Studies on Membrane Filtration in Food Separation Process

Gravity settling represents the main oil-water separation mechanism. Many separation plants rely only on gravity settling with the aid of demulsifiers (direct or reverse breakers) and others chemicals such as water clarifiers if they are required. Yet, other complementary separation methods exist including filtration, flotation, and centrifugation. In terms of results and more specifically with respect to the separated produced-water, the main threshold on its quality is the dispersed oil content. Even with zero discharge and reinjection into hydrocarbon formations, the presence of residual oil in the aqueous phase represents a concern. High oil content results into formation damage and losses in injectivity which necessitates formation stimulations and hence additional operational expenses. In this work, we investigated the effects of different separation techniques on separated water quality. Based on the results, we identified potential improvements to the existing separation process. We used synthetic well-characterized emulsions. The emulsions were prepared at the forecast water:oil ratio using dead crude oil and synthetic representative brine. To clearly delineate and distinguish the effectiveness of different separation methods, we exacerbated the conditions by preparing very tight emulsions compared with what is observed on site. With that, we investigated three separation techniques: gravity settling, centrifugation, and filtration. First, we used jar tests to study gravity settling, then a benchtop centrifuge at two speeds to evaluate centrifugation potential. Finally, for filtration, we tested two options: membrane and deep-bed filtrations. Concerning the water quality, we performed solvent extraction followed by UV analyses to measure the residual oil content as well as light transmission measurements in order to compare the efficiency of different separation methods. The results of analyses suggest that gravity settling was not efficient in removing oil droplets from water. No separation occurred after 20 minutes in every tested condition. However, note that investigated conditions were severe, tighter emulsions are more difficult to separate compared to those currently observed in the actual separation plant. On the other hand, centrifugation significantly improved light transmission through the separated water. Accordingly, we can conclude that the water quality was largely improved by centrifugation. In terms of filtration, very good water quality was obtained after membrane filtration. However, significant fouling was observed. With deep-bed filtration, produced water quality remained good and fouling was no longer observed. On the basis of those results, we conclude that for our case study, centrifugation and deep-bed filtration techniques can significantly improve quality of the separated and eventually reinjected water. Thereby, integration of any of the two methods in the separation plant will lead to more efficient produced-water reinjection, eliminating formation damage and frequent stimulations. Yet, it is important to note that economics should be further assessed.

Gravity settling represents the main oil-water separation mechanism. Many separation plants rely only on gravity settling with the aid of demulsifiers (direct or reverse breakers) and other chemicals such as water clarifiers if they are required. Yet, other complementary separation methods exist including filtration, flotation, and centrifugation. In terms of results and more specifically with respect to the separated produced-water, the main threshold on its quality is the dispersed oil content. Even with zero discharge and reinjection into hydrocarbon formations, the presence of residual oil in the aqueous phase represents a concern. High oil content results into formation damage and losses in injectivity which necessitates formation stimulations and hence additional operational expenses. In this work, we investigated the effects of different separation techniques on separated water quality. In addition, we studied the impact of enhanced oil recovery (EOR) chemicals on the different separation techniques in terms of efficiency and water quality. Based on the results, we identified potential improvements to the existing separation process. We used synthetic well-characterized emulsions. The emulsions were prepared at the forecast water: oil ratio using dead crude oil and synthetic representative brines with or without the EOR chemicals. To clearly delineate and distinguish the effectiveness of different separation methods, we exacerbated the conditions by preparing very tight emulsions compared with what is observed on site. With that, we investigated three separation techniques: gravity settling, centrifugation, and filtration. First, we used Jar Tests to study gravity settling, then a benchtop centrifuge at two speeds to evaluate centrifugation potential. Finally, for filtration, we tested two options: membrane and deep-bed filtrations. Concerning the water quality, we performed solvent extraction followed by UV analyses to measure the residual oil content as well as light transmission measurements in order to compare the efficiency of different separation methods. The results of analyses suggest that gravity settling was not efficient in removing oil droplets from water. No separation occurred after 20 minutes in every tested condition. However, note that investigated conditions were severe, tighter emulsions are more difficult to separate compared to those currently observed in the actual separation plant. On the other hand, centrifugation significantly improved light transmission through the separated water. Accordingly, we can conclude that the water quality was largely improved by centrifugation even in the presence of EOR chemicals. In terms of filtration, very good water quality was obtained after membrane filtration. However, significant fouling was observed. In the presence of EOR chemicals, filtration lost its effectiveness due to the low interfacial tension with surfactants and water quality became poor. With deep-bed filtration, produced water quality remained good and fouling was no longer observed. However, the benefits from media filtration were annihilated by the presence of EOR chemicals. Based on these results and at least for our case study, we conclude that centrifugation and deep-bed filtration techniques can significantly improve quality of the separated and eventually reinjected water. In terms of the effects of EOR chemicals, the performance of centrifugation is reduced while filtrations are largely impaired by the presence of EOR chemicals. Thereby, integration of any of the two methods in the separation plant will lead to more efficient produced-water reinjection, eliminating formation damage and frequent stimulations. Yet, it is important to note that economics should be further assessed.

