Beverage Industry Microﬁ ltration COPYRIGHTED MATERIALThis guide is meant as a comprehensive guide and learning tool with regard to microﬁ ltration in the beverage industry. Processes

Beverage Industry Microfi ltration

COPYRIG

HTED M

ATERIAL

Chapter 1

Introduction

Introduction

Microfi ltration has become a critical process in beverage manufactur-ing. Many beverage manufacturers do not have a clear understanding of microfi ltration processes and the technologies behind them. This book is meant as a comprehensive guide to help beverage industry professionals with the understanding, selection, operation, and optimi-zation of microfi ltration stages in their plants and processes. There are major beverage manufacturers that have spent time optimizing their microfi ltration processes and, as a result, are several times more effi -cient than comparably sized competitors in the same fi eld. The overall operational savings that result can represent tens of thousands to hun-dreds of thousands of dollars. Improvements may be realized not only in direct fi lter spending but also with regard to product yields, down-time savings, operator usage, utilities, and so forth.

This guide is meant as a comprehensive guide and learning tool with regard to microfi ltration in the beverage industry. Processes vary con-siderably, so it is up to each person, plant, or organization to develop data and procedures relative to their own application. Views and opin-ions expressed in this document are those of the author and are the result of his personal experience gained through extensive work with beverage fi ltration processes. This work does not make any claims or representa-tions and is not meant to replace direct engineering support.

Beverage microfi ltration is unique in that it falls between two vastly different groups of microfi ltration processes. The biopharmaceutical market is, in terms of spending, the largest end-user of microfi ltration technology. The fi lters and the fi ltration processes within the biopharm sector must undergo extensive validation and research. Regulatory agencies demand strict compliance and oversight of fi ltration processes

3

4 Beverage Industry Microfi ltration

employed within drug and comparable biopharm processes. The fi lters used in biopharmaceutical plants can easily reach three to four times the cost of a comparable fi lter used elsewhere. Out of necessity, fi ltra-tion is very well understood and is considered a major process step in most biopharm plants.

Industrial users of microfi ltration, including producers of paints, adhesives, chemicals, etc., use the most fi lters in terms of units; however, the fi lters they use are much less refi ned, considerably cheaper, and are treated as commodity items. Filters remove general debris; there are typically no microbial or health concerns and detailed attention is rarely paid to a well designed, understood, and optimized fi ltration process because the benefi ts of doing so are minimal.

The beverage market does not manufacture high-value goods like the biopharmaceutical industry does. Most beverage plants cannot afford to spend millions of dollars on fi ltration. Many beverage produc-tion volumes are considerably higher than other industries due to sheer consumption rates. Although subject to some regulatory oversight, oversight of the beverage industry, particularly with regard to fi ltration, is in no way on par with the oversight associated with biopharm. Bev-erages are subject to health and spoilage concerns, and producers must deal with consumers who expect much higher quality from their drinks than they do from a can of paint or a tube of glue. Failure to remove harmful microorganisms from a susceptible beverage can be disastrous, even deadly. Microorganisms that cause product spoilage can be fi nan-cially damaging. Most industrial products can still be sold after a failed fi ltration stage; most beverages cannot. This has created a situation where the beverage industry requires a semi-validated quality product that can be consistently relied upon to perform its targeted function. The product cannot be so highly designed and validated, however, that the costs aren’t in line with the market.

Of the fi ve major microfi ltration suppliers in the beverage market, Pall, Cuno, and Domnick Hunter’s total business tends to lean more toward the industrial side, whereas Millipore and Sartorius have much more of a biopharmaceutical focus. The costs and quality of their fi ltra-tion products typically refl ect this divide. Pall may be considered the best-rounded of the fi ve companies in terms of business focus, but the companies all meet in the center of the divide to compete in the bever-age market. They are joined by countless smaller fi ltration companies as well as resellers and distributors.

Introduction 5

Purposes

Microfi ltration often serves as a critical step in ensuring fi nal product integrity. Microorganism removal is essential to beverages in which contamination can lead to consumer illness, as well as to those bever-ages susceptible to microbial spoilage mechanisms. Beverages that are not in danger from microbial contamination may undergo microfi ltra-tion for general particulate removal to ensure the aesthetic quality of the fi nal product. Figure 1.1 depicts the different removal characteris-tics of fi ne fi ltration processes.

Microfi ltration serves many auxiliary functions throughout the bev-erage industry in addition to fi nal product fi ltration. Ensuring process water quality can be crucial to general plant cleaning and sanitation regimens. Gases, such as carbon dioxide, are being used in many product formulations. Bulk or point-of-use fi ltration of these gases is often important to maintaining product quality.

Selective use of microfi ltration can lead to a faster, easier, and more economical process. Brewers can use microfi ltration for both lees recov-ery and as an alternative to pasteurization. Wineries may use microfi ltra-tion for tartrate removal. Whiskey makers can remove chill haze using a fi ltration step. Ceramic crossfl ow systems allow the cleaning and reuse of caustic solution. Each plant’s individual processes, even within the same industry, may have its own uses for microfi ltration.

The bottled water and wine industries are the largest beverage micro-fi ltration users in terms of spending. They are followed by the beer, spirits, and soft drink industries. Other industries that use microfi ltra-

Monovalent SaltsNon-dissociated Acids

Macromolecules

SugarsDivalent SaltsDissociated Acids

MicroorganismsSuspended Particles

Reverse Osmosis

Nanofiltration

Ultrafiltration

Microfiltration

Water

Figure 1.1. Various fi ltration mechanisms.


tion include juice, sports drink, energy drink, coffee and tea, neutra-ceutical, oils, as well as various liquid or semi-liquid product or component producers.

Capabilities

Microfi ltration systems can be built to a process or application. There are practically no removal, size, or fl ow rate limitations. Oftentimes a single stage system is suitable, while other times one or more stages using several different housings or fi ltration formats must be used.

The primary limitation of microfi ltration systems is usually the service life of the fi lter and its associated change-out costs. More refi ned forms of microfi ltration devices, such as membrane fi lter cartridges, can be hundreds of times more expensive than other fi lter formats, such as bag or sheet fi lters. It therefore becomes critical to have a multi-tiered fi ltration system that combines various fi lter media that work together in order to achieve the most economic fi ltration process. Filter service life is further extended through proper design, operation, maintenance, cleaning, and/or fi lter regeneration. The dif-ference in operating costs between an optimized fi ltration process and an un-optimized fi ltration process can sometimes be the deciding factor in whether or not to implement microfi ltration. With adequate knowl-edge of microfi ltration processes and technologies, a facility can greatly improve the economics of fi ltration and may be able to implement further procedures benefi ting the entire production process.

