Research On The Removal Effect And Mechanism Of MSW Incineration Fly Ash On High Phosphorus Wastewater

With the rapid development of modern industry,a large amount of phosphorous waste liquid will be generated in related industries such as electroplating,medicine,pesticide chemical industry,metal processing,and papermaking,which will cause great harm to water resources and natural ecology.On the other hand,the output of municipal solid waste（MSW）in my country is increasing year by year,and the MSW incineration fly ash,as a kind of hazardous waste,urgently needs to be effectively treated.MSW incineration fly ash is a kind of hazardous waste generated from waste disposal in waste incineration plants.At present,there is insufficient research on fly ash as adsorbent for phosphorus removal and waste liquid with high phosphorus content（concentration above 1000mg/L）.In view of the above problems,the purpose of this paper is to effectively remove the waste liquid containing high phosphorus by using MSW incineration fly ash,so as to realize the purpose of treating waste with waste,and to study the influence of fly ash modification on phosphorus removal and the release effect of heavy metals.According to the physical and chemical characteristics of MSW incineration fly ash,the effect of phosphorus removal was evaluated based on the types of MSW incineration fly ash,the solid-liquid ratio between MSW incineration fly ash and waste liquid containing phosphorus,reaction time and initial reaction temperature.The results show that for 1000mg/L dipotassium hydrogen phosphate solution,using a MSW incineration fly ash,when the reaction time reaches 40min,the initial reaction temperature is 313K,the solid-liquid ratio of MSW incineration fly ash to waste liquid is 12～14g/L,the best phosphorus removal effect,phosphorus removal efficiency reaches 99.95%,the final phosphate concentration is 0.4391mg/L.With b fly ash,when the reaction time reaches 250min,the initial reaction temperature is 313K,and the solid-liquid ratio is 33～35g/L,it has the best phosphorus removal effect,phosphorus removal efficiency reaches 99.88%,and the final phosphate concentration is 1.12mg/L.It is noted that the MSW incineration fly ash produced in different places will greatly affect the phosphorus removal process because of the different origins and different waste treatment methods.On the basis of experiments,XRD,EDS,SEM and other analytical methods and adsorption equilibrium theory are used to conduct an in-depth analysis of the phosphorus removal mechanism of MSW incineration fly ash.The results showed that the chemical reaction between Ca and P and the multilayer adsorption process on the solid surface together led to the removal of phosphorus.In order to further improve the ability of fly ash to remove phosphorus,sulfuric acid,sodium hydroxide,potassium chloride,and microwave are used to modify MSW incineration fly ash.And explore the mechanism of phosphorus removal by modified fly ash and the release of heavy metals during the treatment process.The results showed that for a MSW incineration fly ash,it had promoting effect in 1%sulfuric acid solution,2%sodium hydroxide solution and 2%potassium chloride solution,while for b fly ash,it had promoting effect in 1%potassium chloride solution.In the study of the heavy metal release of two kinds of fly ash,it was found that most of the heavy metal elements As,Cd,Cu,Mn,Ni and Zn had obvious linear change trend to the MSW incineration fly ash modified by H₂SO₄,while Cr and Pb had different change trend to different modification conditions.Microwave modification can inhibit the release of As,Hg,Mn,Ni and Zn in the process of phosphorus removal from fly ash to a certain extent.The experimental results show that the MSW incineration fly ash conforms to the quasi-secondary adsorption kinetic model and the Freundlich isothermal adsorption model.In summary,the adoption of MSW incineration fly ash can effectively remove the waste liquid containing high phosphorus,and ensure that the release of heavy metals in the fly ash in the process of phosphorus removal can meet the national sewage discharge standards,providing a basis for subsequent research.