The Natural Clinoptilolite Removing Ammonia Nitrogen From Flue Gas Desulfurization(FGD) Wastewater

Coal-fired power plant flue gas desulfurization often uses wet limestone-gypsum treatment process.Due to the special characteristics of this desulfurized wastewater embodied by this process,it is difficult for traditional“Triple Box Process”?neutralization?sedimentation?flocculation?to meet all water quality indicators,especially the ammonia nitrogen pollutant of which is,a rigid indicator of wastewater treatment,affects the production process.As an absorbent,natural zeolite has strong adsorption capabilities for many pollutants,and could be recycled and has low cost.This,entails a practical significance for ammonia nitrogen treatment in wastewater desulfurization.In this project,the natural clinoptilolite for ammonia nitrogen was firstly determined by experimental comparison and selection process;the extent of impact and patterns of various factors of using natural clinoptilolite on the treatment of ammonia nitrogen were determined by orthogonal test.On this basis,the static adsorption and regeneration test of wastewater desulfurization was performed.The optimal and best conditions for static adsorption regeneration tests were determined.Thereafter,the process and properties of natural clinoptilolite for adsorption of ammonia nitrogen were studied.Finally,a dynamic continuous flow test for adsorptive wastewater desulfurization was conducted to determine the dynamic adsorption operating parameters.Based on this,a cyclic regeneration adsorption experiment was conducted to examine the stability of ammonia nitrogen in wastewater desulfurization treated with natural clinoptilolite.The specific conclusions are as follows:1)The results of orthogonal test and range analysis showed that the order of the influence factors of natural clinoptilolite to treat ammonia nitrogen from wastewater desulfurization was as follows:dosage>particle size>reaction time>temperature>pH.2)Through the study of zeolite particle size,dosage,reaction time,temperature and pH,the ammonia nitrogen removal rate of wastewater desulfurization exceeds 97%;the saturated adsorption zeolite is regenerated with 6%sodium chloride solution,and the desorption rate exceeds 64%with good results.3)During the treatment of wastewater desulfurization by natural clinoptilolite,other metal cations have different degrees of influence on the adsorption effect.The main order of influence is:Na⁺>K⁺>Mg²⁺>Ca²⁺.4)The adsorption characteristics of zeolites showed that the adsorption of ammonia nitrogen by natural clinoptilolite is more consistent with the Lagergren pseudo-secondary kinetic model;the adsorption isotherm model is more in line with the Langmuir adsorption isotherm,and the single molecule chemical adsorption is dominant;Through implementation of thermodynamic study,the adsorption of the natural clinoptilolite on ammonia nitrogen process is determined as a spontaneous endothermic reaction.5)During the continuous flow dynamic cycle test of wastewater desulphurization by natural clinoptilolite adsorption column,selecting 1 L/h for the optimal flow of 40 cm high adsorption device has resulted in,an amount of 4.39 mg/g ammonia nitrogen adsorbed and an average of 24.5L desulfurized wastewater treated by natural clinoptilolite the loop processing effect is stable.6)The paper proposes that when the natural clinoptilolite is first regenerated,by using the concomitant modification property of natural clinoptilolite on regeneration liquid eliminates the cost of modification of the natural clinoptilolite.The feasibility of this thesis has been validated by the test results.