Laboratory-Scale Biodegradation of Fuel Oil No. 6 in Contaminated Soils by Autochthonous Bacteria

Abstract

In order to evaluate the degradation of fuel oil no. 6 (FO6) in contaminated soil, laboratory-scale bioreactors were set up to study biostimulation, bioaugmentation, and natural attenuation processes. A solution of fertilizers was added in biostimulation and biouagmentation (0.03% N, 0.01% P). To the bioaugmentation process, an enrichment culture of indigenous hydrocarbon-degrading microorganisms was also added once a week. Total aerobic and hydrocarbon-degrading microorganisms were determined by plate count, and total petroleum hydrocarbon (TPH) concentration was determined gravimetrically (EPA method 9071b) every 15 days. After 1 year of study, degradation rate was higher for biostimulation (0.19 g TPH/day), followed by natural attenuation (0.18 g TPH/day) and bioaugmentation (0.16 g TPH/day). TPH showed a change in composition of hydrocarbons, attributed to microbiological activity. Microbial counts of hydrocarbon-degrading microorganisms were on the range of 4-6 log CFU/g soil. Preliminary bacterial identification corresponded to Pseudomonas, Rhodococcus, Actinomyces, and Bacillus strains; randomly amplified polymorphic DNA (RAPD); and denaturing gradient gel electrophoresis (DGGE) analysis demonstrated a large microbial diversity. From the degradation rates, it can be predicted that such limits will be achieved by increasing further 107-117 days of the treatments. Results demonstrated to be efficient on the restoration of contaminated soil, being an alternative to treat soils contaminated with heavy hydrocarbons.

Comparative Analysis of Microbial Consortiums and Nanoparticles for Rehabilitating Petroleum Waste Contaminated Soils

“…The consortium prepared from these genera is effective and degraded TPHs in a short incubation time. This is in agreement with the findings of Piñón-Castillo and colleagues [ 62 ], Goetz and coworkers [ 63 ], M’rassi and colleagues [ 64 ], and Ali and others [ 65 ], who reported that single strain Acinetobacter sp. A3 is capable of degrading 70% of TPH from crude oil-contaminated soils.…”

Chitosan-Coated Lignin Nanoparticles Enhance Adsorption and Proliferation of Alcanivorax borkumensis at the Hexadecane–Water Interface

“…54 Since hexadecane is the primary energy source for the cells, it may be inferred that this increase in cell concentration was because of the increased consumption of hydrocarbons. 55,56 Based on our bacterial growth rate studies and MATH test, we can conclude that the growth rate and adsorption of A. borkumensis to the oil−water interface is enhanced by the addition of chitosan-coated lignin NPs. The chitosan-coated lignin NPs do attach to the bacterial surface as shown in our scanning electron microscope (SEM) image (Figures 4b and S4), thus further impacting the bacterial adhesion to the oil− water interface.…”

“…Thus, as the cells replicate in the presence of hydrocarbons, the alkB genes have a stronger expression and higher catabolic activity, resulting in increased degradation . Since hexadecane is the primary energy source for the cells, it may be inferred that this increase in cell concentration was because of the increased consumption of hydrocarbons. , …”