Anaerobic uptake of different organic substrates by an enhanced biological phosphorus removal sludge

A stationary laboratory scale sequencing batch reactor (SBR) process for enhanced biological phosphorus removal (EBPR) was developed, and the anaerobic uptake of different organic substrates was studied in hatch experiments. The stationary process was developed using a synthetic waste,vater composed of glucose and peptone, and the excess sludge removed from the process contained 6.5% phosphorus. Two series of batch anaerobic experiments were conducted, using glucose and peptone (Series I) and acetate (Series 2) as carbon sources, and different COD concentrations. High phosphorus release rates, when acetate was used, could indicate the presence of a pre-fermentation step in the anaerobic phase of the A/O process, The maximum phosphorus release obtained under anaerobic conditions was 57% of the total phosphorus sludge content, that was reached using high COD concentrations. Metabolic mechanisms of COD uptake, apart from the known PAOs metabolism, were detected when glucose and peptone were used. These mechanisms were inhibited when acetate was used, probably because the microorganisms were not accustomed to acetate.