The Research On The Chemical Phosphorous Removal By Immobilization Of Activated La₂O₃ And Vacuum Regeneration Phosphors In Reducing Phosphate From Wastewater

Phosphorous is one of the control factors of water eutrophication.The thesis begins with cost decrease of phosphorous removal,high efficient phosphorous removal agent regeneration and recovery of phosphorous extracting from the sewage.Electrolysis immobilizes La₂O₃,which is regenerated by vacuum operation to recover phosphorous.Single factor and orthogonal test the fact impacts of current intensity,electrolysis temperature and time,pH value and concentration of electrolyte.Orthogonal table was used. The results indicates the best reactive condition is 3.0 of pH,23mA of current intensity,40 rain.of electrolysis time,1mol/L of concentration of electrolyte,57℃of electrolysis temperature,pH and current intensity are main control elements.Maximum absorption volume of phosphorous by La₂O₃ experiment tests the variation of the absorption capacity by changing the impact elements of CO₃^2-and OH^- concentration, using pure phosphate liquor as the control sample.In pure control sample,Maximum absorption volume is 198mg phosphorous / g La₂O₃.Chemical absorption drops from 195mg phosphorous / g La₂O₃ to 70mg phosphorous / g La₂O₃ interfered by the concentration ratio between CO₃^2-and phosphorous of 10.Chemical absorption drops from 192mg phosphorous / g La₂O₃ to 38mg phosphorous / g La₂O₃ interfered by the concentration ratio between OH^- and phosphorous of 5,when pH value is from 10 to 14.Vacuum furnace recovers phosphorous and regenerate La₂O₃ and the condition of 1800℃,1kPa,10hours.the experiment indicates vacuum evaporation can regenerate the La₂O₃ and recover phosphorous under certain conditions.Regenerating rate of La₂O₃ is about 35.9%.absorption volume of regenerate La₂O₃ is 57.9mg phosphorous / g La₂O₃ Recover rate of phosphorous is about 42.4%.recover volume of phosphorous is 68.2mg phosphorous / g La₂O₃.In addition,the thesis appraises the technical and economical feasibility of 1000t immobilization of La₂O₃ phosphorous removal agent production.The result indicates the regeneration of La₂O₃ and the recovery of phosphorous can greatly lower down the cost of phosphorous removal in sewage.The sewage treatment cost of removing 0.5mg/L phosphorous is only 0.072RMB/kt,10 times lower than that of traditional phosphorous removal methods.Moreover,the regeneration of La₂O₃ makes 5 thousand RMB per year and recovers of phosphorous makes 1.649MRMB per year.