The effect of substrate composition on the nutrient removal potential of sequencing batch reactors

Experimental results suggest that sequencing batch reactors (SBR) are not e fficient for enhanced biological phosphorus removal from domestic sewage wi th low/medium organic carbon content when denitrification preferentially co mpetes for available carbon. Total COD is not a meaningful parameter to ref lect available substrate for N and P removal; COD fractionation and identif ication of the readily biodegradable COD fraction are required for an accur ate assessment of system performance. The degree of soluble COD removal in the non-aerated phase is observed to be much higher than what may be calcul ated from stoichiometric relationships for removal and P release, indicatin g the existence of competing mechanisms such as organic carbon storage by n on-polyP bacteria under anaerobic conditions.