Sweetening Up the Process: Experiences with Corn Syrup at the Henrico County WRF

The purpose of this study was to evaluate a non-methanol carbon donor for enhanced denitrification in order to provide an effective means of nitrate reduction. A corn syrup waste product was evaluated at the Henrico County Water Reclamation Facility from August until December of 2006 and was resumed in May of 2007. The corn syrup waste, which is primarily glucose, was found to contain a significant and variable fraction of starch which is less effective in driving the denitrification reaction. Bench scale tests were undertaken to determine the denitrification rate of the corn syrup and compare it to the denitrification rate of pure simple sugars. The theoretical dose for corn syrup was found to be 7.4 lb corn syrup/lb NO3-N. Corn syrup was also added to the secondary anoxic zones of the HCWRF BNR basins for several months. During this time the effluent total nitrogen concentrations decreased consistently. The day to day variability in the plant effluent was reduced when corn syrup was used as a supplemental carbon source. The plant was able to successfully use corn syrup as a carbon donor to improve the denitrification performance of the facility. In May 2007, a more extensive full scale evaluation was renewed to better quantify the effect of corn syrup on secondary anoxic zone denitrification.