Impact of the Chlorine Ion on a Sequencing Batch Reactor Operated Under Enhanced Biological Phosphate Removal Mode – Reactor Performance & Bacterial Community
| Autor: | Wu-Hon Lin, 林文宏 |
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| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Activated sludge system with alternating anaerobic and aerobic process, also being known as enhanced biological phosphate removal (EBPR) system, has been successfully applied to treat wastewater containing high concentration of phosphorus. Although these EBPR systems had been widely used in full-scale wastewater plants, poor wastewater-treating efficiency often occurs for unknown reasons. In this study, a sequencing batch reactor (SBR) was operated under EBPR mode and was found to have poor phosphorus removal efficiency. Form the results of chemical analysis, it was suggested that the high and fluctuated concentration of chlorine in the mixed liquor could be the reason causing the failure of phosphorus removal. Subsequent experiments were performed to compare the difference on microbial structures between EBPR systems with high and low chlorine concentration. It was found that the level of anaerobically phosphorus released in system with low chlorine concentration was higher than that with high chlorine concentration. Similar results of aerobically phosphorus accumulating was also observed in these study. From the results of microbial structure analysis by using Fluorescence in situ Hybridization(FISH), it was showed that alpha- and beta-Proteobacteria were the dominated bacterial population in system influenced by a high and fluctuated chlorine concentration. It was also found that beta-Proteobacteria and Gram-positive bacteria with high GC bases content were dominated in system operated under a low and steady chlorine concentration. According to these results, alpha-Proteobacteria in this reactor may have higher salt tolerant capacity, such as chlorine, than the others microorganisms. Once the usual high salt concentration was controlled, alpha-Proteobacteria would lose its advantage to compete with others in EBPR system. Additional, most of beta-Proteobacteria existed in the system belong to the members of the β-1 and β-2-Proteobacteria which were identified as not the member of GAOs could also be responsible for the deterioration of phosphate removal efficiency in EBPR system. This group were also confirmed with relative higher tolerant capacity to salt to others in EBPR system, and doesn’t lose the advantage to compete with others under low chlorine concentration. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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