Enhanced Biodegradation of Naphthalene and Anthracene by Modified Vermiculite Mixed with Soil

Abstract

Hydrophobic modified vermiculite mixed with soil was investigated in biodegradation experiments of naphthalene and anthracene. The experiments had been carried out on mixtures of soil and vermiculite at a proportion of 2%, 10%, and 15% and also in the absence of clay used for control. Biodegradation of the pollutants was followed by the decline of naphthalene and anthracene concentration, measured by CG. Compound mineralization was also proved by the evolution of CO 2 . The results showed that in the mixture with a higher proportion of vermiculite biodegradation is enhanced compared to that performed in the absence of vermiculite. In general, when vermiculite proportions are increased, the rate of degradation increases, which may account for the bioavailability of compounds. Bioavailability is an important factor for the degradation of compounds with low solubility. Comparison of biodegradation rates shows that naphthalene is degraded faster than anthracene. The chemical structure could be responsible for this observation. However, although we did not identify the microorganism that was in the soil, we can conclude that vermiculite could be an alternative for the bioavailability of such compounds. Vermiculite in the modified form could also be very useful as a barrier to retain organic pollutants in accidental spills.

Predicting bioaccumulation of PAHs in the trophic chain in the estuary region of Paranagua, Brazil

“…Most of (Table 1). Compounds with lower molecular weights may already have been biodegraded (Froehner et al 2009b).…”

“…Thus, it is imperative to understand the fate of PAHs and their effects on the ecosystem. Generally, rivers and lakes are major recipients of PAHs, since because of their hydrophobic characteristics, they are rapidly adsorbed by sediments, and especially in those places where sedimentation is favorable such as in natural pool areas (Froehner et al 2009b), PAHs from sediment can enter the trophic chain (Hyötyläinen and Oikari 2004).…”

Low temperature oxidation of a coking plant soil organic matter and its major constituents: An experimental approach to simulate a long term evolution

“…The released CO 2 concentration during the oxidation was determined every 15 days with an infrared absorbance measurement ( = 2325.6 cm −1 ) performed with an infrared Binos analyzer. After each measurement, the bottles were opened to renew the flask atmosphere (especially air oxygen) [26][27][28][29]. After the oxidation time, samples were stored at −18 • C before analysis.…”

Bioremediation of PAHs and VOCs: Advances in clay mineral–microbial interaction

“…The situation with other combinations of bacteria, clay minerals and contaminants might be completely different and certainly warrants investigation. For instance, modified vermiculite could stimulate the microbial degradation of naphthalene to a greater extent than anthracene (Froehner et al, 2009). This could be attributed to the molecular weight of PAHs; the LMW compounds degrade faster than the HMW ones (McAllister and Semple, 2010; Morelli et al, 2013).…”

“…Due to the size factor, a bacterium cannot enter the tiniest interlayer spaces and pores of clay minerals, rendering the locked substances unavailable to microbial action. One possibility to desorb the contaminants into an available form is to use a surfactant (Froehner et al, 2009;Laha et al, 2009;Rosen and Kunjappu, 2012; see Section 5.1.2.1) or a biosurfactant (Congiu and Ortega-Calvo, 2014;Xia et al, 2014; see Section 5.1.2.2). It can: firstly, reduce the surface tensions that occur in all phases; and secondly, enable the compounds to be available for microbial degradation.…”