Research On Treatment Of Coal Gasification Wastewater By UASB-BioAX-Ozone-Fluidized Bed Combined Process

Coal gasification wastewater is a kind of high concentrated organic wastewater, which contains complicated ingredients and a great variety of pollutants and which is great toxic. It has the characteristics of high COD, being hard to biodegrade, great diversity quality and quantity and high color. As an industrial wastewater, it is very difficult to treat. Now, the treatment technologies of coal gasification wastewater from abroad and domestic usually had several problems, such as unsatisfactory effluents, poor stability and high handling costs.This article introduces the forming and characteristics of the coal gasification wastewater and makes a comprehensive review of its treatment technology. It is presented that:Combined Treatment Process Route of Coal Gasification Wastewater after pretreatment including anaerobic (A)-aerobic (O)-O3-fluidized bed and Laboratory-scale were carried out for long time. The experimental research of the process of optimal technological parameters.And the experimental results show below.The research shows that the pretreatment of high concentration wastewater by micro-aerobic hydrolysis acidification reactor is effective, thus greatly improving the biodegradability of wastewater. The optimal hydraulic retention time of anaerobic acidification was48h.And the removal ratio of COD, T-ph and NH4-N were49%,20%and10%respectively; Erobic have the characteristics of stability of effluent water quality. The optimal hydraulic retention time of erobic was30h.And the removal ratio of COD, T-ph and NH4-N were36%,68%and60%respectively; The experimental results showed that biodegradability of wastewater was significantly improved and the color was obviously removed by O3as the pretreatment process. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable.The COD removal efficiency was improved with an increase in ozone concentration. Ozone aeration rate and reaction time were1L/min and30min. And the removal ratio of COD, T-ph and NH4-N were7%,12%and0respectively; For biological degradability of coal gas wastewater is low and the single use of physical-chemical treatment is high in the cost, it is necessary to improve biological degradability of coal gasification wastewater through chemical pre-oxidation method, and then go on biological treatment. In this paper, advanced treatment of O3-fluidized bed achieved good results. The optimal hydraulic retention time of fluidized bed was20h.And the removal ratio of COD and NH4-N were4%and30%respectively.The experience of UASB-BioAX-Ozone-Fluidized bed combined process used for treating coal gasification wastewater is introduced during the influent water at the case of below1500mg/L of COD,100mg/L of NH4-N,320mg/L of T-ph and180mg/L of V-ph. The process was efficiency and the removal ratio of COD, NF4-Nand T-ph were95%,100%and96%respectively. In conclusion, the concentration of COD and NH3-N is lower than20mg/L and2mg/L, respectively. The effluent water can meet the first class of the Integrated Wastewater Discharge Standard (GB8978—1996), having the characteristics of impact resistance load and stability of effluent water quality.In the process solution, the inhibition of the decomposition of NH4+-N and persistent organic substances due to toxic substances in coal gasification wastewater is resolved. Thus the total removal ratio of the COD and NH4+-N is improved. It is an effective as well as promising combined process for advanced treatment of the secondary effluent for reuse purpose.