Degradation of nonylphenol in water by microorganisms immobilized on bamboo charcoal.

Abstract

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.