Whey
A by-product of the Dairy Industry
Aidan Doyle,
Hugh Holland,
And Mark Naughton
Introduction to Whey
Whey or milk plasma is the liquid remaining after milk has been curdled and
strained; it is a by-product of the manufacture of cheese or casein and has several
commercial uses. Whey is used to produce ricotta and gjetost cheeses and is used to
make many other products for human consumption and as an animal feed. The whey
protein separated from this mixture is often sold as a nutritional supplement. In
addition, liquid whey contains lactose, vitamins, and minerals along with traces of fat.
Because there are many types of cheese, there are many types of whey; but they fall
into two major categories: sour/acid whey and sweet whey.
 Sweet whey. This is also termed cheese whey and is produced during cheesemaking, when rennet is used. Sweet whey forms a very large family of
products. Their compositions may vary only slightly but their properties are
very different. The pH value of sweet whey can range between 5.2 and 6.7
 Sour whey. This can be acid whey, quark or cottage-cheese whey and sour
sweet whey. Acid whey, also known as casein whey, originates from the
manufacture of casein by means of lactic acid and hydrochloric acid. The
origin of quark or cottage-cheese whey is self-explanatory. Lactic acid created
through natural fermentation gives the whey a high acidity. The pH values of
these types of whey range from 3.8 to 4.6. If insufficient care is given to the
cheese whey, it becomes sourer by continued natural fermentation. Such a
process is of course undesirable so that soured (not sour) whey cannot be
considered a natural product
Individual Whey Proteins
Whey does not have a constant composition. The concentrations of individual
proteins are affected by breed of cow, climate and weather, and stage of lactation. The
whey composition is somewhat influenced by the type of cheese being made, as well.
Carbery Group Ltd Whey Protein

b -lactoglobulin 50%

a -lactalbumin 20%

Immunoglobulins 20%

Serum Albumin 5%

Minor Proteins 5%
b -Lactoglobulin. This predominant whey protein naturally exists as a dimer
consisting of two identical monomer units, each having a molecular weight of 18,000.
It thus behaves like a protein with a MW of 36,000 and retains this form throughout
most milk processing and food applications. Most of the functionality of whey
products can be accurately predicted from studies of the pure b -lactoglobulin. Until
recently its purpose was completely unknown, and the protein is absent from the milk
of some species, including humans. Dairy scientists have now discovered that it binds
very strongly to retinol, the most important form of vitamin A in food and feeds, and
it is thought to play a significant role in the transport and absorption of vitamin A in
the intestinal tract.
a -Lactalbumin. This second most abundant whey protein has a molecular weight
of about 14,400 and interacts with b -lactoglobulin on denaturation to account for
virtually all of the whey protein functionality. By itself, a -lactalbumin is much more
readily heat-denatured than b -lactoglobulin, but it readily reverts to its native form
when the heat is removed. This led earlier researchers to report that it is very heatstable, based on their comparisons of its structure before and after heating. When both
a -lactalbumin and b -lactoglobulin are present, as they are in whey protein
concentrates and whey protein isolates, they form intermolecular crosslinks on
denaturation which stabilize the unfolded form of a -lactalbumin after the mixture is
cooled. It has been known for some time that a -lactalbumin plays an important part in
the enzymic process for synthesizing lactose in mammary tissue. One should not
confuse the specific protein, a -lactalbumin, with the commercial protein preparation
known as "lactalbumin" which is a heat-precipitated mixture of whey proteins.
Immunoglobulins. The immunoglobulins in whey are antibodies, of the types
IgA, IgG, IgE and IgM, with molecular weights of 150,000 to 450,000 or greater.
Some of them represent the normal antibody components of the cow and are the same
as those found in the bloodstream; however, there is a secretory form of IgA which is
produced in the mammary gland in response to infectious organisms. From a
physiological standpoint, the immunoglobulins are important in establishing the
infection-fighting capacity of the newborn calf, and they are present in very high
concentrations in the first milk of lactation, called colostrum. They are of high
nutritional value but do not appear to play an essential physiological role in the adult
animal or in the use of bovine milk or whey for human consumption.
