OPTIMIZATION OF HETEROTROPHIC DENITRIFICATION USING GLYCEROL AS A SUSTAINABLE EXTERNAL CARBON SUBSTRATE

Nutrients removal from residential and industrial wastewaters are essential for environmental and public health protection. Removal of nutrients from wastewater can be achieved chemically or biologically. Biological nutrient removal (BNR) is a series of anaerobic, anoxic, and aerobic zones to provide conditions for the biomass to uptake the nitrogen and phosphorus species, and comes in different configurations such as A/O, A²O, and 5-stage Bardenpho^TM. However; BNR systems require a sufficient carbon source which most wastewaters lack. The goal of this study is to use a sustainable carbon source to optimize the 5-stage Bardenpho^TM biological nutrient removal (BNR) systems and reduce the chemical cost. The experiments were carried out using two pilot-scale 5-stage Bardenpho^TM biological nutrient removal (BNR) systems coupled with side-stream prefermenters. Glycerol, a biodiesel by-product, was used as a sustainable carbon source by direct addition or after fermentation. The results from both systems were beneficial to the BNR system and resulted in similar effluent quality. Both systems achieved complete denitrification and excellent phosphorus removal (82% - 89%). Co-fermentation of glycerol and primary solids resulted in a significant increase in the volatile fatty acids (VFAs) loading beyond the estimated results, but did not correlate to better behavior between the two pilots since both systems achieved complete denitrification.