Soil Remediation by Electro-Fenton Process

Abstract

Soil remediation by electro-Fenton (EF) process has been recently proposed in literature. Being applied for solutions treatment, EF is mainly combined with soil washing (SW)/soil flushing (SF) separation techniques to remove the organic pollutants. The main criteria influencing the combined process have been identified as: (i) operating parameters (electrode materials, current density and catalyst (Fe 2+ ) concentration), (ii) the matrix composition (nature and dose of extracting agent, pH, complexity of SW/SF solutions), and (iii) the environmental impact (acute ecotoxicity and biodegradability of effluent as well as impact on soil microbial activity). The influence of these parameters on the SW/EF and SF/EF integrated processes has been reviewed. Energy consumption calculations have been finally considered as it constitutes the main source of operating cost in EF process.

Removal of persistent textile dyes from wastewater by Fe(ii)/H2O2/H3NOH+ integrated system: process performance and limitations

“…Fenton's reagent (H 2 O 2 , Fe( ii )), initially described over a century ago, 4 produces highly reactive ˙OH radicals ( E 0 = 2.8 V/NHE) to begin a radical reactions chain (eqn (1)–(8)), 5,6 and destroys a variety of organic pollutants in water and soil 7–13 with high reaction rate constants of 10 8 to 10 11 M −1 s −1 . 14 The Fenton process is the oldest advanced oxidation process.Fe( ii ) + H 2 O 2 → ˙OH + Fe( iii ) + OH − , k 1 = 63–76 M −1 s −1 Fe( ii ) + ˙OH → Fe( iii ) + OH − , k 4 = (3–4.3) × 10 8 M −1 s −1 ˙OH + ˙OH → H 2 O 2 , k 7 = (4.2–5.5)×10 9 M −1 s −1 …”

Electrochemical treatment of highly concentrated wastewater: A review of experimental and modeling approaches from lab- to full-scale

“…As soil washing/flushing only transfers the pollution from solid to liquid matrix, there is a need for a post-treatment to remove the contaminants. In the past few years, advanced electrochemical treatment has appeared as a promising alternative to biological post-treatment, since those pollutants are barely biodegradable (Mousset et al, 2017).…”

“…Table 9 presents the state of the art of electrochemical treatment of soil washing/flushing solutions. Generally, it is observed that organic pollutants represent only 1% to 5% of the total organic carbon fraction, the remaining part consisting mostly of the extracting agent, while the organic matter content extracted from soil is negligible (Mousset et al, 2017). Interestingly, using different families of extracting agents has shown to affect the electrochemical treatment efficiency.…”

“…Such treatment even allows reusing the cyclodextrins for further soil washing/flushing cycles in order to decrease the treatment cost. Still, Tween 80 surfactant could extract ten times more pollutants from soil than cyclodextrin, which counterbalanced the ability of cyclodextrin to be more easily recycled (Mousset et al, 2017). Even if surfactants are the most important family of agents employed in soil washing/flushing owing to their cost-effectiveness, it is important to emphasize that an overview of the complete soil remediation treatment needs to be obtained before the selection of a suitable extracting agent can be made.…”

“…Even if surfactants are the most important family of agents employed in soil washing/flushing owing to their cost-effectiveness, it is important to emphasize that an overview of the complete soil remediation treatment needs to be obtained before the selection of a suitable extracting agent can be made. Additionally, treating soil washing/flushing solutions electrochemically leads to high energy consumption (100-500 kWh m -3 ) (Mousset et al, 2017) and the faradaic yield, i.e. the ratio between the electric energy devoted to the target compound and the total electric energy applied, is in this case an important parameter to optimize when treating such soil solutions.…”