Using Compounds Derived from the Glycerol Fermentation as a Carbon Source for Denitrification and Biological Phosphorus Removal

Biological nitrogen and phosphorus removal often requires an external carbon source to be effective during wastewater treatments. The purpose of this work was to evaluate a sequencing batch reactor (SBR) operated in a non-conventional anoxic/aerated (An/O) regime (alternated condition) treating synthetic wastewater simulating secondary anaerobic effluent mainly composed by P-phosphate and N-nitrate. The focus was to report the achieved biological efficiency removal of phosphorus and nitrate from the synthetic inlet when adding pre-fermented glycerol as the sole external carbon source. Experimental phase I aimed at the glycerol fermentation in batch reactors, leading to the formation of ethanol and volatile fatty acids. During experimental phase II, a non-acclimated (C1) and an acclimated biomass (C2) were used as inoculum of the SBR operated in the (An/O) regime. The anoxic phase was set to couple denitrification and P-release/uptake. The aerated phase was set to remove any remaining phosphorus. The fermented glycerol was applied in 15 gCOD g−1 N-NO3− and 29 gCOD g−1P-PO4−3 ratios in a sequential batch reactor during a non-aerated phase. This operation favored the development and maintenance of phosphorus-accumulating organisms (PAO), as well as denitrifying organisms, resulting in approximately 90 ± 11% and 98 ± 3% for phosphorus and nitrogen removal, respectively. The study showed that the fermented glycerol can be successfully applied as an electron donor for biological nitrogen and phosphorus removal during wastewater treatments.