Mecha Achisa C, Onyango Maurice S, Ochieng Aoyi, Momba Maggy N B
Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa; Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Pretoria, South Africa E-mail:
Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa.
Water Sci Technol. 2016;74(3):756-65. doi: 10.2166/wst.2016.276.
The study investigates the influence of process parameters on the effectiveness of ozonation in the removal of organic micro-pollutants from wastewater. Primary and secondary municipal wastewater containing phenol was treated. The effect of operating parameters such as initial pH, ozone dosage, and initial contaminant concentration was studied. An increase in contaminant decomposition with pH (3-11) was observed. The contaminant removal efficiencies increased with an increase in ozone dose rate (5.5-36.17 mg L(-1) min(-1)). Furthermore, the ultraviolet absorbance (UV 254 nm) of the wastewater decreased during ozonation indicating the breakdown of complex organic compounds into low molecular weight organics. Along the reaction, the pH of wastewater decreased from 11 to around 8.5 due to the formation of intermediate acidic species. Moreover, the biodegradability of wastewaters, measured as biological and chemical oxygen demand (BOD5/COD), increased from 0.22 to 0.53. High ozone utilization efficiencies of up to 95% were attained thereby increasing the process efficiency; and they were dependent on the ozone dosage and pH of solution. Ozonation of secondary wastewater attained the South African water standards in terms of COD required for wastewater discharge and dissolved organic carbon in drinking water and increased significantly the biodegradability of primary wastewater.
该研究调查了工艺参数对臭氧化去除废水中有机微污染物效果的影响。对含有苯酚的城市一级和二级废水进行了处理。研究了初始pH值、臭氧剂量和初始污染物浓度等运行参数的影响。观察到随着pH值（3 - 11）升高，污染物分解增加。污染物去除效率随着臭氧剂量率（5.5 - 36.17 mg L(-1) min(-1)）的增加而提高。此外，臭氧化过程中废水的紫外吸光度（UV 254 nm）降低，表明复杂有机化合物分解为低分子量有机物。在反应过程中，由于中间酸性物质的形成，废水的pH值从11降至约8.5。此外，以生物需氧量和化学需氧量（BOD5/COD）衡量的废水生物降解性从0.22提高到0.53。从而实现了高达95%的高臭氧利用效率，提高了工艺效率；且它们取决于臭氧剂量和溶液的pH值。二级废水的臭氧化在废水排放所需的化学需氧量和饮用水中的溶解有机碳方面达到了南非水质标准，并显著提高了一级废水的生物降解性。