Serum Albumin. As the name implies, serum albumin (also known as BSA)
comes from the cow’s bloodstream where it is the carrier of free fatty acids and is
important in maintaining the physical properties of the blood serum. It has a
molecular weight of 68,000 and is quite high in the amino acid cystine. Serum
albumin is present in the milks of all known species and apparently comes directly
from the bloodstream.
Minor Proteins. The least numerous 5% of the whey proteins are of many types,
which were often simply assigned to the category "proteose peptones" before the
individual components had been identified. Some of them represent breakdown
products of the caseins which were formed either before or during cheese making.
Others are specific enzymes or other proteins which have known physiological
functions. A few of these minor proteins are worthy of more detailed discussion here.
Glycomacropeptide is not normally tallied as part of the milk serum proteins
because it is not present until cheese is made, but it can potentially account for more
than 16% of the protein in commercial whey products. The cheese making process
involves treating milk with a proteolytic enzyme of the class known as rennet’s. These
enzymes break a specific peptide bond in k -casein between the phenylalanine at
position 105 and the methionine at position 106, which destabilizes the casein micelle
and allows the cheese curd to form. The part of k -casein consisting of amino acid
residues 1-105 is known as para-k -casein and stays with the cheese. The portion
consisting of residues 106-169 is released into the whey and is known as
glycomacropeptide (GMP) because it usually contains a number of carbohydrate
attachments (hence the "glyco-" term). Its molecular weight, based on its amino acid
content, is about 7,000; however, the carbohydrate units make it behave as if it were
somewhat larger. This is important because the ultrafiltration membranes used to
prepare whey protein concentrates and whey protein isolates perform their function
based on molecular size.
GMP was not recognized as a major whey protein for many years because of two
unusual characteristics. It contains no aromatic amino acids (phenylalanine, tyrosine
and tryptophan) so it does not absorb ultraviolet light at 280 nm, which is the most
common means of detecting proteins which are being analyzed by high-performance
liquid chromatography (HPLC). Furthermore, it does not readily bind Coomassie
Blue, the stain that is usually employed to detect individual protein bands on
polyacrylamide electrophoresis gels. Thus, GMP is rendered invisible in the most
powerful methods for studying protein mixtures unless special procedures are used to
detect it.
PROCESSING OF WHEY
Membrane Filtration
Membrane processing is a technique that permits concentration and separation
without the use of heat. Particles are separated on the basis of their molecular size and
shape with the use of pressure and specially designed semi-permeable membranes.
There are some fairly new developments in terms of commercial reality and is gaining
readily in its applications: There two main forms of membrane filtration involved in
the whey processing industry Ultrafiltration (UF) and Microfiltration (MF).
Ultrafilteration
Ultrafiltration (UF) designates a membrane separation process, driven by a
pressure gradient, in which the membrane fractionates components of a liquid as a
function of their solvated size and structure. The membrane configuration is usually
cross-flow. In UF, the membrane pore size is larger allowing some components to
pass through the pores with the water. It is a separation/ fractionation process using a
10,000 MW cutoff, 40 psig, and temperatures of 50-60°C with polysulfone
membranes. In UF milk, lactose and minerals pass in a 50% separation ratio; for
example, in the retentate would be 100% of fat, 100% of protein, 50% of lactose, and
50% of free minerals.
Diafiltration is a specialized type of ultrafiltration process in which the
retentate is diluted with water and re-ultrafiltered, to reduce the concentration of
soluble permeate components and increase further the concentration of retained
components.
Microfiltration
Microfiltration (MF) designates a membrane separation process similar to UF
but with even larger membrane pore size allowing particles in the range of 0.2 to 2
micrometers to pass through. The pressure used is generally lower than that of UF
process. The membrane configuration is usually cross-flow. MF is used in the dairy
industry for making low-heat sterile milk as proteins may pass through but bacteria do
not.
The most valuable component of whey is the whey proteins. Ultrafiltration and
diafiltration membrane technology have provided the means to further concentrate
and separate whey components. The protein and fat (retentate) in the whey are
separated from the lactose and minerals (permeate) by these processes. Once whey is
dried, a producer can provide "whey protein concentrates," or WPCs, with protein
levels from 34% to 90%.