Eggshells and eggshell membranes have high-value recycling applications and have been widely used in pharmaceutical, chemical, and food research. The separation of eggshells and eggshell membranes is a prerequisite to efficiently using both. Therefore, the pressure-vacuum experiment equipment was designed. In this study, research on the separation of eggshells and eggshell membranes from waste eggshells using the pressure-vacuum experiment equipment was carried out. The flash evaporation experiment process controlled the experimental factors to obtain a sufficient moisture content between the eggshell and eggshell membrane with vigorous flash evaporation. The effects of experimental factors such as superheat (5-10°C), temperature (50-70°C), initial pressure (0.6-0.8MPa), pressurization time (0-40min), and particle size (6-8mm) on the separation rate were investigated in the pressure-vacuum experiment process. Through single-factor and orthogonal experiments, it was found that the separation rate was most affected by changes in temperature, initial pressure, and particle size, followed by the interaction of temperature and particle size. The experimental results suggested that the optimum separation of eggshell membranes from eggshells was achieved at higher superheat, higher temperature, higher initial pressure, medium pressurization time, and smaller particle size. Through optimization by response surface methodology, the optimal conditions for the separation of eggshells and eggshell membranes using the flash evaporation method were determined as 15°C of superheat, 70°C of temperature, 0.8MPa of initial pressure, and 6mm of particle size. Flash evaporation method is an effective and environmentally friendly method, which provides a new solution for the recycling of waste eggshells. PRACTICAL APPLICATION: In this study, pressure-vacuum experiment equipment was utilized to reuse of waste eggshells, and an innovative and environmentally friendly method of eggshell membrane and eggshell separation was established. The pressure-vacuum experiment equipment has a simple structure and low energy consumption. The results of flash evaporation experiments are instructive for further in-depth studies on the separation of eggshells and eggshell membranes. Furthermore, the separation of eggshells and egg membranes by flash evaporation is of great research value. Most importantly, the separated eggshells and eggshell membrane are available for high-value applications in food, chemical, and biological fields.

Membrane separation processes are space and cost-efficient, easy to scale-up operations, which have proved to treat food industrial wastewaters efficiently. Beside the advantages like high separation efficiency without any chemical changes and low energy-intensity, membrane filtration also has drawbacks, like decreased operational efficiency caused by flux decile resulting from fouling and concentration polarization. Combination of oxidation pre-treatment and membrane filtration is a promising method for decreasing fouling due to the physicochemical changes caused by pre-oxidation of the wastewater in structure of colloidal pollutants and in the interactions between the foulants and the membrane material. The aim of this work is to identify the parameters affecting the membrane fouling during treatment of dairy wastewaters, and present the current trends of research in this field.

Mathematical modelling plays a key role in the prediction, understanding, and minimisation of operational problems that affect the performance of fluid–particle separation processes. In this chapter, the reader will be exposed to a case study of mathematical modelling of fouling process in a fluid–particle separation system. The focus of the case study will be on a membrane filtration system, particularly membrane bioreactor (MBR). In some membrane systems that involve compressible material like MBRs, continuous filtration results in the compression of deposited material which negatively impacts the membrane performance. Modelling membrane filtration processes is essential in getting a prior prediction and understanding of the fouling problem and its effect on the membrane filtration performance. This chapter presents the general principles of mathematical modelling that describes fluid–particle separation through a membrane, the fouling process, and its effect on the membrane filtration process. First, the development of a mathematical model that describes the change in membrane filtration performance due to fouling is presented. This is followed by a solution procedure for the model, which was implemented in MATLAB® and Python. Thereafter, validation of the model with experimental data obtained at various operating conditions such as different applied pressures, applied flux with different feed concentrations in the filtration of synthetic wastewater, is outlined. Finally, the assessment of the applicability of the developed model to a real wastewater feed from an MBR is presented.

Wastewater treatment using a hybrid system combining adsorption, photocatalytic degradation and membrane filtration processes

CoFe2O4-catalytic ceramic membrane for efficient carbamazepine removal via peroxymonosulfate activation

The intelligent prediction of membrane fouling during membrane filtration by mathematical models and artificial intelligence models

Surfactants widely exist in various kinds of wastewaters which could be treated by pressure-driven membrane separation (PDMS) techniques. Due to the special characteristics of surfactants, they may affect the performance of membrane filtration. Over the last two decades, there are a number of studies on treating wastewaters containing surfactants by PDMS. The current paper gives a review of the roles of surfactants in PDMS processes. The effects of surfactants on membrane performance were discussed via two aspects: influence of surfactants on membrane fouling and enhanced removal of pollutants by surfactants. The characteristics of surfactants in solution and at solid-liquid interface were summarized. Surfactants in membrane filtration processes cause membrane fouling mainly through adsorption, concentration polarization, pore blocking, and cake formation, and fouling degree may be influenced by various factors (feed water composition, membrane properties, and operation conditions). Furthermore, surfactants may also have a positive effect on membrane performance. Enhanced removal of various kinds of pollutants by PDMS in the presence of surfactants has been summarized, and the removal mechanism has been revealed. Based on the current reports, further studies on membrane fouling caused by surfactants and enhanced removal of pollutants by surfactant-aided membrane filtration were also proposed.

