臭氧氧化去除二级出水中PPCPs的研究

药品及个人护理用品(PPCPs)是一类痕量、顽固的新兴有机污染物,采用传统水处理工艺不易去除,需深度处理。采用批量试验方法,研究了臭氧氧化二级出水中添加的19种PPCPs的去除效果,考察了臭氧投加量、p H值、自由基抑制剂对去除效率的影响,并根据氧化产物推断可能的反应途径。结果表明,在原水水样p H=7.1条件下,臭氧质量浓度为1.2 mg/L时,能有效去除大多数PPCPs。其中,抗生素类PPCPs和个人防护类PPCPs的去除率分别达到了68%和70%,而雷尼替汀和噻苯咪唑去除效果不明显,仅为17.73%和12.3%。增加臭氧投加量或提高反应p H值会显著提高除雷尼替汀和噻苯咪唑外的PPCPs去除率。加入的自由基抑制剂对臭氧氧化PPCPs有明显抑制作用。PPCPs的氧化降解产物有机酸会降低反应p H值,进而影响PPCPs的去除效果。

On the removal of PPCPs in a secondary effluent by ozonation

The objective of this paper is to make an exploration of the impact of ozonation on the pharmaceutical and personal care products(PPCPs) removal in a secondary effluent.In the experiment we have laid out,we have made an investigation for the removal efficiency of the three analgesic or anti-inflammatories (acetaminophen,diclofenac,diphenhydramine),the four antibiotics (miconazole,trimethoprim,sulfamethoxazole,and ciprofloxacin),and the five anti-hypertensive or neurological drugs (diltiazem,atenolol,caffeine,primidone,atorvastatin),the two amide pharmaceuticals(ranitidine and DEET),and the rest five other pharmaceuticals(propanolol,cimetidine,thiabendazole,cotinine,and TCEP) in a secondary effluent by ozonation in a batch mode experiment.The residuals of PPCPs after processing of ozonation have been quantified by solid-phase extraction (SPE) and UPLC-MS/MS.In the above said research,we have also made a careful study of the effects of the applied ozone dose,pH value,and the free radical inhibitors on PPCPs removal.In addition,we have also made a discussion of the possible pathways for degrading PPCPs through analyzing the oxidation products,the TOC and pH value variations.The results of the present study tend to show that most of the selected PPCPs can effectively be removed at the original pH (7.1) of the water sample with the adopted ozone dose of 1.2 mg/L.Under the above conditions,the antibiotics and the personal care products can also be remarkably removed at the respective rates of 68％ and 70％.Moreover,the anti-hypertensive or neurological drugs can also be obviously removed by a rate as high as over 60％.Nevertheless,it would not be so easy to remove the ranitidine and thiabendazole with their removing rate no more than 17.73％ and 12.3％.But,in contrast,under the following three conditions,i.e.the optimally selected ozone dose,say,2.0 mg/L and pH range of 7-8,it would be possible to remove almost entirely PPCPs.Nevertheless,in general,the degradation rate of PPCPs tends to increase with the increase of pH value and the ozone dose adopted,except for ranitidine and thiabendazole.All the above results prove that in all the product of PPCPs adopted,there must exist some less sensitive ones that are stubborn and refused by ozonation.It is just for this reason that it would be necessary to resort to other technologies,such as adsorption,air stripping,membrane separation or biodegradation as an integrated way-out for the purpose.Besides,the removal efficiency of PPCPs may also be greatly retarded by adding free radical inhibitors.To our experience,it is possible to increase the removal efficiency of PPCPs at the presence of carbonate scavenger.When observing the oxidation products,we can find that some organic acids can be formed after degrading the PPCPs,which tends to reduce pH value of the solution,thus affecting its removal efficiency.