SCREENING MICROORGANISMS FOR PHOSPHORUS REMOVAL IN SALINE WASTEWATERRAFITAH HASANAH, TSUYOSHI IMAI, ARIYO KANNO, TAKAYA HIGUCHI, MASAHIKO SEKINE AND KOICHI YAMAMOTOAbstract This study aimed at screening salt-tolerant phosphorus (P) accumulating organisms (PAOs) and investigating the P release and uptake of the organisms in saline wastewater. Batch experiments were conducted over 98 days in solutions with a salinity of 3.5% and P concentrations of 1, 5, 10, and 20 mg-P/L. The P-uptake ability of microorganisms increased by increasing P concentration from 1 to 20 mg-P/L. A high P removal percentage with an average of 85% was obtained at 10 mg- P/L after day 56. The uptake and release of P were observed in saline wastewater, signifying that salt-tolerant PAOs could grow in the saline solution. Bacterial screening by isolation and sequence analysis using 16S rRNA demonstrated that two cultivated strains, TR1 and MA3, had high similarity with Bacillus sp. and Thioclava sp. EIOx9, respectively.The colony morphology analysis showed that the colonies of TR1 were rod-shaped, milky-colored, round, shiny-viscous, smooth with a defined margin, while colonies of MA3 were cream-colored with smooth surfaces and raised aspect. The TR1 was gram-stain-positive with approximately 6-10 μm long and 1.2 μm wide cells, and MA3 was gram-stain-negative withabout 0.9 μm long and 0.5 μm widecells. The results demonstrated the involvement of Bacillus sp. and Thioclava sp. in the release and uptake of P, owing to their ability to grow in saline wastewater. |