Li Ting, Ren Yuan, Wei Chao-Hai
College of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
Huan Jing Ke Xue. 2013 Jul;34(7):2899-905.
Due to the effects of outer environment and concentration limit on the biodegradation of m-cresol, a carrier with adsorption ability was synthesized. A PVA-SA-PHB-AC composite membrane was prepared by adding SA, PHB and AC into PVA immobilization carrier using the combination of freezing-thawing and boric acid methods. A highly-effective m-cresol-degrading strain Lysinibacillus cresolivorans was entrapped in it and the effects of structural properties such as micro-structure, stability and diffusion coefficient on m-cresol biodegradation were investigated. The results showed that PVA-SA-PHB-AC composite membrane had uniform pore opening, of which the average pore size, specific surface area, m-cresol adsorption capacity and diffusion coefficient was 33.68 nm, 15.30 m2 x g(-1), 3.86 mg x g(-1) and 5.62 x 10(-8) m2 x min(-1), respectively. It could be reused for more than two months, m-Cresol removal by immobilized L. cresolivorans was the coupling of adsorption and biodegradation, and the removal rate was jointly determined by mass-transfer rate and biodegradation rate. When the initial concentration of m-cresol was lower than 350 mg x L(-1), the mass-transfer rate of PVA-SA-PHB-AC was smaller than the biodegradation rate. The m-cresol removal rate depended on the mass-transfer rate, when the concentration was higher than 380 mg x L(-1), it was determined by the biodegradation rate. The addition of adsorbent could decrease the mass transfer coefficient in the carrier, while the higher concentration of substrate could be tolerated and the efficient biodegradation could be achieved in a wider range of concentrations. The biodegradation of m-cresol by immobilized microorganism showed that the modified carrier increased the reaction kinetics in a range of initial concentrations.
由于外部环境和浓度限制对间甲酚生物降解的影响，合成了一种具有吸附能力的载体。采用冻融法和硼酸法相结合的方法，将海藻酸钠（SA）、聚羟基丁酸酯（PHB）和活性炭（AC）加入聚乙烯醇（PVA）固定化载体中，制备了PVA-SA-PHB-AC复合膜。将高效间甲酚降解菌株间甲酚赖氨酸芽孢杆菌包埋其中，研究了微观结构、稳定性和扩散系数等结构性质对间甲酚生物降解的影响。结果表明，PVA-SA-PHB-AC复合膜孔径均匀，平均孔径、比表面积、间甲酚吸附容量和扩散系数分别为33.68 nm、15.30 m2·g-1、3.86 mg·g-1和5.62×10-8 m2·min-1。该复合膜可重复使用两个多月，固定化间甲酚赖氨酸芽孢杆菌对间甲酚的去除是吸附和生物降解的耦合过程，去除率由传质速率和生物降解速率共同决定。当间甲酚初始浓度低于350 mg·L-1时，PVA-SA-PHB-AC的传质速率小于生物降解速率。间甲酚去除率取决于传质速率，当浓度高于380 mg·L-1时，由生物降解速率决定。吸附剂的加入可降低载体中的传质系数，同时可耐受更高的底物浓度，在更宽的浓度范围内实现高效生物降解。固定化微生物对间甲酚的生物降解表明，改性载体在一定初始浓度范围内提高了反应动力学。
