Studying On The Removal Ammonia Of Coking Wastewater Pretreated With Coal Gas Flow Desorption In Pilot-scale

In recent years, with the economic development and the accelerated urbanization, water shortage and pollution is getting worse in China. Ammonia nitrogen becomes the one of main pollutants causing water eutrophication because the emissions of nitrogen compounds increase dramatically and especially high concentration ammonia nitrogen wastewater is more serious to pollution of water. Coking plant wastewater comes from the surplus ammonia water, which is treated commonly by combination of pretreatment and biological treatment process, and its water quality only meet the national emission standard partly. The advanced treatment of coking plant wastewater can increase the cycling rate of wastewater and control the pollution of water, besides, it can satisfy the low-carbon economy development model.There is no a treatment technology of ammonia wastewater can meet the demand of cost-effective and no-secondary pollution treatment technology. At the situation that current coking plant wastewater can not meet the discharge standard of ammonia nitrogen, this research pre-disposes coking plant ammonia through the"coal gas adsorption process"instead of ammonia stripping with water steam method. The treatment technology of this research create favorable conditions for the following biological treatment and advanced treatment.The results of research show that: In the small-scale industry experiment, this paper researches the effect of temperature named T, gas-liquid ratio named n, pH, desorption additive dosage namedρ, time named t et al on the removing rate of ammonia nitrogen, the most good desorption conditions is:T=90℃, n=850:1,ρ=20 mg·L-1, pH=10.4, t=120min, in this condition, the removing rate of ammonia nitrogen is 94.79%, the concentration of residual ammonia nitrogen is 194 mg·L-1, which meet the water requirements of biochemistry treatment fully. Besides, this paper develops visual control system though software like STEP7-Micro/Win, WinCC, PC Access et al so as to monitor and collect test parameters, the system is stable and the data is reliable. This paper also analyzes the removal of ammonia nitrogen by the desorption of coal gas flow theoretically, the process is a gas-liquid mass transfer process with chemical reaction base on the chemical equilibrium theory and two-film theory. Take coke plant whose output is 6 million tons coke a year as example, compared with ammonia stripping process, the technology in this paper can reduce the dosage of steam about 376,600 tons and sodium carbonate about 5700 tons a year. Therefore, the coal gas stripping and adsorption process used for removing ammonia nitrogen from surplus ammonia water is an energy saving technology and has a bright future.