DEVELOPMENT OF THE MICROBIAL COMMUNITY OF A FULL-SCALE BIOLOGICAL NUTRIENT REMOVAL ACTIVATED-SLUDGE PLANT DURING START-UP

The bacterial populations capable of accumulating polyphosphate in pur e culture were followed during the first 10 months of operation of a f ull scale biological nutrient removal plant with a modified U.C.T. con figuration. Special emphasis was placed on the Acinetobacter isolates obtained. Results showed that of these, most could be identified as A. johnsonii (genospecies 7) although other genospecies including 9 and 12 were also found in smaller numbers. A large number of these could n ot be identified with the Biolog system. Several other Gram positive a nd Gram negative bacterial genera capable of removing polyphosphate we re also isolated from the biomass. The filamentous bacterial populatio ns seen in the mixed liquor and foam were monitored regularly over thi s period, and after early changes, Microthrix parvicella and Eikelboom Types 0092 and 0041/0675 gradually assumed dominance in the mixed liq uor,while Nocardia amarae-like organisms and Type 0092 together with M . parvicella were in the foam.