Ask The Brewmasters

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

Could it be microbial generation of CO?

https://www.sciencedirect.com/science/article/pii/S0048969725004954

As I'm sure you know, you are reading dangerous levels of CO;. IDLH = 1200 ppm.

IDLH is "Immediately dangerous to life and health" which is safety jargon for it can kill you right then and there. Venting it outside may not alleviate the issue.

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

------------------------------
Daniel Carey
Brewmaster
New Glarus Brewing Company
New Glarus WI
(608) 527-5850

Original Message:
Sent: 06-15-2025 22:43
From: Patrick McMahon
Subject: High CO Levels in Effluent Tank

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

------------------------------
Patrick McMahon
Head Brewer
Castle Danger Brewery
Two Harbors, MN
patrick@castledangerbrewery.com
218-830-0629
------------------------------

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers, 

Hello everyone,

Due to being a regional brewery in a rather small town, we have been collecting our brewery waste (brewhouse residuals, FV dumps, yeast, and hops) in a 60bbl effluent unitank. This waste is processed using a GEA CF 3000 decanter centrifuge and then pumped out to a 3000gal plastic holding tank outside to be picked up and shipped to a waste water treatment facility. This procedure has been in place since 2018 and has been problem free until now. 

Recently, we noticed an increase in CO levels around the brewery (50ppm+). After walked around the brewery with the CO meter, it was determined that the CO was coming from the 60bbl effluent unitank spray ball port which we do not cap and use as a simple vent. The meter maxed at 1500ppm. We used a Honeywell 4-point gas monitor to verify and it maxed at 2000ppm. We have been able to fix this issue by venting directly outside and are continuously monitoring the brewery. I am quite unfamiliar with CO production aside from it being mainly caused from incomplete combustion from vehicles such as our LP forklift. 

A quick google search yielded pyrolysis as a potential reason, but after speaking with the waste water facility, they said pyrolysis occurs around 500F. The side of the effluent tank is warm to the touch, more so than normal. Does anyone have any insight on what could be causing this CO production and how to mitigate it? 

Cheers,