Three chemical oxidation treatments (KMnO4, H2O2 and Fenton-like) were applied on three PAH-contaminated soils presenting different properties to determine the potential use of these treatments to evaluate the available PAH fraction. In order to increase the available fraction, a pre-heating (100 °C under N2 for one week) was also applied on the samples prior oxidant addition. PAH and extractable organic matter contents were determined before and after treatment applications. KMnO4 was efficient to degrade PAHs in all the soil samples and the pre-heating slightly improved its efficiency. H2O2 and Fenton-like treatments presented low efficiency to degrade PAH in the soil presenting poor PAH availability, however, the PAH degradation rates were improved with the pre-heating. Consequently H2O2-based treatments (including Fenton-like) are highly sensitive to contaminant availability and seem to be valid methods to estimate the available PAH fraction in contaminated soils.

A bioslurry batch experiment was carried out over five months on three polycyclic aromatic compound (PAC) contaminated soils to study the PAC (PAH and polar-PAC) behavior during soil incubation and to evaluate the impact of PAC contamination on the abundance of microbial communities and functional PAH-degrading populations. Organic matter characteristics and reactivity, assessed through solvent extractable organic matter and PAC contents, and soil organic matter mineralization were monitored during 5 months. Total bacteria and fungi, and PAH-ring hydroxylating dioxygenase genes were quantified. Results showed that PAHs and polar-PACs were degraded with different degradation dynamics. Differences in degradation rates were observed among the three soils depending on PAH distribution and availability. Overall, low molecular weight compounds were preferentially degraded. Degradation selectivity between isomers and structurally similar compounds was observed which could be used to check the efficiency of bioremediation processes. Bacterial communities were dominant over fungi and were most likely responsible for PAC degradation. Abundance of PAH-degrading bacteria increased during incubations, but their proportion in the bacterial communities tended to decrease. The accumulation of some oxygenated-PACs during the bioslurry experiment underlines the necessity to monitor these compounds during application of remediation treatment on PAH contaminated soils.

While some recent studies have discussed various effects of temperature on the electric and electromagnetic properties of multiphase porous media, the effect of temperature changes in multiphase porous media polluted by dense non-aqueous phase liquids (DNAPLs) has rarely been documented. We attempted to characterize how relative permittivity and electrical resistivity vary with temperature in multiphase porous media. The measurements were carried out using two different column sizes. Glass beads with a 1 mm diameter were used to simulate porous media. Spectral induced polarization (SIP) and time domain reflectometry (TDR) were used to measure complex electrical resistivity and relative permittivity, respectively. We investigated the geophysical characteristics of two DNAPLs, coal tar (CT) and chlorinated solvent (CS), from 20 to 50°C; ultra-pure water was used as the reference fluid. Experimental data on the relative permittivity and complex resistivity of pure water obey empirical models, validating our experimental setup and protocol. Results demonstrated that the real parts of relative permittivity and electrical resistivity are functions of temperature in the medium with the presence or absence of a solid phase. While we did not study the imaginary part of relative permittivity, our observations in the DNAPL samples indicated that temperature increases decreased the imaginary parts of the complex electrical resistivity of DNAPLs tested, whether in the presence or absence of the solid phase. Temperature dependency of relative permittivity and complex resistivity were also studied in multiphase porous media, after drainage (80 % DNAPL and 20 % water) and after imbibition (8 % DNAPL and 92 % water). The effect of temperature increases on complex resistivity has a secondary effect on frequency domain and Cole-Cole parameters. It was found that the relationship between temperature and resistivity is linear; therefore, resistivity temperature coefficients were obtained for water and both DNAPLs with the presence and absence of solid phase.

Experimental study of the temperature effect on two-phase flow properties in highly permeable porous media: Application to the remediation of dense nonaqueous phase liquids (DNAPLs) in polluted soil. (2020)

SEM/EDX images of nPd/μZVI (Figure S1) and the production of nonchlorinated C 4 compounds versus time for the effects of nPd/μZVI loading, temperature, HCBD initial concentration, and PLA content (Figures S2−S5) (PDF) ■ AUTHOR INFORMATION