Study On The Diffluent Disposal Of The Wastewater From Coke Plant

Coke plant wastewater is a kind of low biodegradability wastewater and hard to dispose because of the large amount of drainage and high concentration of toxic organic compounds. The diverse effluents from coke plant's different sections contain discrepant ingredients and the quantity of each effluent is also different. As Chinese coke production is increasing year by year, coking wastewater pollution has also increased. The traditional chemical and biological approaches are difficult to meet the environmental protection requirements. Based on the in-site investigation, the process of coking and different kind of wastewater from the coke-gas plant in Tangshan Steel Co. is studied, and seven pollution indicators of six effluents are detected respectively. The equivalent pollution load method is adopted to analyze the strength of each effluent and pollutant. The idea of diffluent disposal is brought forward for the treating of various quality and quantity wastewater from the emission source. Some advanced oxidation processes like the supercritical water oxidation, UV catalytic TiO2, ozonation and several integrated methods are carried out for the experiments of treating wastewater from tar and benzene extraction process.Based on the idea of separate treating for different drainage, experiments of supercritical water oxidation (SCWO) treating wastewater containing high concentration of phenol and other pollutants from coke plant's tar extraction process are designed and conducted in a batch reactor. The orthogonal tests study under different conditions of temperature, pressure, reaction time and degree of excess oxygen-hydrogen peroxide show the optional reaction conditions are as follows: T=420℃, P=25MPa, Time=30min, and degree of excess oxygen one, under which the CODCr removal from the treated wastewater is 99.1%. Except NH4+-N, other indicators meet the second order of GB13456-92. The adding of homogeneous catalyst Cu (NO3)2 will further enhance the efficiency of the CODCr conversion.The mainly product of SCWO, as detected by gas chromatography is O2, N2, CO2. The experiment results indicate that the supercritical water oxidation (SCWO) technique is satisfactory for the treatment of high concentration organic pollutant and small flow rate wastewater from the coke plant.Another kind of wastewater from coke plant, benzene extraction wastewater is treated by some other advanced oxidation process.The organic component in it is analyzed by GC-MS apparatus. After that, different treating method like ultraviolet catalyzing nano TiO2 particles, ozone oxidation, ultrasound operation and their combined technique are adopted to treat the water. The regularity of CODCr removal is obtained and the effects of those method and their united techniques are compared. Ozone oxidation together with UV and TiO2 nano-particles shows a synergistic effect as the CODCr removal rate is higher when they are adopted together. After treating for two hours and deposited for three hours, ultrasonic method with ozone oxidation can remove CODCr up to 60%, which is the best result.