| Summary: | 博士 === 國立暨南國際大學 === 土木工程學系 === 107 === This study developed a method for sludge reduction by using ultrasonic technic with low consumed energy, combined with biotreatment (active sludge process) to conduct tests of organic sludge reduction in one industrial area of Taiwan. The wastewater indexes include pH (Hydrogen Ion Concentration), CODt (Total Chemical Oxygen Demand), CODs (Solubility Chemical Oxygen Demand ), SS (Suspended Solid), MLSS (Mixed Liquid Suspended Solid), MLVSS (Mixed Liquid Volatile Suspended Solid). The test interval is divided into laboratory test, activated sludge method with ultrasonic technics test, contact filter with ultrasonic technics test (15 L / min, 25 L / min, 40 L / min aeration) to observe the effect of sludge reduction. An independent sample T test was then added to analyze the association between the control group and the ultrasound group. In the ultrasonic processing time test, the CODs concentration increased 3 times and 9 times from 0 to 10 mins and 0 to 60 mins. SS and VSS concentrations decreased with the increase of the ultrasonic processing time, which showed that the 10 mins ultrasonic processing time was the optimum condition. The SOUR was increased by 6.57 times (from 3.36 to 22.08 mg O2/mg MLVSS-hr) by adding 200 mL of ultrasonic treated sludge solution. In the energy-consuming test, after 285 mins of ultrasonic treatment, the sludge VSS concentration reduced from 4950 to 2010 mg/L, the reduction effect was up to 60%. This method can save 1593 NT dollars per ton of sludge by considering of savings in shipping and the increased electricity bills. Ultrasonic combined with activated sludge test was carried out based on above results, which showed that the best sludge reduction effect of 79.6% in laboratory test. In on-site test, the difference between CODt and CODs at ultrasonic and control groups was within 10%, which indicated that it is no effect on activated sludge reduction via ultrasonic treatment. In SVI tests, activated sludge was puffed after ultrasonic treatment because the data of ultrasonic group was larger than control group. The amount of MLSS, MLVSS and waste sludge in the aeration tank was higher in the control group than in the ultrasonic group, which caused the sludge age in the ultrasonic group increased and activated sludge reduction effect decreased, and the reduction was 21.9±15.4%. The early 60 days was culture process in ultrasonic with contact filter system. Contact filter was placed in the 61st day, and ultrasonic treatment was added to the return sludge. Then, the system tended to stable after 90 days process, and average reduction was 49.74%. Therefore, the best result is ultrasonic combined with contact filter among the above tests.
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