| Summary: | 碩士 === 國立雲林科技大學 === 環境與安全工程系碩士班 === 94 === Biodegradable plastics－PHAs (polyhydroxyalkanoates) can’t compete with the traditional plastics due to its high production cost. Therefore, reducing the manufacturing expenses of PHAs has recently became the major purpose of further research. This study explore the suitable source of activated sludge and the best operation conditions for PHAs production by utilizing the waste biological sludge obtained from wastewater treatment. Experimental results shows that the PHAs production bacteria can be obtained from different activated sludge systems, not only in the A/O process. These different sources of sludge, including traditional activated sludge process, pure oxygen process and SBR process, demonstrated similar PHAs production capability. Additionally, the PHAs production capability of sludge from the completely mixing activated sludge systems was more than that from A/O process. Operating conditions on weak alkalinity (pH 8), high electron acceptor (O2) concentration (aeration capacity=900 ml Air/L/min), low substrate concentration (high acetate concentration (COD>6000 mg/L) will inhibit the bacterial activities) obtained the high PHAs content and PHAs conversion ratio in PHAs production batch experiments. It was also found that the PHAs porduction capability for activated sludge system with an short SRT (5 days) was better than that of the sludge with an long SRT (15 and 10 days).
Furthermore, this research investigated the efficiency of P removal and the metabolism of the activated sludge while no sludge was wasted in an EBPR system (anaerobic-oxic(A/O) SBR reactor). The results indicated that the concentration of PO43--P increased up to 2.24 mg/L at the end of aerobic stage when no sludge was wasted from the system over 2 days. The above findings indicated that it was necessary to keep wasting the excess P-rich sludge in the anaerobic-oxic activated sludge system for maintaining the steady P removal.
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