Enhance biological nitrogen and phosphorus removal in wastewater treatment process by adding food waste fermentation liquid as external carbon source

The problem of poor carbon source is a common technical bottleneck inhibiting the nutrients removal in biological wastewater treatment. This study aimed to investigate the feasibility of using food waste (FW) fermentation liquid (FL) as the external carbon source to enhance biological nitrogen and phosphorus removal (BNPR) in sequencing batch reactors. It was found that the ammonium nitrogen (NH₄-N) and phosphate (PO₄-P) in FL was not need to be removed before it was added into wastewater treatment system, and the added FL did not cause the external deterioration of NH₄-N and PO₄-P removal. The effect of volume ratio of FL to wastewater (FL/W) on BNPR process was investigated, and the results suggested the optimum ration of FL/W was 1/90. Compared to the control system with no acetic acid and FWFL as external carbon source, the experimental system with 1/90 of FL/W exhibited higher PO₄-P and NH₄-N removal efficiencies, which were 92.70 % and 92.38 %. Moreover, the analysis of this study suggested that the high removal rates of PO₄-P and NH₄-N were mainly attributed to the extra volatile fatty acid in added FWFL and the accumulated intracellular polyhydroxyalkanoates (PHAs) in anaerobic stage, which could be the main energy sources for the denitrification and PO₄-P removal.