Principles of Filtration

A basic understanding of fl uid dynamics and the mechanics of fi ltration can be extremely helpful when both designing and operating a beverage fi ltration process. It is important to understand fl ow dynamics, fi lter removal mechanisms, the differences among fi ltration media, as well as the contaminants being removed.

Basic Fluid Dynamics of Filtration

A fl uid is a substance that conforms to its container. Fluids may be either incompressible, such as liquids, or compressible, such as gases. A driving force is required in order for a fl uid to fl ow. Driving forces

Introduction 7

are based on the differences in physical parameters surrounding or involving the fl uid, such as pressure, temperature, or concentration. Pressure is usually the key driving force in microfi ltration. Pressure gradients can be created via height, mechanical pumps, or the positive or negative compression of a gas.

Pressure is expressed most commonly in the English unit of pounds per square inch (psi) or its metric equivalent of bar or mbar. Atmo-spheres (atm), Pascals (Pa), or inches of water/mercury may also be used to express pressure. A value known as gauge pressure is some-times used for liquid fi ltration and corresponds to the pressure in addi-tion to atmospheric pressure. Absolute pressure — pressure relative to zero — is often used in gas fi ltration.

Pressure Differential (Pressure Drop) across a FilterDuring normal fl ow liquid fi ltration the driving force used to push liquid through the fi lter is the pressure differential across the fi lter. Differential pressure or pressure drop is defi ned as the inlet (upstream) pressure minus the outlet (downstream) (See Figure 1.2) pressure as given by Equation 1.1. There will always be a differential pressure across a fi lter when there is some fl ow.

ΔP P PIn Out= − (1.1)

In most crossfl ow fi ltration processes (also called tangential fl ow or TFF) the driving force is the transmembrane pressure. A principle similar to normal fl ow differential pressure, the transmembrane pres-sure is basically a correction for the fact that there is a pressure loss

Retentate

Inlet Feed Upstream

Filter

Outlet Downstream Permeate Filtrate

Figure 1.2. Filter fl ow terminology.


on the feed side due to the tangential feed and retentate fl ow. The upstream pressure is the average of the feed pressure and the retentate pressure and is determined by Equation 1.2.

PP P

UpstreamFeed tenate= + Re

2 (1.2)

Substituting the expression for upstream pressure into that for dif-ferential pressure yields the expression for the trans-membrane pres-sure (Equation 1.3).

Transmembrane essureP P

PFeed RetentatePermeatePr = + −

2 (1.3)

For gases, the mass of the gas depends on the pressure of the gas. This means that the gas fl ow through the fi lter will depend on the gas pressure, because different pressures will have different masses.

If all else is kept the same, there is typically a linear relationship between differential pressure and fl ow rate:

• When fl ow rate increases, the differential pressure will increase.• When fl ow rate decreases, the differential pressure will decrease.

In conditions where the fi lter is impacting the pump and fl ow rate, it is possible to see the following relationships:

• When differential pressure across a fi lter increases, fl ow rate will decrease.

• When differential pressure across a fi lter decreases, fl ow rate will increase (provided pumping capacity is available).

A common example of this situation is a centrifugal pump feeding a bottling line. As the fi lter plugs and differential pressure increases, the fl ow rate to the bottling line will gradually decrease until there is no longer adequate fl ow to maintain the process. As any bottling manager knows, the fl ow rate is a limiting factor for many processes, so a fi ltra-tion run will not only be limited by how much fi lter capacity is left, but also by how much fl ow it is capable of supplying to the downstream process. Pressure drop is a key factor when determining the fi lter area

Introduction 9

of a system during design. If a process’s fl ow rate is to be maintained at 200 gpm (45,420 lph), then the fi ltration area and pump that can supply that fl ow with an appropriate pressure drop should be selected.

Fluid ViscosityThe viscosity of the fl uid is an important factor affecting pressure drop and fl uid fl ow and should be taken into consideration. Increases in viscosity will increase the pressure drop. At a constant pressure, the viscosity will have a directly linear relationship on fl uid fl ow rate through the fi lter. Generally, at a constant pressure, if the viscosity is doubled, the fl ow rate will be halved. If the viscosity is halved, the fl ow rate will be doubled. An example of this can be seen in comparing water and oil. Water will fl ow through a fi lter at upward of 50–70 times the fl ow rate of oil running through the same fi lter at the same differ-ential pressure. A cold fl uid will have a higher viscosity than the same fl uid when heated. This can be signifi cant. The viscosity of water will change about 4.5% per degree F (about 2.5% per degree C). Most solvents, such as alcohols, will have a lower viscosity than water. Some highly viscose products, such as maple syrup, will require heating in order to properly fl ow through a fi ltration process.

Changing the temperature of a process stream will change the pres-sure drop per fi lter at a given fl ow rate. This is due to the increased viscosity of a cooler process stream versus a warmer one. The change, for example, from a 75 F (24 C) beer stream to one that is 36 F (2.2 C) is enough to result in up to a 75% increase in differ-ential pressure through some wrapped, depth trap or prefi lter car-tridges given the same fl ow rate. This can have dramatic effects on system sizing.

In certain open depth fi lters the viscosity may not always have a directly linear relationship to pressure. In this instance, a viscosity versus pressure drop chart or other data should be supplied by the fi lter manufacturer.

Flow RateFlux is a value used to normalize the fl ow rate for fi lters or fi ltration systems with different fi ltration areas. It is defi ned as the fl ow rate


per unit of surface area. Flux units would be expressed as l/min/m2 or gal/min/ft2 and can be obtained by simply dividing the fl ow rate by the fi lter’s surface area. The term “face velocity” is sometimes used within the fi lter industry to mean fl ux. Face velocity can be specifi ed per fi lter device, such as l/min/cartridge. Lowering the fi lter fl ux or face velocity will have a positive effect upon the fi lter’s throughput, overall service life, and performance. Particles are removed more easily from slow-moving streams. Colloidal matters tend to more effi ciently block pores at higher process speeds. Flux and face velocity are important consid-erations during both the design and operation of fi ltration equipment.

Flux is used to calculate fi lter permeability. The permeability for normal fl ow fi ltration is expressed by Equation 1.4.

