CHARACTERIZATION OF ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL ACTIVATED SLUDGES WITH DISSIMILAR PHOSPHORUS REMOVAL PERFORMANCES

A sequencing batch reactor (SBR) was operated for enhanced biological phosphorus removal (EBPR) and dramatic differences in the P removing c apabilities were obtained in different stages of the operation. At one stage extremely poor P removal occurred and it appeared that bacteria inhibiting P removal overwhelmed the reactor performance. Changes wer e made to the reactor operation and these led to the development of a sludge with high P removing capability. This latter sludge was analyse d by fluorescent in situ hybridisation [FISH) using a probe specific f or Acinetobacter. Very few cells were detected with this probe indicat ing that Acinetobacter played an insignificant role in the P removal o ccurring here. Analysis of the chemical transformations of three sludg es supported the biochemical pathways proposed for EBPR and non-EBPR s ystems in biological models. A change in operation that led to the imp roved P removal performance included permitting the pH to rise in the anaerobic periods of the SBR cycle. (C) 1998 IAWQ. Published by Elsevi er Science Ltd.