HIGH FRUCTOSE CORN SYRUP AS A SUBSTRATE FOR DENITRIFICATION

An alternative substrate to methanol was sought for tertiary denitrification. High fructose corn syrup (HFCS) was identified as the most cost effective alternative, which would also be much safer to handle. This should also render HFCS subject to less legislation at all levels of government. A pilot scale test was conducted. The test confirmed that HFCS is a suitable substrate. A dose of 7.4 g HFCS/g nitrate-nitrogen (NO3-N) removed was achieved and effluent NO3-N was reduced from 8.1 to 3.3 mg/L. Excluding a period of upset conditions, the dose was 5.9 g HFCS/g NO3-N, and the reduction was from 8.8 to 2.7 mg/L. This compares to a theoretical dose of 4.2 g HFCS/g NO3-N based on stoichiometry and a typical methanol dose of 3 g/g NO3-N. Factors that may have contributed to the high dose include variability of the feed NO3-N concentration and occasionally insufficient NO3-N for the available substrate. A preliminary cost estimate indicated that the simple payback for a methanol dosing system would be between 5 and 17 years, depending on the actual HFCS dose.