title: Coupling electrokinetics with microbial biodegradation enhances the removal of cycloparaffinic hydrocarbons in soils.
abstract: An innovative approach that couples electrokinetics with microbial degradation to breakdown cycloparaffinic hydrocarbons in soils is described. Soils were spiked with cyclododecane, used as a model pollutant, at approximately 1000mgkg-1. A mixture of petroleum-utilizing bacteria was added to achieve about 106-107CFUg-1. Then, three treatments were applied for 25 days: (1) no electric field, control; (2) a constant voltage gradient of 1.3Vcm-1in one direction; and (3) the same electric field, but with periodical switching of polarity. The degradation pathway of cyclododecane was not changed by the electric field, but the dynamic processes were remarkably enhanced, especially when the electric field was periodically switched. After 25 days, 79.9% and 87.0% of the cyclododecane was degraded in tests 2 and 3, respectively; both much higher than the 61.5% degraded in test 1. Analysis of the intermediate products strongly indicated that the competitive advantage of the electric field was the increase in ring-breaking of cyclododecane, resulting in greater concentrations of linear substances that were more susceptible to microbial attack, that is, β-oxidation. The conditions near the cathode were more favorable for the growth and metabolism of microorganisms, which also enhanced β-oxidation of the linear alkanoic acids. Therefore, when the electric field polarity was periodically switched, the functions of both the anode and cathode electrodes were applied across the whole soil cell, further increasing the degradation efficiency.
authors: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China; Safety Evaluation Center, Shenyang Research Institute of Chemical Industry, Shenyang, China.
authors: Ye
authors: Y
authors: Yuan
authors: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China. Electronic address: shuhaiguo@iae.ac.cn.
authors: Shuhai
authors: S
authors: Guo
authors: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors: Fengmei
authors: F
authors: Li
authors: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors: Bo
authors: B
authors: Wu
authors: College of Life Science and Bioengineering, Shenyang University, Shenyang, China.
authors: Xuelian
authors: X
authors: Yang
authors: Pesticide Testing Laboratory, Shenyang Research Institute of Chemical Industry, Shenyang, China.
authors: Xuan
authors: X
authors: Li
mesh_terms: D001673:Biodegradation, Environmental; D003516:Cycloparaffins / Q000737:chemistry / Q000302:isolation & purification*; D004560:Electricity; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007850:Lauric Acids / Q000032:analysis; D010084:Oxidation-Reduction; D059392:Petroleum Pollution; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D003516:Cycloparaffins; D007850:Lauric Acids; D012989:Soil Pollutants; C030358:lauric acid
keywords: Cyclododecane; Electrokinetics; Ring-breaking; β-oxidation