Effect of Ultrafiltration of Milk Prior to Fermentation on Mass Balance and Process Efficiency in Greek-Style Yogurt Manufacture

Ultrafiltration (UF) can be used to concentrate yogurt to produce Greek-style yogurt (GSY) (UF-YOG), but this generates acid whey permeate, which is an environmental issue. However, when UF is applied before fermentation (UF-MILK), a nonacidified whey permeate is generated. For this study, two model GSYs (UF-YOG and UF-MILK) were produced to compare the composition, UF performance, and energy consumption of the two processes. For UF-MILK, skim milk was ultrafiltered with a 30 kDa spiral-wound UF membrane to achieve a 3× volume reduction factor (VRF). The retentate was fermented to a pH of 4.5. The UF-YOG process was the same except that regular yogurt was ultrafiltered. Both GSYs had similar protein (~10%) and solid content (~17%). As expected, lactic acid/lactate was not detected in UF-MILK permeate, while 7.3 g/kg was recovered from the UF-YOG permeate. Permeation flux values (11.6 to 13.3 L m−2 h−1) and total flux decline (47% to 50%) were constant during UF-MILK, whereas drastic decreases in these two membrane performance indicators (average flux: 38.5 to 10.9 L m−2 h−1; total flux decline: 2% to 38%) were calculated for UF-YOG. Moreover, for UF-YOG, UF membrane performance never recovered, even when drastic and repeated cleaning steps were applied. Energy consumption was 1.6 kWh/kg GSY and remained constant for UF-MILK, whereas it increased from 0.6 to 1.5 kWh/kg GSY for UF-YOG. Our results show that, although the composition of GSYs was similar for both processes, the UF step of yogurt concentration affected process efficiency due to drastic and permanent membrane fouling.

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Influence of Processing Temperature on Membrane Performance and Characteristics of Process Streams Generated during Ultrafiltration of Skim Milk

Foods ◽

10.3390/foods9111721 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1721

Author(s):

Ritika Puri ◽

Upendra Singh ◽

James A. O’Mahony

Keyword(s):

Inverse Relationship ◽

Skim Milk ◽

Biochemical Properties ◽

Processing Temperature ◽

Casein Micelle ◽

Plasmin Activity ◽

Membrane Performance ◽

Flux Decline ◽

Dairy Ingredients ◽

Β Lactoglobulin

The effects of processing temperature on filtration performance and characteristics of retentates and permeates produced during ultrafiltration (UF) of skim milk at 5, 20, and 50 °C were investigated. The results indicate that despite higher flux at 50 °C, UF under these conditions resulted in greater fouling and rapid flux decline in comparison with 5 and 20 °C. The average casein micelle diameter was higher in retentate produced at 5 and 20 °C. The retentate analysed at 5 °C displayed higher viscosity and shear thinning behaviour as compared to retentate analysed at 20 and 50 °C. Greater permeation of calcium and phosphorus was observed at 5 and 20 °C in comparison with 50 °C, which was attributed to the inverse relationship between temperature and solubility of colloidal calcium phosphate. Permeation of α-lactalbumin was observed at all processing temperatures, with permeation of β-lactoglobulin also evident during UF at 50 °C. All UF retentates were shown to have plasmin activity, while lower activity was measured in retentate produced at 5 °C. The findings revealed that UF processing temperature influences the physicochemical, rheological, and biochemical properties of, and thereby govern the resulting quality and functionality of, retentate- and permeate-based dairy ingredients.

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Filtration of biological suspension: membrane performance

Water Science & Technology Water Supply ◽

10.2166/ws.2005.0103 ◽

2005 ◽

Vol 5 (3-4) ◽

pp. 227-232

Author(s):

S. Delgado ◽

F. Díaz ◽

R. Villarroel ◽

M.D. García ◽

L. Vera ◽

...

Keyword(s):

Membrane Fouling ◽

Wastewater Reuse ◽

Process Efficiency ◽

Government Regulations ◽

Quality Requirements ◽

Membrane Performance ◽

Several Variables ◽

Dead End ◽

Appropriate Treatment ◽

Treatment Technologies

Wastewater reuse provides a substantial non-conventional water resource, mainly for agriculture. However, it requires appropriate treatment technologies and previous evaluation so as to meet quality requirements imposed by government regulations and crop needs. Among all the technologies applied to wastewater treatment, membrane-based systems have gained increasing importance, although their main drawback is progressive membrane fouling, which affects process efficiency enormously. The present study analyses the filterability of some biological suspensions as well as the influence of several variables in membrane fouling. Classic dead–end filtration models are used in an attempt to better understand fouling mechanisms and develop methods to prevent or retard it.

