Electro-bioremediation at the prototype scale: What it should be learned for the scale-up

Abstract

A large scale electro-bioremediation test is carried out in a prototype of 32 m 3. Soil polluted with a mixture of two herbicides 2,4-D and oxyfluorfen undergoes a combined treatment in which the electrochemically assisted remediation produced by six electrodes placed in an hexagonal alternating configuration is aimed to be enhanced with the addition of concentrated activated sludge in a central position of the prototype. Results demonstrate that this technology can remove pollutants down to a very low concentration although, as compared to a previous study, its performance does not differ significantly of that followed in a process in which bioremediation was not included. In both studies, volatilization was found to be the key mechanisms to explain the removal of both herbicides. After a treatment period slightly over month, only 7.10 % of the 2,4-D and 9.22% of the oxyfluorfen remained in soil and these values are very similar to those obtained by applying non biological EKF in which 10.10 of the 2,4-D and 13.03% of the oxyfluorfen remained in the soil after the treatment. Results pointed out that it is very difficult to optimize simultaneously electrokinetic and biological processes because most of the processes caused by the electric field affect negatively to the microorganisms viability. Results also pointed out the significance of the sampling procedure to characterize an electro-bioremediation process at full scale.

[Preprint] An overview of electrokinetic soil flushing and its effect on bioremediation of hydrocarbon contaminated soil

“…The number of pesticides collected in the anode is more than the cathode. This finding shows that electrophoresis/electromigration phenomenon is more dominant in removing pesticides and distributing surfactant better in a short period of time (Barba et al, 2018 (Risco et al, 2016).…”

“…However, only limited research that studied about two-dimensional configuration. The examples of two-dimensional configuration are hexagonal, square, and triangular configuration (Barba et al, 2018;Kim et al, 2013). Onedimensional configuration is not practical to use in the field since a half of the total area is ineffective for electrokinetic reaction (dead zones).…”

“…Nutrients, such as ammonium, sulfate and phosphate are concentrated and precipitated in the area near electrode due to electromigration, which then causing nutrient deficiency in the biobarrier. Microorganisms are only found in the middle (biobarrier) because the environmental condition (temperature, nutrient, and pH) still support viability of microorganism (Barba et al, 2018;Li et al, 2012a;Li et al, 2013).…”

A new electrochemically-based process for the removal of perchloroethylene from gaseous effluents

“…In previous work of our group, it was found [1][2][3] that during the treatment of wastes or soils contaminated with volatile pollutants a very important fraction of the pollution contained in the soil can be transferred to atmosphere, shifting the environmental concern from soil to atmosphere. In fact, at large scales, volatilization was found to be the primary removal mechanisms during the electrochemically-assisted treatment of soil, for instance using conventional thermal treatment [4].…”

Techno-economic analysis of the scale-up process of electrochemically-assisted soil remediation

“…Very relevant scientific conclusions have been obtained in such studies. One of those conclusions was that scale-up studies cannot be bypassed to demonstrate the viability of an EASR process because otherwise conclusions drawn may be significantly wrong (Barba et al, 2018;López-Vizcaíno et al, 2017a, b).…”