O3/BAC工艺中臭氧作用条件优化研究

为优化以长荡湖为水源的臭氧/上向流生物活性炭(O3/BAC)工艺的运行效能,通过小试装置,采用响应面Box-Behnken设计方法,探究臭氧氧化过程中甲醛的生成规律;借助中试装置,研究臭氧CT值(C为水中臭氧浓度,T为臭氧接触时间)以及臭氧投加比例对O3/BAC工艺处理效能的影响,优化臭氧运行参数。结果表明,臭氧氧化过程中,各水质因子对甲醛生成量的影响程度从大到小分别为TOC浓度、臭氧投加量、pH值和Br-浓度,随着臭氧投加量的增大,出水中甲醛含量呈现先增大后减小的变化趋势;针对长荡湖水源,以CODMn、UV254、氨氮、三卤甲烷生成势和甲醛为控制指标,建议臭氧CT值采用0.45 mg·min/L(臭氧投加量为1 mg/L,臭氧接触时间为15 min),臭氧投加比例采用3∶1∶1;同时,液相色谱/有机碳测定仪(LC/OCD)分析结果表明,在该臭氧运行条件下,臭氧能明显改变有机物性质,有助于提高生物活性炭的处理效能。

Optimization of Ozone Action Conditions in O3/BAC Process

In order to optimize the operational efficiency of ozone/upflow biological activated carbon(O3/BAC)process treating Changdang Lake raw water,formation rule of formaldehyde in a bench-scale equipment during ozonation process was explored by using response surface methodology designed by Box-Behnken Design.The effects of ozone CT value(C:ozone concentration;T:ozone contact time)and ozone dosing ratio on purification efficiency of O3/BAC in a pilot plant were explored,and the operational parameters of ozonation were optimized.In the ozonation process,the influence degree of each water quality factor on formaldehyde formationin descending order was TOC concentration,ozone dosage,pH and Br-1 concentration,respectively.With the increase of ozone dosage,the formaldehyde in the effluent increased first and then decreased.For the raw water from Changdang Lake,CODMn,UV254,ammonia nitrogen,trihalomethane formation potential and formaldehyde were taken as the control indexes,and the ozone CT value and ozone dosing ratio were suggested to be 0.45 mg·min/L(the corresponding ozone dosage was 1 mg/L,and the ozone contact time was 15 min)and 3∶1∶1.At the same time,ozone could significantly change the properties of organic matter under the above operational condition according to the results of liquid chromatography and organic carbon analyzer,which was helpful to improve the treatment efficiency of biological activated carbon.