Characterization of membrane–foulant interactions with novel combination of Raman spectroscopy, surface plasmon resonance and molecular dynamics simulation

Adsorptive fouling, by phenolic compounds, is a serious issue regarding the development and use of membrane based filtration technologies for water purification and wastewater treatment. We have developed a novel, combined, protocol of Raman spectroscopy and surface plasmon resonance (SPR) experiments, along with molecular dynamics (MD) simulation, to study the interaction of vanillin, a model phenolic compound, with the polyethersulfone (PES) surface of a membrane. The adsorption of vanillin to the PES surface was found to be highly pH dependent; the source of this was determined, by MD simulation, to be the stronger interaction with the protonated form of vanillin, predominant at low pH. Vanillin interacts with the PES surface, both through entropy driven, hydrophobic, interactions and, for the case of the protonated form, H-bonding of the hydroxyl group with the sulphur oxygens of the PES molecules. In addition to general insight into the fouling process that can be used to develop new methods to inhibit adsorptive fouling, our results also elucidate the specific interaction of the PES membrane with vanillin that can be used in the development of anti-fouling coatings, based on the structure of vanillin.Peer reviewe

Nanofiltration and reverse osmosis as a platform for production of natural botanic extracts: the case study of carob by-products

Carob kibbles are a low-cost and renewable source of economically relevant phenolic compounds (high value catechin and its derivatives and gallic acid) and abundant in small sugars. This work aims at producing two distinct natural extracts from carob kibbles, one extract enriched in catechin and its derivatives for the nutraceuticals market and an extract enriched in sugars for the food industry. This valorisation strategy involves an integrated process based on membrane technology that fulfils the zero discharge principle and may be applied to other agro-industrial by-products. Different aqueous extraction schemes were considered (a one-step process and a two-steps approach). The aqueous extracts obtained were fractionated by diananofiltration and the fractions obtained were evaluated in terms of their content in target products. An integrated scheme for production of fractionated extracts is proposed based on the experimental work developed assuring, simultaneously, a minimal use of resources and emission of waste

Markkinointisuunnitelma Varjolan tila – Bistro Sylvi

Opinnäytetyön toimeksiantajana toimi Laukaassa sijaitseva Varjolan tila Oy, jonka kahvila-ravintola Bistro Sylvin markkinointi kaipasi kehittämistä. Bistro Sylvi on toiminut vuodesta 2012 lähtien, mutta sen yleinen tunnettuus oli heikkoa ja tähän haluttiin muutosta. Yritykselle ei ole aiemmin tehty markkinointisuunnitelmaa. Tarkoituksena oli laatia varteenotettava, johdonmukainen ja hyödyllinen markkinointisuunnitelma, jonka avulla toimeksiantaja saisi ideoita ja keinoja Bistro Sylvin markkinoinnin kehittämiseksi. Tutkimus toteutettiin kvalitatiivisena tutkimuksena, jonka tavoitteena oli saavuttaa ymmärrys käsiteltävästä ilmiöstä ja löytää sopivia keinoja tutkimusongelmien ratkaisemiseksi. Yrityksen toimintaympäristöä ja lähtökohtia tarkasteltiin SWOT-analyysin avulla. Lisäksi analysoitiin Bistro Sylvin kilpailijoiden toimintaa sosiaalisessa mediassa, matkailusivustoilla sekä kotisivuilla. Tutkimukset antoivat kattavasti hyödyllistä tietoa markkinointisuunnitelman laatimista varten. Markkinointisuunnitelmaan rajattiin käsiteltävät aiheet mahdollisimman tarkasti, jotta siitä saatiin mahdollisimman suuri hyöty irti toimeksiantajaa varten. Monipuolisten aineistojen perusteella syntyi konkreettinen markkinointisuunnitelma, jota toimeksiantaja voi hyödyntää Bistro Sylvin markkinoinnin kehittämisessä, tunnettuuden lisäämisessä ja kohdeasiakkaiden tavoittamisessa. Bistro Sylvin tulisi ennen kaikkea panostaa säännölliseen markkinointiin ja huolelliseen sisällön suunnitteluun. Vuosikello-työkalu on hyvä keino tähän, sillä siitä näkee suoraan vuoden tärkeimmät markkinointitoimenpiteet

