Sepra offers several technological solutions for milk debacterization, whey and proteins concentration, brine recovery and other liquid by-product coming from dairy industry.
Membrane filtration · Dairy industry
Separation by membrane filtration emerged in the early 1960s and, about twenty years later, became a technology used also within the dairy industry for a wide range of applications. Although the underlying principle is conceptually simple, the use of membrane filtration involves complex aspects, such as:
- technological expertise concerning both the product to be processed and the fractions resulting from separation;
- engineering solutions capable of achieving the expected industrial performance.
In recent years, membrane separation technologies have gained increasing ground and a growing range of applications in the dairy sector, both within the production cycle and in the management of by-products.
SEPRA provides a complete line of membrane elements for food-grade applications, used to concentrate, separate and purify across a vast range of applications.
Integrated management of process fluids and water
From water to water
Thanks to consolidated expertise across every area of fluid management, Sepra is able to oversee the entire water and process balance of a dairy plant, ensuring complete and integrated control of every operational stage.
Applications
Membrane separation processes by means of cross-flow filtration have been used for more than 20 years to treat food solutions of various kinds. Membrane processes, in fact, offer several distinctive features that are well suited to this type of product:
- High flexibility, thanks to the possibility of using membranes with pores of different sizes and elements of different construction
- Low energy demand
- Hygienic conditions and good microbiological control
- Mild mechanical and thermal stress on the product
The type of membrane used naturally depends on the objectives of the specific application. By acting on the membrane porosity it is possible to intervene selectively on the various components: the attached "Filtration Spectrum" table illustrates these possibilities.
In recent years, membrane separation technologies have seen a growing range of applications in the food sector, more specifically in the dairy industry. These techniques are used in aspects relating to the concentration of milk, whey and second whey, and therefore in the production of cheese and dairy products in general.
There are four main membrane separation processes, each specific in allowing the retention or permeation of particular components as they pass through the semipermeable membrane. Below are some applications of the technology in the dairy sector.
Milk debacterization, microfiltration
It is used today for the production of high-quality milk and long-life milk, where all properties are kept unaltered, as an alternative to traditional heat treatment, which modifies the organoleptic composition.
Fat removal from milk
It makes it possible to obtain high-quality, microbiologically pure milk with a low fat content.
Milk protein concentration
It is widely used to standardize the protein fraction in milk destined for cheesemaking, or to produce a concentrate with a high protein value.
Concentration of flush water
It makes it possible to recover and concentrate the residual milk fraction contained in the water at the end of the water displacement in the product transfer lines.
Purification of brines and curd-firming water
The solutions traditionally used to treat brines in dairy plants have low efficiency and present considerable drawbacks. As an alternative, membrane separation technology is therefore gaining ground today, with microfiltration and ultrafiltration systems that use spiral-wound elements.
Compared to traditional treatments, it makes it possible to eliminate the bacterial fraction and impurities while keeping the composition unaltered chemically, and also significantly reducing renewal operations.
Whey protein concentration (WPC)
A technology that enables the total recovery of the protein fraction and the concentration of the whey, which can be used in the production chain, for example to increase ricotta yield, or destined for the food and pharmaceutical market.
Ultrafiltration is an extremely effective method for achieving the concentration and standardization of the whey protein component.
On average, the production yields from whey previously concentrated by ultrafiltration, calculated on the basis of the quantity of raw whey used, and the material recoveries, are higher even up to 70%, reaching high recovery values (5-6 times).
Second whey protein concentration
The traditional process of transforming whey into ricotta entails significant losses of useful matter, in particular proteins of high biological value and, to a lesser extent, fat, which accumulate in the end-of-process whey (second whey). The extraction technique and the incomplete flocculation of whey proteins, under conventional process conditions, are the main causes.
Studies show that the recovery of useful matter in ricotta production increases significantly in relation to the degree of protein concentration in the whey, owing to the proteins' greater ability to form aggregates following the transformations induced by heat.
Concentration of whey, second whey, buttermilk and stretching water
The concentration of by-products deriving from milk processing is widely used for the reduction of volumes and, consequently, of the costs due to their transport for disposal, with, in addition, the possibility of reusing the water obtained within the plant or discharging it according to current regulations.
Concentrated whey is stable because the high sugar concentration blocks spontaneous fermentation, and it can therefore be stored and transported without special precautions.
Concentrated whey is an excellent ingredient for the formulation of complex feeds if suitably mixed, for example, with cereals or vegetable-oil extraction meals and, as such, it has a real market value and can therefore be considered a genuine product and no longer a waste to be disposed of from dairy processing.
Whey desalination
The high ash content in milk whey can negatively affect the flavor and nutritional quality of products. Reducing the saline component makes it possible to obtain a product of excellent quality.
Demineralization is commonly used for the pre-concentration of whey destined, for example, for the production of sweet whey powders, abundantly employed in the production of infant products or used in certain particular dietary regimes.
Lactose separation
Lactose is widely used in the food and pharmaceutical industries. With membrane filtration a pre-concentration is obtained.
