Experimental Study Of Advanced Treatment Of Coking Wastewater

The composition of coking wastewater, which containing colour and a large number of organic pollutants which is difficult to biodegradation, is very complex. Hence, the pollution of the wastewater from coking industry has been the focus in the field of industrial and environmental sector. China is the largest producer of coke in the world and a large amount of coking wastewater discharge to the surrounding which cause serious pollution. With the further increasing of environmental protection management strength and the serious shortage of water resources, the discharge standard will be more stricter. So, the advanced treatment of coking wastewater becomes very urgent .Because the area of Shandong province lacks of water resource, the government and corporates pay much attention to environmental pollution.The subject is the branch of the project which is the research on regional wastewater recycling and demonstration.In the paper, COD_cr and chroma are the main indexs of evaluation and controling optimum operation conditions. The advanced treatment study of coking wastewater was carried out by experiments of coagulation, activated carbon adsorption, O₃ oxidation and biological filtration. The experimental combining processes of O₃ oxidation-biological plus activated carbon adsorption, PAC coagulation plus activated carbon adsorption and PAC coagulation plus O₃ oxidation were adopted respectively on the basis of single factor optimization. The economic parameters of the processes were analyzed. The methods of the preliminary experimental study and theoretical analysis for wastewater recycling and the advanced treatment of coking wastewater were done in this paper.Experimental results showed as following:(1)The optimum pH value of PAC and PFS are 7.0; the optimum coagulant dosage are 6.0g/L and 5.5g/L respectively; the removal efficiency of COD_cr are 44.83% and 38.71% respectively, the color removal efficiency of the two are 80.0%.(2)The effects of pH and temperature on the removal efficiency of COD_cr and color with activated carbon treatment process are not significant; the third category activated carbon treatment was the optimum and the optimum dosage is 20g/L, the optimum adsorption time is 20 min.(3)O₃ oxidation experiment the optimum access time is 35min, the removal rate of COD_cr is 63.25% and removal rate of color is 96%.(4)Biological activated carbon treatment is the optimum method in Biological filtration experiments, the removal rate of COD_cr is 51.90% and removal rate of color is 80%.(5)Five processes of combining treatment experiments all can reach the national discharge standards, the optimum result is the process of the O₃ oxidation plus biological activated carbon adsorption, the second is the process of O₃ oxidation plus activated carbon adsorption, the last is the process the PAC coagulation plus activated carbon adsorption.