Any chlorine in brewing water?

[wholehop]

Is there an allowable threshhold for chlorine ppm in mash water? i assume most/ all are using an activated charcoal filter of some sort to remove chlorine but is .5 ppm acceptible. i make pretty consistent beer without a filter but was thinking of getting one . Do I need to? This number came from my water dept. Thanks guys

[liammckenna]

I would say no. Others may disagree on mash water, specifically (vs. sparge water or make-up water)

Chorine is very reactive with organics. It will easily form chlorophenols (and others like chloroform) These compounds can be flavour active in beer at the ppb level. Think medicinal, TCP, hospital, band-aid, plastic smell. It will react with various husk phenolic components pretty instantaneously to form some of these pretty powerfully flavoured chemicals.

If your beer is very hoppy it may be masked.

The best way to deal with is an appropriately sized (for desired flow rate) carbon filter(s). Ideally, you will backwash them regularly and test the outflowing water daily for residual total and free chlorine.

You can also deal with it by using a small amount of metabisulfite in your water if it's at a low level. you'd want to test this so as not to overdo it. If you're using either sodium or potassium form of SO2 it may significantly increase the levels of those ions in your brewing water (leading to subsequent flavour, yeast health and other changes). Yeast won't like the excess either.

Ascorbic acid can also work. Can't remember the chemistry. Not sure how much you'd need or flavour/other effects. Probably pretty safe method. It might have some pH effect. Yeast probably won't mind.

You can also boil the water first, or leave it hot over night in an open vessel. Not really practical though.

The other thing that carbon filters remove is chloramines. I'm not sure the other techniques mentioned above will deal with it. They probably do. UV also breaks down choramines. Some municipalities are replacing chlorine with chloramines. Can't remember why but I do know this: although they are much less flavour active in beer/wort than free chlorine, they will break down in an acid environment (like beer) to release free chlorine thus leading to previously mentioned flavour effects. Yeast don't like 'em either.

This is a pretty simple cheap test kit. Don't rely on your municipality for your chlorine analysis. It tends to spike on occasion. Virtually everywhere.

A few thoughts as I merrily ramble away from the question...

Pax.

Liam

[wholehop]

Liam, thank you for your input. Pretty much what i knew but it is great to have corroboration. Thanks again.

[WaterEng]

Chlorine removal is critical to avoiding off flavors in beer. The 0.5 ppm concentration that Wholehop mentions is not really a good goal. Considering that the typical chlorine residual in a water system is about 2 ppm, the potential for off flavors still exists. In addition, is that 0.5 ppm 'free chlorine' or 'total chlorine'? If the water system uses chloramination instead of chlorination, the free chlorine value will be very low and the total chlorine can be much higher. Its the total chlorine concentration that is important and it should be on the order of 0.2 ppm or less.

The sizing of carbon vessels depends on the flow rate your brewery needs. A good rule of thumb is for the vessel volume to be such that the volume divided by the flow rate gives a residence time of at least 10 minutes (ie. 100 gallon vessel / 10 gpm = 10 min). A residence time of less than this will end up costing you more in activated carbon replacement costs. That is something that the carbon suppliers won't tell you since having you waste more of your carbon is to their advantage.

I have to disagree with Liam on one point. Under NO CIRCUMSTANCE should anyone backwash a granulated carbon filter unit. If there is a problem with clogging, a prefilter should be employed. Backwashing jumbles the arrangement of spent carbon in the bed and you will get quicker contaminant breakthrough. That is another thing that the carbon suppliers will tell you to do, but again it is a ploy to get you to destroy your carbon bed and sell you more carbon. Properly sized carbon vessel(s) will have low flow rate through them and would not suffer from clogging effects and would never need to be backflushed.

One problem with proper design of a carbon system is that you will utilize much more of the capacity of the carbon bed before it is exhausted. But, when the bed goes, it will typically go all at once. You must have replacement carbon onsite at all times or an extra vessel so that you can just switch over. It is also a very good idea to have a sample port near the outlet of the bed so that you can monitor and test when the bed is getting exhausted.

