Fenton法处理焦化废水的试验研究

THE STUDY OF TREATING COKING WASTEWATER USING FENTON METHOD

目的确定Fenton法对焦化废水深度处理的去除率、投药比和反应时间。方法选取生化后的二沉出水,加入硫酸调节水样pH值至3.5,加入H_2O_2氧化剂和FeSO_4催化剂,在充分搅拌条件下,由Fe^(2+)催化H_2O_2反应产生羟基自由基(·OH),利用其超强氧化能力深度分解氧化有机物,从而有效去除废水中生物难分解的COD。通过调节H_2O_2、Fe^(2+)用量以及记录不同反应时间下的结果,从而分析出COD最佳去除率的COD:H_2O_2:FeSO_4的摩尔比以及反应时间,以便确定工程应用时的最佳工艺条件。结果通过试验得知,COD:H_2O_2的摩尔比为1∶4时是比较理想的投加比,随着Fe^(2+)投入量的增加,COD去除效果先增加后下降,继续增加Fe^(2+)用量后COD去除率再次上升随后又下降,其变化曲线呈M状,最高去除率为84.6%。随着反应时间的延长,COD去除率上升,在20~30 min左右基本趋于稳定。结论利用Fenton试剂处理对焦化废水进行深度处理时,Fenton药剂投加比与COD去除率的关联曲线为"M"型;药剂最佳投加摩尔比有两个区间,即COD:H_2O_2:FeSO_4=1:4:2.5~3和1:4:4~4.5区间,应避开效果不理想的1:4:3~4;从技术经济角度考虑,最佳反应时间可取30~45 min;控制好Fenton药剂投加比和反应时间,均能使出水COD降低至80 mg/L以下。

Objective Determine the removal rate, drug delivery ratio and reaction time of Fenton method for advanced treatment of coking wastewater. Methods Using water from secondary sedimention tank after biochemical treatment, adding sulphuric acid to adjust water pH value to 3.5, adding H2O2 oxygenant and FeSO4 catalyst. Under the condition of fully mixing,use Fe2＋ catalyst supported on H2O2 to make oOH, use its strong oxidation ability to decompose organic matter oxide deeply to remove COD, which is difficultly decomposed by biological action, in wastewater. Adjusting the dosage of H2O2,Fe^2＋ and recording the results under different reaction time, then analyze the best removal efficiency of COD on molar ratio of COD：H2O2：FeSO4 and reaction time, in order to determine the optimum process conditions of engineering application. Results The experiment results indicated that the optimum molar ratio of COD：I-I202 is 1：4, the removal efficiency of COD increase at first and then descend with the increase of Fe2＋ dosage, the removal efficiency of COD rising then falling again when continue to increase the dosage of Fe2＋, the shape of changing curve is ＂M＂, the best removal efficiency is 84.6 %. The removal efficiency of COD increasing tendency with the prolonging of reaction time, it will become stable after 20-30 min. Conclusion The shape of curve that Fenton reagent dosage and removal efficiency of COD is ＂M＂, when the coking wastewater is deeply treated by Fenton reagent ; there are two regions that the optimum molar ratio of COD： H202： FeSO4, 1：4：2.5-3 and 1：4：4-4.5, to avoid thel：4：3-4 region that result is not satisfactory; Considering economy and technology, the best reaction time is 30-45 min; It can make effluent COD reduced to less than 80 mg/L with a propriate control of Fenton dosage ratio and reaction time.