玉米芯、竹炭及油枯吸附-海藻酸钠包埋施氏假单胞菌PFS-4对二氯喹啉酸的降解

Degradation of quinclorac by corncob,bamboo charcoal,canola meal adsorption-sodium alginate immobilized Pseudomonas stutzeri PFS-4

采用玉米芯、竹炭及油枯吸附-海藻酸钠包埋对分离到的施氏假单胞菌PFS-4进行复合固定.采用正交试验对固定化条件进行优化,研究了固定化菌剂及游离菌体对二氯喹啉酸的降解效果.结果表明:固定化菌剂制备的最佳条件为:海藻酸钠质量分数为4%、吸附载体比例(玉米芯∶竹炭∶油枯)为1∶2∶1、CaCl_2质量分数为3%、交联时间4 h.固定化菌剂在温度为30℃、初始pH=7的条件下,经6 d培养后,对浓度为800 mg·L^(-1)的二氯喹啉酸降解率为91.4%,而游离菌体的降解率为72.8%.将游离菌体和固定化菌剂用于实际污水及土壤处理时,固定化菌剂对水中及土壤中二氯喹啉酸去除率仍能分别达到84.2%和74.3%.研究结果表明,载体及其联结方式对土壤中二氯喹啉酸去除产生显著影响,翻动频率与土壤中二氯喹啉酸的去除率呈显著正相关.因此,玉米芯、竹炭及油枯吸附-海藻酸钠复合固定施氏假单胞菌PFS-4对不良环境具有较好的缓冲性能,对二氯喹啉酸污染水体及土壤原位生态修复具有潜力.

To enhance the degradation of quinclorac in soil and water, corncob, bamboo charcoal, canola meal and sodium alginate were used as complex carriers to immobilize previously isolated bacterial strain Pseudornonas stutzeri PFS-4. Orthogonal experiment was conducted to optimize im- mobilization condition, and the degradation efficiency of quinclorac by immobilized bacteria and free bacteria in water and soil were further investigated. The results indicated that the optimal conditions for immobilization were： alginate concentration 4%, proportion of adsorption carrier （corncob： bamboo charcoal ： canola meal= 1：2 ： 1 ）, calcium chloride 3%, crosslinking time 4 h. Immobilized bacteria and free bacteria could effectively degrade 91.4% and 72.8% of quinclorac （ 800 mg ~ L-1 ） after 6 d inoculation at 30 ~C and pH 7.0. The removal rates of quinclorac by immobilized bacteria and free bacteria were affected in actual wastewater and soil treatments, but the quinclorac removal rate remained at 84.2% in soil and 74.3% in water, respectively. The results also demonstrated that the carrier and entrapment media significantly affected the quinclorac removal in soil, and the deg- radation rate of quinclorac in soil was significantly positively correlated with turnover frequency. Therefore, the approach of corncob, bamboo charcoal, canola meal adsorption-sodium alginate im- mobilized P. stutzeri PFS-4 possesses application potential in in situ remediation of quinclorac con- taminated water and soil due to its buffering to adverse conditions.