| Coking wastewater is produced by the pyrolysis (heating in absence of air) of suitable grades of coal, coal gas purifying and in the process of refining chemical products. There are many pollutants in the wastewater, such as hydroxybenzene, ammonia (usually recovered ammonium sulfate), cyanogen , phenol, indole uinnoline and so on.. Components in the wastewater are very complicated. Concentration of the pollutants, its color and toxicity are high. And its character is stabilized. Coking wastewater is a kind of typical refractory one. In the study. the method of coagulation- air flotation was adopted to treat coking wastewater.The process of air flotation is often used in the treatment of water and waster water as an effective method to separate the solid form the water. In order to make full use of the removal capability of it, it is usual to cast coagulant into wastewater to make the pollutant unstable and coagulated so as to make the water purified. Most of studies of coagulation were carried out based on the sedimentation at present. In this paper, the research studies feasibility that coagulant-air flotation acts as pretreatment. The experimental results show coagulant consumption is low, the flotation time is short and the purification efficiency is high. The purification efficiency of turbidity , chroma and COD are98.8%, 57.1% and 57.3% respectively. Different coagulation have different efficiency. If complex reagent is adopted, its purification efficiency is higher and its consumption is lower than the corresponding index of the single coagulation.Electro-coagulation dealing with coking wastewater goes on the discussion also in testing, the result of the test indicates that there has an effect that electro-coagulation dealing with coking wastewater. When turbidity of the wastewater is 190, chroma is 275, COD is 3250mg/L, after electro-coagulation deals with coking wateswater, the purification efficiency of turbidity . chroma and COD are 99.6%, 54.89% and 22.89% respectively.
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