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Mechanical Vibration for the Control of Membrane Fouling in Direct Contact Membrane Distillation

Symmetry ◽

10.3390/sym11020126 ◽

2019 ◽

Vol 11 (2) ◽

pp. 126 ◽

Cited By ~ 3

Author(s):

Frank Huang ◽

Carolyn Medin ◽

Allie Arning

Keyword(s):

Packing Density ◽

Membrane Fouling ◽

Direct Contact ◽

Mechanical Vibration ◽

Water Flux ◽

Similar Rate ◽

Membrane Distillation ◽

Membrane Performance ◽

Direct Contact Membrane Distillation ◽

Flux Decline

One of the biggest challenges for direct contact membrane distillation (DCMD) in treating wastewater from flue gas desulfurization (FGD) is the rapid deterioration of membrane performance resulting from precipitate fouling. Chemical pretreatment, such as lime-soda ash softening, has been used to mitigate the issue, however, with significant operating costs. In this study, mechanical vibration of 42.5 Hz was applied to lab-scale DCMD systems to determine its effectiveness of fouling control for simulated FGD water. Liquid entry pressure and mass transfer limit of the fabricated hollow fiber membranes were determined and used as the operational constraints in the fouling experiments so that the observed membrane performance was influenced solely by precipitate fouling. Minimal improvement of water flux was observed when applying vibration after significant (~16%) water-flux decline. Initiating vibration at the onset of the experiments prior to the exposure of foulants, however, was promising for the reduction of membrane fouling. The water-flux decline rate was reduced by about 50% when compared to the rate observed without vibration. Increasing the module packing density from 16% to 50% resulted in a similar rate of water-flux decline, indicating that the fouling propensity was not increased with packing density in the presence of vibration.

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Predictability of fouling-potential of raw water for ultrafiltration membranes

Water Science & Technology Water Supply ◽

10.2166/ws.2011.078 ◽

2011 ◽

Vol 11 (4) ◽

pp. 481-489

Author(s):

S. Krause ◽

A. Obermayer

Keyword(s):

Water Quality ◽

Membrane Fouling ◽

Large Scale ◽

High Capacity ◽

Raw Water ◽

Ultrafiltration Membranes ◽

Small Water ◽

Lab Experiments ◽

Flux Decline ◽

Public Drinking Water

The public drinking water supply of southern Germany is characterized by a rather decentralized network. Due to the hydrogeological setting in these parts of Germany many of the small water works with an average capacity of 50 m3/h have to treat raw water extracted from karstic or cliffy aquifers. These raw waters tend to be contaminated with particles and pathogens acquired during snowmelt or after strong rainfalls. In the last decade ultrafiltration has become the technology of choice for the removal of the aforementioned contaminants. Flux decline caused by unanticipated membrane fouling is the main limitation for the application of ultrafiltration membranes. This paper describes how membrane fouling phenomena can be predicted by using a statistical approach based on data from large scale filtration systems in combination with field and lab experiments on raw water quality and membrane performance. The data defines water quality and respective fouling phenomena both in technical scale filtration plants and in lab experiments of eleven different raw waters. The method described here is more economically feasible for small water works when compared to typical pilot experiments that are used for high capacity water works.

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Separation of Biologically Active Compounds by Membrane Operations

Current Pharmaceutical Design ◽

10.2174/1381612822666161027153823 ◽

2017 ◽

Vol 23 (2) ◽

pp. 218-230 ◽

Cited By ~ 4

Author(s):

Xiaoying Zhu ◽

Renbi Bai

Keyword(s):

