Effect of alternating bioremediation and electrokinetics on the remediation of n-hexadecane-contaminated soil

Abstract

This study demonstrated the highly efficient degradation of n-hexadecane in soil, realized by alternating bioremediation and electrokinetic technologies. Using an alternating technology instead of simultaneous application prevented competition between the processes that would lower their efficiency. For the consumption of the soil dissolved organic matter (DOM) necessary for bioremediation by electrokinetics, bioremediation was performed first. Because of the utilization and loss of the DOM and water-soluble ions by the microbial and electrokinetic processes, respectively, both of them were supplemented to provide a basic carbon resource, maintain a high electrical conductivity and produce a uniform distribution of ions. The moisture and bacteria were also supplemented. The optimal DOM supplement (20.5 mg·kg−1 glucose; 80–90% of the total natural DOM content in the soil) was calculated to avoid competitive effects (between the DOM and n-hexadecane) and to prevent nutritional deficiency. The replenishment of the water-soluble ions maintained their content equal to their initial concentrations. The degradation rate of n-hexadecane was only 167.0 mg·kg−1·d−1 (1.9%, w/w) for the first 9 days in the treatments with bioremediation or electrokinetics alone, but this rate was realized throughout the whole process when the two technologies were alternated, with a degradation of 78.5% ± 2.0% for the n-hexadecane after 45 days of treatment.

Field test of electrokinetically-delivered thermally activated persulfate for remediation of chlorinated solvents in clay

“…The period of voltage fluctuation is hypothesized to be due to an increase in stoppages of applied current and or a decrease in electrical conductivity ( Figure D3, Appendix D). Due to EK operations, cations and anions are expected to migrate towards the electrodes by EM and accumulate over time resulting in a decrease in electrical conductivity in the middle of the cell Wang et al, 2016). This decrease in electrical conductivity would increase resistance and therefore voltage would decrease.…”

Bioelectroremediation of hexadecane in electrical cells containing Aspergillus niger immobilized in alginate

“…Using the HXD model to test traditional bioremediation has yielded some successful results using different microorganisms, such as Pseudomonas aeruginosa (Cruz et al, 2021). Additionally, Yuan et al (2013) achieved an HXD biodegradation of 53.7% using a bacterial consortium with a constant voltage gradient of 1.3 V cm -1 for 42 days in pristine soil; and Wang et al (2016) used alternative bioremediation and electrokinetic technologies with soil bacteria to obtain 78.5% HXD degradation after 45 days of treatment. Using the fungus Aspergillus brasiliensis, Velasco-Alvarez et al (2011) achieved a biodegradation of 96% with a current of 0.42 mA cm -2 .…”

Impact of bioaugmentation of soil with n-hexadecane-degrading bacteria and phosphorus source on the rate of biodegradation in a soil-slurry system

“…Bioremediation is a remedial approach treating the contaminated soil with the advantages of simplicity, costeffective and environmentally friendly technology (Vidali M., 2001;Dehghani M. et al, 2013;Wang S. et al, 2016). But this method has some disadvantages such as long treatment time (Cha D.K.…”