Figure 1. The Whey filtration process
WPCs have been around for years, but product developers can expect better
performance today.
A higher quality product means improved functionality for the product
developer. Some of the basic properties that a WPC can provide in a food application
are whipping/foaming, emulsification, high solubility, gelation, water-binding, and
viscosity development. Generally, WPCs with higher protein content have improved
functionality over those with lower protein content.
Some very exciting work in progress involves the use of 34% WPC in various
food applications. This demonstrates their ability to work well in some applications,
but not in conflict with the applications designed for the higher protein ingredients.
High solubility over a wide pH range makes WPCs a good candidate for a sports
beverage or meal-replacement beverage. Their water-binding capabilities also make
them suitable for processed meats, cakes or breads.
Gelation characteristics will increase WPC benefits in some of the same
products that profit from water-binding. Salad dressings, coffee whiteners, soups,
cakes, infant formulas and sausages all can utilize the emulsification abilities of WPC.
They also address the functional needs of viscosity in products such as soups and
gravies. Cakes, desserts and whipped toppings can always use the added foam
stability of a WPC.
Whey protein conformation and functionality are interrelated and dictated by
changes in their globular folded structure. Their functional properties are affected by
several factors within a food application, including concentration, state of the whey
proteins, pH, ionic environment, (pre-) heat treatment and the presence of lipids.
In the native state, whey proteins are highly soluble and adeptly perform
emulsification and whipping functions in a food application. However, heating whey
proteins can result in a loss of solubility due to denaturation of the proteins, especially
in the pH range of 4.0 to 6.5. While solubility is adversely affected by heat,
emulsification can be improved through controlled heat denaturation of the protein.
As the whey protein unfolds, hydrophobic amino acid residues are exposed, which
enhance the ability of the protein to orient at the oil/water interface. The presence of
salts during the emulsification process influences whey protein conformation and
solubility. In their undenatured form, whey proteins can form rigid gels that hold
water and fat, and provide structural support. The formation of disulfide bonds and
ionic bonding controlled by calcium ions appears to determine gel structure.
Water-binding capacity is a measure of the amount of water held in a gel
under a specific set of conditions. The water-binding abilities of whey proteins can
help reduce formula costs due to the added water being held by the proteins. Other
properties associated with water-binding - swelling, gelation and viscosity - are
primary determinants of texture in processed cheese, yogurt and reduced-fat foods.
Whey proteins also contribute to browning by reacting with lactose and other
reducing sugars present in a formulation, providing color to baked goods and sauces.
Not only are WPCs functional, they also are bland-tasting and contribute no foreign or
off-flavors to foods when used as an ingredient.
The category of specialty WPCs includes demineralized and hydrolyzed
versions. The demineralized products are often used in infant formula, while lactose
hydrolyzed products work well in cheese-type spreads and yogurt. In this case, the
hydrolysis of the lactose into glucose and galactose allows for the addition of dairy
solids with some added sweetness to the product.
Research involving whey protein isolates, alpha-lactalbumin, betalactoglobulin, lactoferrin, bovine serum albumin, lactoperoxidase, peptides and
immunoglobulins has gained recent press attention. Research is currently in progress
on the use of whey protein concentrate in the diet and its anti-tumor effects for headand neck-cancer patients. Whey protein has been shown to stimulate cell-mediated
and humoral immunity; to have an antioxidant role by increasing tissue glutathione;
and to improve the body's nutritional status in stressed individuals, thereby inhibiting
growth of several tumor types.
Whey protein isolates (WPI) are those products with a protein content of over
90%. Various processes remove the nonprotein components. These include
precipitation, microfiltration and ion exchange. The composition (protein, lactose and
mineral content) and product characteristics can vary with the process used.
Whey protein isolates can also be manufactured by selective ion exchange
processes to select the primary functional proteins, beta-lactoglobulin and alphalactalbumin. They provide high gel strength, viscosity, aeration, water binding, and
high solubility to an application. In their pure form, they can be used to replace other
ingredients, such as soy protein, egg whites, or gelling agents. These isolates consist
of completely undenatured protein and also contain up to 10% to 12% biologically
active immunoglobulins.