PermeabilityFlux

P=

Δ (1.4)

The permeability for tangential fl ow fi ltration is expressed by Equation 1.5.

PermeabilityFlux

Transmembrane essure=

Pr (1.5)

Pore size will impact fl ow rate. A tighter pore size will increase the differential pressure given the same fl ow. Because of this interaction, caution should be taken when tightening down the pore size rating of a particular fi ltration stage. Tightening a pre-bottling fi lter from 1.2 μm to 0.45 μm, for example, will increase the differential pressure com-pared to what it had been previously. Filtration housings or pumps may have to be modifi ed as a result. Adding depth will increase the differ-ential pressure and, as a result, reduce fl ow. This means that changing a 0.5 μm surface fi lter to a 0.5 μm wrapped, depth fi lter will increase differential pressure and restrict fl ow. The fl ow equation is expressed in Equation 1.6.

FlowP A T

V L= ( )( )( )( )

( )( )Δ r

(1.6)

ΔP Differential Pressure=ρ = Pore Size

Introduction 11

A Area=T Temperature=V Viscosity=L Path Thickness=

Pump SelectionPumps used for the fi ltration of beverages are either positive displace-ment or centrifugal. Centrifugal are common for large-scale applica-tions. Positive displacement (PD) pumps, of which there are several types, such as rotary, peristaltic, or diaphragm, are more common for smaller applications and for such uses as chemical addition, laboratory functions, or small product batches. If a PD pump is being used for larger applications, such as fi ltration skid feed, it should be normally of the rotary type.

The main operating difference between the two pump types is that centrifugal pumps are affected by pressure, whereas positive displace-ment pumps are not. As the differential pressure of the fi ltration stage increases, the effi ciency of the centrifugal pump will decrease. The decrease in effi ciency causes the fl ow rate supplied by the pump to decrease. Centrifugal pumps used as fi ltration feed pumps must be sized accordingly so that the pump can maintain the required outlet fl ow rate minimum up to the point (pressure) at which the fi ltration stages are completely plugged. This includes when there are multiple fi ltration stages and it is necessary to achieve the maximum throughput per fi ltration run. The effi ciency of a positive displacement pump remains relatively the same as outlet pressure increases.

An automatic pressure relief line should be installed to relieve pres-sure build-up if a PD pump is selected. Many processes or equipment skids will have this automatically built in. Fluid pulsation, often caused by PD pumps, also needs to be mitigated.

TIP

Running a carbonated product with a centrifugal pump?If the process or line is running poorly and/or operating in hot

weather, the carbon dioxide can come out of the solution in the product line. This will cause pump cavitation and lead to a loss of

Continued


Water Hammer and PulsationRapid closing of valves, certain types and operation of pumps, and vertical piping can all create pressure spikes that can severely damage fi lters, o-rings, gaskets, and other equipment. Water hammer is a result of the fact that liquids are incompressible and therefore any energy applied to the fl uid is transmitted.

Water hammer is essentially a rapid change in liquid velocity. Flow rapidly stopping, starting, or changing direction can all lead to water hammer. The most common cause is the rapid closing of a valve. The rapid closing of a valve can lead to a pressure spike as high as fi ve times the normal operating pressure and can be calculated via Equation 1.7.

PL V

t PShock

Inlet

= ( )( )( )+( )

0 070. (1.7)

P Increase in pressureshock =L Length of upstream piping=V Velocity of flow=t Valve closing time=P Inlet pressureInlet =

Pulsation most often occurs as a result of positive displacement pumps as the liquid accelerates and decelerates. Pulsation can be observed as vibration and can lead to pressure spikes many times the normal fl ow pressure. Pulsation dampeners or surge suppressors — nothing more than a pressurized vessel fi lled with a gas — is one method of controlling the effects of pulsation.

fl ow. The pump will need to be bled off and restarted. If this is a problem, try the following:

• Decrease the length of hose or piping to the suction of the pump.

• Elevate the hose or piping on the suction side of the pump.• Try to avoid allowing the product to sit for prolonged periods of

time or to heat up.

Introduction 13

Particle Separation

The particles and mechanisms by which they are removed can have a signifi cant effect upon fi ltration process performance. It is always rec-ommended to perform a detailed analysis of plugging components and particles contained within the feed stream at the onset of designing or altering a fi ltration process. It is relatively easy to determine the type and size of particles, and this information can be paired with trial data to determine the mechanism(s) by which the particles are being removed and/or are plugging the fi lter. Knowledge of particulates is also valu-able in the determination of a proper fi lter cleaning or regeneration regimen, when applicable.

Particle TypesParticles can essentially be broken down into two primary categories:

1. Hard (non-deformable) particles such as dust, sand, DE, and metal fi nes

2. Soft (deformable) particles such as gels, colloids, microbes, clay, and carbohydrates

Soft deformable particles are more diffi cult plugging agents than hard particles. This is because soft particles generally plug a fi lter via a pore blockage model, while hard particles will be more prone to plug via cake formation at the fi lter’s surface (See Figure 1.3). Cake formation leaves channels that, while restricting some fl ow, will still allow for some fl ow through the fi lter for a longer period of time. Soft particles such as gels, colloids, proteins, and gums exhibit higher fouling than microorganisms.

Hard Particle Caking

Soft Particle Caking

Figure 1.3. Hard and soft particles exhibit different caking mechanisms.


Particle Removal MechanismsThere are six commonly recognized capture mechanisms for dealing with gases and liquids in microfi ltration processes:

1. Adsorption — Removal via attractive forces between the particles and the fi lter matrix

2. Size exclusion or sieving — Removal of particles that are larger than the fi lter openings (removal at the surface)

3. Interception — Removal of particles as they fl ow through the fi lter matrix (removal within the depth)

4. Diffusion — Removal that occurs when particles move in a way as to increase their probability for a collision with the fi lter matrix

5. Gravitational settling — Separation when particles settle out of a moving stream due to gravity

6. Inertial impact — When a particle’s inertia causes it to be impacted on the fi lter matrix as fl ow is diverted around the fi lter

The main capture mechanisms of a liquid fi lter are size exclusion, interception, and adsorption. Absolute membrane fi ltration is deter-mined mostly based on size exclusion. Gas fi lters operate on size exclusion, diffusion, inertial impaction, and adsorption. The types of removal mechanisms employed will change based on particle type, size, and fl ow speed. Slow-moving streams with large particles will be more susceptible to gravitational settling, for example.