Dynamics of microbial community and their effects on membrane fouling in an anoxic-oxic gravity-driven membrane bioreactor under varying solid retention time : A pilot-scale study

Membrane fouling in a membrane bioreactor (MBR) is highly influenced by the characteristics of the influent, the mixed liquor microbial community and the operational parameters, all of which are environment specific. Therefore, we studied the dynamics of microbial community during the treatment of real municipal wastewater in a pilotscale anoxic-oxic (A/O) MBR equipped with a gravity-driven membrane filtration system. The MBR was operated at three different solid retention times (SRTs): 25, 40 and 10 days for a total period of 180 days in Nordic environmental conditions. Analysis of microbial community dynamics revealed a high diversity of microbial species at SRT of 40 days, whereas SRT of 25 days was superior with microbial richness. Production of soluble microbial products (SMP) and extracellular polymeric substances (EPS) was found to be intensely connected with the SRT and food to microorganism (F/M) ratio. Relatively longer operational period with the lowest rate of membrane fouling was observed at SRT of 25 days, which was resulted from the superior microbial community, lowest production of SMP and loosely bound EPS as well as the lower filtration resistance of larger sludge flocs. Abundance of quorum quenching (QQ) bacteria and granular floc forming bacterial genera at SRT of 25 days provided relatively lower membrane fouling tendency and larger floc formation, respectively. On the other hand, substantial amount of various surface colonizing and EPS producing bacteria was found at SRT of 10 days, which promoted more rapid membrane fouling compared with the fouling rate seen at other tested SRTs. To sum up, this research provides a realistic insight into the impact of SRT on microbial community dynamics and resulting characteristics of mixed liquor, floc size distribution and membrane fouling for improved MBR operation. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Membranfiltration von Prozessabwasser – in situ real-time Monitoring von organischem Membranfouling

Process wastewater from separation and purification processes in the food and biotech industries as well as in biorefineries often contain components that can be recovered as valuable by-products in the context of closed-loop recycling with membrane processes. These effluents have a high proportion of organic components and are particularly complex, which is why they have a high fouling potential and organic membrane fouling occurs more frequently. Membrane fouling is a constant challenge for the application of membrane processes. It often results in a drastic reduction of the membrane filtration capacity and a change of the membrane retention. In addition, membrane life is often reduced by increased membrane cleaning, resulting in increased process costs.The development of effective strategies to minimize membrane fouling is therefore highly desirable. One possibility is process monitoring with conventional fouling monitoring methods, e.g. membrane flow and transmembrane pressure. These conventional methods often only register membrane fouling when it is already advanced and therefore no longer reversible.In contrast, in-situ real-time monitoring methods can provide early warning and additional information on the extent, quality or distribution of the fouling on the membrane surface. These methods are needed to achieve one of the major goals in the development of membrane processes - elimination/minimization of fouling to achieve stable membrane flow and retention. Despite these obvious advantages, the use of real-time monitoring methods is not widespread even in the fouling-prone industries - food and biotech industries and biorefineries. In this presentation different insitu real-time monitoring methods and their theoretical basics are presented. The respective advantages and disadvantages are discussed with a focus on methods that could be used in connection with membrane processes in fouling susceptible industries

In situ real-time monitoring techniques for membrane fouling in food, biorefinery and biotechnology industries