Several whey protein fractions have been considered as dietary ingredients, with
potentially greater activity against the development of colon cancer than the total
whey protein product. Lactoferrin-supplemented diets have enhanced the protective
effect of total whey protein in animal studies relating to colon cancer. Clinical trials
with whey protein isolate have been conducted on children with AIDS. It has been
demonstrated that the ability of lymphocytes to offset oxidative damage is measured
by determining the capacity of these cells to regenerate glutathione. Patients in this
study who started with low blood-lymphocyte glutathione exhibited a substantial
increase in glutathione content after including whey protein isolate in the diet.
Several protein fractions display antimicrobial, as well as antiviral, activity. These
fractions include lactoferrin, lactoperoxidase, lysozyme and immunoglobulins.
Technology has been developed on a commercial scale to produce these proteins for
use as biopreservatives and as natural anti-infectious components for prophylactic and
therapeutic treatment of bacterial and viral diseases.
One fraction receiving a high level of interest for its nutraceutical properties is
lactoferrin. This iron-binding protein, in addition to its bacteriostatic properties, is
also associated with enhanced iron absorption, stimulation of bacterial gut organisms,
such as bifidobacteria, as well as a potential immune-stimulating role. It is one of the
principal whey proteins in human milk, present at a level of about 30% of total whey
proteins.
"Lactoferrin, as well as being an antioxidant, binds certain gastric pathogens
and is bactericidal against a variety of pathogenic bacteria and yeasts," he adds. "This
could lead to its use for treatment of intestinal ulcers and other gastric disorders.
Not all research has focused on fractions for purely physiological functions.
Currently, research is under way on the use of beta-lactoglobulin as a fat replacer in
meats. Licensed technology exists for producing heat-induced, beta-lactoglobulin gels
that resemble animal fat. Use of alpha-lactalbumin in infant formulas is becoming
more common as research attempts to get closer to the composition of human breast
milk. Alpha-lactalbumin also has been modified in attempts to perform some of the
same functionalities found in egg white and its application in angel food cake.
Lactose or milk sugar is in abundant supply due to increasing cheese production.
Lactose can be produced from whey or whey permeate. Its primary use is in bakery
and confectionery products. Similar to other components of milk or whey, interest
also has focused on the development and production of new lactose derivatives. The
current news concerning lactose focuses on its derivatives, the galactooligosaccharides. Commercially successful examples are lactitol and lactulose.
Lactitol is produced by the chemical hydrogenation of lactose. Lactulose is
produced by chemical isomerization of lactose. Galacto-oligosaccharides are an
important part of the functional foods trend as a factor in the well-being of the
digestive tract. Galacto-oligosaccharides are not digested or absorbed in the small
intestine, so they reach the colon where they are fermented by beneficial colon
bacteria, bifidobacteria.
Lactulose has a considerable influence in the medical treatment of some forms
of liver disease, and it aids and/or restores health after bouts of salmonellosis. When
used as a food ingredient to improve nutritional value, lactulose can be added to many
applications, without loss of functional or nutritional properties due to processing.
Some applications include: infant formulas or baby food; yogurt; diabetic sweetener;
sugar substitute in confectionery products; and dried and liquid nutritional
supplements for seniors.
As the nutraceutical market grows, consumers will be seeing more whey-derived
ingredients on their foods. A family of perhaps more obscure products that are derived
from whey, bacteriocins, comes from fermentation with lactic acid bacteria. Foodgrade bacteriocins are proteinaceous antimicrobial compounds with bactericidal or
bacteriostatic activity. Nisin A is one bacteriocin produced commercially and used as
a food preservative in processed cheese and canned foods to prevent growth of
clostridia and other pathogens. With demands for natural food additives increasing,
applied research is currently focused on producing, by economically viable means,
large amounts of bacteriocins for these applications. Other areas of research on whey
permeate have focused on its antioxidant activity in meat products.
