EVIDENCE OF DECHLOROMONAS Sp. PARTICIPATING IN ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL (EBPR) IN A BENCH-SCALE AERATED-ANOXIC REACTOR

This study investigated the addition of small amounts of dissolved oxygen during the anaerobic stage of enhanced biological phosphorus removal (EBPR). Bench scale EBPR reactors were bubbled with N2 gas amended with 0.3%, 0.6% and 1.2% oxygen during the anaerobic period of operation. A phosphorus removal efficiency ranging from 84 to 95% was achieved depending upon the amounts of oxygen added during the anaerobic period. The microbial diversity in the reactors, monitored using fluorescent in situ hybridization (FISH), revealed enrichment of Rhodocyclus-related microorganisms. A finer scale analysis using 16S rRNA gene cloning and sequencing, showed that DECHLOROMONAS sp. instead of Cand. A. phosphatis were enriched under all three operational modes tested.