Blocked filters and screens are a regular draw on plant operators’ time, not to mention the production time lost. The solution lies in the evolution of the commonly used static filter into a self-cleaning filter. These are widely used in the food processing industry across Europe, with manufacturing sites typically installing multiple units once the benefits are seen.
The widespread use of static bag filters and strainers in the food and dairy processing industries for removing suspended solids from liquid flows remains an important processing step, but the fouled filter surface eventually needs to be cleaned.
Malcolm Frith, technical specialist, SC Filtration, says this is where self-cleaning filtration is being applied.
“An automatic self-cleaning filter is designed for applications that would otherwise use a standard wedgewire screen filter or a filter bag in a housing,” Frith says. “The difference is that periodically the filter surface is cleaned by rotating scrapers, and then the solids are discharged.”
The high uptake of these self-cleaning filters is largely due to the elimination of manual cleaning. Static filters require operators to physically clean a filter screen or change filter bags, which involves opening the filter housing – a job that operators never enjoy.
“Forward production flow can continue even during the cleaning step,” Frith says. “This removes the need to have a standby set of filters so that the plant may remain in production or pausing production while the filter is dealt with.”
The filtration equipment supplied by SC Filtration is manufactured by Elfi Filtration, an Italy-based specialist in self-cleaning filtration systems. Being European made provides assurance around quality standards, from materials of construction through to individual components. The sanitary construction of the Spiroclean filter is certified by MOCA, the European standard for materials in contact with food.
The Elfi Spiroclean self-cleaning filter has filter media that goes down to 50 microns. Often the self-cleaning filter is used as a pre-screening step before a finer filtration, or as a way to ensure consistent product properties.
Caustic recovery in dairy processing
One recent installation at a large New Zealand dairy factory was for removing impurities from a used caustic solution, before recovery and re-use of the caustic. The used caustic can pick up a relatively high level of total suspended solids during the cleaning operations.
“Having a self-cleaning filter means that plant operators do not need to open and clean a static filter, which is hazardous due to dealing with the chemicals held up in the housing,” Frith says.
The application highlights both the operational and safety advantages of removing manual intervention from the process. The ability to filter and recover caustic without exposing operators to the contents of the filter housing removes a known hazard, while also improving consistency in the recovery process.
Pre-filtration for whey processing
Dairy factories find significant benefit in using Spiroclean filters during whey processing, upstream of whey ultrafiltration plants. Removal of larger particles before the whey reaches the ultrafiltration system ensures that the membrane filter operates in the way it is intended – focusing on protein separation.
“Without effective pre-filtration, the ultrafiltration system is also removing debris, which reduces the effectiveness of the protein separation function,” Frith says. “Removing the larger particles upstream of the ultrafiltration system results in less fouling of the membrane and subsequently longer production runs.”
Not needing to open the filter housing for cleaning also means that there is no microbial risk from having an exposed point in the production process, which is particularly important in dairy applications.
This approach supports both product quality and operational efficiency, ensuring that the ultrafiltration stage is used for its intended purpose rather than compensating for upstream variability.
Beer clarification in brewing
In breweries, hygienic self-cleaning filters add value when they are used upstream of ultrafiltration. During the clarification step, a 50 micron self-cleaning filter removes larger debris such as yeast flocs or hop fragments.
This becomes particularly important when tank bottoms are being recovered, where solids loading is significantly higher. Removing these larger particles before further processing ensures more stable downstream performance and improved overall clarity.
The Elfi Spiroclean self-cleaning filter operates by introducing the feed flow into a cylindrical filtration chamber, where particulate matter is deposited on the surface of the filter media. When fouling causes the pressure drop across the filter surface to reach a pre-defined set point, rotating scrapers are automatically started.
“These rotating scrapers remove the particulates, transferring them to a discharge chamber at the base of the filter housing,” Frith says. “The solids are then discharged to drain without interrupting forward flow.”
A key benefit of this type of filter is that there is no interruption to forward production during the discharge step. Additionally, because the self-cleaning and discharge mechanism is fully automated, there is no additional workload or involvement required from plant operators.
Applications extend beyond dairy and brewing into areas such as fruit juice, oat milk, syrups and even cooling water, where consistent filtration supports stable processing conditions.
As the Spiroclean filter is a compact unit, it is an easy addition to existing plant. For this reason, it is often retrofitted into established processing lines.
“In any situation where there is a regular cleaning of a pre-filter screen or changing of filter bags, a self-cleaning filter should be considered. benefits in reducing the demand on plant operators’ time, avoiding production stoppages and, in some cases, avoiding risk for staff, make it a worthwhile investment.”
Sponsored content: For more information phone 0800 002304, email technical@selfcleaningfilters.co.nz or visit www.selfcleaningfilters.co.nz.