Membrane Filter PluggingEvery process stream will plug in a different manner. No plugging model has ever been developed that can be applied to all fi lter types in all processes. There are three primary models that can be used to describe fi lter plugging:

1. Gradual Plugging — Pores progressively plug as more volume fl ows through the fi lter and particles are removed. Gradual plugging is usually characterized by materials building up in the pores of the membrane.

2. Complete Blocking — A particle completely blocks one or more pores. Plugging is often at the surface and completely restricts fl ow through the pore(s).

Introduction 15

3. Particle Caking — Particles build up on the surface of the fi lter, not always completely blocking the pores, often leaving channels available for fl ow.

The three methods of pore blockage are shown in Figure 1.4. It is much better for a stream to operate in a particle-caking mode than in a gradual or complete blocking mode. Plugging of fi lters, in reality, actu-ally occurs by combinations of these mechanisms and usually with a great degree of randomness.

Hard particles often form a cake on the surface of the membrane. This is one reason why membrane crossfl ow technology is increasingly being used for the rough clarifi cation stage in certain beverage pro-cesses. The cake formed on the fi lter can be removed by creating fl uid fl ow along the surface of the membrane rather than perpendicularly into it. Soft and deformable particles are more likely to completely or gradually block the membrane pores.

Filter manufacturers will typically size new membrane systems based on the gradual pore-plugging model. Membrane fi lters are more likely to fi lter smaller soft and deformable particles, such as bacteria, colloids, clays, and carbohydrates, when there are upstream clarifi ca-tion and prefi ltration steps to remove a majority of the hard particles, such as fi nes, silt, or general debris.

Zeta PotentialZeta potential is a term that mostly relates to sheet and lenticular fi lters. When a depth fi ltering matrix is charged (normally positive for bever-age fi ltration), oppositely charged particles will adhere better to its surface. Most particles that are removed in wine and beer fi ltration are

Complete PoreBlocking

Gradual PoreBlocking

ParticleCaking

Figure 1.4. Pores may be blocked by one, two, or three mechanisms.


negatively charged. A problem with Zeta potential is that it takes time for it to establish and is disrupted when fl ow stops. It is possible for particles that were retained via this mechanism to be released when the fi ltration stops and restarts again. Some cartridge-style depth fi lters can have a slight Zeta potential effect, but this is less of a factor than when dealing with sheet or lenticular fi lters.

Filter Effi ciency and Beta RatioFilter effi ciency is sometimes reported in terms of Beta ratio (β). A fi lter’s Beta ratio relates to the fi lter effi ciency through Equation 1.8.

%Efficiency = − ×bb

1100 (1.8)

The Beta ratio is calculated based on Equation 1.9.

bxP x Upstream

P x Downstream= ( )

( ) (1.9)

βx Beta ratio for particles of size X= “ ”

P Upstream Number of particles of size X upstream of tx( ) = “ ” hhe filter.

P Downstream Number of particles of size downstream x( ) = “X” oof the filter

ExampleA retention test is run. A fi lter retained 3,000 of 9,000 initial particles.

b = =9 000

3 0003

,

,

The Beta ratio is 3.

% %Efficiency = − × =3 1

3100 67

The fi lter’s effi ciency in this instance is 67%.

Introduction 17

A fi lter will have a Beta ratio at each pore size rating, and it is important to assess the entire range. Be wary if only a single Beta ratio or effi ciency is presented. Challenge and retention tests are often used to convey a message that is incorrect. Table 1.1 illustrates some theo-retical retention test data.

One could legitimately make the following statements regarding the challenge test presented in Table 1.1:

• The fi lter has a 92% effi ciency at 0.22 μm and above.• The fi lter has 97% effi ciency at 0.45 μm and above (considered

absolute by some).• The fi lter has 60% removal effi ciency of 0.45 μm particles.• The fi lter has absolute retention at 1.0 μm and above.• The fi lter has zero retention at 0.22 μm.

By contrasting the fi rst and last statements, it is easy to see how chal-lenge test data can be used misleadingly. In looking at the actual data, it is clear that no particles are being retained at 0.22 μm, and that only 60% of the particles are retained at 0.45 μm. There are instances similar to this in beverage industry documents. Actual data can be even more diffi cult to decipher and misleading, as there will not be 100 particles, but many thousands in some instances. Most manufacturers will have this data to provide. Depth-style fi lters are much more sus-ceptible to this type of “creative marketing” than are membranes, but there is no standard set of rules when dealing with any fi lter.

Table 1.1. Example removal effi ciency test data.

Particle pore size (μm) Initial particles Ending particles

Removal effi ciency at pore size

0.22 5 5 0.00%0.45 5 2 60.00%0.65 10 1 90.00%1.0 10 0 100.00%2.0 10 0 100.00%3.0 10 0 100.00%5.0 50 0 100.00%

Total 100 8 92.00%


General Filter Structure

Depth fi lter media is a random porous structure that retains particles as they pass through the tortuous and irregular fl ow paths. A magnifi ed image of this type of structure is shown in Figure 1.5. The way this type of microfi ltration works is similar to the way a diatomaceous earth or sand fi lter operates. Sheet fi lters, lenticular fi lters, bag fi lters, and some cartridge fi lters function as depth fi lter media. Those cartridge fi lters that function predominantly as depth fi lters are typically of either a wrapped or wound format.

Cartridge fi lters may use non-membrane media that fi lter at the surface. These fi lters are made from materials similar to those used in depth fi lters and are constructed by laying multiple layers of fi lter media together on a support structure. The media is then pleated to increase surface area. Particles are usually retained at the surface of the media, but are also retained within the matrix of layers. They are more retentive than depth fi lters, less retentive than membrane fi lters, and have a dirt-holding capacity that is less than depth fi lters but greater than membrane fi lters. Table 1.2 shows the differences between the three types of cartridges.

A membrane fi lter is a thin layer of a regular, porous structure. This type of structure is shown in Figure 1.6. Membranes operate mainly at the fi lter surface and have less dirt-holding capacity than depth or non-

Figure 1.5. An SEM characteristic of depth media.

Introduction 19

membrane surface fi lters. Membrane fi lters can have absolute particle retention at a specifi ed pore size rating. Production-scale membranes are available in cartridge format and as the fi lter media used in cross-fl ow microfi ltration systems.

Beverage Contaminants

Particle sizes are expressed in terms of microns (micrometers, μm) for extremely fi ne fi ltration processes such as microfi ltration. One micron equates to 10−6 meters in length, or one millionth of a meter. This cor-responds to 0.00003937 inches. Common conversions are shown in Table 1.3. A human hair is about 100 microns in diameter. Microfi ltra-

Table 1.2. Cartridge fi lter media attributes.

