Study On Phosphorus Removal Performance And Reuse Of Composite Ceramsite

Phosphorus is a key element that causes eutrophication of water bodies,and it is also one of the strategic resource for the development of industry and agriculture in China.Therefore,it is of great significance to seek high-efficiency and low-cost phosphorus removal materials and to simultaneously recover phosphorus resources.Adsorption method can not only quickly remove phosphorus in wastewater,but also realize the recovery and reuse of phosphorus resources through desorption and other means,so it has been widely used.This study uses oyster shell as effective phosphorus removal component,montmorillonite as binder,and straw as pore-forming agent to prepare phosphorus removal ceramics,and study its adsorption performance under static and dynamic conditions.The reaction mechanism of phosphate removal was revealed,and the possibility of adsorption saturated ceramsite as slow release phosphate fertilizer was explored to realize the recycling of phosphorus resources.The results are as follows:(1)The effects of the ratio of ceramsite materials,calcination temperature and time,the dosage of adsorbent,reaction time and initial p H on the phosphorus removal by composite ceramsite were investigated in static experiments.According to the results of adsorption kinetics and adsorption isotherm model,the static adsorption process of phosphorus removal by composite ceramsite conforms to the pseudo-second-order kinetics model and Langmuir adsorption isotherm model,indicating that monolayer adsorption occurs at the solid-liquid interface.The thermodynamic study shows that the dephosphorization process of composite ceramsite is a spontaneous endothermic process.(2)Dynamic column experiment,respectively,to explore the effects of calcined pyrite addition on effluent p H,influent phosphate concentration,filling method,mass ratio and flow rate of the composite ceramsite adsorption phosphorus removal system.The results show that the calcining pyrite is added in the composite ceramsite system can not only improve the phosphate adsorption capacity of the system,It can also reduce the p H value of the effluent,and the equilibrium adsorption capacity of the composite ceramsite is 15.88 mg/g under experimental conditions.(3)In addition,SEM,BET,XRD,XPS and other characterization methods were used to analyze the physical and chemical characteristics of composite ceramsite before and after the reaction,and to study its adsorption mechanism.The results show that the adsorption mechanism of phosphorus removal by composite ceramsite is mainly electrostatic attraction,hydroxyl ligand exchange and chemical precipitation reaction between phosphate ion and calcium ion.(4)The possibility of saturated composite ceramsite as slow-release phosphate fertilizer was studied through laboratory scale pot experiment.The results showed that the phosphorus containing composite ceramsite promoted the germination of rape seeds and the growth of early seedlings,indicating that the composite ceramsite prepared in this study can not only be used as adsorbent to remove phosphorus,also can be used as slow-release phosphorus fertilizer to realize the recycling of phosphorus.