| Summary: | 碩士 === 國立中央大學 === 環境工程研究所碩士在職專班 === 99 === Aeration is a key control activated sludge processes, which can be achieved by various methods. The performance of membrane fine bubble diffuser was studied here. A model system similar to real aeration tank, that is, depth of 3~4 m, was used to eliminate the size effects in studies of small scale. The effects of temperature, water depth, aeration velocity, and salt concentration on the overall oxygen transfer coefficient (KLa20) were examined. The temperature correction factor was confirmed to be similar to that suggested by ASCE. The KLa20 was also found to be decreased than increased before 200 mg/L of sodium chloride and remained similar after that. It was similar to the effects of suspended solids, for which the reason is still not clear. The oxygen transfer coefficient and correction factors of two different municipal wastewaters and a organic pigment wastewater were examined. It was found that although the municipal wastewater came from different places and the compositions of them were slightly different, the values of the correction factors are similar, which is 0.67 ~ 0.69. However, for the organic pigment wastewater, the correction factors varied significantly from batch to batch. The result suggested that due to the variation in wastewater quality, the aeration efficiency might be affected correspondingly and, therefore, the performance of activated sludge system was not stable.
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