Filter typePrimary removal location

Dirt-holding capacity Retention Cost

Depth Depth Highest Lowest LowestSurface

(non-membrane)Surface Medium Medium Medium

Membrane Surface Lowest Highest Highest

Figure 1.6. An SEM characteristic of membrane media.


tion is technically considered fi ltration in the 0.1 to 10 μm range but, in practice, is often thought of as dealing with particulates up to 100 μm. Generally speaking, particles under 100 μm will require some type of media fi ltration. Particles over 100 μm can be removed via screens or similar mechanisms. It is important to recognize the types and sizes of particulates and microorganisms when designing and running a microfi ltration process. Figure 1.7 is an example of a fi ltra-tion spectrum showing common materials relative to their pore size.

Microorganisms

There are many different microorganisms that can be present in bever-age products or process streams. A stable, safe product usually requires

Table 1.3. Comparative particle size conventions.

U.S mesh Inches Centimeters Microns (μm)

10 0.0787 0.1999 2000 12 0.0661 0.1679 1680 14 0.0555 0.1410 1410 16 0.0469 0.1191 1190 18 0.0394 0.1001 1000 20 0.0331 0.0841 841 25 0.0290 0.0737 707 30 0.0232 0.0589 565 35 0.0197 0.0500 500 40 0.0165 0.0419 420 45 0.0138 0.0351 354 50 0.0117 0.0297 297 60 0.0098 0.0249 250 70 0.0083 0.0211 210 80 0.0070 0.0178 177100 0.0059 0.0150 149120 0.0049 0.0124 125140 0.0041 0.0104 105170 0.0035 0.0089 88200 0.0029 0.0074 74230 0.0024 0.0061 63270 0.0021 0.0053 53325 0.0017 0.0043 44400 0.0015 0.0038 37

Introduction 21

the removal of these microorganisms. Producers of some beverage streams, such as highly alcoholic products, will not have to worry about microorganisms while others, such as producers of bottled water, must be very concerned with the health and quality aspects of incomplete removal. The microbial concerns for wineries and breweries are typi-cally related more to shelf life than to health concerns. These concerns are equally as important to address.

ProtozoaProtozoa are single-celled eukaryotes. The word protozoa comes from the Greek for “fi rst animals.” Protozoa are sometimes classifi ed with animals based on certain characteristics. They can also be classifi ed with certain algae and molds, or even be considered to be their own kingdom. Protozoa are usually quite large (Table 1.4) in comparison to most microbial contaminants found in beverages, and as such they are easily removed. The two most common protozoa of concern are Cryptosporidium and Giardia; images of these are shown in Figure 1.8.

Failure to remove these organisms from susceptible beverages, such as bottled water, can be fatal to the consumer. Outbreaks within both bottled and drinking water supplies have led to several guidelines being

100 µm 10 µm 1.0 µm 0.1 µm 0.01 µm

Yeast

Bacteria

Human Hair

Virus

Pollen

Red Blood Cells

Colloidal Silica

Smallest Visible Particle

Gelatin

Crypto

Diatomaceous Earth

Giardia

Tobacco Smoke

Figure 1.7. Filtration spectrum of common materials.


developed for the removal and/or elimination of dangerous protozoa. The relative diffi culty in detecting Cryptosporidium and Giardia, and their resistance to some chemicals, has made the use of fi ltration a common recommendation for ensuring product safety. Despite their larger pore size, a 1.0 μm absolute rated fi lter, often a membrane, is recommended for the complete removal of Cryptosporidium and Giardia.

Cryptosporidium and Giardia are typically found in surface waters or waters that have been exposed to the outdoors environment; they are not found in spring or mineral sources unless there has been some type of contamination or the water is subject to runoff or open-air collecting.

Mold and FungiFungi are eukaryotic organisms, and mold is a form of fungus. There are thousands of types of molds and even more types of fungi. Most species are fairly large with respect to beverage microfi ltration. The

Table 1.4. Cryptosporidium and Giardia sizes.

Protozoa Size (μm)

Cryptosporidium parvum 4–6Giardia lamblia 8–12

Cryptosporidiumparvum

Giardia lamblia

Figure 1.8. Cryptosporidium and Giardia are hazardous microorganisms found in water. Photo Credit: H.D.A. Lindquist, U.S. EPA.

Introduction 23

typical particle size is larger than 3 μm. Although some species are in the 1–2 μm range, some are bigger than 10–15 μm.

Mold and fungi are commonly introduced to many beverages by way of product packaging materials, such as containers or closures. This can make fi ltration of the liquid product ineffective at completely ensuring fi nal packaged product quality. Water used to rinse corks, caps, bottles, and so forth should be rinsed with water that has either been fi ltered or dosed with a chemical agent.

It is common for quality-control personnel to immediately look at the fi ltration train when microbes are present in the fi nal bottled product. Rather, the entire operation and all fi nal components should be assessed from the beginning to ensure total quality.

AlgaeAlgae may be broken into two groups; prokaryotic and eukaryotic. The only prokaryotic algae, blue-green algae, are actually more accurately represented as a division of bacteria. The correct name for blue-green algae is Cyanobacteria. The classifi cation confusion results from the fact that Cyanobacteria derive their energy from photosynthesis, just as plants do. Eukaryotic algae have many different forms, ranging from mono-cellular organisms to complex multi-cellular organisms such as seaweeds and kelps. Forms of eukaryotic algae include red, brown, green, glaucophytes, euglenids, chlorarachniophytes, chromista, and dinofl agellates.

Algal blooms can be troublesome in some processes, particularly with bottled water, or when contaminated water is untreated and added to a susceptible product. Many municipal water supplies have frequent algae issues, but most beverage processing plants and facilities never develop problems with algae. Generally speaking, those plants with frequent algae problems must enact countermeasures against them and be prepared for periodic, or sometimes frequent, incidents. Plants that have no history of algae problems will not likely develop them unless there is a signifi cant process or supply change. In addition to being susceptible to UV, algae can be removed via microfi ltration. A 1.0 μm absolute fi lter will certainly remove any algae that may be present. Large-micron depth fi lters in the 2–5 μm nominal range are also effec-tive at algae removal but can present problems related to grow-through and contaminant unloading if not properly maintained. For a plant trying to control algae, it is best to do so as far upstream as possible.


