Treatment of Wastewater by Carbon Adsorption from Activated Carbon Equipment

Activated carbon has the capability of adsorbing mercury and mercury compounds, but its adsorptive capacity is limited, so it is only suitable for treating wastewater with low mercury content. If the concentration of mercury is high, it can be treated by chemical precipitation method. After treatment, the mercury content is about 1 mg/L, which can reach 2-3 mg/L at high level. Then activated carbon can be used for further treatment.

3.4 Activated Carbon for Treatment of Phenolic Wastewater
Phenolic wastewater is widely derived from petrochemical plants, resin plants, coking plants and refineries. Experiments show that the adsorption performance of activated carbon on phenol is good, the increase of temperature is not conducive to adsorption, so that the adsorption capacity decreases, but the time to reach adsorption equilibrium is shortened when the temperature is raised. There is an optimum amount of activated carbon and adsorption time. Under acidic and neutral conditions, the removal rate does not change much. Under strong alkaline conditions, the removal rate of phenol decreases sharply, and the stronger the alkalinity, the worse the adsorption effect.
3.5 Activated Carbon Equipment for Treatment of Wastewater Containing Methanol
Activated carbon can adsorb methanol, but its adsorptive capacity is not strong. It is only suitable for treating wastewater with low methanol content. The results of engineering operation show that the COD of mixed liquor can be reduced from 40 mg/L to less than 12 mg/L, and the removal rate of methanol can reach 93.16%~100%. The effluent quality can meet the water quality requirement of water reused to boiler desalination system [9].
3.6 Refinery Advanced Treatment
Oily wastewater from refineries is treated by oil isolation, air flotation and biological treatment, and is further treated by sand filtration and activated carbon filtration. The phenol content in wastewater decreased from 0.1 mg/L (after biological treatment) to 0.005 mg/L, cyanide from 0.19 mg/L to 0.048 mg/L, and COD from 85 mg/L to 18 mg/L.
4 Prospects
With the progress of science and technology and the special requirements of wastewater treatment, the research of activated carbon has gradually developed from its pore structure and specific surface area to the effect of surface functional groups on the adsorption performance of activated carbon.
For example, activated carbon fibers (ACF) have attracted the attention of researchers in wastewater treatment in recent years. Its diameter is generally 5-20 um. The preparation principle of ACF is the same as that of traditional activated carbon, i.e. activated carbon fibers are treated with steam or carbon dioxide at 800 C or above. The pore structure of fibrous activated carbon is mainly microporous, with few mesoporous and almost no macroporous, and its specific surface area can reach 2500 m2/g. It has the characteristics of high adsorption and desorption rate, large adsorption capacity and high conductivity.
The experimental results show that the adsorption capacity of ACF for phenol is 248 mg/g, and the adsorption capacity is almost unchanged after several regeneration after adsorption saturation. The adsorption performance of ACF is better than that of activated carbon. At room temperature, under acidic or neutral conditions, 0.5g activated carbon fibers were added to phenol-containing simulated wastewater with a concentration of 282mg/L at 100mL, and the phenol removal rate could reach 91% after 30 minutes of constant temperature oscillation.
Recently, it has been found that activated carbon not only has adsorption properties, but also exhibits catalytic properties. The catalytic oxidation method developed from this has attracted more and more attention, and its research is also deepening. In order to improve the treatment efficiency, starting from the study of catalytic oxidation mechanism, the surface structure of activated carbon was changed, the ability of activated carbon was improved, and the ideal adsorbent was found.