Evaluation of Alternative Supplemental Carbon Sources at Four BNR Facilities

Supplemental carbon addition is often required to comply with low TN limits. Methanol is the most prevalent carbon donor for denitrification at wastewater treatment plants; however there are several promising carbon sources viewed as safer, more sustainable products including corn syrup waste and glycerin-based products derived from biodiesel production.The objective of this investigation is to establish whether glycerin and corn syrup are effective carbon sources for denitrification at wastewater treatment plants. Field and bench-scale data from four wastewater treatment facilities were compared to assess the performance of these products.Glycerin and corn syrup are effective supplemental carbon sources when applied to the postanoxic zones of biological nutrient removal processes and can reduce nitrate concentrations comparably to methanol. Limiting dissolved oxygen just upstream of the carbon addition point, proper mixing and effective zone partitioning are required to efficiently utilize these products. Full-scale design must account for these issues to effectively utilize alternative carbon sources.