竹炭固定化微生物对水中壬基酚的降解效率

Degradation of nonylphenol in water by microorganisms immobilized on bamboo charcoal

竹炭是一种优质生物质炭,不仅比表面积大,孔隙发达,而且机械强度高,是微生物固定化载体的最佳选择之一.本文采用正交试验确定了竹炭固定化微生物的最佳制备条件,对比了竹炭固定菌和游离菌对水中类雌激素壬基酚的降解效果,并考察了竹炭固定菌的重复利用性.结果表明:固定化后降解菌大量地附着在竹炭表面及内部孔隙中,其最佳制备条件为温度30℃、pH=7、竹炭粒径35目.壬基酚的降解符合一级动力学方程,在不同的壬基酚初始浓度下(30、50、80、100 mg·L^(-1)),竹炭固定菌对壬基酚的7 d降解率分别为100%、75.3%、67.3%和78.7%,显著优于游离菌(54.2%、51.5%、30.6%和23.5%).经过8轮重复利用后,竹炭固定菌对壬基酚的降解率仍可达到36.5%,而此时游离菌的降解率仅为8.9%,说明竹炭固定菌具有长期可重复利用性,在去除废水有机污染物中具有较好的工程应用前景.

Bamboo charcoal is a high-quality biochar,with a large surface area,well-developed pores,and high mechanical strength. Therefore,it is one of the best choices of microbial immobilization carrier. In this study,the optimal preparation condition was examined for microorganisms immobilized on bamboo charcoal by the orthogonal test. The degradation effects of estrogen nonylphenol were compared between the bacteria immobilized on bamboo charcoal and free bacteria,and then feasibility of the reuse of immobilized bacteria was investigated. The results showed that lots of degrading bacteria could adhere to the surface and internal pores of bamboo charcoal. The optimum conditions for the preparation of immobilized microorganisms were as follows： 30 ℃,pH = 7,35-mesh bamboo charcoal. The degradation rate of nonylphenol was in good agreement with the first order kinetics equation. When the initial concentrations of nonylphenol were 30,50,80 and 100 mg·L^（-1）,the degradation rates of nonylphenol of immobilized bacteria for seven days were 100%,75.3%,67.3% and 78.7%,respectively,which were significantly higher than those of free bacteria(54.2%,51.5%,30.6% and 23.5%）. After eight rounds of reuse,the degradation rate for immobilized bacteria still reached as high as 36.5%,while it was only 8.9% for free bacteria. Our results indicated that the microorganisms immobilized on bamboo charcoal had long-term reusability,and thus had good prospects in the application of organic pollutants removal in wastewater.