Biotechnology Bulletin ›› 2021, Vol. 37 ›› Issue (1): 223-233.doi: 10.13560/j.cnki.biotech.bull.1985.2020-0675

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

ZHANG Xiao-hong1(), TAO Hong1,3(), WANG Ya-juan2, LI Yi-chun1, ZHANG Rui1   

  1. 1. College of Resources and Environment,Ningxia University,Yinchuan 750021
    2. College of Economics and Management,Ningxia University,Yinchuan 750021
    3. Key Laboratory(China-Arab)of Resource Evaluation and Environmental Regulation of Arid Region in Ningxia,Yinchuan 750021
  • Received:2020-06-02 Online:2021-01-26 Published:2021-01-15
  • Contact: TAO Hong E-mail:1748194359@qq.com;ayy06@163.com

Abstract:

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)ortho-phthalate)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.

Key words: immobilized microspheres, phthalate esters, embedding method, soil pollution remediation