Drying Of Whey
All types of whey can be spray-dried. Each, however, requires its own handling
techniques. Layouts for spray-dried whey can vary from the very simple to the
sophisticated. Generally speaking, sweet (cheese) whey is easier to dry than acid
whey. The main operations used for the manufacture of whey powder are as follows:







Preheating
Concentration
Flash cooling
Precrystallization
Spray drying
Cooling in a vibrated fluid bed
Spray Drying without Crystallization Treatment
Processing consists of preheating, concentration, spray drying and
pneumatic cooling. Ordinary whey powder obtained by this process is very fine,
dusty, hygroscopic and therefore caking. Hygroscopicity and caking are influenced by
the type of whey and by local climatic conditions. The hygroscopicity, caking and all
the problems associated with the stickiness of ordinary whey powder are mainly due
to lactose being present in an amorphous glassy state.
In the spray drying of milk products, lactose is in an amorphous state and is
not stable in atmospheric air or normal humidity. The only form of lactose that is
stable to humidity is a-lactose monohydrate. Since the lactose content of whey
powder comprises more than 70% of the total solids in comparison with 30% in whole
milk the problem of the lactose content in whey powder is more severe. However,
since the solubility of lactose is 17 g/100 cm3 H2O at 20°C, it is easy to guide the
drying process in such a way that a great part of the lactose can be transformed to the
stable a-lactose monohydrate form during the drying process.
Fig 2. Evaporator, crystallization tanks, and spray dryer with pneumatic conveying
system
Precrystallization and Crystalline Treatment
The basic process layout is modified by conducting a precrystallization before
spray drying. During the precrystallization process, it is easy to keep ideal conditions
for crystallization. Viscosity of the concentrate is reasonably low, temperatures may
be exactly adjusted and controlled, displacement of used solution from the surface of
crystals may be accelerated by agitation, and the required amount of suitable crystals
of lactose may be ensured by proper seeding. Furthermore, there is normally time
enough for the pre-crystallization process so reaching the theoretical degree of
crystallization at this stage is no problem. The product made by this process is noncaking and, being agglomerated, is dustless and free-flowing. The agglomerates tend
to be small and thus the bulk density is relatively high.
Fig 3. Whey crystallization tanks
The drying chamber with integrated fluid bed is fitted with pressure-release
vents and a fire-extinguishing system. Cyclone, bag filter and external vibrating fluid
bed have similar safety features. The cyclone(s) and bag filter may today be replaced
by a sanitary bag filter to improve operating costs.
CHOICE OF WHEY PROCESS
The choice of process depends upon the type of whey available, the intended
market for the whey powder and the plant location. The ability to handle sweet whey
and yet produce a non-caking product permits use of a simpler layout than if sour
whey is to be processed. If the dried powder is intended for dry powder mixes,
flowability is essential and the process must be equipped with crystallization and
cooling stages to ensure that this property is obtained. Local climate should also be
considered. If the climate is too humid, it is advisable to use a process that produces a
less hygroscopic product with low caking tendencies.
Fermentation of Whey to Ethanol (Case study on Carbery Group)
(Ethyl alcohol or grain alcohol) is a clear, colorless liquid with a
characteristic, agreeable odor. In dilute aqueous solution, it has a
somewhat sweet flavor, but in more concentrated solutions it has a
burning taste. Ethanol, CH3CH2OH, is an alcohol, a group of chemical
compounds whose molecules contain a hydroxyl group, -OH, bonded to a carbon
atom.
Ethanol Manufacture
whey, a by product of the casein manufacturing process, containing 4 percent
lactose, provides the sugar which is broken down into alcohol by lactose specific
yeasts. The lactose stream produced during whey ultrafiltration is pumped into one of
the eight fermentation vessels in the fermentation room. Yeast is added to each
fermentation vessel at the beginning of vessel filling. Conditions in each fermentation
vessel are set to enable the fast and efficient conversion of lactose to ethanol. The
fermentation process is complete in each vessel within 24 hours. The yeast used for
fermentation is recovered and reused a number of times before it is discarded. The
yeast is recovered at the end of the fermentation by settling and mechanical
clarification of the beer solution. At the end of fermentation the ethanol level is
between 3.5% v/v and 4.2% v/v.
Beer Still Distillation
Beer liquor is pumped to the beer wash column and the ethanol level is
concentrated at 96% v/v which is called feints. In addition to concentrating ethanol,
congeners i.e. alcohol like compounds are also removed from feints.
