Biodegradation of 2,6-ditert-butylphenol by immobilized microorganism strains

Article type: Research Article

Authors: ZHANG, Ya-lei | ZHANG, Zhi-gang | XU, De-qiang | QIANG, Zhi-min | LI, Guang-ming | ZHAO, Jian-fu

Affiliations: Key Laboratory of Yangtze Water Environment of Ministry of Education, Tongji University, Shanghai 200092, China | School of Life Science, Fudan University, Shanghai 200433, China | Department of Civil, Architectural and Environmental Engineering, University of Missouri-Rolla, Rolla, MO 65409, USA | State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China

Note: [] Corresponding author. E-mail: [email protected]

Abstract: 2,6-Ditert-butylphenol (2,6-DTBP) is a major organic contaminant presenting in acrylic fiber manufacturing wastewaters. This compound is of high bio-resistance due to its complex structure which consists of one phenol group and two highly branched tert-butyl groups. This research attempted to improve the biodegradation efficiency of 2,6-DTBP through various strain immobilization methods. The stratified immobilization can settle oxygen transmission in the single microorganism immobilization, and can realize two-process reaction in the single device by choosing two symbiotic microorganisms. Two effective strains, named F-l-4 and F-3-4, which were screened out in our previous work, were used to degrade 2,6-DTBP after being immobilized in calcium alginate gel. Results indicate that the substrate removal efficiency of various immobilization methods follows the order: stratified > single F-3-4> mixed ≈ single F-1-4. The immobilized biodegradation capacity was higher than the free one. After an incubation time of 12 d, 91% of 2,6-DTBP could be degraded by the stratified immobilization method, compared to 79% achieved by the mixed immobilization method with an initial 2,6-DTBP concentration of 100 mg/L. The stratified immobilization satisfies the oxygen demand nature of the aerobic F-3-4 and the facultative F-1-4, thus yielding the highest degradation efficiency. Both the outer layer strain F-3-4 and the inner layer strain F-1-4 can grow actively on the substrate of 2,6-DTBP, as illustrated by SEM images. This study shows that the highly bio-refractory compound, 2,6-DTBP, can be effectively degraded using appropriately immobilized microorganism strains.

Keywords: biodegradation, 2,6-ditert-butylphenol, immobilization, microorganism strains

Journal: Journal of Environmental Sciences, vol. 18, no. 2, pp. 369-372, 2006