Energy Consumption ◽

Bioactive Compounds ◽

Membrane Fouling ◽

Membrane Separation ◽

Separation Efficiency ◽

High Energy ◽

Separation Processes ◽

Membrane Processes ◽

Separation Technology ◽

Pressure Driven

Background: Bioactive compounds from various natural sources have been attracting more and more attention, owing to their broad diversity of functionalities and availabilities. However, many of the bioactive compounds often exist at an extremely low concentration in a mixture so that massive harvesting is needed to obtain sufficient amounts for their practical usage. Thus, effective fractionation or separation technologies are essential for the screening and production of the bioactive compound products. The applicatons of conventional processes such as extraction, distillation and lyophilisation, etc. may be tedious, have high energy consumption or cause denature or degradation of the bioactive compounds. Membrane separation processes operate at ambient temperature, without the need for heating and therefore with less energy consumption. The “cold” separation technology also prevents the possible degradation of the bioactive compounds. The separation process is mainly physical and both fractions (permeate and retentate) of the membrane processes may be recovered. Thus, using membrane separation technology is a promising approach to concentrate and separate bioactive compounds. Methods: A comprehensive survey of membrane operations used for the separation of bioactive compounds is conducted. The available and established membrane separation processes are introduced and reviewed. Results: The most frequently used membrane processes are the pressure driven ones, including microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). They are applied either individually as a single sieve or in combination as an integrated membrane array to meet the different requirements in the separation of bioactive compounds. Other new membrane processes with multiple functions have also been developed and employed for the separation or fractionation of bioactive compounds. The hybrid electrodialysis (ED)-UF membrane process, for example has been used to provide a solution for the separation of biomolecules with similar molecular weights but different surface electrical properties. In contrast, the affinity membrane technology is shown to have the advantages of increasing the separation efficiency at low operational pressures through selectively adsorbing bioactive compounds during the filtration process. Conclusion: Individual membranes or membrane arrays are effectively used to separate bioactive compounds or achieve multiple fractionation of them with different molecule weights or sizes. Pressure driven membrane processes are highly efficient and widely used. Membrane fouling, especially irreversible organic and biological fouling, is the inevitable problem. Multifunctional membranes and affinity membranes provide the possibility of effectively separating bioactive compounds that are similar in sizes but different in other physical and chemical properties. Surface modification methods are of great potential to increase membrane separation efficiency as well as reduce the problem of membrane fouling. Developing membranes and optimizing the operational parameters specifically for the applications of separation of various bioactive compounds should be taken as an important part of ongoing or future membrane research in this field.

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Potential Pitfalls in Membrane Fouling Evaluation: Merits of Data Representation as Resistance Instead of Flux Decline in Membrane Filtration

Membranes ◽

10.3390/membranes11070460 ◽

2021 ◽

Vol 11 (7) ◽

pp. 460

Author(s):

Bastiaan Blankert ◽

Bart Van der Bruggen ◽

Amy E. Childress ◽

Noreddine Ghaffour ◽

Johannes S. Vrouwenvelder

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Data Representation ◽

Strong Impact ◽

Experimental Conditions ◽

Permeable Membrane ◽

Dead End ◽

Flux Decline ◽

The Difference ◽

Filtration Flux

The manner in which membrane-fouling experiments are conducted and how fouling performance data are represented have a strong impact on both how the data are interpreted and on the conclusions that may be drawn. We provide a couple of examples to prove that it is possible to obtain misleading conclusions from commonly used representations of fouling data. Although the illustrative example revolves around dead-end ultrafiltration, the underlying principles are applicable to a wider range of membrane processes. When choosing the experimental conditions and how to represent fouling data, there are three main factors that should be considered: (I) the foulant mass is principally related to the filtered volume; (II) the filtration flux can exacerbate fouling effects (e.g., concentration polarization and cake compression); and (III) the practice of normalization, as in dividing by an initial value, disregards the difference in driving force and divides the fouling effect by different numbers. Thus, a bias may occur that favors the experimental condition with the lower filtration flux and the less-permeable membrane. It is recommended to: (I) avoid relative fouling performance indicators, such as relative flux decline (J/J0); (II) use resistance vs. specific volume; and (III) use flux-controlled experiments for fouling performance evaluation.

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Membrane fouling mechanisms and permeate flux decline model in soy sauce microfiltration

Journal of Food Process Engineering ◽

10.1111/jfpe.12599 ◽

2017 ◽

Vol 41 (1) ◽

pp. e12599 ◽

Cited By ~ 7

Author(s):

Ye Sun ◽

Zhen Qin ◽

Liming Zhao ◽

Qiming Chen ◽

Qingyun Hou ◽

...

