Study On Treatment Of Coking Wastewater With Aerobic Fixed Bed–Coagulation–Fenton Oxidation Process

The amount of coking wastewater is increasing along with the development of Chinese coke industry. Coke industry has become one of industries which cause severely environmental pollution. So the development of treatment process for coking wastewater becomes an important task in Chinese wastewater treatment field. During the experiment of treating wastewater from one coke plant, the possibility and feasibility of aerobic fixed bed-coagulation-Fenton oxidation were being studied.Aerobic fixed bed is a kind of biofilm treatment process. A great amount of microorganism is fixed in the packing. Microorganism can degrade not only organic pollutants such as phenol, benzene, naphthalene, pyridine, anthracene and other PAHS, but also inorganic pollutants such as ammonia-nitrogen, cyanide, sulfide etc. efficiently. When HRT is 48 h, the value of COD can be decreased to 500 mg/L from 6000 mg/L. The value of ammonia can be decreased to 10 mg/L from 140 mg/L. The value of phenol can be decreased to 0.1 mg/L from 1000 mg/L. The value of cyanide can be decreased to 0.1 mg/L from 30 mg/L. The value of sulfide can be decreased to 0.6 mg/L from 34 mg/L. Aerobic fixed bed can resist shock load of wastewater and have a stable treatment effect.Coagulation is a traditional chemical treatment process. By experiment, the FeSO4 was used to treat the effluent from aerobic fixed bed. SS and part of organics can be removed. At the same time, the color of the effluent is also decreased. When the dosage of FeSO4 is 1367 mg/L, the COD of the effluent after coagulation is about 430 mg/L or so.Fenton oxidation is a kind of advanced oxidation technique.·OH which is formed in reaction process has strong oxidation ability. If the dosage of FeSO4 is 1367 mg/L, the dosage of H2O2 is 825 mg/L, and the pH keeps at 3, the reaction time is 4h, the COD of effluent can be decreased to 150 mg/L below.The combined process of aerobic fixed bed-coagulation-Fenton oxidation is a good solution of the coke wastewater treatment. It only need little reforms to the original treatment plant. The new process need no additional area and operators. The operation and management cost is also not increased.