| Biological phosphorus removal is an accepted phenomenon applied to reduce phosphorus concentrations from wastewaters-activated sludge process with alternating aerobic/anaerobic conditions and application of a suitable chelator. The aerobic-anaerobic processes have been successfully used to enhance biological phosphorus removal (EBPR) as reported by Mino et al. (1987), and Smolder et al. (1994a & b) in recent years. Other findings in the laboratory reported by Jensen, Sicko-Goad, and Ayala (1977), and McGrath (1998) have indicated that under aerobic conditions some heterotrophic organisms store polyphosphate intracellularly. The phosphorus serves as an energy source during periods of starvation. The objective of this study was to investigate the release of phosphorus from the polyphosphate bodies of various microbes.; The uptake and release of phosphorus by pure culture of Synechococcus leopoliensis, Plectonema boryanum, Saccharomyces cerevisiae, and Rhodotorula rubra were investigated under aerobic, anaerobic conditions, different pH ranges, and the application of EDTA, and time duration (days). The total phosphorus released by these microbes varied greatly under the various experimental conditions.; The effect of pH on the aerobic release of phosphorus by these phosphorus-accumulating organisms (PAO) in this investigation was performed at pH 7.2, 8.5, and 9.0 (normal growth conditions). Cells reached their normal growth 14–17 days and percent of phosphorus released by the cells at various pH ranges, 7.2, 8.5, and 9.0, and time period 4, 6, and 8 days was low, 25.29%, 30.49%, and 33.40% by S. leopoliensis. At the same token, during the anaerobic conditions, there was more P release (54.14%, 76.50%, and 86.85%) respectively. When 0.25M EDTA was added, the average release was 81.33%. P. boryanum released 31.08%, 32.23%, and 33.66%. During the anaerobic condition, it released 72.27%, 83.02%, and 95.24%. S. cerevisiae released 10.41%, 10.87%, and 11.08% aerobically. Anaerobically, 54.75%, 68.93%, and 87.54%. R. rubra, aerobically released 11.56%, 12.07%, and 25.22%. Anaerobically, P released was 36.69%, 53.27%, and 69.04%. The greatest amount of P release was in the anaerobic condition by all the microbes. When EDTA was added to the culture in the aerobic conditions for the same time period and the same pH values P release was 76.07%, 79.68%, and 88.71% by S. leopoliensis. 77.76%, 79.70%, and 91.04% by P. boryanum. S. cerevisiae released 65.97%, 75.19%, and 90.35%. R. rubra released 66.17%, 75.05%, and 86.51%. These results are discussed in relation to anaerobic conditions, pH variations, time (days), and addition of EDTA studies of phosphorus release from polyphosphate bodies from various microbes. This uptake and release of P by these microbes in response to high pH values, anaerobic conditions, and with the addition of EDTA provide evidence to the importance of phosphorus during growth and development and in their response to environmental stress. |
