KINETICS OF ANAEROBIC ORTHOPHOSPHATE RELEASE AND SUBSTRATE UPTAKE IN ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL FROM SYNTHETIC WASTE-WATER

This paper presents some new results about the kinetics of orthophosph ate release and substrate uptake occurring under anaerobic conditions in a lab-scale activated sludge plant consisting of an anaerobic first and an aerobic second step (A/O-process). The synthetic wastewater co ntained acetate, peptone and yeast extract. The mixed culture was enri ched from activated sludge samples from a large-scale plant with enhan ced biological phosphorus removal. Anaerobic batch experiments were ca rried out with this enriched mixed culture using acetate as the only s ource for carbon and energy. In the first experiments, high acetate co ncentration was only partly consumed by the bacterial culture, resulti ng in a nearly total emptying of the poly-P-store (poly-P-limitation). In the next experiments, only a relatively low acetate concentration was added, resulting in a total acetate uptake and in partial emptying of the poly-P-store (acetate-limitation). This experimental strategy was successful in studying the complex kinetics of the anaerobic proce ss in enhanced phosphorus removal. Most of the calculated kinetic coef ficients depend on temperature; a dependence on pH cannot be postulate d with certainty. A comparison with known results shows conformity but also differences. (C) 1997 Elsevier Science Ltd.