Ultrasonic Crack And Resource Technology For Excess Sludge From Modified Oxidation Ditch Process

With the rapid development of urbanization and socio-economic in our country in recent years,the production of domestic sewage and industrial wastewater has being significantly increased.At the same time,the traditional sewage treatments pay attention to sewage but contempt for sludge,which leads to the increase of the amount of sludge after wastewater treatment.With the awareness of public environmental protection increasing growth,the requirements to sludge disposal requirements also becomes higher and higher.Due to the high moisture content,large volume,active substances and other pollutants of excess sludge,the disposal remains a major problem.The disposal methods of excess sludge include landfill,ocean landfill,sludge drying,etc.The mishandled of excess sludge can bring forth the potential environmental risks.Meanwhile,intracellular nutrients within the sludge have not yet been fully utilized.Ultrasonic crack excess sludge can release intracellular nutrients from the sludge and provide the conditions for subsequent use.At present,ultrasonic crack sludge technology research lack of systematic is lack of systematic researches,which still in the stage of laboratory study.And the ultrasonic mechanism and optimum conditions are still not clear now.Therefore,the concentration changes of COD,total nitrogen,total pHosp Horus,ammonia,nitrate and protein in the supernatant before and after ultrasonic treatment were investigated by changing the time,power,and frequency of ultrasonic.Based on the analyzed results,the optimum ultrasonic time,power and frequency of ultrasonic crack conditions of excess sludge were identified,which can provide conditions for subsequent sludge utilization.The ultrasonic crack conditions of excess sludge were controlled mainly by the following three ways:(1)with the fixed ultrasonic frequency and power,monitored the concentrations of COD,total nitrogen,total pHospHorus,ammonia,nitrate and protein by changing the ultrasonic time,analyzed nutrients released by sludge nutrients under the action of ultrasonic,meanwhile determined the optimal time of ultrasonic treatment;(2)with the fixed ultrasonic time and frequency,monitored the concentration of COD,total nitrogen,total pHospHorus,ammonia,nitrate,protein by changing ultrasonic power,analyzed nutrients released by sludge nutrients under the action of ultrasonic,meanwhile determined the optimal power of ultrasonic treatment;(3)with the fixed ultrasonic time and the power,monitored the concentration changes of COD,total nitrogen,total pHospHorus,ammonia,nitrate,protein by changing the frequency,and analyzed nutrients released by sludge nutrients under the action of ultrasonic,meanwhile identified the optimal frequency of ultrasonic treatment and finally summarized and found the optimal combination.The ultrasonic generator was used to crack sludge of sewage treatment plant,Hefei Economic Development Zone in this study.Through the optimization analysis of different experimental conditions,the main results were as follows:(1)When the ultrasonic power(600W)and frequency(22KHz)being fixed,the effect of ultrasound cracked sludge grew more significant with the time increasing,and the effect was the most obvious when ultrasonic time was 5 min.Because the effect increased slowly or kept steady after 5 min,the optimal time of ultrasonic crack sludge was 5 min.(2)When the ultrasonic time(5min)and frequency(22KHz)being fixed,the effect of ultrasound cracked sludge became more significant with the power increasing,and the effect was obvious when the ultrasonic power was 600 W.Due the effect of ultrasonic crack increase slowly or kept steady after 600 W,the optimal power of ultrasonic crack sludge was 600 W.(3)When the ultrasound time(5min)and power(600W)being fixed,different ultrasonic frequencies were obtained by changing the probe and the optimum frequency was 22 KHz.