多相催化臭氧化处理采油废水试验研究

RESEARCH ON THE HETEROGENEOUS CATALYTIC OZONATION TO TREAT THE OIL-FIELD WASTEWATER

采用多相催化臭氧化技术在实验室条件下去除采油废水中的COD。考察了催化剂的种类、吸附作用和投加量以及pH、反应时间、HCO3-和CO32-对多相催化臭氧化去除采油废水COD的影响。试验最佳工艺条件为:臭氧质量浓度为80 mg.L-1、催化剂为A3、催化剂投加量为1 000 mg.L-1、pH为10.8和反应时间为50 min。结果表明,在最佳工艺条件下,采用A3/O3氧化工艺处理采油废水,COD去除率可达到79.40%,比O3、A1/O3和A2/O33种氧化工艺对COD的去除率分别提高了33.00%、14.00%和18.10%,出水COD为118.450 mg.L-1,达到了国家污水综合排放标准的二级排放标准;催化剂对采油废水中的有机物具有一定的吸附作用;pH对反应影响显著,pH越大越有利于COD的去除;COD去除率随反应时间的延长其增幅逐渐减小,最终趋于平衡;HCO3-和CO32-对多相催化臭氧化去除COD的效果具有很大的抑制作用,在HCO3-和CO32-质量浓度为200 mg.L-1时,COD去除率分别为39.89%和27.59%,比HCO3-和CO32-质量浓度为0 mg.L-1时的COD去除率分别降低了39.51%和51.81%,试验还发现,CO32-对自由基的抑制作用强于HCO3-。这在某种程度上证明了多相催化臭氧化对有机物的降解遵循羟基自由基氧化机理。

The heterogeneous catalytic ozonation process for COD of oil-field wastewater in laboratory condition was investigated.The effects of the type and adsorption and dosage of catalyst,pH value,reaction time,HCO3-and CO32-on the heterogeneous catalytic ozonation for the removal of COD were studied.The optimum conditions were as follows： the ozone density was 80 mg·L-1,the catalyst was A3,the catalyst dosage was 100 mg·L-1,initial pH value was 10.8 and reaction time was 50 min.The results indicated that the removal rate of COD reached 79.40% under the optimum conditions,which was increase by 33.00%,14.00% and 18.10% respectively compared with O3,A1/O3 and A2/O3,the concentration of COD in the effluent was 118.45 mg·L-1,which can meet the second discharge standard specified in the Integrated Wastewater Discharge Standard.The catalyst had certainly absorption to some organics in oil-field wastewater;the pH value had more influence on the reaction,and it helpful to removal the COD with higher pH value;and a suitable long reaction time may helpful to increase the COD removal rate.The HCO3-and CO32-had greatly inhibiting on the degradation efficiency of the COD in the heterogeneous catalytic ozonation,the COD removal rate obtained 39.89% and 27.59% when the concentration of HCO3-and CO32-was 200 mg·L-1,which were increased by 39.51% and 51.81% respectively compared with the concentration of HCO3-and CO32-was 0 mg·L-1.The experimental research found that CO32-had obvious scavenging effective to inhibiting the formation of hydroxyl radical than HCO3-.It had proved that the degradation of organic in the heterogeneous catalytic ozonation process followed the mechanism of oxidization by hydroxyl free radical（·OH）,to a certain extent.