Because activated carbon has high requirements in water preprocessing and the price is expensive, it is mainly used to remove micro pollutant in wastewater to achieve the purpose of purification.
1. Used for treating chrome-containing wastewater
Chromium is a larger dosage mental material in electroplating. Hexavalent Chrome is existed with different forms for the different PH. Activated carbon has very advanced microporous structure, large specific surface area and strong physical adsorption can effectively adsorb Cr (VI) in wastewater. The surface of activated carbon owns a plenty of oxygen groups such as hydroxy (-OH), carboxyl (-COOH), etc. all of which have static adsorption function can make chemical adsorption effect for Cr (VI). After absorption the wastewater can achieve national discharge standards. Experiment shows that Cr (VI) mass concentration in solution is 50 mg/L, PH is 3, adsorption time is 1.5h, the activated carbon adsorption and strainaway rate of Cr (VI) can achieve best results. So the process of using activated carbon to treat chromium-containing wastewater is the result of comprehensive effect of physical adsorption chemical adsorption, chemical reduction of Cr (VI) and etc. in solution. Activated carbon is used to treat chromium-containing waste water, which is stable adsorption, high processing efficiency, low operating cost, and has some social and economic benefits.
2. Used for treating cyanide-containing wastewater
In industrial production gold and silver wet extraction, Chemical fiber production, coking, ammonia synthesis, electrofacing, gas production and etc. all use cyanide or byproduct cyanide. So in the process of production must emissions a certain number of cyanide-containing wastewater. Activated carbon used for wastewater purification has a long history. There are more and more reports about applying to cyanogens-contained wastewater. But because activated carbon has small adsorption capacity of the CN HCN, it is not worthwhile in handling costs.
3. Used for treating mercury -containing wastewater
Activated carbon has the performance of adsorbing mercury and mercuride, but the adsorption ability is limited, just suitable for treating low mercury content wastewater. If there are higher concentration of mercury in water, firstly can use chemical precipitation method to treat, after treating mercury is about 1 mg/L, even can reach 2—3 mg/L, secondly can use activated carbon do further treatment.
4. Used for treating phenol -containing wastewater
The phenol-containing wastewater comes from petrochemical plant, resin factory, coking plant and refining plant. Proved by the experiment that activated carbon has good ability to adsorb phenol, rising temperature goes against adsorption, which will make adsorption capacity become small, but the time of adsorption equilibrium becomes short for elevated temperature. The dosage and adsorption time of activated carbon have optimum value, in acidic and neutral condition the removal rate has not changed much, in strong alkaline condition phenol removal rate falls sharply, the more alkaline is, the worth adsorption effect.
5. Used for treating methanol -containing wastewater
Activated carbon can adsorb methanol, but the adsorption capacity is not strong, just suitable for the treatment of low methanol-containing wastewater. Engineering operation shows that we can make the COD of the mixture liquor from 40mg/L drop to 12mg/L, the removal rate of methanol can reach 93.16%---100%. So the outlet water quality can satisfy the standard of reusing into the boiler water desalination water system.