where to sterile filter?
I'm setting up our bottling line, and I'm looking for advice on where to do the sterile filtration. The beer will be filtered into the bright tank using a DE filter, carbonated, and from there to a 4-head Meheen filler. I want to pass the beer through a sheet filter with sterile sheets before it is bottled. Would it be better to put the sterile sheet filter in-line after the DE filter, or would it be better to put the sterile filter between the bright tank and the bottling line? I would first say the latter option is better, but I am worried about a big pressure drop across the filter causing foaming problems at the bottle filler. Anyone out there doing anything similar? If you are sterile-filtering your beer, where in the process do you do the sterile filtration?
sterile filter - bottling
because you are using a sheet filter you have no other choice then to put this filter prior to your bright beer tank, that is in line after the DE Filter and not infront of a filler!
Sheet Filter are highly pressure sensitive and will fail when you have a pressure bump during operation!
A different story would be if you were using a Membrane filter preferably with a frequency regulated pump!
You have to keep a close eye on the sizing of the sheet filter!
You can only run this filter at 1hl/sqm/h! So make sure your filter is large enough to handle the troughput!
Putting a membrane filter right infront of the filler gives you a better sequrity, since it also catches possible contamination from your bright beer tank and the filler line.
I am guessing that the sterile filter being described is DE impregnated cellulose pads. If this is correct than you can place this before the filler and have the advantage that Peter mentioned. De impregnated pads are not pressure shock sensitive (as long as maximum pressure differential is not exceeded) nor flow stoppage sensitive. Only horizontal filters with DE dosing are.
I have used this type of arrangement in one brewery I worked at and foaming was not a problem (a shenck filter...now owned by Pall!) We didn't have foaming problems due to pressure drop across the filter but we also had a beer pump delivering the beer at elevated pressures. Consult with a filter rep who can suggest the surface area needed for your application.
One more thought. I believe the flow rates on a 4 head Maheen filler are pretty slow. That said, the filter design you described is hard to sterilize, hard to de-aerate and hard to fully flood with beer. These are more common in higher volume breweries where they value the much greater surface area as compared to other designs.
A more common application for small size sterile filtration is a polypropylene depth cartridge. These are cheaper, easy to clean/sanitize and much better on beer loss.
Hope that helps.
Hopefully to tie together the previous comments - suggest you use 2 cartridge filters in series immediately after your KG filter, the first being a 1 micro trap, to retain any particulate breakthrough from the DE filter (particularly DE if using a horizontal leaf or candle filter) followed by a 0.45 micron sterilising filter.
Follow the filter cartridge suppliers instructions for exact details of cleaning and sterilisation, normally a completely seperate process from DE filter cleaning / sterilisation. Again, the suppliers advice re sizing, cleaning schedules, performance validation should be followed closely for best results. These guys really do know what they are talking about.
Have a good look at the filter housing design, to ensure you are happy with the quality of the housings, ease of changing over cartridges etc. My experience is that the ring clamp sealing mechanism is less robust than the bolt down system, even if the latter is slightly more fiddly. Don't oversize your filters for longer life - it doesn't work normally as the cartridges tend to block up due to early blinding, and make sure your services can cope easily.
First I have to say that I respect everybody on this forum and it is not my attention to discredit anybody who puts his wisdom out there.
But lets be clear about the fact that you cannot put a sheet filter in front of a filler/keg machine or any other packaging equipment.
With a sheet filter you have a so-called unstable matrix that means there is no absolute barrier that can guarantee the removal of bacteria!
Sheet filters are made up of some DE as well as polymer fiber and other materials. The differential pressure is low (1-1.5 bar), which can easily occur during production cycles (beginning/end!!) and definitely during stops and start-ups!!
So, again to be clear about that don't use a sheet filter right in front of packaging equipment!!!!!
However Pall has a another version of a sheet filter system, the Supradisc System, which is less pressure sensitive compared to regular sheet filters, plus it is also a so called closed system which has many more positive side effects as well!!
With Horizontal DE Filters like with any other conventional DE System you have also an unstable matrix. However the horizontal filter has more security and is less pressure sensitive than vertical system especially candle type filters!!
About the foaming issue, foaming usually occurs when co2 is dissolved from beer due to pressure drop/loss, or when temp. Is too high (especially after filter sterilization and not enough cold-enough water have been applied!
And I don't even want to comment on the paragraph where Tbrew talks about sterilizing filter/filler with respect on how to do it, that's a process/operational issue and you should always follow the manual or supplier recommendations!
Than at last also one thing about cartridges/membrane filters,
It is imperative that you use absolute rated membranes only for sterile filtration (min.0.45 micrometer).
These are a great alternative and make sense also economically!
If you need more info on that get in touch with me!
Hey, at least give me credit for suggesting that a brewer should talk to a filter rep!
Thanks Peter for pointing out the limitations of the sheet filter. It is interesting that I have seen and used this application in breweries (some making large amounts of beer).
After a good look I found only two references to the issue of sterile sheet filters before packaging. One is in the MBAA Practical brewer which notes that for sterile sheet filters “Pressure shocking does not affect outlet turbidity, but it does allow the passage of microorganisms”. I’m not sure what the exact definition of pressure shocking is but I will accept that non-constant flow is “pressure shocking”.
The second is this journal article on a similar technology that you described (not encapsulated though) for sterile filtration before package lines.
So both back up your point.
My mistaken impression that these filters can be placed before fillers is due to plants I have worked at. I have worked for a brewery with this improper setup that was achieving a significant and consistent reduction in counts. So while apparently it was not a truly sterile operation it was effective at some level (sorry don’t have data to share). So as with anything knowing your limitations (in this case I wasn’t fully aware of them…thanks) and deciding the best course for your plant is the answer…oh and most importantly, always, always consult your favorite filter rep!
I know this is older but ...
You can sheet filter before bottling...
Sheet filtration after bright tank before bottling is a depth filtration and is used extensively to protect your membrane filters ( absolute filtration). It allows you to lessen the stress of potential loading the membrane will see and give longer life to your membrane filters.
It is never recommended to use a depth filter by its self before bottling and a membrane by itself can become prematurely blinded by any resudual materials.
Good luck and cheers!
Do you have a dedicated bottling tank? I worked at a brewery once where they DE filtered into serving tanks, and then ran whatever they wanted to bottle back through a sterile filter into the bottling tank. It worked great!