Membrane fouling is a constant challenge of membrane processes in separation and purification of organic, biomass originated compounds in food, biorefining and biotechnology industries. It persists due to the complexity and high fouling tendency of the bio-based streams and may result in a decrease of filtration capacity, rejection alteration, reduction of membrane lifetime and increase of operational costs. Hence effective fouling prevention strategies are highly desired. Conventional fouling monitoring and control methods are often based on process performance or product quality, usually revealing membrane fouling after it occurred in a severe and non-reversible way. Thus, in situ real-time monitoring techniques are required providing early warning about extent, quality and distribution of foulants accumulated on the membrane surface in order to reach one of the ultimate goals in the development of membrane based technologies - a non- or controlled-fouling process with a steady flux and retention. Despite the evident advantages of different real-time monitoring tools, adaptation of them in fouling-concerned food, biorefining and biotechnology industries has not been widely published. Hence, this work compares advantages and disadvantage, as well as aims to investigate potential uses of in situ real-time membrane fouling monitoring techniques in the field of these industries. Different in situ real-time techniques are presented and their characteristics highlighted. Emerging techniques are identified and a future perspective is discussed

High Precision UTDR Measurements by Sonic Velocity Compensation with Reference Transducer

An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol’skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 µm, while using the calculated sonic velocity the standard deviations were 21–39 µm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol’skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements

Utilization of DES-Lignin as a Bio-Based Hydrophilicity Promoter in the Fabrication of Antioxidant Polyethersulfone Membranes

Enhancement of membrane permeability at no detriment of its other performances, e.g., selectivity, is a goal-directed objective in membrane fabrication. A novel antioxidant DES-lignin (lignin extracted from birch wood by using a deep eutectic solvent) polyethersulfone (PES) membrane, containing 0–1 wt % DES-lignin, was fabricated with the phase inversion technique. The performance and morphology of the fabricated membranes were characterized by a pure water flux, polyethylene glycol (PEG) retention, Fourier transform infrared spectroscopy, scanning electron microscopy, and contact angle measurements. Membranes with less negative charge and better hydrophilicity were obtained when the DES-lignin content in the polymer solution was increased. With the highest dosage, the incorporation of DES-lignin in the membrane matrix improved the membrane permeability by 29.4% compared to a pure PES membrane. Moreover, no leakage of DES-lignin from the membrane structure was observed, indicating good compatibility of DES-lignin with the PES structure. It was also found that the improvement of both rejection and pure water flux could be achieved by using a small dosage of DES-lignin (0.25 wt %) in membrane fabrication. The membranes incorporated with DES-lignin showed higher DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) scavenging activity compared to the pure membrane, where 2.6 and 1.1 times higher DPPH and ABTS scavenging activity was observed with the highest DES-lignin content (1 wt %). Thus, the results of this study demonstrate well the feasibility of utilizing DES-lignin as an antioxidant bio-based hydrophilicity promoter in the fabrication of ultrafiltration membranes

Real-time fouling monitoring in food and biorefining industries – Needs and possibilities

Fouling is a constant challenge in membrane-based technologies. As conventional fouling monitoring and control methods are often based on process performance or product quality, they might reveal fouling so late that it has already damaged the membrane in severe and non-reversible way. Thus, surface sensitive online monitoring techniques capable of providing early warning capacity and information about extent, quality and distribution of foulants accumulated on the surface of the membrane are needed. Despite the evident advantages of different real-time monitoring tools, adaptation of them in fouling-concerned food and biorefining industries has not been widely published. Hence, this study aims to explore views on importance, usability and potential of real-time membrane fouling monitoring techniques in the field of these industries. Interview survey was conducted to identify properties needed in real-time fouling monitoring, to find out how established different techniques are in practice and what kind of challenges have been faced in the implementation of in situ tools. Interviews were chosen to concentrate on industrial practitioners working with membranes and persons involved in sales of analysis instruments. To get and overview of the emerging techniques the future perspective is also discussed based on interviews and recently published literature

Focus on fouling monitoring

In many industrial sectors membrane fouling is a problem which limits the wider use of membrane processes. This article discusses a survey of experienced industrial membrane users and analytical equipment suppliers giving their views of in situ real-time monitoring of membrane fouling