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

Abstract

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 Pseudomonas stutzeri PFS-4. Orthogonal experiment was conducted to optimize immobilization 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 ℃ 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 degradation rate of quinclorac in soil was significantly positively correlated with turnover frequency. Therefore, the approach of corncob, bamboo charcoal, canola meal adsorption-sodium alginate immobilized P. stutzeri PFS-4 possesses application potential in in situ remediation of quinclorac contaminated water and soil due to its buffering to adverse conditions.

Keywords: bamboo charcoal and canola meal carrier; bioremediation; corncob; immobilization; quinclorac.