Study On The Dissolution Law Of Chemical Oxidation Phosphorus From Waste Sludge And The Phosphorus Recovery Efficiency Of Superparamagnetic Composite Material

Phosphorus is an essential element for life and a non-renewable non-metallic mineral resource.Due to the blind mining of phosphorus resources and improper recovery of phosphorus resources,phosphorus pollution and serious loss of phosphorus resources,phosphorus recovery and utilization becomes particularly important.The recovery of phosphorus from the residual sludge of sewage treatment plant can not only reduce the pollution of phosphorus pollutants to the environment,but also solve the problem of the shortage of phosphorus resources.In this thesis,the residual sludge as the research object,through low p H heat treatment,ozone oxidation treatment,alkali treatment as pretreatment methods,with superparamagnetic composite material as adsorption means,explore the residual sludge phosphorus leaching rule,explore phosphate adsorption and desorption regeneration performance,analysis of phosphate on the surface of superparamagnetic composite adsorption-desorption mechanism.In this study,the superparamagnetic composites loaded with four transition elements,La,Ce,Zr and Hf,were prepared by coprecipitate method,and the structure of the superparamagnetic nanocomposites was characterized by scanning electron microscopy,X-ray diffraction analysis and X-ray fluorescence spectroscopy.The results showed that: The layered bimetallic hydroxide(LDH)structure is composed of uneven particles with obvious crystal structure.The optimal control conditions of residual sludge heat treatment at low p H value was 90 min treatment at 70°C,the optimal control conditions of ozone oxidation treatment was 5 L/min ozone flow rate and 30 min treatment,and the optimal control conditions of alkali treatment was 0.05 mol/L Na OH dosage and2 h treatment.The phosphorus leaching effect followed the order of low p H heat treatment > ozone oxidation > alkali treatment,and the highest phosphorus leaching rate was 90.26%.The phosphate adsorption-desorption test showed that the maximum phosphate adsorption capacity of the superparamagnetic composite was 22.16 mg/g and the adsorption process was consistent with Freundlich adsorption isotherm model.The material has strong adsorption selectivity for phosphoric acid and can adapt to background conditions such as p H,DOM component and heavy metal in complex solution systems.After ten adsorption and desorption cycles,the adsorption efficiency of Mg Al-La and Mg Al-Ce of the composite was still above 60%,indicating the high reusability.In this project,the adsorption energy between phosphoric acid and LDH was calculated by means of lattice method through Materials Studio software,and it was concluded that the inner sphere complexation was dominant,which provided theoretical basis for phosphate adsorption mechanism.The phosphorus recovery method of surplus sludge pretreatment-superparamagnetic composite material proposed in this study is conducive to realizing the reuse of phosphorus resources in domestic sewage under circular economy,which has far-reaching engineering and social significance.