Total nitrogen removal is a bottleneck for achieving acceptable effluent quality for many municipal wastewater treatment plants (WWTPs). Inadequate denitrification is often the cause of insufficient total-nitrogen removal, and a deficiency of electron donor is a frequent cause. Soybean-processing wastewater (SPW) is potential electron donor. SWP contains electron donors to drive denitrification, but they are polymers that need to be hydrolyzed first. This work evaluated how bioaugmentation with a small amount of Rhodococcus ruber accelerated denitrification with soluble SWP. Compared with normal acclimated denitrifying biomass alone, addition of 0.45% (w/w) R. ruber accelerated the NO