During this operation a partial demineralization of the product is also obtained; it is known that the purity and yield in lactose production are higher when the mineral content present in the raw material is reduced.
And much more…
Polisher
The permeate coming from reverse osmosis or nanofiltration processes and the condensate from evaporators are practically water. With a further reverse osmosis treatment, this water can be further purified and reused within the plant.
Recovery of wash water
The water coming from processing in dairy industries concerns: plant washing (CIP), container washing, floor washing. Milk whey containing lactose, proteins and fats cannot be sent to the drain.
In the absence of a biological purifier, due to the high load of pollutants, a treatment by means of membrane plants is required, exploiting the multiple-barrier concept; each treatment stage is optimized for the removal of specific contaminants.
CIP disinfection with ozone
The use of ozonated water as the final rinse after CIP washing ensures a complete disinfection of pipes and tanks, eliminating the entire bacterial load without the use of chemical products, thereby also avoiding the risk of the formation of any potentially harmful by-products.
Whey debacterization with UV
Debacterization systems designed to reduce the bacterial load of whey destined for further transformation operations (concentration, protein separation, etc.). This technique proves particularly useful for preserving the quality of the whey.
Technical support
Sepra offers technical support of high added value, founded on the combination of three key competences: engineering, process and fouling management. This integration makes it possible to act on plants with a complete and performance-oriented approach.
- Engineering competences — In-depth knowledge of hydraulic dynamics, pumping systems, membranes and automation logic allows Sepra to analyze the behavior of plants with objective and quantifiable criteria. The technical intervention is not limited to solving the issue, but includes the evaluation of operating conditions and of the margins for improvement.
- Process competences — Sepra has a thorough knowledge of the specifics of the dairy process: fluid characteristics, seasonal variations, criticalities linked to milk composition, management of flows and of the concentration steps. This process vision makes it possible to optimize the plant not only from a mechanical standpoint, but above all in terms of product quality and production continuity.
- Fouling management — The extensive experience in membrane fouling allows Sepra to identify the main causes of performance decline, anticipate its evolution and define targeted prevention strategies. Through dedicated audits, performance monitoring and tests on pilot plants, cleaning solutions, operating settings and management strategies are identified that maximize the useful life of membranes and keep production efficiency constant.
The result
Truly complete technical support, capable of improving performance, process stability, product quality and operating costs, ensuring the dairy plant a more efficient and reliable management of the entire membrane system.
Cleaning of membrane filters
For membrane filtration in the dairy sector, fouling phenomena are well known and documented, caused by the accumulation of protein and fatty matrices on the surface and within the porosity of the membrane, which gradually inhibit its permeability.
The chemical/physical characteristics of the product (whey) sent for concentration, the operating conditions to be maintained during processing as required by the user, and the sensitivity of the operators managing the plant synergistically determine the rate of membrane fouling.
Detergents
Drawing on its own experience in the use of membranes in cross-flow filtration plants, SEPRA has developed a line of chemical products aimed at solving the specific problems that occur in them, such as fouling, scaling, bacterial contamination, sanitization and preservation.
Cleaning protocols
Through procedures for identifying the fouling present, SEPRA is able to develop the best cleaning procedures dedicated to the detergency of membrane filtration plants, to be implemented in order to ensure optimal productivity.
- Restoration of flow rates
- Maintenance of high-performing plants
- Economical
- Action against biofilm development
- Responsible choice
Integration of the enzymatic phase into the cleaning of membrane filters in the dairy sector
An enzyme is defined as a catalyst of a biological process; its role consists in facilitating reactions through the interaction between the substrate (the molecule or molecules taking part in the reaction) and its own active site (the part of the enzyme where the reactions take place), forming a complex. Once the reaction has occurred, the product is released from the enzyme, which remains available to start a new one.
The enzyme therefore essentially transforms organic matter irreversibly into smaller, water-soluble residues that are easily removed.
Depending on the type of substrate on which they act, they are grouped into different families; for example:
- Proteases → Hydrolytic action on the protein fraction
- Lipases → Hydrolytic action on the fatty fraction
- Amylases → Hydrolytic action on the sugar fraction
- Cellulases → Hydrolytic action on the fibrous fraction
For membrane filtration in the dairy sector, fouling phenomena are well known and documented, caused by the accumulation of protein and fatty matrices on the surface and within the porosity of the membrane, which gradually inhibit its permeability.
The chemical/physical characteristics of the product (whey) sent for concentration, the operating conditions to be maintained during processing as required by the user, and the sensitivity of the operators managing the plant synergistically determine the rate of membrane fouling.
It is therefore well known in the field that there is a need to integrate the traditional cleaning protocol, with alkaline and acid detergents, with at least one enzymatic phase, more or less intensive and frequent depending on what has just been described.
Water treatment for use and reuse in the dairy sector
The production activity of a dairy plant requires large quantities of water, used both for processing the product and for washing and disinfecting premises and equipment.
