Microbrewery Positions Itself for Growth with SUPRAdisc™ II Sheet-Based Modules

A microbrewery producing 1500-2000 hL per year had not used filtration in the past but needed to respond to consumer demand for a more visually clear, particle- and yeast-free premium craft beer. Beer from the fermentation step typically went to a maturation tank, where sedimentation took place over 4-6 weeks. From there, it went directly to the bright beer tank and carbonation before bottling. The microbrewery required an economically reasonable primary clarification installation providing high-quality beer to the bright tank.

The filtration installation at this small microbrewery is a cost-effective solution, which produces a consistently high quality beer with a desired shelf-life of six months

After the maturation tank, the result was a two-step SD II module installation to handle 10 hL/hour. With 16-inch diameter modules stacked in two-high Pall lenticular housings, the first step consists of a coarser sheet grade (SD II 700), followed by the second step with a finer sheet grade (SD II 200). A final polishing step was added before the bright beer tank, using Pall Precart PP II 1-micron pleated back flushable cartridges.

Pall SD II modules are available in a diameter of 287 mm/ 12 inch (1.8 m²/19.4 ft² filtration area) and 410 mm/16 inch (5 m²/53.8 ft² filtration area). They employ the same well-known filter sheet media, which has been proven over many years in the brewing industry. They capitalize on the excellent removal performance of the filter sheets while overcoming the marked disadvantages of filter presses. Modules are installed in enclosed housings, providing a hygienic solution without drip losses. They allow for the pressurization of beer with carbon dioxide from within the housings, resulting in higher yields. Additionally, there is no exposure to air or other environmental contaminants, and mould growth on the edges of sheet filters—common with traditional filter presses—is eliminated.

The SD II module sizing and service life are directly affected by beer filterability, which is influenced by the suspended solids load and the nature of the contaminants in the beer. Beer filterability is related to the length of sedimentation time in the maturation tank. Demand peaks in the summer, shortening the available sedimentation time, thus reducing the filterability of the beer.

There are two significant aspects of SD II design, which enable the best possible service life and an economical solution despite lower beer filterability.

• SD II 410 mm/16-inch diameter modules offer the highest filtration area among lenticulars in the industry, namely 5 m2 / 53.8 ft2, exceeding the closest commercially available ones by 28%.
• The ability to regenerate and reuse the modules is the other aspect that positively impacts service life.

The highly robust design of the SD II modules makes it possible to regenerate them by multiple forward and reverse flushing steps. With the use of special backflush devices, they can initially be backflushed with cool water at a maximum 0.5 bar (7.3 psid) differential pressure. This process helps to remove hop particulates, residues, yeast, and other particles from the surface. The initial rinse continues until the rinse water is free of foam. Following this, a forward flush with warm water, typically at 60 °C (140 °F), is performed to dissolve contaminants while avoiding trace proteins' denaturation, which could lead to premature module plugging. The effectiveness of the flushing can be monitored by checking the color or turbidity of the flushing water or measuring its conductivity. The procedure is completed with hot water or steam sanitization, followed by a cooling phase.

The brewery can prolong its service life and achieve high throughputs by regenerating the modules after every 1-2 batches ranging in size from 10-40 hL. Throughputs achieved with the SD II modules after 6 weeks of sedimentation range from 145 hL per module on the coarse (SD II 700) grade to 225-250 hL per module on the fine (SD II 200) grade. When running less than 4 weeks of sedimentation in the summer, throughputs are reduced by about 20% on the coarse grade and 10-16% on the fine grade. The filterability of the beer determines how often the modules are cleaned and regenerated.

Another feature that has proven economical for this microbrewery is the ability to reuse the modules for different types of beer. The modules can be stored for 4 to 6 weeks between uses. After cleaning and regeneration, they are steam sterilized or hot water sanitized, cooled, and stored under carbon dioxide-positive pressure in their housings until they are needed again. Before the subsequent use, they are sanitized once more.

SUPRAdisc II modules differ significantly from typical lenticular modules. Commonly available lenticular modules are designed according to a traditional stacked disc concept, in which the filter sheets are exposed and unprotected from reverse flow or back pressure shocks. On the other hand, the unique performance and robustness of SUPRAdisc II modules are due to its patented double separator design, which provides upstream and downstream support for the filter media. The media is individually sealed and separated between polypropylene flow distribution plates, resulting in optimal flow, higher throughput through the available surface area, and a mechanically robust module in both forward and reverse flow operation.