Pilot Study On Advanced Treatment Of Coking Wastewater With Biological Activated Carbon Technology Based On Effective Compound Bacteria

The coking wastewater after secondary biological processing still contains avariety of organics and inorganic salts which are high toxic and difficult to bedegraded by microorganisms, particularly, polycyclic aromatic hydrocarbons andheterocyclic aromatics hydrocarbons are difficult to be biodegraded. According tothe characteristics of coking wastewater from secondary treatment, the Subject wasbased on degrading strains with independent intellectual property which wereisolated and screened for refractory organics in coking wastewater. Pilot scale studywas conducted in biological treatment plant of coking company Wuhan iron and steelcooperation where the self-built pilot scale study device was estabilished.Preparation of biological activated carbon in the self-designed wastewaterpurification tower by physical adsorption immobilization method with intermittentcycle was applied to advanced treatment for coking wastewater in order to satisfy thereuse standards of reclaimed water.The research result indicated:(1) The results of determination of biomass anddehydrogenase activity on BAC as well as scanning electron microscope observationshows that the microorganisms on the BAC grow well and microbial degradationactivity of wastewater purification tower is higher;CODCrof effluent could bereduced to less than60mg.L-1, whose removal rate basically reached50%, andchromaticity of effluent was no more than50degrees, whose removal rate reached70%.(2) The CODCrand chromaticity removal rate were declined in linearly withincreasing of flow as well as the variety trend was basic consistent of CODCrremoval rate and temperature;the purification tower with high removal rate whenwastewater temperature close to30degrees.(3) The removal of organics inwastewater by the purification tower mainly concentrates in the middle and lowerlayer of activated carbon, the CODCrremoval rate of which accounts for77.6%ofthe total; with the increase of concentration of coking wastewater, the removal rate of CODCrand UV254increased at first and then decreased, has a little influence onthe Chromaticity removal rate.(4) Under different hydraulic loading, through modelanalysis and data fitting, the degradation kinetic equation of wastewater purificationtower: Ce/CO=exp{-2.4064H/L0.962}, through the verification of the dynamicequations, the predicted value and the measured data are basically consistent.(5) Thewastewater purification tower using air-water backwashing process and hydraulicloading is2～3L/m2.s, aeration loading of3～4L/m2.s, backwash cycle is10days,backwashing time25min.(6) The effluent compared to inflow absorption in the UVregion decreased significantly in the Pilot scale test period;the results of theGC-MS analysis of the effluent show that BAC technology did well in degradationof refractory organic compounds in coking wastewater;the results of the GC-MSanalysis report of ammonia stripper wastewater and recycled water indicated thatlarge number of long-chain alkanes in outflow water comes from recycled water.(7)the result of the economic analysis for advanced treatment of coking wastewaterby biological activated carbon technology with the processing capacity of100m3/hwas1.47yuan/T (power consumption by1yuan/kWh).