Keeping Up With Wastewater Treatment – Odor Management Update
Doug Emerson, Environmental Affairs Manager
In the fall of 2015, I wrote about what has provided for a relatively non odorous 2015 summer. At that time we were in progress of cleaning out the anaerobic digester at our East Grand Forks plant. The photo below is what the inside of the digester looks like (without the cover). Prior to this photo, the digester was full of calcium carbonate that deposited in the tank over time. The volume taken up by those solids consumes treatment capacity.
Cleaning of the digester, among other things, allows American Crystal Sugar Company to reduce odor potential in our storage ponds by keeping high strength wastewater volumes low and moving water on through the system. Equally important is the ability to produce wastewater treatment plant effluent that is high quality and meets river discharge parameters to keep storage requirements/holding times to a minimum. We want to store as little water as possible to reduce and eliminate odors and/or hydrogen sulfide (H2S).
Did cleaning out the digester help? Absolutely! The chart below shows treatment plant discharge over the past few years. You can see that Chemical Oxygen Demand (COD) of waters going to our final storage ponds greatly improved this past year. Note this is not river discharge, we hold water in ponds until it meets all quality parameters prior to river discharge.