Italian
A beverage production plant was using activated carbon treatment as part of its process-water system before the final filtration stages.
The downstream filtration line included polypropylene filter cartridges with progressively finer micron ratings. Under normal conditions, these cartridges were expected to operate for several weeks. However, the plant began experiencing unusually frequent cartridge replacement.
In some operating periods, the first-stage cartridges needed to be changed approximately every two weeks.
The customer initially suspected that the cartridge quality was the main problem. After reviewing the filtration process, however, the actual cause was found upstream.
The activated carbon vessel was releasing a certain amount of fine carbon particles into the downstream water.
These particles were relatively small, but the total contaminant load was high enough to rapidly block the polypropylene cartridges installed after the carbon tank.
As the cartridges became loaded, differential pressure increased and system flow gradually decreased.
Simply replacing the existing cartridges with a finer filter would not solve the problem. In fact, installing a finer cartridge at this position could cause even faster clogging.
The filtration system needed an additional stage specifically designed to capture the carbon fines before they reached the disposable polishing filters.
After evaluating the operating conditions, Pullner Filter recommended adding a 10 μm 316L stainless-steel pleated filter cartridge between the activated carbon vessel and the existing fine-filtration system.
The stainless-steel element was selected for three main reasons.
First, its pleated structure provided sufficient filtration area while maintaining relatively low flow resistance.
Second, 316L stainless steel offered good mechanical strength and corrosion resistance for the water-treatment environment.
Most importantly, the cartridge could be removed, cleaned, and reused instead of being discarded after each contamination cycle.
The original downstream polypropylene cartridges were retained as polishing filters.
The filtration sequence therefore changed from:
Activated Carbon → Disposable Fine Filters
to:
Activated Carbon → 10 μm Stainless-Steel Prefilter → Disposable Fine Filters
During the trial period, a visible amount of carbon residue was captured by the stainless-steel element before it could reach the downstream cartridges.
The customer reported that the pressure drop across the disposable filters increased more slowly than before.
As a result, the replacement interval of the downstream cartridges was extended, while cartridge consumption and maintenance frequency were reduced.
Another practical benefit was easier troubleshooting. When an abnormal amount of carbon was released from the activated carbon vessel, operators could inspect and clean the stainless-steel prefilter instead of immediately replacing several disposable cartridges.
The customer considered the modification more economical than continuously increasing the number of disposable cartridges.
They also preferred the reusable design because maintenance personnel could clean the stainless-steel element during scheduled service rather than replacing clogged cartridges frequently.
The project demonstrated an important filtration principle: when cartridges clog too quickly, the solution is not always a “better" cartridge. The first step should be identifying where the contaminant is coming from and whether the filtration stages are arranged correctly.
Activated carbon fines, rust, catalyst particles, resin fragments, and other upstream contaminants can significantly shorten filter cartridge life.
Adding an appropriate prefiltration stage can reduce contaminant loading on downstream filters, stabilize differential pressure, and lower long-term filtration costs.
Pullner Filter provides polypropylene filter cartridges, pleated membrane cartridges, stainless-steel filter elements, and customized industrial filtration solutions.