Biodegradation of 2,6-ditert-butylphenol by immobilized microorga- nism strains

摘要

2,6-Ditert-butylphenol(2,6-DTBP) is a major organic contaminant presen ting in acrylic fiber manufacturing wastewaters. This compound is of high bio-re sistance due to its complex structure which consists of one phenol group and two highly branched tert-butyl groups. This research attempted to improve the biode gradation efficiency of 2,6-DTBP through various strain immobilization methods. The stratified immobilization can settle oxygen transmission in the single micr oorganism immobilization, and can realize two-process reaction in the single dev ice by choosing two symbiotic microorganisms. Two effective strains, named F-1-4 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 t he substrate removal efficiency of various immobilization methods follows the or der: stratified > single F-3-4 > mixed ≈single F-1-4. The immobilized biodegra dation 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, compa red 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 de mand nature of the aerobic F-3-4 and the facultative F-1-4, thus yielding the hi ghest degradation efficiency. Both the outer layer strain F-3-4 and the inner la yer 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-DTB P, can be effectively degraded using appropriately immobilized microorganism str ains.