A laboratory feasibility study on a new electrokinetic nutrient injection pattern and bioremediation of phenanthrene in a clayey soil

MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China.
Journal of hazardous materials (Impact Factor: 4.33). 12/2010; 184(1-3):798-804. DOI: 10.1016/j.jhazmat.2010.08.111
Source: PubMed

ABSTRACT Electrokinetic (EK) injection has recently been proposed to supply nutrients and electron acceptors in bioremediation of low permeable soils. However, effective pH control and uniform injection of inorganic ions have yet to be developed. The present study investigated a new EK injection pattern, which combined electrolyte circulation and electrode polarity reversal on a clayey soil. Soil pH could be controlled ranging from 7.0 to 7.6 by circulating the mixed electrolyte at a suitable rate (800 mL/h in this study) without any buffer. Ammonium and nitrate ions were distributed more uniformly in soil by electrode polarity reversal. The developed electrokinetic injection technology was applied primarily in bioremediation of phenanthrene contaminated soil. Over 80% of the initial 200mg/kg phenanthrene in soil could be removed in 20 d, and greater phenanthrene removal was achieved using electrode polarity reversal. Hence, the present study provides a promising electrokinetic injection technology for bioremediation of contaminated soils.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Biodesulfurization of the model oil using Rhodococcus erythropolis PTCC1767 (R.erythropolis) and Bacillus subtilis DSMZ 3256 (B.subtilis) strains assisted by applying electrokinetic was investigated as a novel method for desulfurization. The yield of biodesulfurization is low because it takes long time to be completed. Electrokinetic reduces the process time and accelerates degradation of the sulfur compounds. A mixture of normal hexadecane with 10 mM dibenzotiophene (DBT) was employed as the model oil. The biodesulfurization experiments were initially performed. The results represented 34% and 62% DBT conversions after 1 and 6 days by R.erythropolis and the biodesulfurization yields were 11% and 36%, respectively. However, the DBT conversions for B.subtilis strain after 1 and 6 days were 31% and 55% and the biodesulfurization yields were 9% and 31%, respectively. The electrokinetic biodesulfurization experiments were studied at different current densities and the optimum current density was selected. According to the results, DBT conversion and biodesulfurization yield for R.erythropolis after 3 days were 76% and 39%, respectively, at the current density of 7.5 mA/cm2. At the same conditions, the DBT conversion and biodesulfurization yield for B.subtilis were 71% and 37%, respectively. The experimental results indicate that the electrokinetic significantly reduces the biodesulfurization time. The combination of electrokinetic and biodesulfurization has the potential to obtain ‘zero sulfur’ products.
    Journal of Hazardous Materials 09/2014; 280. DOI:10.1016/j.jhazmat.2014.09.006 · 4.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study investigates and quantifies the influence of physical heterogeneity in granular porous media, represented by materials with different hydraulic conductivity, on the migration of nitrate, used as an amendment to enhance bioremediation, under an electric field. Laboratory experiments were conducted in a bench-scale test cell under a low applied direct current using glass bead and clay mixes and synthetic groundwater to represent ideal conditions. The experiments included bromide tracer tests in homogeneous settings to deduce controls on electrokinetic transport of inorganic solutes in the different materials, and comparison of nitrate migration under homogeneous and heterogeneous scenarios. The results indicate that physical heterogeneity of subsurface materials, represented by a contrast between a higher-hydraulic conductivity and lower-hydraulic conductivity material normal to the direction of the applied electric field exerts the following controls on nitrate migration: (1) a spatial change in nitrate migration rate due to changes in effective ionic mobility and subsequent accumulation of nitrate at the interface between these materials; and (2) a spatial change in the voltage gradient distribution across the hydraulic conductivity contrast, due to the inverse relationship with effective ionic mobility. These factors will contribute to higher mass transport of nitrate through low hydraulic conductivity zones in heterogeneous porous media, relative to homogeneous host materials. Overall electrokinetic migration of amendments such as nitrate can be increased in heterogeneous granular porous media to enhance the in situ bioremediation of organic contaminants present in low hydraulic conductivity zones.
    Ground Water Monitoring and Remediation 04/2015; DOI:10.1111/gwmr.12107 · 1.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Removal of diesel from spiked kaolin has been studied in the laboratory using coupled electrokinetic soil flushing (EKSF) and bioremediation through an innovative biological permeable reactive barrier (Bio-PRBs) positioned between electrode wells. The results show that this technology is efficient in the removal of pollutants and allows the soil to maintain the appropriate conditions for microorganism growth in terms of pH, temperature, and nutrients. At the same time, EKSF was demonstrated to be a very interesting technology for transporting pollutants, microorganisms and nutrients, although results indicate that careful management is necessary to avoid the depletion of nutrients, which are effectively transported by electro-migration. After two weeks of operation, 30% of pollutants are removed and energy consumption is under 70 kWh·m−3. Main fluxes (electroosmosis and evaporation) and changes in the most relevant parameters (nutrients, diesel, microorganisms, surfactants, moisture conductivity and pH) during treatment and in a complete post-study analysis are studied to give a comprehensive description of the most relevant processes occurring in the soil (pollutant transport and biodegradation).
    Journal of Hazardous Materials 09/2014; DOI:10.1016/j.jhazmat.2014.08.069 · 4.33 Impact Factor