Optimization Of Parameters On Sludge Ultrasonic Disintegration Reactor And Analysis Of Energy Benefit On Mesophilic Anaerobic Digestion Of Disintegrated Sludge

Anaerobic digestion is considered as the best way of decreasing and reusing waste activated sludge. Ultrasonic disintegration of waste activated sludge can accelerate anaerobic digestion of waste activated sludge and increase biogas yield. But, at present, professional ultrasonic reactor in the field of disintegration of waste activated sludge is not found in China. Ultrasonic reactor of microbial cell lysing or ultrasonic cleaner is used in laboratory, and it is low efficient and high energy-consuming. In order to reduce the energy-consuming of ultrasonic reactor and help it to be used in waste activated sludge pretreatment field in China, the optimal analysis and study of ultrasonic reactor principle, work parameters and energy-consuming were completed in this dissertation.The static experiment and dynamic experiment were finished in laboratory. Ultrasound field and ultrasonic cavitation field were measured by thermoelectric probe method and dyeing method. At same time, the effect of ultrasonic parameters (frequency and power), characters of waste activated sludge (concentration, pH and initial temperature), experimental conditions (stirring or blowing) on ultrasonic disintegration of waste activated sludge was analyzed with SCOD+, DDSCOD and flocs size of waste activated sludge.Analyzing ultrasonic field and cavitation field of three kinds of frequency (20kHz, 28kHz and 40kHz), when one transducer is working, it is concluded that ultrasound intensity and cavitation intensity are fluctuant and liking cucurbits along the axes of transducer in distilled water, and reduce gradually with distance increase. But, cavitation intensity reduction is faster than ultrasound intensity. And ultrasound intensity and cavitation intensity of different frequency are different: ultrasound intensity and cavitation intensity of 28kHz are all strongest, and then 40kHz's second place, finaly, 20kHz's the weakest. When two transducers are working simultaneously, wave of ultrasound intensity and cavitation intensity along the axes of transducer are accordant with one transducer's. The reduction of ultrasound intensity and cavitation intensity along the centre line of two transducers is lesser than that along the axes of transducer because of interference and overlap. And ultrasound field and cavitation field of two transducers are better-proportioned than one transducer's. Another conclusion in waste activated sludge is obtained that ultrasonic intensity of any frequency reduces suddenly nearby transducer face and reduces quickly along the axes of transducer.Effect of three kinds of frequency (20kHz, 28kHz and 40kHz) and frequency combination on ultrasonic disintegration of waste activated sludge by using ultrasonic bath was analyzed. At single frequency working, 28kHz is the best; at more frequencies working, disposal of transducers parallel and opposite of 28kHz and 40kHz is the best. Furthermore, analysis of more ultrasonic powers combination was carried out. Single power working, low power with long treatment time is advantaged, but with lower disintegration speed. Power combination working, low power combination can enhance efficiency. Another found proves that characters of waste activated sludge (concentration, pH and initial temperature) and experimental conditions (stirring or blowing) are also increase the efficiency of disintegration of waste activated sludge.In addition, data of dynamic experiment indicates dynamic disintegration is better than static disintegration when the concentration and volume specific energy consume are the same value. And during experimental time, the reaction of ultrasonic disintegration of dynamic waste activated sludge is also accord with one-order reaction.At the same time, analysis of energy benefit on mesophilic anaerobic digestion of ultrasonic treated waste activated sludge was finished. Compare of treated sludge and untreated sludge was also completed with, specific net energy and periodic net energy. It is found that net energy of ultrasonic disintegrated and untreated sludgy is increasing with percent of volatile solid increasing, and mesophilic anaerobic digestion technology is not fit for the sludge with low percent of volatile solid. Dynamic disintegration sludge with ultrasonic bath with proper time can accelerate anaerobic digestion of waste activated sludge when percent of volatile solid is higher.