Experimental Study On The Optimization Of The Sludge Reduction Ultrasonic Pretreatment

With the acceleration of the process of industrialization and urbanization, more and more without treatment sludge generalized from the city sewage treatment plant. The traditional sludge disposal method have the problem of the complex process or chemical pollution, and therefore other more effective sludge dewatering methods need to be developed. Ultrasonic technique as a research focus is increasingly concerned by the people, due to its mild reaction condition, no pollution and obvious dehydration effect. The sludge disintegration, cell decomposition, organic substances released into the soluble, so as to replace or partially substitute for sludge hydrolysis, accelerating the anaerobic digestion of sludge.According to the city sewage treatment plant sludge as the research object, using OSA technology, ultrasonic technology combined with OSA were exploratory studied to optimize sludge reduction. By using the single factor and the orthogonal regression optimization experiments, the experiments of the ultrasonic pretreatment disintegrating sludge, strengthening the anaerobic digestion and improving sludge dewatering performance were studied, respectively. With the best combination of ultrasonic technology parameters, ultrasonic combined the OSA process sludge reduction were studied. The main conclusions of the study:1. Through the single factor experiment, study the single frequency ultrasonic, dual-frequency ultrasonic, ultrasonic time, the different energy density conditions, changes of COD, TP, NH3-N increment.2. This paper through the orthogonal experiment select the optimal conditions of ultrasonic pretreatment decompose sludge. For index VSS/SS,NH3-N is concerned, has significant impact on the order is the double frequency combination> ultrasonic density> ultrasonic time. For index VSS/SS is concerned, the best ultrasonic pretreatment parameter combination is:double-frequency combination18kHz,20kHz, ultrasonic density0.075W/ml, ultrasonic time5min; For index NH3-N is concerned, the best ultrasonic pretreatment parameter combination is:double-frequency combination18kHz,20kHz, ultrasonic density0.1W/ml, ultrasonic time5min.3. Study on the effect of sludge disintegration with ultrasonic pretreatment, H2O2 pretreatment and ultrasonic pretreatment combined with H2O2pretreatment. The results show that:after the ultrasonic pretreatment, in a certain time range with the prolonging the ultrasound time, the sludge SCOD and the protein content in supernatant increased, the value of VSS/SS nonlinear changes. With H2O2pretreatment, the value of sludge SCOD reduce with increasing the amount of H2O2. With H2O2and ultrasonic pretreatment, the increments of SCOD was significantly higher than that of only using ultrasonic pretreatment and H2O2pretreatment, respectively. Experiments show that with pretreatment the sludge gas production increased significantly compared with untreated, and shortens the time of sludge anaerobic digestion.4. The sludge dewatering effect and its influencing factors were investigated. The influencing factors studied are ultrasonic, flocculants, and ultrasonic combined flocculants. The results show that, separately using ultrasonic pretreatment, the sludge dewatering effect of using double frequency ultrasonic pretreatment is better than that of single frequency ultrasonic; separately using flocculants treatment, aluminum sulfate (Al2(SO4)3) improving the sludge dewatering performance is better than that of ferric sulfate (Fe2(SO4)3) and polyacrylamide (PAM). Contrast test results show that at the same time adding aluminums sulfate (Al2(SO4)3) and ultrasonic pretreatment, the sludge dewatering effect is the best. The linear relationship among orthogonal regression optimization ultrasonic time (X1), flocculants dosage (X2) and ultrasonic power (X3) is y=0.864+0.13X1+0.09X2+0.01X3+0.03X1X2.5. Study on the ultrasonic pretreatment of sludge return to the anaerobic tank, effect on sewage effluent quality and sludge reduction effect. Compared to the no reaction tank ultrasonic pretreatment, ultrasonic-OSA effluent SS, COD, TN, TP reached the national effluent discharge standards, sludge production and ultimately reduce the31.17%. Ultrasonic technology combined with OSA technology can realize the reduction of sludge.The results show that the dual-frequency ultrasound is more conducive to sludge disintegration. Ultrasonic pretreatment disintegrating sludge which return to anaerobic pool, combined OSA process is conducive to the reduction of sludge.