Filters should be located at the product or component entry point into the plant to avoid algae contamination and growth in other equipment such as RO fi lters or carbon towers.

Microfi ltration or some rough form of particulate removal prior to a UV stage helps to improve the UV performance. This is because the particulate matter in the stream absorbs some of the UV light and can shield the microorganisms.

YeastYeasts are technically fungi, as are molds, mushrooms, and comparable organisms. For the purposes of beverage microfi ltration, yeasts are largely thought of as a separate grouping of contaminants. This is par-tially because yeasts are among the smallest fungi, so their removal typically requires a specifi c fi lter selection. Yeasts are considered unique because of their signifi cant presence in many processes. Yeasts are an essential component to fermented beverages and can be present in huge quantities both in the product and in the general production facility in such places as hoses, product lines, drains, and so forth.

There are many different types of yeast relevant to the beverage industry. Many of the strains and genera are closely related to one another, with some being hybrids of others. In addition to the yeast strains that are either naturally present or are intentionally added, there are many strains that can be incidentally introduced and are harmful to the consumer or product. Some yeasts are considered pathogenic. The manner by which yeasts are classifi ed is shown in Figure 1.9.

The family Saccharomycetaceae contains 24 genera. Three genera stand out with regard to beverage processing, especially with fer-mented beverages:

• Saccharomyces• Dekkera (Brettanomyces)• Zygosaccharomyces

The genus of Saccharomyces contains nearly two dozen different species of Saccharomyces strains. Several are important to the bever-age industry. Saccharomyces cerevisiae are oval shaped and about 5–10 μm in diameter. It is the most common strain used industrially and is used to make beer, wine, and bread. In beer fermentation, it is nor-mally used to make ale and stout and is considered “top” fermenting

Introduction 25

yeast for the manner in which it separates within the fermentation tank. Saccharomyces uvarum is closely related to Saccharomyces cerevisiae. It is used in the fermentation of some lagers and is called a “bottom” fermenting yeast due to the way in which the yeast settles to the bottom of the tank after the fermentation process is complete. Saccharomyces pastorianus is another bottom-fermenting lager yeast. Saccharomyces bayanus is yet another species within the Saccharomyces genus. It is commonly used for wine and cider fermentation.

Zygosaccharomyces is another genus within the Saccharomyceta-ceae family. It is a common spoilage-causing yeast within beverage processes. Zygosaccharomyces has a high tolerance for both alcohol and sugar and is able to withstand environments of 18% and 50–60%, respectively. It is also tolerant of sulfur dioxide, sorbic acid, and benzoic acid. There are about a dozen strains of Zygosaccharomyces.

Brettanomyces (as it is commonly known), formally called Dekkera, is another genus contained within the Saccharomycetaceae family. Brettanomyces has six strains and is considered both a favorable com-ponent and a spoilage mechanism within winemaking and brewing. Even when intentionally used during wine or beer production, it is usually kept at low quantities and fi ltration is often used to remove the yeast before too many sensory-altering compounds are produced. The recommended pore size ratings for various yeast removal applications are given in Table 1.5.

Family (Example: Saccharomycetaceae)

Genus (Example: Saccharomyces)

Species (Example: Saccharomyces

cerevisiae)

Figure 1.9. Yeast are classifi ed according to Family, Genus, and Species.


BacteriaBacteria are the most abundant form of life on the planet. There are many dozens of different species that can be found within agricultural and beverage processing. Some of the most relevant bacteria species are given in Table 1.6 along with the required membrane pore size for absolute-rated removal from a beverage stream.

Some bacteria are deliberately added to a process. Malolactic fer-mentation of wine is one such instance. Yogurt and cheese production, through the addition of lactobacillus species, is another common example. Industries that use bacteria within a process can encounter particularly diffi cult challenges in subsequent processing steps, when controlling those organisms can become critical. All bacteria can be removed through the use of a 0.22 μm membrane fi lter. Some indus-tries, such as wine and beer, fi nd that they only need to fi lter to 0.45 μm in order to remove bacteria of concern.

Table 1.5. Recommended membrane pore sizes for yeast removal.

Yeast Recommended Membrane Removal Size (μm)

Saccharomyces 0.65Zygosaccharomyces 0.65Brettanomyces 1.0

Table 1.6. Recommended membrane pore sizes for bacteria removal.

Bacteria Recommended membrane removal size (μm)

Brevundimonas diminuta 0.22Pseudomonas aeruginosa 0.22Bacteriophage 0.22Escherichia coli 0.45Leuconostoc oenos 0.45Pediococcus damnosus 0.45Lactobacillus hilgardii 0.45Oenococcus oeni 0.45Lactobacillus brevis 0.45

Introduction 27

Miscellaneous Organics

Various organic contaminants can be present in many streams. This is often true for products that are originally plant based, such as wine and beer. These organics are typically soft, deformable particles, which can be highly plugging in nature. They are much like microorganisms in that they are fairly easily removed from fi lters during cleaning and regeneration through the use of hot water and/or chemical treatments.

Plant-Based OrganicsThere are many plant-based organics that can cause membrane plug-ging or decreased product fi lterability. Pectins, a heterosaccharide found abundantly in wine and juices, are a common plugging agent. Pectinase additions can be used to mitigate their effects. Pectins are intentionally added to certain beverages, which increases viscosity and decreases the fi lterability of the product. Pectins may be precipitated out by adding certain tannins to the product. This is used in some processes in which pectins cause rapid plugging of fi lters. Lignin, often resulting from some aging processes, can be found on membrane fi lters in alcoholic beverage industries. This is not surprising for beverages aged in wood, since lignin comprises from 1/4 to 1/3 the dry mass of wood.

Carbohydrates can interact with materials present in a process stream to form a precipitate or to facilitate plugging. This is often observed in products such as wine coolers and premixed alcoholic beverages. Sugar crystals must be fi ltered from sugar syrup additions; sugar crystal fi ltering is the primary microfi ltration application in the soft drink industry. Glucans are a form of complex carbohydrate. Beta-Glucans are very problematic in beer fi ltration and often require the addition of beta-glucanase enzyme to either the beer stream being fi ltered or the fi lter housings during cleaning procedures. Cellulose is also a form of carbohydrate.