Alcohol Rectification
This is a 3 stage distillation process which removes the smallest levels of
impurities which results in the production of very clean neutral spirit. The 96% v/v
ethanol feints is diluted with water and pumped into the extractive distillation column.
Congeneric compounds miscible in ethanol, but immiscible in water are removed. The
main ethanol stream is pumped to the final rectification column to reconcentrate the
ethanol and remove the remaining impurities in the spirit. A number of side streams
are drawn from the final rectifies and fed to the heads concentration column.
Constant monitoring of spirit quality takes place. This involves laboratory analysis
including gas-liquid chromatography analysis and spirit tasting to ensure consistent
quality.
Alcohol Dehydration
Spirit which leaves the final distillation column is concentrated to 96% v/v.
However, over 30% of Carbery ethanol is sold at actual strength of 99.5% or greater
(anhydrous ethanol). Dehydration is achieved by passing 96.2% v/v ethanol (wet
ethanol) over a bed of molecular sieve beads. These beads contain tiny microscopic
pores which selectively remove water from the ethanol because of its smaller
molecule size compared with ethanol. The ethanol drying system comprises of a
double bed system which allows one bed to dry ethanol while moisture which has
been extracted from the ethanol is being removed from beads in the second bed.
Boru Vodka Manufacture
The main ingredients used in the manufacture of Boru Vodka, finished grain
spirit and Atlantic Irish Oak charcoal are prepared at West Cork Distillers Ltd.,
Finished grain spirit is distilled in small batches using pure spring water. Atlantic Irish
Oak charcoal is prepared using fallen oak from local woodlands. The wood is cut to
specific lengths and burned using a special procedure.
This milestone marked the culmination of 3 years research to develop a yeast
to efficiently convert lactose to ethanol. After a painstaking selection procedure a
strain of yeast from the Kluyveromyces fragili s family was successfully introduced
to the Carbery Lactose fermentation process. Production of ethanol has grown from
over 2,500,000 litres alcohol in 1980 to over 8,000,000 litres currently.
COMMERCIAL APPLICATION OF AN INNOVATIVE MEMBRANE
BIOREACTOR FOR WASTEWATER TREATMENT AT THE NBIA
INGREDIENTS LTD GLANBIA (Case Study)
The Ballyragget site is one of the largest milk and Whey Processing facilities
in the world. In 2000, almost 800 million litres of milk and almost 700 million litres
of Whey (equivalent to about 45,000t of milk solids) will be processed at Ballyragget.
The majority of the Whey will be processed as a co-product in the manufacture of
rennet and acid caseins and Cheddar cheese. The remainder will be sourced externally
from other cheese manufacturers.
The Ballyragget site has been subject to an environmental discharge licence
since 1977 and was the first dairy industry site in Ireland to be awarded an Integrated
Pollution Control (IPC) licence in December 1998. The environmental discharge and
emission values outlined in this licence, which are stringent, necessitated the
identification, assessment, procurement and deployment of advanced wastewater
treatment Technology to meet the imposed discharge limits during the 1999
manufacturing season. The advanced wastewater treatment Technology deployed was
a membrane bioreactor system (Kubota Corporation, Tokyo, Japan) not previously
used commercially in the dairy industry. The membrane bioreactor system was
deployed after technical discussions with Wessex Water Ltd, who had adopted this
system in 1998 at the Porlock sewage system in Somerset, England. The membrane
bioreactor system deployed at Ballyragget is a high-MLSS (mixed liquor suspended
solids) activated sludge process wherein 74 membrane (0.44mm pore size) treatment
units are submerged within extended activated sludge tanks. Typically, the effluent
feed is fed under gravity (1.0–1.5m head pressure) to the membrane bioreactor units,
and the activated sludge is maintained at an MLSS concentration of 15,000–20,000mg
l −1. The system has a minimum flow rate of 7200m 3per day. Flow rates of up to
9000m3per day have been achieved. The tight pore size has resulted in significant
improvement in the chemical and biological quality of the discharge stream, which in
turn has been correlated with improvement in the biological quality of the local
watercourse. In this regard, the proportion of daily discharges failing to meet the
licensed limits of 15mg l for suspended solids, 10mg l or biological oxygen demand
(BOD) and 0.6mg l for orthophosphates was reduced to nil (from 75%), nil (from
72%), and 13% (from 93%), respectively, during a 3-month study period in 2000,
compared with the same study period in 1999. Moreover, the discharge stream is now
of a higher quality than the receiving water to the site, thus providing an opportunity
for re-use/recycling. Research is ongoing to achieve this objective.
