Research On Pretreating Ammonium-nitrogen Wastewater With High Concentration By The Jion Technology Of Ultrasonic Stripping-Chemical Precipitation And Comprehensive Utilization

With the rapidly development of the agriculture and industry, the problems of nitrogen pollution on waters are getting worse and make people keep an eye on them. The ammonia nitrogen is the main of the water eutrophication and it can be transformed into nitrite which can cause cancer in human body. The treatment of ammonia nitrogen wastewater is still a problem in China. The studies of economical and effective denitrification technique have been becoming key points and hot spots in water pollution control engineering.The treatment of petrochemical wastewater is a burning question in the worldwide because of the complex water quality, low treatment efficiency and high treatment cost. The optimum process flow was proposed in the paper on the basis of the study of a great deal references, petrochemical corporation case and considering the environmental protection, resources saving and the ability to shoulder economically of the corporation. Some conclusions are gained as follows:1. The application of the ultrasonic stripping-chemical precipitation-A/O multiple techniques on the treatment of ammonia nitrogen wastewater with high concentration showed a fairly good treatment effect. When the inlet's average ammonia nitrogen concentration is 3450mg/L and a steady outlet's concentration of 51.7mg/L was achieved. And the outlet's concentration can meet the A/O process' inlet's demands of ammonia nitrogen concentration. The specific process flow and the treatment effect are as follows:The ammonia nitrogen wastewater(NH₃-N initial concentration was 3450mg/L) was gathered in the adjusting tank firstly across the pipeline to adjust the quality and quantity, then lift to the ultrasonic purging-tower and conditioned the pH 11. The purging process was operated with gas-liquid ratio 800:1, time 45min, water temperature 40℃and the power 80W. The purged NH₃ was absorbed with dilute hydrochloric acid and the products NH₄Cl was returned to the ammonium fertilizer's producing system. The outlet's from the ultrasonic purging-tower(NH₃-N concentration was 345mg/L) was inpoured into chemical precipitation separation reactor across transitional pool to go further denitrification treatment, The denitrification process was operated with the chemical medicament MgCl₂·6H₂O and Na₂HPO₄·12H₂O, pH 11, Mg:P:N(the mol ratio)=1.2:1:1, time 10min, precipitation time 25min, and the outlet's ammonia nitrogen concentration was 51.7mg/L, it can make the A/O process' needs. The precipitation MAP was returned by centrifuge and sold.2. The multiple techniques has a low cost, good treatment effect, no secondary pollution, simple operation, easy management and a good promotional value.