ProteinsProteins and protein hazes are common in many beverages. Oftentimes, these hazes are precipitated through interaction with other materials such as various ions or carbohydrates. Proteins and carbohydrates may interact to form effective plugging agents. Proteins may be present on fi lters as a result of microbiological activity. This is not always the case,


but the possibility should be understood when presented with a plug-ging component analysis. Chill hazes in beer are a result of the amount of high-mass proteins. The amount of chill hazes present in a product can therefore be linked all the way back to the grain selected for production.

Miscellaneous Inorganics

Inorganic contaminants are extremely diversifi ed and can range from sand to processing aids to the minerals present in water supplies.

Several processes, such as bottled water and soft drinks, use various fl occulents and coagulation agents for the pretreatment of water. These agents can be extremely effective plugging agents and can even rapidly block open pore size rated depth microfi lters. If it is necessary to use one of these materials, and microfi ltration is a downstream process, it may be necessary to fi rst fi lter through a different fi ltration mechanism such as a sand fi lter.

Diatomaceous Earth (DE)Diatomaceous earth (DE, kieselguhr, or diatomite) is one of the most common medias used for large-scale industrial beverage fi ltration. Beer processed on a large scale is clarifi ed almost exclusively on DE fi lters. Wineries and juice manufacturers are also heavy DE users. Diatomaceous earth consists of fossilized diatoms, which are ancient, hard-shelled algae. It is mined, then milled and graded for a particular application. DE used in beverage fi ltration is usually of a very fi ne grade in comparison to DE used for other applications. DE usage is being regulated increasingly across the world. The quality of world-wide DE is steadily decreasing as quantities are mined. These two issues have raised many concerns about the long-term use of DE fi ltra-tion in the beverage industry.

Facilities may use different grades of DE in their processes depend-ing on the starting product clarity and desired end product clarity. The particle size distribution for a common fi ltration grade DE is given in Table 1.7. The particle size distribution will shift slightly based on the grade of DE used and by manufacturer or mining location.

Introduction 29

It can be seen that DE has a wide range of particle sizes even within a single grade. Many trap fi lters for DE fi nes removal are in the 1–4 μm range; however, even high effi ciency trap fi ltration down to 1 μm can still allow some fi nes to progress downstream.

Carbon FinesCarbon fi nes can be a diffi cult problem for many beverage facilities. While removing color or contaminants from the product, the carbon itself can become a contaminant. Many facilities will microfi lter prior to bottling in order to remove carbon fi nes from the product. It is actu-ally more effi cient to locate the fi ltration directly after the carbon tank or carbon fi ltration step. This prevents a build-up of fi nes in the sub-sequent tanks and piping. The amount of carbon fi nes leaving a carbon tower will often increase after cleaning, particularly steam cleaning, and towers should be thoroughly fl ushed afterward. The majority of carbon particles will be sized in the hundreds of microns, but fi nes in the single-digit micron range can be present or generated.

Table 1.7. Size distribution for common fi ltration grade diatomaceous earth.

Typical medium-fi ne grade

Size (μm) Wt % below size

1 2 2 4 3 5 4 8 6 15 8 22 12 36 15* 50 24 65 32 75 48 87 65 92 96 97125 99200 100

* median particle size of 15 μm.


BentoniteBentonite is a fi ning agent most commonly used in wineries. Bentonite is an extremely effi cient plugging agent — so much so that it is one of the most common materials used by fi ltration companies to simulate fi lter plugging in their own studies. Bentonite starts as a dry powder but hydrates and swells to form a clay-like material. The material con-glomerates and, if used in a process, can bind to other materials, such as proteins. Bentonite conglomerations are typically large enough to plug any microfi ltration stage. Bentonite should be primarily removed via some mechanism such as centrifugation or DE clarifi cation. A plugging component analysis of plugged fi lters will determine if ben-tonite is causing premature fi lter blockage.

PerlitePerlite, shown in Figure 1.10, is an amorphous volcanic glass. It is used as a fi ltration media and fi lter aid in the beverage industry. Perlite par-ticles can serve as plugging agents to any downstream microfi ltration processes. Perlite is primarily composed of about 75% silicon dioxide and 15% aluminum dioxide. Several other oxides make up the balance. While most perlite is of a fairly large particle size, fi ne-grade perlite used for beverage fi ltration will typically have a median particle size of about 17 μm.

Figure 1.10. Perlite fi lter cake is used in many media fi ltration applications.

Introduction 31

Silt and SandSilt and sand, as well as any other general debris, is usually large in size. Nominal depth-type fi lters of an open rating should be used to remove such contaminants. Mechanical separation tools such as Y or basket strainers or mesh screens can be effective for removal before any microfi ltration stages. It is common for bottled water spring sources to have fi lters specifi cally for large debris removal located right at water entry to the pipeline or plant.

Silicates and CarbonatesSilicates and carbonates are usually introduced to the fi ltration process by untreated or poorly treated CIP (“cleaning-in-place”) or process water. These contaminants can be diffi cult to remove from fi lters, par-ticularly membranes. Some carbonates can be removed by a rinse with citric acid. If silicates and carbonates are present, the best course of action is usually to treat the service water before it reaches the process fi ltration stages. These contaminants do not necessarily have a pore size, as do other contaminants, but rather are deposited onto the fi lter’s surface or within the fi lter’s depth. Some of these molecules, such as calcium carbonate, can facilitate microorganism growth leading to the formation of colonies or biofi lms within the fi ltration system or the fi lter itself.

While not technically a contaminant, the water component of a beverage can plug the fi lter if it is cooled to a point at which partial freezing occurs. Beer, wine, coolers, and many specialty products are kept at a temperature just above freezing. An improper chiller set-point or other such problem can cause the fi ltration system to perform poorly due to ice build-up on the fi lter.

Plugging Component Analysis

Filter manufacturers and suppliers will sometimes offer a plugging component analysis as part of their services. Many will perform the testing for free for customers, within reason. Plugging component analysis can be useful for both process troubleshooting and new product and process development.


During the new product development phase, the types of plugging agents and contaminants can be determined and used to target the point(s) in a process where a fi ltration stage is needed. Plugging com-ponent analysis becomes more critical in new, untested applications or in complex products because component interactions can often lead to a decrease in fi lterability or product clarity.

