Optimal growth conditions and nutrient removal characteristic of a denitrifying phosphorus-accumulating organism

A highly efficient, denitrifying and phosphorus-accumulating bacterial strain was isolated from the Xuzhou Water Operation Co., Ltd, sewage treatment plant. The strain contains ploy-P and PHB granules. It was identified as a Klebsiella sp. using 16S rDNA sequencing and physiological and biochemical analyses, and named as Klebsiella sp. N14. The growth of the strain and its capability of nutrient removal were affected by pH, temperature, and the carbon source. The optimal pH for growth and nutrient removal was 8, and the optimal temperature was 30 degrees C. Sodium acetate was identified as the best carbon source. The phosphorus (<-P) concentration in the culture supernatant resulting from aerobic training of N14 in synthetic wastewater for 24h decreased from 81 to 12.4mg/L. The phosphorus removal rate was 84.69%. The nitrate (-N) concentration decreased from 180 to 15mg/L. The nitrite (-N) concentration decreased from 44 to 6.7mg/L. The denitrification rate was 87.94%. This study describes a novel denitrifying, phosphorus-accumulating bacterial strain, and the optimal conditions for nitrogen and phosphorus removal by this strain.