Surfactant Solubilization of Organic Compounds in Soil/Aqueous Systems

During the microbial treatment of a sandy model soil artificially contaminated with polycyclic aromatic hydrocarbons (PAHs), a large residual pollution was found. The remaining PAHs were sorbed into the micropores of the soil and were therefore not bioavailable. Using a lab-scale percolator, the microbially pretreated soil was subjected to aftertreatment with surfactants with the aim of further degradation of its pollution. Two commercial nonionic surfactants of the polyethoxylate type, Prawozell F1214/5 N and Sapogenat T-300, were used. The surfactants differ both in their physicochemical properties (CMC value, PAH solubilization capacity, adsorption onto soil) and in their microbial degradability. During aftertreatment under permanently aerobic conditions, only a weak PAH accumulation in the liquid phase was observed, which was due to a low solubilization rate as well as to simultaneous microbial degradation of the dissolved PAHs. Temporary anaerobiosis successfully suppressed the microbial degradation of both the surfactant and the solubilized PAHs, resulting in a more intensive PAH accumulation. But the PAH content of the soil -the essential criterion for evaluating the efficiency of surfactant application -was not decreased to a larger extent with surfactants than without them. To find out why the surfactants failed to act, the surfactant and hydrocarbon distribution among the liquid and solid phases was studied in mixtures of phenanthrene-spiked soils and Prawozell-containing liquids; at heavy phenanthrene loading, the aqueous phase was saturated with PAH; at weak loading, it was unsaturated. Model-aided data analysis showed that the soil may contain PAH in two fractions: strongly sorbed into soil pores and, in the case of heavy loading, also weakly attached to the soil surface. The latter is easily extractable, resulting in a PAH-saturated liquid, while strongly adsorbed PAH is only partially dissolved due to competition between the micelles and the soil pores for the PAH. The microbially pretreated soil contains only strongly bound PAHs, which are as difficult to extract by surfactants as they are poorly accessible for microbes.

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“…[lo], who referred to a model introduced by EDWARDS ef al. [23], the results were not discussed in detail. Fig.…”

Section: 0mentioning

confidence: 99%

“…[23], who simply described the HOC distribution between the aqueous phase, the micelles and the sorbent by partitioning coefficients (i.e. assumption of constant relations between the HOC contents within the three phases considered).…”

Section: Modellingmentioning

confidence: 99%

Improvement of the bioavailability of hydrocarbons by applying nonionic surfactants during the microbial remediation of a sandy soil

Löser¹,

Seidel

Zehnsdorf

et al. 2000

Acta Biotechnologica

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“…Edwards, et al [17] reported sorption of surfactant to soil increased the equivalent fractional organic contents, which tended to increase the amount of hydrophobic organic compound sorbed.…”

Section: Trickling Biofilter Performance Without and With Surfactantmentioning

confidence: 99%

Improvement of trickling biofilter purification performance on treating chlorobenzene in waste gases using surfactant

2007

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A laboratory-scale trickling biofilter column, filled with Raschig rings and inoculated with Pseudomonas putida (ATCC 1785) was used to purify chlorobenzene contained waste gases. Sodium dodecyl sulfonate (SDS) was used to enhance the performance of trickling biofilter. Purification performance of the trickling biofilter was examined for chlorobenzene inlet concentration of 1.20∼5.04 g/m 3 at different EBRTs between 76∼153 s. Without SDS addition, with simultaneous increase in chlorobenzene inlet loading rate and gas flow rate, 100% removal efficiency was achieved at EBRT of 109 s and inlet loadings below 5120 mg/m 3 . Addition of SDS to nutrient solution led to improvement of trickling biofilter purification performance. By introducing 25 mg/L SDS, the removal efficiency was increased by 21% and elimination capacity up to 234 g/(m 3 ·h) was achieved at chlorobenzene inlet loading of 241 g/(m 3 ·h). Although SDS concentration experienced a low rate reduction after continuous nutrient solution recirculation, this result has little influence on trickling biofilter's removal efficiency in monitoring period.

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“…In a conventional slurry bioreactor system, the amount of water used for separation and washing of the soil mixture is over ®ve times more than that required for the reactor operation itself. 5,19 In the present reactor system, the soil mixture including sand can be treated without separation and washing and, therefore, less water is required. The amount of water required ranged from 0.42 to 2.3 dm 3 kg À1 soil depending on the soil texture.…”

Section: Estimation Of Reactor Capacitymentioning

confidence: 99%

Evaluation of drum bioreactor performance used for decontamination of soil polluted with polycyclic aromatic hydrocarbons

Woo

Park

1999

J. Chem. Technol. Biotechnol.

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A laboratory-scale drum bioreactor system was used to study engineering aspects of soil bioremediation. Polycyclic aromatic hydrocarbons (PAHs) were chosen as contaminants in soil. In the operation of the reactor, different mixing strategies were applied according to the size of soil without separate washing of sand. The effect of the water content of the soil mixture on solid mixing time and phenanthrene degradation rate was of particular interest. At 20% water content, which was below the saturation level, the mixing ef®ciency of soil and the degradation rate of phenanthrene was lower than those at 30% or 40% water content. Optimal water content was variable according to the soil texture. The drum bioreactor was operated under optimal water content and PAH concentration (¯uorene, phenanthrene, anthracene, pyrene) and microbial numbers were measured in each soil phase (sediment and suspension). Over 95% of PAHs with three or four rings (¯uorene, phenanthrene, anthracene, pyrene) were degraded at 270 mg kg À1 soil within 20 days. The degradation rate of PAHs in the suspension phase was higher than that in sediment phase.

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Surfactant Solubilization of Organic Compounds in Soil/Aqueous Systems

Cited by 113 publications

References 25 publications

Improvement of the bioavailability of hydrocarbons by applying nonionic surfactants during the microbial remediation of a sandy soil

Improvement of the bioavailability of hydrocarbons by applying nonionic surfactants during the microbial remediation of a sandy soil

Improvement of trickling biofilter purification performance on treating chlorobenzene in waste gases using surfactant

Evaluation of drum bioreactor performance used for decontamination of soil polluted with polycyclic aromatic hydrocarbons

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