Study On Treatment Of Desulfurization Wastewater From Coal-fired Power Plant By Adsorption Process

Based on the previous research on the treatment of desulfurization wastewater by physical and chemical methods,this study carried out the research on the advanced treatment of desulfurization wastewater by adsorption method.This research mainly consists of three parts.The first part mainly studied the adsorption effect of conventional adsorbents on various pollutants in desulfurized wastewater,and studied the removal mechanism of various pollutants in combination with related models of adsorption kinetics,thermodynamics and penetration curves;The second part mainly studied the best conditions for acid and high temperature modification of fly ash.The obtained fly ash modified materials are subjected to adsorption thermodynamics and kinetics experiments,and related models are used to study the removal mechanism of various pollutants.On the basis of the above research,the third part carried out experimental simulation research on different combinations of chemicals,adsorption and filtration systems,and explored the optimal multi-stage adsorption-filtration system for desulfurization wastewater treatment of coal-fired power plants.The main results of this study are as follows:(1)The results of adsorption studies on conventional adsorption materials show that the optimal adsorption conditions are adsorption time of 144minutes,adsorption temperature of 40?,dosage of adsorbent 25g/L,and pH=7.The best adsorption materials hydroxyapatite,anthracite and activated alumina have the removal rates of heavy metals Cr,Ni and Zn above 90%,85%and 80%,respectively,and the effluent concentrations are below 0.20mg/L 0.30mg/L,and 0.40mg/L respectively.The type and amount of adsorbent have a significant effect on the adsorption of various pollutants,and the adsorption time and pH have no significant effect on the adsorption of various pollutants.The adsorption kinetics of hydroxyapatite,anthracite and activated alumina for fluoride and COD conform to the quasi-second-order kinetic model,and the adsorption kinetics of chloride and calcium ions conform to the quasi-first-order kinetic model,in which active oxidation Aluminum has the largest adsorption capacity for various pollutants,and anthracite has the highest adsorption rate for various pollutants.The adsorption thermodynamics of the adsorption materials for fluoride,COD,chloride and calcium ions conform to the Freundlich adsorption isotherm model.The adsorption of various pollutants belongs to preferential adsorption.For the adsorption of fluoride and chloride ions,the effect of activated alumina and hydroxyapatite are better,and the adsorption effect of anthracite is better for COD and calcium ions.(2)The results of adsorption studies on fly ash modified materials show that the best conditions for acid modification experiments are:the best acid type is nitric acid,the best acid concentration is 0.011mol/g fly ash,and the best liquid-solid ratio is 9mL/g fly ash,the best modification time is 120min.High temperature modification experiments determined that the best conditions were:the best blowing agent is calcium carbonate,the best addition amount was 8wt%,the best flux was calcium oxide,and the best addition amount is 8wt%.The adsorption kinetics of chloride ion,COD and fluoride by the fly ash modified material conforms to the quasi-second-order kinetic model,the adsorption amount is 69.21mg/g,35.55mg/g and 8.40mg/g,respectively,and the activation energy is 14.69KJ/mol,9.53KJ/mol and 9.48KJ/mol,respectively.The adsorption thermodynamics of chloride ion,COD and fluoride with the fly ash modified material conform to the Freundlich adsorption isotherm model,and the enthalpy change?H0 is 3.41KJ/mol,5.28KJ/mol and 9.35KJ/mol,respectively.Judging from the adsorption intensity index,the adsorption of chloride ion belongs to favorable adsorption,and the adsorption of COD and fluoride belongs to preferential adsorption.(3)The results of the multi-level adsorption-filtration study show that the dynamic adsorption behavior of fluoride and COD by five kinds of adsorbent materials,such as activated alumina,anthracite,hydroxyapatite,activated carbon and iron-carbon filler,conforms to the Yoon-Nelson model,and is suitable for calcium ion and chlorine The dynamic adsorption behavior of ions conforms to the Thomas model,and the hydroxyapatite has the largest adsorption rate for fluoride,the activated carbon has the highest adsorption rate for COD and chloride ions,and the activated alumina has the largest adsorption rate for calcium ions.A comprehensive comparison of the five groups of multi-stage adsorption-filtration systems shows that the fifth group has a more stable and efficient adsorption effect on COD,and the second group has a more stable and efficient adsorption effect on fluorideFigure[79]table[44]reference[97]...