Research on activated carbon adsorption of biologically treated coking wastewater and its condition optimization

Key words: 
• coking wastewater /
• organic pollutants /
• activated carbon /
• selection /
• optimization

Abstract: The over standard of the COD and the color value mainly resulted from the refractory organics existing in the biologically treated coking wastewater. In this work, the adsorption of these organic compounds on activated carbons (AC) was studied through adopting different kinds of AC, modifying the surface chemical properties of AC, and optimizing the adsorption conditions. Taking the biologically treated coking wastewater from a 1 320 m3/d scaled A/O/H/O process as an object of study, the COD and the color values of the wastewater treated by 13 kinds of AC were analyzed. The results indicated that the AC with higher methylene blue value and tannic acid value had a higher adsorption capability, while after the modification of the AC surface, AC with less acid functional groups were advantageous in enhancing the adsorption capacity. Furthermore, it was found that the AC had higher adsorption capacity under lower pH value conditions, and the aeration could shorten the adsorption equilibrium time. The COD and the color values of the biologically treated coking wastewater could be reduced by the optimal AC under a suitable reaction condition to below 60 mg/L and 20 times, respectively, which could satisfy the industrial circulating cooling water quality under low operating cost conditions.