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The objective of this study was to investigate the effect of two factors: the stability degree (0.37-4.55 mg O(2) g(-1) Organic Matter h(-1)) of different composts derived from the organic fraction of municipal solid wastes and the concentration of a complex mixture of PAHs including fluorene, phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)anthracene in the bioremediation of soil. The two factors were systematically studied applying central composite design methodology. The obtained results demonstrated that compost stability degree was particularly important during the first stage of the process. Stable composts enhanced the levels of degradation in soil-compost mixture and a degradation rate of 92% was achieved in this period, but only 40% was degraded with the least stable compost. The PAHs concentration was also important during the process, since the degradation rates increased with the increase in the PAHs concentration. Moreover, all the individual PAHs demonstrated a notable decrease in their concentrations after the incubation period, but pyrene was degraded to lower levels in some treatments compared to others PAHs., (2010 Elsevier B.V. All rights reserved.)

Bioremediation of contaminated soils has gained increasing interest in recent years as a low-cost and environmentally friendly technology to clean soils polluted with anthropogenic contaminants. However, some organic pollutants in soil have a low biodegradability or are not bioavailable, which hampers the use of bioremediation for their removal. This is the case of polycyclic aromatic hydrocarbons (PAHs), which normally are stable and hydrophobic chemical structures. In this review, several approaches for the decontamination of PAH-polluted soil are presented and discussed in detail. The use of compost as biostimulation- and bioaugmentation-coupled technologies are described in detail, and some parameters, such as the stability of compost, deserve special attention to obtain better results. Composting as an ex situ technology, with the use of some specific products like surfactants, is also discussed. In summary, the use of compost and composting are promising technologies (in all the approaches presented) for the bioremediation of PAH-contaminated soils. [ABSTRACT FROM AUTHOR]

The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) is the main limiting factor for the remediation of soils and aquifers. Surfactants are amphiphilic substances which encourage the transfer of hydrophobic compounds from the solid to the liquid phase. While the interaction between organic matter and surfactants has been widely studied, there is a lack of knowledge concerning the relationship between surfactant efficiency and the granulometry of soil and/or geologic material. In this paper, three non-ionic surfactants (Tween 80, Gold Crew, and BS-400) were used to study the desorption of pyrene, chosen as a representative PAH, in soils with different grain size proportions (1%, 5%, 10%, and 20% of clay and silt) and no organic matter (<0.1%). The best quantity of surfactant to apply is closely related to the proportion of fine materials. Tween 80 gave better maximum desorption than Gold Crew and BS-400 (89%, 40%, and 36%, respectively). As an important proportion of aquifers show fine material above 1%, the effective critical micellar concentration obtained when applying surfactants to this type of geologic materials has to be higher than 150 mg L for Tween 80, and higher than 65 mg L, and 100 mg L for Golf Crew and BS 400, respectively. Furthermore, results indicate that carrying out simple laboratory tests before the use of surfactants on a field scale is necessary to improve the efficiency and minimize the financial and environmental impact of its application. [ABSTRACT FROM AUTHOR]

Abstract: The degradation of several polycyclic aromatic hydrocarbons (PAHs) in soil through composting was investigated. The selected PAHs included: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, and chrysene, with concentrations simulating a real creosote sample. The degradation of PAHs (initial concentration 1 g of total PAHs kg−1 dry soil) was assessed applying bioaugmentation with the white-rot fungi Trametes versicolor and biostimulation using compost of the source-selected organic fraction of municipal solid waste (OFMSW) and rabbit food as organic co-substrates. The process performance during 30 days of incubation was evaluated through different analyses including: dynamic respiration index (DRI), cumulative oxygen consumption during 5 days (AT5), enzymatic activity, and fungal biomass. These analyses demonstrated that the introduced T. versicolor did not significantly enhance the degradation of PAHs. However, biostimulation was able to improve the PAHs degradation: 89% of the total PAHs were degraded by the end of the composting period (30 days) compared to the only 29.5% that was achieved by the soil indigenous microorganisms without any co-substrate (control, not amended). Indeed, the results showed that stable compost from the OFMSW has a greater potential to enhance the degradation of PAHs compared to non-stable co-substrates such as rabbit food. [Copyright &y& Elsevier]