Keyword(s):

Membrane Fouling ◽

Soy Sauce ◽

Permeate Flux ◽

Flux Decline

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Application of forward osmosis in reusing the brackish concentrate produced in reverse osmosis plants with secondary treated wastewater as feed solution: a case study

Journal of Water Reuse and Desalination ◽

10.2166/wrd.2016.097 ◽

2016 ◽

Vol 6 (4) ◽

pp. 533-543 ◽

Cited By ~ 1

Author(s):

W. D. Wang ◽

M. Esparra ◽

H. Liu ◽

Y. F. Xie

Keyword(s):

Reverse Osmosis ◽

Membrane Fouling ◽

Water Flux ◽

Forward Osmosis ◽

Pump Energy ◽

Feed Solution ◽

Disinfection Byproducts ◽

Treated Wastewater ◽

Membrane Flux ◽

Flux Decline

This study evaluated the feasibility of forward osmosis (FO) in diluting and reusing the concentrate produced in a reverse osmosis (RO) plant in James City County, VA. Secondary treated wastewater (STW) was used as the feed solution. Findings indicated that pH had slight effects on the water flux of the FO membrane. As the concentration of total dissolved solids (TDS) in the concentrate was diluted from 12.5 to 1.0 g/L or the temperature in the STW decreased from 23 to 10 °C, the membrane flux decreased from 2.2 to 0.59 and 0.81 L/(m2 h), respectively. The FO membrane showed a good performance in the rejection of organic pollutants, with only a small part of the protein-like substances and disinfection byproducts permeating to the diluted concentrate. During an 89-hour continuous operation, water flux decline due to membrane fouling was not observed. Controlling the TDS in the second-stage FO effluent at 1.5 g/L, approximately 8.3% of the pump energy input could be saved. The consumption of groundwater was reduced from 22.7 × 103 to 10.6 × 103 m3/d. FO was proved to be an effective method in both diluting the discharged concentrate and reducing the energy consumption of RO.

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Membrane Fouling Controlled by Adjustment of Biological Treatment Parameters in Step-Aerating MBR

Membranes ◽

10.3390/membranes11080553 ◽

2021 ◽

Vol 11 (8) ◽

pp. 553

Author(s):

Dimitra C. Banti ◽

Manassis Mitrakas ◽

Petros Samaras

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Municipal Wastewater ◽

Operating Conditions ◽

Transmembrane Pressure ◽

Aeration Tank ◽

Filamentous Bacteria ◽

Membrane Performance ◽

Low Concentrations ◽

Fouling Reduction

A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtration. In this work, these parameters were investigated in a step-aerating pilot MBR that treated municipal wastewater, in order to control the filamentous population. When F/M loading in the first aeration tank (AT1) was ≤0.65 ± 0.2 g COD/g MLSS/d at 20 ± 3 °C, DO = 2.5 ± 0.1 mg/L and HRT = 1.6 h, the filamentous bacteria were controlled effectively at a moderate filament index of 1.5–3. The moderate population of filamentous bacteria improved the membrane performance, leading to low transmembrane pressure (TMP) at values ≤2 kPa for a great period, while at the control MBR the TMP gradually increased reaching 14 kPa. Soluble microbial products (SMP), were also maintained at low concentrations, contributing additionally to the reduction of ΤΜP. Finally, the step-aerating MBR process and the selected imposed operating conditions of HRT, F/M and DO improved the MBR performance in terms of fouling control, facilitating its future wider application.

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Refined palm oil fractions: Effect of skim milk powder and maltodextrin on emulsion properties and microencapsulation by spray drying

Acta Alimentaria ◽

10.1556/066.2021.00069 ◽

2021 ◽

Author(s):

K. Cevik ◽

H. Yalcin

Keyword(s):

Spray Drying ◽

Palm Oil ◽

Palm Olein ◽

Milk Powder ◽

Skim Milk ◽

Palm Stearin ◽

Skim Milk Powder ◽

Solid Content ◽

Coating Materials ◽

Oil Fractions

Abstract The aim of this study was to investigate microencapsulation of palm oil fractions (palm olein (POL) and 90% palm olein+10% palm stearin (POS)) using skim milk powder (SMP) and maltodextrin (MD) by spray drying. Twenty-seven emulsions with POL were prepared to determine appropriate solid content (SC) and oil/coating material ratio (O/CM) of the emulsions to be fed into the spray dryer. Emulsion properties, such as viscosity and stability, were affected by SC and coating materials. The effects of coating materials used in microencapsulation of POL and POS were also tested by using different ratios of SMP and MD. The microencapsulation efficiency (69.28–84.97%), the microencapsulation yield (14.50–31.79%), and the peroxide value (4.12–7.07 meq O2/kg oil) of the powders were affected by the coating materials (P < 0.05).

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