Breweries make a lot of hot water. Brew kettles are often full of boiling water. CIP cycles throughout the brewery use hot water. It should be no surprise that the wastewater leaving a brewery tends to be hot as well. For years I used to heat an entire building in winter just with wastewater in an uninsulated tank (it was a 30,000 gal tank).
Ideally, all of this waste heat would be captured before going to the sewer, but this rarely happens. However I think if someone were to calculate the value of this waste heat and propose a use for it- such as heating a building or even a neighbors building, things would change quick.
Waste heat leaves a brewery in wastewater to sewer, side stream water going on fields, and in spent grain. Boiler exhaust is another source, but that’s another topic for another day. Side stream water is hot, I never really measured it because it didn’t matter operationally, but it probably averages 130 F or so. This will vary with each brewery, but you get the idea- it’s hot.
Water going down the floor drains (what I call low strength wastewater) is also hot, averaging about 120 F. I do have data to back this up, but it’s only for 1 brewery.
Spent grain probably shouldn’t even be discussed, it’s semi-solid and therefor hard to recapture any heat. But leaving the lauter tun it’s 150 F or so.
Anyway, why am I writing all of this? Some municipalities will implement an upper temperature limit for brewery wastewater discharge. I have 1 client who has a limit of 140 F. Seems reasonable. I wouldn’t worry too much if your brewery gets a similar limit unless its under 120 F. Wastewater cooling towers exist, but that sounds expensive, ugly, and stinky. I think the best strategies to use if you do get an upper temperature limit and your water does get too hot is to either store it until it cools, or add some cold water. It’s also not unheard of to start asking around. Where is this water coming from? Do they need to use so much water? Chances are there really isn’t a good reason and you just came up with a way to save the brewery money. While you’re at it, look around, are there other areas where you can save energy?