The benefi ts of plugging component analysis as a troubleshooting tool are obvious. In determining what materials are present on the fi lter, the source of the materials can be pinpointed. For example, presence of carbon fi nes can indicate a problem in the carbon tower. DE present on the fi lter may indicate that a trap fi ltration stage is not functioning properly or, if no trap is present, a mesh screen (as in pressure leaf fi lters) might need repair. Component analysis can be used to determine seasonal or batch-to-batch product quality changes. An example is the decrease in fi lterability that results in many bottled water plants during the summer months when water levels are low, after extreme periods of rain, or in conjunction with the winter thaw in cold climates. There are three main plugging component analyses that are performed:

• Fourier Transform Infrared Analysis (FTIR)• Scanning Electron Microscopy (SEM)• Energy Dispersive X-Ray Spectroscopy (EDS)

Fourier Transform Infrared Analysis (FTIR)

Fourier Transform Infrared (FTIR) analysis takes a sample of material from the fi lter’s surface and analyzes the resulting spectrum. If analyz-ing a depth fi lter, sometimes a section of media is taken and soaked in ultra-pure water. The water is then fi ltered through a membrane and the membrane analyzed. Comparing the sample’s spectrum to libraries of known spectra allows determination of the materials that are present on or in the fi lter. FTIR works particularly well with organic materials. Most product streams have many components being removed by the fi ltration, so the sample spectra generated are typically combinations of several plugging agents. The technician performing the analysis should be able to compare the most relevant matches to determine the individual plugging agents in a mixture.

A proper analysis will take the process and product stream into consideration. Results from an FTIR test are not always straightforward

Introduction 33

and can require some refl ection. Yeast present on a fi lter’s surface, for example, will usually be presented as “protein” material by the FTIR analysis. An FTIR analysis would not be able to identify any particular yeast strain or even whether the protein was bacteria-related as opposed to yeast-related.

Scanning Electron Microscopy (SEM)

Scanning electron microscopy (SEM) involves magnifying the fi lter’s surface and observing any foreign materials that might be present. Various magnifi cations can be used to see the different-sized contami-nants. Specifi c microorganisms can sometimes be determined using SEM analysis. When SEM is used along with normal microscopy, general debris such as metal fragments, fi bers, or fi ne particulates can be identifi ed (Figure 1.11).

Energy Dispersive X-Ray Spectroscopy (EDS)

Energy dispersive x-ray spectroscopy (EDS) analysis (Figure 1.12) displays the elements present and their relative concentrations within a sample. It is effective for determining the presence of inorganic materials such as carbon, carbonates, and silicates.

Figure 1.11. Sample SEM analysis. Bacteria on a track-etched membrane.


An EDS analysis works by polarizing a semiconductor with a high voltage. When an x-ray photon hits the detector, electron hole pairs are created that drift due to the high voltage. The resulting electric charge is collected. Since the voltage of the condensator is proportionate to the energy of the photon, the energy spectrum can be determined.

The fi lter’s composition is incorporated into the test results, so it is important that the individual running the test knows what fi lter was used and what elements are the primary constituents of the fi lter. Peaks of carbon (C), oxygen (O), and fl uorine (F) are inherent to a PVDF fi lter, for example. Strong carbon, oxygen, and sulfur (S) peaks are a natural result of testing a PES membrane.

FDA CFR 21 Guidelines

The Federal Drug Administration (FDA) considers fi lters a direct food contact item. This is because the beverage passes through the fi lter. The FDA also considers fi lters an Indirect Food Additive in most situations. All wetted parts of the fi lter must therefore be compatible and approved for use by the FDA. Materials used in the construction of any fi lter components must also be approved.

The FDA guidelines relating to fi lters generally come from CFR 21 Sections 174 to 189. The FDA uses the term “food” indiscriminately to refer to all foods and beverages. The main section numbers and headings relevant to beverage fi ltration are listed in Table 1.8.

Figure 1.12. Sample EDS analysis.

Introduction 35

There are several important subsections, given in Table 1.9, that relate directly to fi lters or fi lter materials. Not all fi lter and fi lter com-ponent materials are listed in their own subsection. Materials may be listed under “Generally Recognized as Safe” or elsewhere. There are rare instances when there is a confl ict between different sections. The FDA itself, or other reliable source, should be contacted in this situa-tion. A searchable full-text listing of CFR 21 and its subsections can be found on the FDA’s website.

Table 1.8. FDA CFR 21 sections relating to fi lters and fi lter components.

Section Name

174 Indirect Food Additives. General175 Indirect Food Additives. Adhesives and Components of Coating176 Indirect Food Additives. Paper and Paperboard Components177 Indirect Food Additives. Polymers178 Indirect Food Additives. Adjuvants, Production Aids, and Sanitizers180 Food Additives Permitted in Food or in Contact with Food on an

Interim Basis Pending Additional Study182 Substances Generally Recognized as Safe184 Direct Food Substances Affi rmed as Generally Recognized as Safe186 Indirect Food Substances Affi rmed as Generally Recognized as Safe189 Substances Prohibited from use in Human Food

Table 1.9. FDA CFR 21 subsections.

Subsection Name Topic

176.1700 Components of paper and paperboard in contact with aqueous and fatty foods

Regenerated cellulose

177.1500 Nylon resins Nylon177.1520 Olefi n polymers Polypropylene and similar177.1550 Perfl uorocarbon resins PTFE177.2250 Filters, microporous polymeric Filter devices and materials177.2260 Filters, resin-bonded Filter devices and materials177.2440 Polyethersulfone resins PES177.2510 Polyvinylidene fl uoride resins PVDF177.2600 Rubber articles intended for

repeated useO-ring and gasket materials


Filters being specifi cally marketed to the beverage industry should always meet FDA guidelines. If a fi lter is being acquired from an un-reliable source or is usually used strictly in non-food and beverage industries, it may not be appropriate or approved for beverage process-ing. Filter manufacturers should be able to provide a letter stating that their products are FDA compliant. Manufacturers will often state com-pliance on fi lter datasheets or in the quality certifi cate mailed with the fi lter. Personal experience has shown that most compliance issues within the beverage industry typically involve one of the following:

• Using a fi lter not at all geared toward the food and beverage market.

• An overlooked component that may or may not be relevant, such as the bag the fi lter is shipped in.

• A chemical or component present in manufacturing that is not present in the fi nal shipped product.

Compliance is rarely an issue with top-level manufacturers who are meticulous on this issue. Filter companies whose products are used in the biopharmaceutical industry or who have a substantial presence in the biopharmaceutical industry tend to be more thorough and experi-enced with these regulations. This is due to the signifi cantly higher focus of the government and of end users in that market.

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Beverage Industry Microﬁ ltration COPYRIGHTED MATERIALThis guide is meant as a comprehensive guide and learning tool with regard to microﬁ ltration in the beverage industry. Processes