BIOAUGMENTATION OF SEQUENCING BATCH REACTORS FOR BIOLOGICAL PHOSPHORUS REMOVAL - COMPARATIVE RIBOSOMAL-RNA SEQUENCE-ANALYSIS AND HYBRIDIZATION WITH OLIGONUCLEOTIDE PROBES

Four laboratory-scale sequencing batch reactors (SBRs) were operated t o evaluate whether bioaugmentation with Acinetobacter spp. can be used to improve start-up and performance of enhanced biological phosphorus removal (EBPR) systems. Two of the SBRs were bioaugmented during star t-up by adding pure cultures of Acinetobacter spp., the third reactor received an amendment of activated sludge from a laboratory-scale EBPR system, and the fourth reactor, receiving no amendment, served as a c ontrol. Various chemical parameters were measured to monitor the perfo rmance of the four SBRS. Oligonucleotide probes of nested phylogenetic specificity were designed to quantify the contribution of Acinetobact er to EBPR. The probes were characterized for use in quantitative memb rane hybridizations and fluorescent in situ hybridizations. Data from hybridizations with samples collected from the SBRs show declining lev els of Acinetobacter spp. over the experiment. All four reactors achie ved significant phosphorus removal and 90% nitrification after three d ays of operation. The results do not show a positive correlation betwe en levels of Acinetobacter and successful EBPR. (C) 1998 IAWQ. Publish ed by Elsevier Science Ltd.