Technology and Pollution Prevention
Ever since the industrialization of cheese production, whey has in large
amounts been dumped into rivers, lakes or similar water reservoirs. However, as the
whey contains organic substances, oxygen is required for the decomposition, and
dumping of whey will therefore have a great influence on the environment. If the
dumping is of such a quantity that the decomposition requires all the oxygen available
in the water, all life will die followed by a putrefactive process. It is therefore obvious
that the amount of whey which can be dumped per hour depends on the amount of
oxygen available which is again determined by the amount of water per hour and its
content of oxygen. It is therefore difficult to state exact amounts of whey which may
be dumped. Under some IPC license it is required by the licensee to analyse and in
some cases peregrines the final whey before dumping. As a guide, the degree of
organic impurities in waste water is expressed by the requirement for oxygen for
biological decomposition in a 5 days' period, namely the so-called BOD5. Average
waste water from households will have a BOD5 of 300 mg oxygen per liter. With an
average amount of 200 liters per person per day it corresponds to 60 g oxygen, also
known as a person equivalent. For whey the BOD5 is approx. 60 g oxygen/litre, i.e. 1
litre of whey corresponds to 1 person.
Instead of cleaning the whey in special cleaning plants some dairies have disposed
of large quantities of whey by spray-irrigating it over the fields, which is an effective
method giving benefit both to the factory and to the farmer. The amount of whey per
hectare depends on the pasture and the rainfall. The irrigation is usually done in a
cycle with 14 days between each doze, which means there should be plenty of land
near the cheese factory (but at least 200 m from nearest habitation). The amount
which can be sprayed is about 7 m3/ha/day.
Membrane technology is widely used in pollution prevention because of disposal
cost and present and future regulations concerning groundwater, surface water, and
wastewater quality. Pressure driven membrane processes that include Micro-Filtration
(MF), Ultra-Filtration (UF), Nano-Filtration (NF), and Reverse Osmosis (RO) are
found to be reliable technologies for water and wastewater treatment. The pressure
driven processes can “separate, fractionate, and concentrate contaminants or processes
components
Three general categories for the applications of membrane technology in pollution
prevention are as follows.
 Process/Operation
 Water Purification
 Waste Treatment
Membrane-based separation is used to recover water and valuable materials from
different processes/operations in many industries including the Whey industries.
What are the benefits of membrane technology in pollution prevention?
Benefits of membrane technology include:
 Minimal temperature changes and chemical addition
 Operate in either continuous or batch modes
 Use significantly less energy than traditional separation processes
 Do not alter the chemical structure of the processed materials
 Easy to integrate into existing processes due to their modular nature and
compact size
What are the limitations of membrane technology?
 Membrane fouling
Fouling in membranes occurs because of metal oxides, precipitating salts,
suspended solids and colloids, and biological growth. The effects of fouling
can be minimized by “avoidance and remediation
Avoidance: An adequate pretreatment (coagulation/precipitation, or slow sand
filtration)
Remediation: Chemical cleaning by “acids, alkalines, oxidizers, detergents,
and organic solvents
 High investment cost as compared to conventional processes
 High energy consumption in RO as compared to other pressure driven
processes
References:
[1]
Bruggen, B.V., Vandecasteele, C., Gestel, T.V., Doyen, W. and Leysen, R.
(April 2003). “A Review of Pressure-Driven Processes in Wastewater Treatment and
Drinking Water Production.” J. Article American Institute of Chemical Engineers,
New York, N.Y., USA, 22(1), 46-54.
[2]
Postdoctoral Research Program U.S. EPA National Risk Management
Research Laboratory Cincinnati, Ohio, Project # NRMRL 2003-01
http://www.orau.gov/orise/edu/needs/NRMRL2003-01.pdf, accessed November 20,
2005.
[3]
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