Raffa Carla Maria, Vergnano Andrea, Chiampo Fulvia, Godio Alberto
Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy.
Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Torino, Italy.
J Environ Health Sci Eng. 2021 May 28;19(2):1263-1276. doi: 10.1007/s40201-021-00681-2. eCollection 2021 Dec.
This study aimed to monitor the aerobic bioremediation of diesel oil-contaminated soil by measuring: a) the CO production; 2) the fluorescein production; 3) the residual diesel oil concentration. Moreover, the complex dielectric permittivity was monitored through an open-ended coaxial cable. Several microcosms were prepared, changing the water content (u% = 8-15% by weight), the carbon to nitrogen ratio (C/N = 20-450), and the soil amount (200 and 800 g of dry soil). The cumulative CO and fluorescein production showed similar trends, but different values since these two parameters reflect different features of the biological process occurring within each microcosm. The diesel oil removal efficiency depended on the microcosm characteristics. After 84 days, in the microcosms with 200 g of dry soil, the highest removal efficiency was achieved with a water content of 8% by weight and C/N = 120, while in the microcosms with 800 g of dry soil the best result was achieved with the water content equal to 12% by weight and C/N = 100. In the tested soil, the bioremediation process is efficient if the water content is in the range 8-12% by weight, and C/N is in the range 100-180; under these operative conditions, the diesel oil removal efficiency was about 65-70% after 84 days. The dielectric permittivity was monitored in microcosms with 200 g of dry soil. The open-ended coaxial cable detected significant variations of both the real and the imaginary component of the dielectric permittivity during the bioremediation process, due to the physical and chemical changes that occurred within the microcosms.
a）二氧化碳（CO₂）的产生；b）荧光素的产生；c）残留柴油浓度。此外，通过开放式同轴电缆监测复介电常数。制备了几个微型生态系统，改变了含水量（重量百分比u% = 8 - 15%）、碳氮比（C/N = 20 - 450）和土壤量（200克和800克干土）。累积的CO₂和荧光素产生呈现出相似的趋势，但数值不同，因为这两个参数反映了每个微型生态系统内发生的生物过程的不同特征。柴油去除效率取决于微型生态系统的特性。84天后，在含有200克干土的微型生态系统中，含水量为8%（重量）且C/N = 120时实现了最高去除效率，而在含有800克干土的微型生态系统中，含水量等于12%（重量）且C/N = 100时取得了最佳效果。在测试土壤中，如果含水量在8 - 12%（重量）范围内且C/N在100 - 180范围内，生物修复过程是有效的；在这些操作条件下，84天后柴油去除效率约为65 - 70%。在含有200克干土的微型生态系统中监测了介电常数。由于微型生态系统内发生的物理和化学变化，开放式同轴电缆检测到生物修复过程中介电常数实部和虚部的显著变化。
