Using nitrogen limitation to induce polyphosphate metabolism in engineered bioreactors Available to Purchase

Efforts to study enhanced biological phosphorus removal (EBPR) can be hampered by the initial start-up of the culture. A nitrogen limitation was used to select for polyphosphate-accumulating organisms (PAOs) in a mixed culture that did not previously exhibit EBPR characteristics or storage product accumulation. During nitrogen-limiting conditions, accumulation of polyhydroxyalkanoate (PHA) and carbohydrate (CH) was observed, and then the characteristics of polyphosphate metabolism were observed. When the anaerobic–aerobic reactor was operated with an influent COD/N ratio of 25, the PHA and glycogen content increased quickly. During this period, PHA ranged from 13% to 30%, and CH ranged from 10% to 18%, and after 12 d anaerobic P release was observed. Polyphosphate metabolism persisted even after the nitrogen limitation was removed. Storage product accumulation may have contributed to lower effluent total suspended solids (TSS), but it had virtually no effect on sludge volume index (SVI) or capillary suction time (CST). Key words: enhanced biological phosphorus removal, microbial storage products, nutrient limitation.