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

Coking wastewater from the secondary biological processing system still contains a varietyof harmful organic compounds, including polycyclic aromatic hydrocarbons and heterocyclicaromatics which are difficult to biodegrade. According to the characteristics of cokingwastewater from secondary treatment, effective compound bacteria technology arises at thehistoric moment, and has achieved good results. Effective compound bacteria with independentintellectual property were built and biological activated carbon （BAC） which combines effectivecompound bacteria with granular activated carbon was applied to advanced treatment for cokingwastewater in order to satisfy the reuse standards of reclaimed water.The research result showed:（1） Compound bacteria which composed of strains B, Y-4, P,W-1, W-2at the ratio of2:2:0.5:1.5:1（volume ratio of bacterium suspension） had the highestdegradation rate to simulated wastewater, which could reach86.76%within96h. Effectivecompound bacteria were mesophilic and basophilic.（2） Response surface methodology was usedto achieve the highest degradation rate, and the opimal levels included pH of7, temperature of34℃andshaking speed of170r·min^-1. The average degradation rate of organics reached90.3%under the optimized conditions, and the degradation rate of naphthalene, pyridine andisoquinoline were100%,91%and80%respectively. In a real environment of coking wastewater,the average degradation rate of organics was up to72.4%.（3） The degradation rate of organicmatters increased from89.4%to96.7%with glucose of200mg·L^-1; however cometabolismsubstrates soluble starch and phthalate acid hardly had an effect on degradation rate of mixedorganic matters. The degradation rate of simulated wastewater by effective compound bacteriawas much higher than a single strain B, P, Y-4, W-1and W-2. Effective compound bacteria alsocould degrade a wider variety of organic matters.（4） The bacteria on activated carbon pretreatedby hydrochloric acid grew actively, and the removal rate of COD_Crwas much higher. After beingused for16times continuously, the removal rate of COD_Crby BAC made with effectivecompound bacteria still could reach65%and removal rate of UV254could reach90%, which wassignificantly higher than other kinds of BAC made with single strain.（5） With BAC based onhighly effective compound bacteria being applied to continuous advanced treatment for cokingwastewater, COD_Crof effluent could be reduced to less than50mg·L^-1, whose removal ratebasically reached70%, and chromaticity of effluent was no more than50degrees, whoseremoval rate reached90%.（6） When the water flow was less than2.5mL·min^-1, COD_Crofeffluent satisfied the reuse standards of reclaimed water. Removal of organic matter mainlyconcentrated on the lower part of the column of activated carbon, so at the bottom of BACcolumn the dehydrogenase activity was the highest. When the water temperature was from25to32℃, the water quality of effluent was better than the environment with low temperature.（7）According to analysis result of GC-MS, some organic matters in effluent still could not becompletely degraded, which mainly include phthalates, long-chain alkanes and so on.