Contribution of precipitated phosphates and acid-soluble polyphosphate to enhanced biological phosphate removal

Ecological Aspects of Biological Phosphorus Removal in Activated Sludge Systems

“…In fact, Nyren et al (1991) reported a proton-translocating pyrophosphatase in the photosynthetic bacterium Rhodospirillum rub rum. It would be interesting to see whether a proton-translocating poly-P synthase is involved in the synthesis of short-chain poly-P, which is found in the mutant of E. coli lacking PPK and in the sludge organisms that contain considerable amounts of lowmolecular-weight polyP (Mino et aI., 1985;Appeldoorn, 1992b). There is no evidence for this type of poly-P-synthesizing enzyme in A. johnsonii 21OA.…”

“…However, sludges well adapted to phosphorus removal (Appeldoorn et a!., 1992a;Smolders et a!., 1994) excrete Pi at a rate of about 60 nmole min-1 mg protein -1, assuming a protein content of the sludge of 50%, which is probably an overestimation. Measured over the first 60 min of the incubation period, poly-P-Ioaded cells of A. johnsonii 210Arelease Pi at a rate of only about 3 nmole min-1 mg protein-I, and at 15°C no Pi at all was excreted (Appeldoorn et a!., 1992b). The lower phosphate release rate in pure cultures might be related to a much lower content of the cultures in low-polymeric poly-P. One may speculate that the low-polymeric poly-P is much more accessible to the poly-P-degrading enzymes than the high polymeric poly-P, which is by far the predominant poly-P fraction in pure cultures of many acinetobacters (Appeldoorn et al, 1992b;Bonting, 1993).…”

Polyphosphate-dependent enzymes in some coryneform bacteria isolated from sewage sludge

“…In addition, this method [1] did not allow a clear separation of extracellular and intracellular phosphate fractions. Small bands of low polymeric polyphosphates could also be detected for isolates Nos.…”

“…Again, it should be pointed out that the overall process, often simply described as 'biological' phosphate removal from wastewater, is a complex combination of enzyme-mediated biological mechanisms (as reported here and elsewhere [1,4,12,22]), chemical mechanisms including phosphate adsorption at the outer membrane structures [4,20] of microorganisms and phosphate precipitation [1,2]. The exact 'biological' proportion is still to be investigated.…”

“…Appeldoorn et al [1] used cold perchloric acid to extract orthophosphates and low polymeric polyphosphates (LPP, chain length up to 20 residues); however, the latter fraction was calculated by the total phosphate minus the orthophosphate and was not characterized by chain lenght determination. In addition, this method [1] did not allow a clear separation of extracellular and intracellular phosphate fractions.…”