I am attaching a link that I think you will find very interesting. It is a copy of a Power Point handout, presented by Scott Koefod, Principal Scientist for Cargill Deicing Technology, for an APWA conference in 2009.
Scott points out that Ag-byproducts can reduce the freeze point of a deicer, but they don’t melt anything. They help as a corrosion inhibitor, give it viscosity to stick it to the pavement and equipment and granular deicers. But, it’s not the deicer that some claim. It is still about the amount of the active ingredient. Again, PNS states that suggested rates of an Agricultural Byproduct of 20% or more can greatly reduce the performance of your brine.
Best that you read it for yourself and draw your own conclusions. Comments always welcome.