SCREENING AND CHARACTERIZATION OF A NEW DENITRIFYING PHOSPHORUS-REMOVAL BACTERIUM

A new strain of denitrifying phosphorus-removal bacteria (DPB) CL-5 was isolated from sludge in the double sludge switching-sequencing batch reactor (DSSBR) which had been stably operated for two years. The strain contained metachromatic granules found in polyphosphate-accumulating organisms (PAOs) and was a denitrifier. From the phylogenetic analysis of the 16S rRNA gene sequence, CL-5 was identified as Paenibacillus lautus. The optimal temperature for its denitrification and phosphorus removal rate was 30 degrees C and the optimal pH was 7-8. The denitrifying gas product of CL-5 was N-2. Nitrogen removal was analyzed in relation to the NO3--N concentration. Under the initial concentration of 140mg/L NO3--N and 80mg/L PO43-, the efficiencies of nitrogen (N) and phosphorus (P) removal of CL-5 were 57.5% and 50.2% in the first 24 h, 72.3% and 64.1% in 96 h, respectively. Higher N and P removal efficiency and desired final gas production indicated that CL-5 could be applied to the wastewater treatment, especially for the high concentration of N and P wastewater.