Electrocoagulation coupled with conductive ceramic membrane filtration for wastewater treatment: Toward membrane modification, characterization, and application

For separation procedures in biotechnology and food technology, there is a number of well-established and successful methods. Thus, distillation and rectification are preferably used for processing homogeneous liquid mixtures, but liquid-liquid extraction is also employed. In certain cases, one can fall back on adsorption. If a dissolved substance is the component of interest, then precipitation is the usual process which occurs either by supersaturation, evaporation, or cooling. Sedimentation or conventional filtration serves to retain suspended matter. This enumeration of the processes usually applied for separation raises the question of why membrane filtration is required as an additional means. Does membrane filtration only complete the list of the separation processes or are there indeed some advantages of membrane filtration that the conventional processes cannot offer? To answer this question, it seems reasonable to look at filtration in particular.

Purification and fractionation of bioactive peptides through membrane filtration: A critical and application review

The main problems of membrane-based separation methods especially pressure driven ones are fouling and concentration polarization. After increasing cross-flow velocity, use of promoters for inducing turbulence in filtration zone is one of the easiest ways of mitigating concentration polarization in membrane separation processes. Turbulence promoters have the ability to significantly increase the permeate flux in membrane filtration systems by generating alterations in the flow path of the feed. The complexities involved in fluid dynamics which lead to flux enhancement are still not been clearly conceptualized. Various researchers have investigated the effectiveness of promoters on the overall improvement of the filtration efficiency in membrane filtration processes. The flow field generated by these promoters creates turbulence and secondary flows which lead to high shear rates in the vicinity of the filtration surface resulting in scouring of foulant materials and reduction of cake thickness. This ultimately helps in attaining higher levels of flux and mass transfer. Turbulence promoters such as static mixers, Kenics mixers, helical elements, cylindrical rods, thin wires, spacers are widely used in filtration systems to induce turbulence in order to control polarization. This paper reviews the utilization of promoters in membrane-based separation systems, dependence of flux on operational parameters, and effects of different type of promoters on membranes. The effects of cross-flow velocity, Reynolds number, feed properties, membrane properties, pressure, and temperature are reviewed.

This work aimed to​ treat contaminated groundwater with arsenic and ferrous iron pollutants to be drinking water standard following by WHO by co-precipitation process and membrane separation process. The relative effect of different solid media types (scouring sponge, scouring pad, plastic ring, and activated carbon foam) and operating conditions on oxygen mass transfer coefficient (KLa) and hydrodynamic bubble parameters was studied. The optimization process of ferrous oxidation and arsenic removal was observed by Design of Experiment (DOE) with Central Composition Design of Response Surface Methodology (CCD-RSM). Lastly, separation process was experimented with conventional process and membrane technology, i.e., settling process, different effect of scouring sponge loading on turbidity removal, and impact of settling process on ultra-filtration membrane fouling. The result showed that scouring sponge was the most effective solid media to enhance volumetric oxygen transfer coefficient around 9-80% by impact of bubble rising velocity not breaking up bubble mechanism. The maximum removal of ferrous by optimization process was Qg =14 LPM, initial pH=8, initial [Fe2+]=5mg/L, adding [Fe3+]=25mg/L and operating time 25 min. However, for arsenic removal with co-precipitation process, the optimization process found under condition Qg=8, initial pH=8, initial [Fe2+]=36mg/L, adding [Fe3+]=25mg/L and operating time 33 min. Furthermore, initial pH and ferrous initial concentration was defined as the most significant factor. In separation process, the removal of turbidity by settling process was remaining around 60NTU while the highest scouring sponge loading (10%) was able to remove turbidity around 15% (not pass WHO standard). Finally, ultra-filtration was used to get complete clear and clean drinking water. The result showed that the performance of settling process before membrane filtration could reduce the membrane fouling mechanism. Thus, the combination of settling process and membrane technology could provide more benefits.

Separation treatment processes are being investigated as a way to control the formation of disinfection by‐products (DBPs) in finished waters. These processes remove natural organic matter before a disinfectant is applied, thus limiting the amount of material available to form DBPs. Four separation processes were examined in this study—granular activated carbon adsorption, powdered activated carbon adsorption, anion exchange, and membrane filtration—using two waters. Results showed that (1) as the dissolved organic carbon (DOC) decreased, the chlorination of diluted organic matter solutions held at constant bromide concentrations yielded a shift to brominated trihalomethanes (THMs); (2) at low DOC concentrations, the percentage of formed brominated trihalomethanes was higher in treated effluent than in influent water; and (3) the processes were most effective for controlling the formation of chloroform and least effective for controlling the formation of bromoform. Based on these results, it can be concluded that effective control of brominated THMs by these separation processes may be difficult for waters containing significant concentrations of bromide.