cost, large volume of sludge was produced, and potential health problems if the water is consumed. In this study we explore utilization of natural coagulant as an alternative to inorganic salts to treat textile wastewater. This study describes utilization of papaya seeds powder as a natural coagulant for synthetic textile wastewater of drimarene dark red (DDR) with initial concentration of 10 mg/L. The effect of coagulant dosage and pH to the %removal of colour in wastewater was studied using central composite design. The potential active functional groups in papaya seeds powder was characterized using Fourier Transform Infrared Spectroscopy (FTIR). It was found that papaya seeds powder contained –OH, -NH, C=O functional groups that indicate good potential as natural coagulant. The cubic model obtained was in good fit with experimental data, which was shown in R-squared value of 0.995. It was found that coagulant dosage, pH, and its interaction were significant to the removal of synthetic dye in wastewater. The decrease of pH gave higher %removal due to protonation of papaya seeds powder active coagulating agent resulting on better electrostatic interaction with dyes. The increase of dosage also gave increase in %removal until its optimum condition. After optimum condition, the %removal decreased due to colloid re-stabilization. The optimum condition was obtained at dosage of 0.57g/L and pH 1.97 with 84.77% of predicted colour removal and this result was in agreement with experimental response value

    CLINOPTILOLITE TUFF AND OTHER ZEOLITE ADDED VALUE PRODUCTS AS SUSTAINED COMMODITIES IN TRADITIONAL WATER AND WASTE MANAGEMENT

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    Coagulation/flocculation and ion exchange onto natural zeolite clinoptilolite are reviewed and discussed in this paper based on their pilot or industrial applications. Surface water purification by means of chemical coagulation and flocculation supported by the powdered natural zeolite was carried out industrially to save drinking water reservoir (upper part of Ondava river) settled by about ten thousands inhabitants. Therefore, several other surface water samples from the Slovakian reservoirs potentially impacted by contamination were examined to treat with alum coagulation/flocculation and powdered clinoptilolite tuff addition at the laboratory, respectively. Ammonia removal from tannery wastewater using the clinoptilolite tuff with chemical regeneration and regenerant recovery by air stripping, carried out in pilot measure during the several months at the mixed Wastewater Treatment Facility in Otrokovice - WTFO is discussed and evaluated, respectively

    Are pharmaceuticals removal and membrane fouling in electromembrane bioreactor affected by current density?

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    Abstract Pharmaceutical active compounds (PhACs) have been detected at significant concentrations in various natural and artificial aquatic environments. In this study, electro membrane bioreactor (eMBR) technology was used to treat simulated municipal wastewater containing widely-used pharmaceuticals namely amoxicillin (AMX), diclofenac (DCF) and carbamazepine (CBZ). The effects of varying current density on the removal of PhACs (AMX, DCF and CBZ) and conventional pollutants (chemical oxygen demand (COD), dissolved organic carbon (DOC), humic substances, ammonia nitrogen (NH 4 -N), nitrate nitrogen (NO 3 -N) and orthophosphate (PO 4 -P) species) were examined. High COD and DOC removal efficiencies (~100%) were obtained in all the experimental runs regardless of applied current density. In contrast, enhanced removal efficiencies for AMX, DCF and CBZ were achieved at high current densities. Membrane fouling rate in eMBR with respect to conventional MBR was reduced by 24, 44 and 45% at current densities of 0.3, 0.5 and 1.15 mA/cm 2 , respectively. The mechanism for pharmaceutical removal in this study proceeded by: (1) charge neutralization between negatively-charged pharmaceutical compounds and positive electro-generated aluminium coagulants to form larger particles and (2) size exclusion by membrane filtration
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