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St Austell's brewing director Roger Ryman and chief engineer Clive Nichols with Paul Weiden from Pentair

St Austell champions use of crossflow filtration

Crossflow filtration will become the most widely used filtering system in the British beer industry within 10 years.

That’s the confident prediction of Roger Ryman, brewing director at St Austell, following the installation of new equipment at the Cornish firm’s plant.

Pentair’s BMF +Flux Compact S4, the first crossflow system of its size in operation on the UK mainland, has attracted “a flurry of visitors” from other breweries to see it in action, he reported.

UK brewers traditionally use diatomaceous earth (DE) filters to clarify ‘bright’ beers for keg, bottle and can, but according to Ryman the method is already obsolete among cider and wine-markers.

“We’re being quite progressive here, and you have to ask why the brewing industry as a whole has been so slow to replace DE with crossflow filtering. There’s a conservatism, of course. People like to stick to tried and tested technology, and it's a big capital expenditure.

“The initial move has already come from macrobrewers. Carlsberg adopted crossflow several years ago. But it’s only within the last 12 months that this kind of equipment has been scaled down to our size.”

Kegged and bottled beers have grown to account for 45% of St Austell’s production, he said, totalling some 80,000 hectolitres of bright beer a year.

There have been concerns among brewers that beer is ‘too delicate’ for the technique, which clears the filter of trapped particles in a continuous process.

But Ryman has studied the impact in larger breweries, and trials on St Austell’s pilot kit have, to the contrary, brought improvements in beer quality.

They include a reduction in haze and dissolved O2, and the elimination of the risk of pick-up of a metallic taint from the diatomaceaous earth itself.

Another advantage with the four-module Pentair kit, which can handle 60 hectolitres an hour, is that the brewery no longer needs to centrifuge the beer to prepare it for filtration, meaning half the number of tanks is needed.

“The system is also highly automated, saving us time, labour and energy, and reducing the amount of CIP cleaning we have to do,” added Ryman.

There are health and safety and environmental benefits, too.

“Diatomaceous earth is the fossilised remains of microfauna. It’s a good medium but it’s messy and it can be harmful to operators, so it can be difficult to handle from a health and safety point of view.

“Then there is the cost of disposal - and the fact that, because DE is basically fossils, there’s a finite supply.”

Phil Mellows
23rd January 2018

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