固定化微球降解土壤中PAEs效果及影响因素

旨为研究土壤邻苯二甲酸酯污染修复中,固定化微球降解土壤中邻苯二甲酸酯的效果及影响因素。以海藻酸钠为载体,采用包埋法对课题组前期提取的微小杆菌进行固定化,比较固定化微球和游离菌降解土壤中邻苯二甲酸酯(Phthalates esters,PAEs)的效果及pH、温度、重金属、无机盐等对降解菌降解目标物的影响。结果显示:(1)在土壤环境相同条件下,固定化微球对邻苯二甲酸二甲酯(Dimethyl ortho-phthalate,DMP)、邻苯二甲酸二正丁酯(Di-n-butyl ortho-phthalate,DnBP)和邻苯二甲酸二(2-乙基己)酯(Bis(2-ethylhexyl)ortho-phthalate,DEHP)的降解效果高于游离菌,DMP在7 d可降解完全,DnBP在10 d内可降解完全,DEHP在20 d降解率63.73%;而游离菌则在15 d内完全降解DMP,20 d内完全降解DnBP,DEHP在20 d降解率48.77%;(2)不同pH值时,固定化微球对DMP、DnBP、DEHP的降解率均高于游离菌,pH9时,固定化微球对于DMP、DnBP、DEHP的降解率最高分别为96.81%、89.39%、58.35%;(3)不同温度,固定化微球对DMP、DnBP、DEHP的降解率也均高于游离菌,温度为30℃时,固定化微球对于DMP、DnBP、DEHP的降解效率达到最高,分别为96.27%、89.19%、59.01%;(4)重金属使游离菌对DMP、DnBP、DEHP降解率下降较多,而使固定化微球对DMP、DnBP的降解率仅下降了16.35%、9.95%,DEHP不仅没有降低,反而增加2.49%,说明重金属对游离菌起到很强的抑制作用,但对于固定化微球的降解效果影响较小;(5)盐碱条件下,中性盐极大降低了游离菌和固定化微球降解DMP、DnBP、DEHP的降解能力,碱性盐和混合盐对降解菌影响较小,且增强了固定化微球对DnBP、DEHP的降解能力。固定化微球降解PAEs效果明显高于游离菌,对外界环境有更好的适应能力,且对重金属、无机盐污染环境有一定的抵御能力。

Effect and Influencing Factors of Immobilized Microspheres on Degradation of Phthalate Esters in Soil

This work aims to study the effects and influencing factors of immobilized microspheres on the degradation of phthalate esters(PAEs)in the remediation of phthalate esters-contaminated soil.The method of embedding was used to immobilize the microbacteria extracted from the research group’s previous work with sodium alginate as the carrier.The effects of the immobilized microspheres and the free bacteria on the degradation of PAEs in the soil were compared.In addition,the influences of the pH,temperature,heavy metals and inorganic salts on degrading PAEs were evaluated.The results showed that:(1)Under the same conditions of soil environment,the degradation effect of the immobilized microspheres on DMP(Dimethyl ortho-phthalate),DnBP(Di-n-butyl ortho-phthalate)and DEHP(Bis(2-ethylhexyl)orthophthalate)was higher than that of the free bacteria.DMP was completely degraded in 7 d,DnBP was completely degraded within 10 d,and the degradation rate of DEHP was 63.73%in 20 d.However,the free bacteria completely degraded DMP in 15 d,and completely degraded DnBP in 20 d.DEHP degradation rate was 48.77%in 20 d.(2)At different pH values,the degradation rate of the immobilized microspheres to DMP,DnBP and DEHP was higher than that of the free bacteria.When pH9,the degradation rate of the immobilized microspheres to DMP,DnBP and DEHP peaked at 96.81%,89.39%and 58.35%,respectively.(3)At different temperatures,the degradation rate of the immobilized microspheres to DMP,DnBP and DEHP was also higher than that of the free bacteria.When the temperature was 30℃,the degradation efficiency of the immobilized microspheres to DMP,DnBP and DEHP was the highest in 96.27%,89.19 and 59.01%,respectively.(4)The degradation rate of the free bacteria to DMP,DnBP and DEHP was significantly reduced by heavy metals;while the degradation rate of the immobilized microspheres to DMP and DnBP was only reduced by 16.35%and 9.95%.In addition,the degradation rate to DEHP increased by 2.49%.These indicated that heavy metals had a strong inhibitory effect on the free bacteria,but had little impact on the degradation effect of the immobilized microspheres.(5)Under saline-alkali conditions,neutral salt greatly reduced the ability of the free bacteria and the immobilized microspheres to degrade DMP,DnBP and DEHP.However,alkaline salt and mixed salt had little impact on the degrading bacteria,and enhanced the ability of the immobilized microspheres to degrade DnBP and DEHP.The immobilized microspheres have obviously better degradation effect compared with the free bacteria,and it had better ability to adapt to the outside environment and to resist the pollution of heavy metals and inorganic salts.