ABSTRACT

The remediation of organic pollutant-heavy metal co-contaminated soil is a great challenge. Immobilized microorganism technology (IMT) is a potential approach to remediate co-contaminated soil. In this study, we evaluated the feasibility of IMT for the remediation of petroleum hydrocarbon-heavy metal nickel (Ni) co-contaminated soil. The Ni resistant and hydrocarbon-degrading bacteria strain Citrobacter sp. was added to co-contaminated soil by immobilizing on corncob biochar. The potential performance in biodegradation of petroleum hydrocarbon and changing the mobility and speciation of nickel (Ni) in soil were determined, with consideration of the influences of the soil properties and dehydrogenase activity. The results demonstrated that the degradation rate of petroleum hydrocarbons by immobilized microorganisms group (IM) was 45.52%, significantly higher than that of the free bacteria (30.15%), biochar (25.92%) and blank group (18.47%) (P<0.05). At the same time, IM was more effective in immobilizing Ni in the soil by transforming available Ni to a stable fraction with a maximum residual concentration increasing by 101.50 mg·kg⁻¹, and the carcinogenic nickel sulfide was not detected after remediation in IM. IM exhibited a higher level of soil dehydrogenase activity (0.3956 μg·mL⁻¹·h⁻¹·g⁻¹) than that of free bacteria (0.2878 μg·mL⁻¹·h⁻¹·g⁻¹). A linear correlation was found between the petroleum pollutants degradation rate and dehydrogenase activity (P<0.05). This study indicates the effectiveness and potential of IMT application in degrading petroleum hydrocarbon and immobilizing heavy metals in co-contaminated soil.

摘要

有机污染物-重金属共污染土壤的修复是一项巨大的挑战。固定化微生物技术（IMT）是修复共污染土壤的一种潜在方法。在这项研究中，我们评估了 IMT 修复石油烃-重金属镍 (Ni) 共污染土壤的可行性。耐镍烃降解菌Citrobactersp。通过固定在玉米芯生物炭上，将其添加到共同污染的土壤中。考虑到土壤性质和脱氢酶活性的影响，确定了石油烃生物降解和改变土壤中镍 (Ni) 的迁移率和形态的潜在性能。结果表明，固定化微生物组（IM）对石油烃的降解率为45.52%，显着高于游离菌（30.15%）、生物炭（25.92%）和空白组（18.47%）（P <0.05 ）。 ）。同时，IM通过将有效Ni转化为稳定部分，最大残留浓度增加101.50 mg·kg ^{-1 ，更有效地将Ni固定在土壤中。}, 在 IM 中修复后未检出致癌的硫化镍。IM表现出比游离细菌更高水平的土壤脱氢酶活性（0.3956 μg·mL ^-1 ·h ^-1 ·g ^{-1 ）（0.2878 μg·mL -1} ·h ^-1 ·g ^-1）。石油污染物降解率与脱氢酶活性呈线性相关（P <0.05）。本研究表明 IMT 应用在降解石油烃和固定共污染土壤中的重金属方面的有效性和潜力。