I hope this is helpful. Please recognize that activated carbon suppliers do want to provide you with the best water quality, but they are also interested in moving more carbon. You need an unbiased engineer working with you on your water treatment system needs.

[banjolawyer]

A good rule of thumb is for the vessel volume to be such that the volume divided by the flow rate gives a residence time of at least 10 minutes (ie. 100 gallon vessel / 10 gpm = 10 min).

Can you explain what it means to have a residence time of 10 minutes? Thanks.

[wholehop]

thanks for all the advice from an unbiased water engineer. Much appreciated

[WaterEng]

Can you explain what it means to have a residence time of 10 minutes? Thanks.

This means that if the vessel that normally contains the activated carbon was emptied and you ran water in at your design flow rate, it would take 10 minutes to fill up.

Of course with the carbon media in the vessel, some of the volume is taken up by the carbon. The flow path through the media is reduced and the actual speed at which the water travels through the vessel increases and the 'true' residence time that the water contacts the carbon decreases.

But to get rid of the variable of the granular carbon (grain size, porosity, etc), we just size the vessel based on what we call "empty bed contact time". That is the 10 minute minimum that I suggest above. Longer contact time is even better, but your capital costs go up since you're buying a larger vessel (or vessels). Its a balancing act.

The carbon companies are more interested in enticing you with a teeny vessel that costs you less, but you'll end up paying for that decision over and over again since the higher flow speed over the carbon does not allow the carbon to effectively remove the contaminants before exiting the vessel. The contaminants 'smear' across the entire carbon bed at low concentrations and you'll see earlier contaminant breakthrough. When properly designed, the contaminants are deposited at much higher concentration into the front end of the bed and that wave of contamination progresses across the bed until it exits at the end of the bed. This ends up utilizing more of the carbon's adsorptive capacity to meet your treatment goals.

[NinkasiSwain]

So, for more background on the relationship of chlorination/chloramination to brewwater ... and various means of its removal, here's a 30-page article referenced in a Wiki on chloramine for a surprising section speaking specifically to chlorine/chloramine and brewing ... but that I cannot quickly locate in original form, peer-reviewed or otherwise. So take it for what it's worth:

http://ajdel.wetnewf.org:81/Brewing_...T_Chlorine.pdf

And to reiterate what Liam wrote, my (former) municipality had switched to using chloramines. And the numbers on the annual water quality report would accurately reflect this ... for 11 months of the year. But, to further speak to the spikes Liam references, every March is the annual "cleaning", when they're required by the state water authorities to stop introducing ammonia post-treatment, and (I think) pause the use of chloramines in favor of direct chlorination (I'd love some clarification on this, for anyone in the know ... also, if you could explain exactly what they're accomplishing yearly? Are they effectively "flushing" the lines? And what's this mean is coming as extra bonus through our tap one month per year?). This would cause significant changes in the taste/smell/daily variability for that month, and I would have to pay more attention that month to my water chemistry.

[WaterEng]

Chlorine is much more proficient in disinfection than chloramine, but chlorine reacts with organic compounds in water to produce carcinogenic trihalomethanes. Organic compounds are typically more prevalent in surface waters compared to groundwater. Therefore, if the water company's supply is from a surface water source, they are more likely to chloraminate. Relatively pristine surface water sources such as the Catskills Reservoirs for NYC and Hecht Hetchy Reservoir for the Bay Area of California are examples of systems that do not have high organic concentrations in their surface water supply.

In the spring, the concentration of organic compounds in surface water sources typically drop and water companies may elect to stop the ammonia feed and just disinfect with chlorine (chlorine + ammonia = chloramine). This provides a more intensive disinfection of the various components of the water system. The switch to chlorination is typically accompanied by a noticable increase in the chlorine odor from the water. Water companies typically notify their customers just prior to this changeover since it ellicits complaints. They do not typically notify the customer when they resume chloramination. They have to notify customers when they are converting to chloramination if they had always been chlorinating in the past. This is due to users like hospitals and dialysis centers being affected by the change.

