Study On Treatment Of Biologically Treated Semi-Coking Wastewater By Fenton Oxidation With Activated Carbon Assistance

As a new kind of carbon material, semi-coking are widely used in various load industries. With the continuous increase of requirements, the scale of production becomes lager, which causes the wastewater increases significantly. Because both the semi-coke production (low temperature coke) and the coke production (high temperature coke) are coking industry, the production itself and the wastewater produced during the productive process are similar though. Thus lots of semi-coking companies apply the biological systems like most of coking plants to processing the wastewater. However, the depth of the process is not enough. Although the organics content of output water is falling strongly, the indice can't meet the national standard. Therefore the study of reducing the pollutants of the biologically treated semi-coking wastewater has great applications.Because of the late beginning of large-scale production, there is few report about the treatment of semi-coking wastewater. So according to review of the various treatment methods of coking wastewater, Fenton oxidation with activated carbon assistance system appeared to be applicable for the treatment of biologically treated semi-coking wastewater. The processes of Fenton oxidation treatment, activated carbon adsorption treatment or Fenton oxidation with activated carbon assistance treatment for the biologically treated industrial wastewater were investigated. The effects of different factors on processing results were discussed and the reasons which may lead to its generating were analyzed, at last the optimum technological parameters were obtained. The function of activated carbon was testified.In the treatment of semi-coking wastewater using activated carbon adsorption, the maximum removal efficiency of COD could reach to 61.8% ; and the amount of COD, after treated, is 231mg/L, under the condition of pH=7, adsorption time 30min, temperature 30 , with the dosage of activated carbon is 5g/L. The indice after removal haven't been met the second demand of the integrated wastewater discharge standard (GB8978-1996).In the treatment of semi-coking wastewater using Fenton oxidation, the maximum removal efficiency of color and COD could reach to 81% and 72.3% respectively; and the amount of COD, after treated, is 167mg/L, under the condition of pH=4, oxidation time 30min, with the dosage of FeSO₄·7H₂O and H₂O₂ is 1500mg/L and 1200mg/L respectively. The indices after removal haven't been met the second demand of the integrated wastewater discharge standard (GB8978-1996).In the treatment of semi-coking wastewater using Fenton oxidation with activated carbon assistance, the maximum removal efficiency of color and COD could reach to 90% and 85.7% respectively; and the amount of COD, after treated, is 86mg/L, under the condition of pH=4, oxidation time 30min, with the dosage of FeSO₄·7H₂O and H₂O₂ is 1000mg/L and 1200mg/L respectively. The indices after removal haven't been met the second demand of the integrated wastewater discharge standard (GB8978-1996). Compared with Fenton oxidation, the dosage of FeSO₄·7H₂O using in this method decrease 500mg/L. The removal efficiency of color and COD is improved by 9% and 14.3% respectively.It is proved that activated carbon play a part in adsorbent and catalyst. And the activated carbon can reuse many times.This shows that the method of Fenton oxidation with activated carbon assistance, which is used in the treatment of semi-coking wastewater, has high potential value and broad application prospect. In the meantime, it can be also used for the reference in wastewater treatment which is unbiodegradation and low concentration.