Falling within the category of food industries, the dairy company must use, for its production cycle, water intended for human consumption, which must necessarily meet certain quality requirements.
As an alternative to supply from the public network, the water resource can be sourced by drawing from surface or underground water bodies.
To ensure the potability of the drawn water, SEPRA is able to formulate proposals for specific treatments based essentially on the use of:
- Traditional filtration systems
- Membrane filtration systems (ultrafiltration and reverse osmosis)
- Disinfection and sanitization systems using UV sterilizers and the use of ozone
- Well water
- Surface water
Water purification in the dairy environment
Membrane bioreactors (MBR)
The activities of transforming milk into dairy products generate large quantities of residual liquids and wastewater.
Dairy wastewater is entirely free of toxic agents or inhibitors of bacterial activity, but due to its high organic content it is not always easy to treat in traditional purification plants. All this leads to difficulties in managing wastewater and often to the failure to meet the limits set by regulations for discharge.
Solutions promoted by SEPRA
Drawing on the experience gained in the field of wastewater treatment, Sepra proposes to approach the problem of wastewater purification with membrane technology.
Biological reactors derive from the coupling of traditional suspended-biomass processes with filtration processes on porous membranes.
Unlike traditional systems, which base their operating principle on the ability of certain bacterial strains to aggregate into settleable flocs, the use of MBR technology makes it possible to break free completely from the settleability characteristics of the biomass. This means a considerable reduction in tank volumes and therefore in the space required for the purifier.
The use of semipermeable membranes makes it possible to eliminate the sedimentation unit, ensuring a fixed and inviolable barrier capable of retaining suspended solids as well as bacteria and some viruses, ensuring an effluent of consistently very high quality.
Valorization of dairy by-products
Biogas
Milk whey is the main by-product of dairy activities. Although rich in many potentially valuable elements, in particular proteins and lactose, the fate of whey is uncertain and its effective valorization is still strongly limited.
Very often whey must be disposed of, and this represents a significant and hardly sustainable problem. This results in a point of criticality for this economic sector and a potential risk of aggravating the environmental impacts associated with it.
SEPRA proposes to address the issue of valorizing dairy by-products through their energy valorization (anaerobic digestion - AD).
In recent years, the market for the by-products of the dairy industry has not guaranteed a stable and sufficient income, owing to the absence of a collection and processing industry. On the contrary, the production of energy from by-products allows access to a system of incentives that gives the investment a long-term stability.
The environmental reasons concern mainly the management of the dairy plant's effluents. With the construction of an anaerobic digestion plant, the costly outsourced disposal of by-products and all the related transport will be eliminated. Moreover, the overall balance of carbon dioxide emissions from the plant turns out to be equal to zero, since what is emitted is what is absorbed by the biological cycle.
State-of-the-art technology…
The process is aimed at providing for the anaerobic treatment of by-products of milk whey or second whey (lactose), overcoming the problems that typically characterize the anaerobic digestion of such a substrate.
The treatment line proposed by SEPRA is reliable and sustainable, capable of ensuring the necessary energy valorization of the substrate in question, regardless of its concentration level.
The matrices to be subjected to digestion treatment are prepared at the dairy plant by means of membrane separation technologies, which make it possible to recover the protein component (ultrafiltration) and to concentrate the remaining fraction to the optimal value (nanofiltration/reverse osmosis).
Downstream of the anaerobic methanization section, the treatment line will include a tertiary MBR (membrane bioreactor) treatment unit with a tubular ultrafiltration membrane, designed to ensure the necessary retention of the biomass while at the same time carrying out a biological-type purification treatment, such as to ensure compliance with the discharge limits into a water body or into the public sewer system.
Pilot plants
The separation of particular compounds contained within a solution derived from an industrial process, the concentration or the clarification of solutions, can be facilitated by the use of new technologies, such as cross-flow membrane filtration systems, which make it possible to achieve excellent results while reducing working times and costs.
To develop a membrane filtration system on particular fluids, it is often necessary to carry out a feasibility study supported by a pilot test, which SEPRA conducts with qualified technicians able to manage the critical phases of the test.
- Laboratory tests and preliminary tests
- Chemical compatibility
- Evaluation of operating parameters
- Indicative scale-up
- Tests on a pilot system at an industrial plant
These tests allow the definitive evaluation of the process:
- Quantitative evaluation and economic definition of the industrial process
- Definition of fouling indices and forecasts of membrane lifespan
- Fine-tuning of cleaning cycles
| Plant | Application |
|---|---|
| LP spiral-wound polymeric plant | MF, UF |
| HP spiral-wound polymeric plant | NF, RO |
| Tubular ceramic plant | MF, UF |
| Ozone generator | Process |
| MBR | Wastewater |
| Spiral-wound polymeric plant | Wash water |
| Anaerobic digester + UF | Biogas |
Components
Drawing on collaboration with the leading national and international manufacturers, Sepra is able to supply all the components needed for the construction of new plants or the revamping of existing installations.
Ask for information On: Dairy Industry