[fa50driver]

As an interesting note - Our water is chlorinated to a level of .5 mg/l according to our water dept. We started brewing without using a filter and simply heated the water up in our kettle to about 180 and circulated it through the whirlpool. We would get a decent "aroma" of chlorine off gassing for the first 15 minutes and then it would diminish. Once it diminished, we would use that water to mash in with. Ditto for sparge water. We have brewed about 25 batches from light lagers to heavy stouts and have never had any off flavors from chlorine that I have been able to ascertain. Perhaps it is because our Chlorine level is pretty low to begin with. The cold water used to temper the mash water during dough in runs through a simple household carbon filter.

It may not be the optimum system for multiple batches, but it worked till we are able to get our carbon filter hooked up.

The chemist in the group may be able to provide some insight regarding time vs temp for chlorine removal.

[boatbeer]

I'm in the midst of setting up our new brewery. We've been brewing with our city water (3 ppm Cl) for six months now, and only recently had an issue of perceptible chlorphenol, so I'm looking for recommendations for a properly sized carbon filter. Our brewhouse is 15bbl, and we have a 30bbl HLT.

As an additional note - when I brought up the option of not carbon filtering our brew water with the equipment manufacturer, this was the response I got in regards to Chlorine effecting the life of the stainless vessels:

"The main problem will be with the Hot Liquor tank. The chlorine degasses when the water is heated and attacks the stainless above the water line. Over time the top half of the tank will look rusted and then may eventually fail."

Like I said - I'm looking for a filter now - and open to any suggestions. Manufacturer says I need flow of 30 gpm @ 50 psig

thanks,

Jesse

jesse@cartonbrewing.com

[gitchegumee]

I have to ask WaterEng how it is possible for a small brewery to have a charcoal filter with a 10 minute residence time. At least how without a cold liquor tank. I run a fairly typical brewery. We have a 10hl system that uses 12hl of water in 30 minutes during knockout. This is our highest water demand. If we were to have residence time of 10 minutes in our charcoal filter, it would be what, a 4hl filter? Seems very large compared to what I see in the industry. We do great with something on the order of maybe less than 1hl free space before adding the charcoal. And I think this swimming pool filter filled with charcoal is fairly standard in breweries up to 50hl. Doesn't the residence time depend on charcoal quality, chlorine loading, and maybe other factors as well? Our total chlorine is somewhere in the neighborhood of 1ppm at the tap. We make about 1000hl of beer a year using maybe 5-8x as much water. And we change the carbon in our filter once in 4 years. Not because we get contaminant breakout, but because it just seemed like we should. It's acid-washed coconut shell made specifically for beverage plants. Besides measuring total chlorine, is there something else I should be measuring to ascertain charcoal filter efficacy?

[liammckenna]

I'm pretty certain I don't have 10 minute residence time. Even though I think my carbon filter system is enormous.

We have twin carbon filter units. Each is about 2 m x .5 m. The most we demand out of this is full bore , 1", 60 PSI flow. Sorry for the mixed units (SI and Imperial). We do have a cold liquor tank for cool in only and a 10 hL system.

I've no idea what kind of flow this is. I do know this. There is no chlorine (free or total) in our brewing/rinsing water.

We just changed our carbon beds about 6 weeks ago. We managed 2.5 years before we started to show a trace on the total chlorine. Changing the bed was pretty painless for us.

Pax.

Liam

[WaterEng]

The 10 minute 'empty bed' residence time is only a good rule of thumb for improving the life cycle and performance of the carbon bed. The system will still remove contaminants if the residence time is less than that. The primary cost to the brewer is that they don't use most of the adsorptive capacity of the carbon bed. Its a trade-off...increased capital costs for larger vessels to improve the carbon life and have lower carbon replacment costs...or go for low capital costs with smaller vessels and then have higher carbon replacement costs.

If you don't have at least 5 minutes of 'empty bed' residence time in the vessel, you are definitely short-changing your carbon performance. That is a minimum that you should be checking for.

At 60 psi with a 1" PVC line that discharges to an open vessel, it would not deliver more than about 120 gpm. If there are many valves, restrictions, long lines, etc. then the max flow rate would drop.

As Liam points out, testing your treated water is an important requirement for activated carbon units.