Research On The Coupling Of Fluidized Bed And Ultrasonic Washing Organic Sand And Gravel

The treatment and disposal of the sludge in the ditch restricts the development of the maintenance of the urban drainage pipe network.At present,the commonly used centralized treatment station method is to separate the inorganic sand and gravel through a series of treatments,so that it can meet the requirements of building material reuse and realize the Ditch sludge recycling,reduction and harmless recycling.Due to the poor sand washing effect in the actual operation of the centralized treatment station,the landfill method can only be used for disposal after the treatment is completed,resulting in a waste of land resources.The coupled sand washing method proposed in this paper is to wash organic sand and gravel by combining traditional fluidized bed washing and ultrasonic washing technology,so that the finished sand and gravel meet the"Technical Regulations for Urban Drainage Sludge Treatment"(T/CECS700-2020)stipulates that"the organic burning loss rate should be less than 5%when organic sand and gravel are reused as building materials",so as to improve the recycling rate of sand and gravel.The specific research content and conclusions are as follows:(1)Research on washing mechanism.The mechanism and characteristics of fluidized bed washing and ultrasonic washing are analyzed and researched.The feasibility of fluidized bed and ultrasonic washing of organic sand and gravel is proposed,and the mechanism of coupled washing is determined.The main factors affecting the washing effect are put forward:ultrasonic time,ultrasonic frequency,fluidized bed inlet water flow,etc,to provide theoretical guidance for subsequent experiments.(2)Fluidized bed sand washing experiment.By changing the flow rate of the fluidized bed inlet water,explore its influence on the sand washing effect.Analyzing the sand before and after washing,it is concluded that the fluidized bed has the best effect of washing organic sand and gravel when the fluidized bed inlet flow rate is 30 m~3/h.(3)Ultrasonic sand washing experiment.Use the ultrasonic cleaning machine to wash the organic sand and gravel,and change the ultrasonic time and ultrasonic frequency to explore its influence on the ultrasonic cleaning effect.Analyzing the sand and gravel before and after washing,it is determined that the ultrasonic washing effect is the best when the ultrasonic frequency is 25 k Hz and the ultrasonic time is 11 min.When analyzing the results,it was found that ultrasonic cleaning caused re-sedimentation due to impurities that could not be taken away in time,which caused the organic burning loss rate to rise again,limiting the effect of ultrasonic cleaning,and further strengthening the feasibility of coupled cleaning.(4)Coupling sand washing experiment.Integrating the conclusions of fluidized bed ultrasonic washing and the limitations of each washing method,explore the effect of ultrasonic time on the coupling washing effect.Compare the organic burning loss rate,particle size distribution,composition and adhesion of surface impurities before and after washing.The final determination of the sand washing plan is:fluidized bed and ultrasonic coupling washing organic sand and gravel under the conditions of fluidized bed inlet water flow of 30 m~3/h,ultrasonic frequency of 25 k Hz,and ultrasonic time of 2 min.The organic ignition loss rate of the washed sand and gravel is reliably lower than 5%.(5)Coupling sand washing experiment.Integrating the conclusions of fluidized bed ultrasonic washing and the limitations of each washing method,explore the effect of ultrasonic time on the coupling washing effect.Compare the organic burning loss rate,particle size distribution,composition and adhesion of surface impurities before and after washing.The final determination of the sand washing plan is:fluidized bed and ultrasonic coupling washing organic sand and gravel under the conditions of fluidized bed inlet water flow of 30 m~3/h,ultrasonic frequency of 25 k Hz,and ultrasonic time of 2 min.The organic loss on ignition of the washed sand and gravel is stable below 5%.(6)Utilization of product sand and gravel resources.According to the composition characteristics of the product sand and gravel,it is compared with related standards such as fired bricks,ceramsites,foundations,pipe base troughs,and cement admixtures,and analyzes the feasibility of using it as a building material to realize its resource utilization.On the one hand,it effectively reduces the waste and pollution of land resources caused by landfill,which has certain environmental benefits;on the other hand,the use of washed sand and gravel as a building material can turn waste into treasure and bring certain economic benefits.