Pretreatment Of Coking Wastewater With Electrochemistry

Coking wastewater is from the process of making coke, purifying coal gas and recovering the coking oil. The components of coking wastewater are very complex, in which there are higher concentrations of the pollutants, color and toxics. The bacteria in biological water treatment systems are inhibited and poisoned by phenol, polycyclic aromatic hydrocarbons and other organic matter in the wastewater. So it is unfeasible to treat the coking wastewater only with traditional biological methods, and some pretreatment must be used prior to biological methods.The pretreatment of coking wastewater was studied with carbon steel scraps and active carbon mixed and electrochemical electrolysis method and the removal mechanism of COD in coking wastewater was also researched with corrosion electrochemical principle. It was found that carbon steel scraps and active carbon mixed reactor effectively removed COD in coking wastewater and the removal rate of COD was up to 80%. There were no obvious effects of pH values on the COD removal of coking wastewater in two hours or so reaction time, and that the COD removal rate was increased 5% or so by adding flocculent. The electrolysis voltage, the electrolysis time, distance between electrodes and electrode material are the main factors when treated by electrochemistry. The experimental results showed that voltage of 0.3V, electrolysis time of 2h, distance of 100mm and carbon steel as electrode material were the most excellent electrolytic processing parameters. And the removal rates of COD was up to 45%.The removal mechanism of COD in coking wastewater was studied by cyclic voltammetry and polarization method. It was found that the COD removal of coking wastewater was done with carbon steel scraps and active carbon mixed reactor and electrochemical electrolysis method mainly through electro-coagulation.