The carbon source separation from fermented sewage sludge for stimulation of denitrification and bisphenol A removal

Since biodegradable carbon source was helpful for both denitrification and cometabolic biodegradation of synthetic organic compounds, the study attempted to obtain a novel liquid carbon source from alkaline hydrolysates of co-fermented sludge and food wastes (HFSF) for the stimulation of denitrification and bisphenol A (BPA) removal in the biofilm system. The biofilm with function of denitrification was cultivated from sequencing batch biofilm reactor, having abundant denitrifiers (Acinetobacter, Paracoccus, Comamonas, Hyphomicrobium, Flavobacterium, etc.). Appropriate addition of HFSF in the systems with mature biofilm could significantly enhance denitrification and BPA removal, while no positive relation occurred. Optimum performances (with denitrification rate of 1.68 mg (Lh)⁻¹, P_DN of 0.348 g N g⁻¹ COD, BPA removal rates of 87.8 ± 4.5%, and less than 100 mg L⁻¹ COD) were obtained at COD/N ratio of 6.0. Optimum HRT was 12 h to avoid nitrite and ammonium accumulation. Biofilm EPS increased as influent COD/N ratio raise from 2.0 to 6.0, which might be related with BPA removal.