| Summary: | 碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 98 === The main purpose of this research is to study three different hydrolysis pretreatment methods (Alkali, Ultrasonic, and Alkali with Ultrasonic)on primary sludge and waste activated sludge inside metropolitan sewage treatment plant to compare the characteristics of gas production from hydrolysis. It is hoped that the anaerobic gas produce rate can be increased through breaking solid organic materials with the hydrolysis methods.
The test result discovers that by hydrolyzing primary sludge of 4% total solids with pH12,its suspended solids(SS)are decreased of 2,510 mg/L and dissolved in 3,732 mg/L of SCOD, the production of dissolved organic from each suspended solid is 1.49g SCOD/g SS. While hydrolyzing by Ultrasonic (about 0.1 kW) for 30 minutes, its SS are decreased of 3,785 mg/L and dissolved in 3,708 mg/L of SCOD, the production of dissolved organic from each suspended solid is 0.98 g SCOD/g SS. If hydrolyzing by alkali with ultrasonic for 30 minutes, its SS are decreased of 13,205 mg/L and dissolved in 16,072 mg/L of SCOD, the production of dissolved organic from each suspended solid is 1.22g SCOD/g SS.
By hydrolyzing waste activated sludge with pH12 alkaline for 30 minutes, its SS are decreased of 2,985 mg/L and dissolved in 4,632 mg/L of SCOD, the production of dissolved organic from each suspended solid is 1.55g SCOD/g SS. While hydrolyzing by Ultrasonic for 30 minutes, its SS are decreased of 2,475 mg/L and dissolved in 2,948 mg/L of SCOD, the production of dissolved organic from each suspended solid is 1.19g SCOD/g SS. If hydrolyzing by alkali with Ultrasonic for 30 minutes,its SS are decreased of 14,820 mg/L and dissolved in 5,018 mg/L of SCOD, the production of dissolved organic from each suspended solid is 0.34g SCOD/g SS.
From test result above, it explains that after being hydrolyzed by alkaline, the waste activated sludge performs better than primary sludge in decreasing suspended solids and SCOD dissolving. However, the primary sludge acts better in Ultrasonic hydrolysis. The alkaline with Ultrasonic hydrolysis method provides similar result of SS decreasing volume to both sludges. Yet, the waste activated sludge has browning reaction caused by damage of cell structure, its dissolute organic materials are obviously lesser than that of the primary sludge. The ammonia and phosphorus are released to water during the hydrolysis process. By hydrolyzing activated sludge of 4% total solids with NaOH adjusted to pH12, the required alkali volume is approximately 70 meq/L, the required electricity for ultrasonic hydrolysis for 30 minutes is approximately 5.5×10-2 kWh/L.
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