Research On The Comprehensive Utilization Of Coal Fly Ash And Coke Powder To Treat Waste Water Containing Ammonia-nitrogen

Coal fly ash is a kind of fine powder, silver-gray or gray in color, solid waste produced from thermal power plant. Coke powder which particle size is less than5mm and gray-black in color is a kind of by-product of the metallurgic and chemical industries produced from the broken process. Their average particle size is very small. Large amounts of these waste or by-product cause serious pollution problems to the environment. However, they contain many useful materials. For example, there is a high content of SiO2and Al2O3in coal fly ash and the fixed carbon in coke powder is up to70%. The utilization of these resources is of great significance to decrease the environmental damage.Coal fly ash is often used to treat waste water based on its multiple pore structure. The particles of the fly ash, however, are very fine. So the treatment efficiency is influenced owing to it easily float with the water. The molding type can improve the application effectively because of the fine particles being forming into massive materials. Coke powder is the fitting raw material. Presently, the molding technologies of coal fly ash have the disadvantages including high cost and complicated preparation process. The activation methods of coke powder mainly were chemical activation using chemical reagents with the defects of high cost and severe second pollution. Based on these, the paper was emphasis on the development of the molding technologies of coal fly ash and the preparation technologies of coke powder to activated carbon with lower cost, simple and clean preparation process. The molding coal fly ash and activated carbon were used to the treatment of ammonia-nitrogen wastewater. The results show that:(1) The preparation conditions of molding coal fly ash including the ratio, the sintering temperature and time were investigated through orthogonal experiments. The molding coal fly ash obtained the optimum absorption efficiency when the raw materials’ratio is80:10:10, the sintering temperature is600℃and the holding time is90minutes with a molding mass of1g.(2) The effects of the activation conditions including the water vapor flow rate, the concentration of O2and the kinds of additives on the performance of activated carbon prepared by coke powder were studied. The optimum preparation condition of activated carbon was the flow rate of2g/min H2O and the addition of5%Fe.(3) The molding coal fly ash and activated carbon prepared from activated carbon were used to treat ammonia-nitrogen water. The optimum adsorption conditions of the molding fly ash and activated carbon both were90min of the adsorption time, lOg of adsorbent dosage and8-9of pH value. The removal efficiencies of ammonia-nitrogen were up to40%and24%respectively under the optimum conditions.