Anaerobic uptake of different organic substrates by an enhanced biologicalphosphorus removal sludge

A stationary laboratory scale sequencing batch reactor (SBR) process for en hanced biological phosphorus removal (EBPR) was developed, and the anaerobi c 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 con tained 6.5% phosphorus. Two series of batch anaerobic experiments were cond ucted, using glucose and peptone (Series I) and acetate (Series 2) as carbo n sources, and different COD concentrations. High phosphorus release rates, when acetate was used, could indicate the presence of a pre-fermentation s tep in the anaerobic phase of the A/O process, The maximum phosphorus relea se obtained under anaerobic conditions was 57% of the total phosphorus slud ge content, that was reached using high COD concentrations. Metabolic mecha nisms of COD uptake, apart from the known PAOs metabolism, were detected wh en glucose and peptone were used. These mechanisms were inhibited when acet ate was used, probably because the microorganisms were not accustomed to ac etate.