A Study On The Disposal Technique Of High Strength Ammonium-chloride Wastewater From Fertilizer Industry

With the development of fertilizer industry in China, the influence to the environment that caused by the industrial wastewater with ammonium-chloride is more and more severe, the large amount of the discharge of ammonia-nitrogen and Cl" (chlorine ion) will do harm to the environment. If the concentration of ammonia-nitrogen is too high, it will cause the eutrophication of the waters and do harm to the health of human beings to some degree. The large amount of Cl" will also change the structure of the soil and do damage to the crops and underground buildings. However, to study the economical and efficient technology of dealing with the high strength ammonium-chloride industrial wastewater is much of important in reality.In this thesis, the author looks up a lot of documents and considers the wastewater of LuNan fertilizer factory. Systematic research is done according to the specialty that the concentration of the ion in ammonium-chloride industrial wastewater is high.With the simulated high.. strength ammonium-chloride wastewater, the author studies the single technology and optimizes the best condition for each technology The best conditions are listed as follows, for air-stripping: pH value is 11, temperatureof water is 50, ratio of air to water is 4000, filling height is 100cm; for chemical precipitation: moore ratio of Mg2+. NR. PCU3- is 1.25:1:1, pH value for reaction is 8.91, temperature of water is 25?C, reaction time is 20min, precipitation time is 20min; for reverse osmosis system: separating pressure is 0.6Mpa, disposal time is 5min, temperature of water is 10; for nanofiltration system: separating pressure is 0.7Mpa, disposal time is lOmin, temperature of water is 10. In the optimized condition, with the technology of air-stripping and chemical precipitation, the ammonia-nitrogen in the wastewater can be removed by 98.4% and 95%, with the technology of reverse osmosis and nanofiltration, the desalination ratio of the wastewater can reach 33.96% and 69.05%. However, it can not reach the emissionstandard with either kind of technology.The features of each disposal method is analyzed and considered, and the tandem technique of combing different methods to dispose of the high strength ammonium-chloride wastewater is carried out. With the tandem technique of air-stripping and precipitation, the concentration of ammonia-nitrogen in the wastewater can be reduced to 30.3mg/L. However, this method is limited in reality because the concentration of Cl" in the final water is too high. With the tandem technique of nanofiltration and precipitation, the concentration of ammonia-nitrogen in the final water can be reduced to 280mg/L. But the Cl" can not be removed from the wastewater and the emission standard can not be reached.Combining the technology of nanofiltration and air-stripping, ammonia-nitrogen in the high strength ammonium-chloride industrial wastewater can be controlled within lOOmg/L with the input concentration of 9500mg/L and reach the emission standard, the concentration of Cl'is reduced from 24055mg/L to 15103mg/L at the same time, in this condition, the cost of disposing wastewater is about RMB 12 Yuan per ton.The tandem technique of nanofiltration technology and air-stripping technology has the virtue of efficient removal ratio without secondary pollution. The high strength wastewater can be reused and the disposal cost is reduced then.