Browsing by Author "Li, Xingang"

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    Influence and interactions of multi-factors on the bioavailability of PAHs in compost amended contaminated soils
    (Elsevier, 2014-04-12) Wu, Guozhong; Li, Xingang; Kechavarzi, Cédric; Sakrabani, Ruben; Sui, Hong; Coulon, Frederic
    Compost amendment to contaminated soils is a potential approach for waste recycling and soil remediation. The relative importance and interactions of multiple factors on PAH bioavailability in soils were investigated using conjoint analysis and five-way analysis of variance. Results indicated that soil type and contact time were the two most significant factors influencing the PAH bioavailability in amended soils. The other two factors (compost type and ratio of compost addition) were less important but their interactions with other factors were significant. Specifically the 4-factor interactions showed that compost addition stimulated the degradation of high molecular PAHs at the initial stage (3 month) by enhancing the competitive sorption within PAH groups. Such findings suggest that a realistic decision-making towards hydrocarbon bioavailability assessment should consider interactions among various factors. Further to this, this study demonstrated that compost amendment can enhance the removal of recalcitrant hydrocarbons such as PAHs in contaminated soils.
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    Influence of particle size and organic carbon content on distribution and fate of aliphatic and aromatic hydrocarbon fractions in chalks
    (Elsevier, 2015-09-06) Cao, Xingtao; Temple, Tracey J.; Li, Xingang; Coulon, Frederic; Sui, Hong
    Although great efforts had been devoted to investigate the fate and transport of various hydrocarbon sources in major aquifers, there is still a need to better understand and predict their behaviour for robust risk assessment. In this study, the fate and distribution of the aliphatic and polycyclic aromatic hydrocarbons (PAHs) of diesel fuel in chalk aquifer was investigated using a series of leaching column tests and then modelled using the Contaminant Transport module of the Goldsim software. Specifically the influence of chalk particle size on the behaviour and fate of the hydrocarbons was investigated. Distribution coefficient () between the water and chalk solid phase according to chalk particle sizes was determined for each hydrocarbon group. The larger sizes of chalk particles have higher values. After 60 d of leaching using a water flow of 45 mm d−1, most of the aliphatic and aromatic hydrocarbon compounds of the diesel were retained within the top 5 cm chalk layer and none of the targeted hydrocarbons were detected in the leachate from the four particles sizes chalk. Further to this, the results showed that the chalk is capable of holding more hydrocarbons than sand and chalk can limit their migration of hydrocarbons. The numerical results and the Monte Carlo analysis showed that the migration of the alkanes and PAHs is greatly retarded by the organic carbon in chalk. It is also observed that the initial mass of the alkanes and PAHs and their respective partition coefficients are important for the decaying of the source at the surface immediately after the spill and the rate-limited dissolution is responsible for entrapping the hydrocarbons in the top layer of the chalk. Overall these results can help to better inform risk assessment and help decision for the remediation strategy.
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    Pilot Application of SVE-Enhanced Bioremediation Technology for in situ Clean-up of a Light Oil-Contaminated Site
    (HARD Publishing; 1999, 2012-12-31T00:00:00Z) Yang, Yuewei; Wu, Guozhong; Li, Xingang; Coulon, Frederic; Li, Hong; Sui, Hong
    Light oil (isooctane) removal using soil vapor extraction (SVE) enhanced bioremediation (BR) was investigated by four steps, including: (i) amendment of substrates in batches (ii) continuous induction of contaminants for 15 days (iii) in situ acclimation for 100 days (iv) biodegradation assisted with SVE venting for 120 h at 20 m³·h-1 Results showed that the total removal efficiency was up to 90% after BR-SVE treatments. BR contributed predominantly to isooctane removal during the last 36 h of BR-SVE treatment. This implied that it would be an important strategy to limit water content at the early stage while increasing water supply at the end stage during implementation of BR-SVE, because water content was a significant factor hindering SVE but favoring BR. The overall results demonstrated a good complementarity between SVE and BR, and a potential for their combination in real-world applications.
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    Recycling of solvent used in a solvent extraction of petroleum hydrocarbons contaminated soil.
    (Elsevier Science B.V., Amsterdam., 2011-02-15T00:00:00Z) Wu, Guozhong; Li, Xingang; Coulon, Frederic; Li, Hong; Lian, Jingyan; Sui, Hong
    The application of water washing technology for recycling an organic composite solvent consisting of hexane and pentane (4:1; TU-A solvent) was investigated for extracting total petroleum hydrocarbons (TPH) from contaminated soil. The effects of water volume, water temperature, washing time and initial concentration of solvent were evaluated using orthogonal experiments followed by single factor experiments. Our results showed that the water volume was a statistically significant factor influencing greatly the water washing efficiency. Although less important, the other three factors have all increased the efficacy of water washing treatment. Based on a treatment of 20g of contaminated soil with a TPH concentration of 140mgg(-1), optimal conditions were found to be at 40°C, 100mL water, 5min washing time and 660mgg(-1) solvent. Semi-continuous water extraction method showed that the concentration of the composite solvent TU-A was reduced below 15mgg(-1) d.w. soil with a recovery extraction efficiency >97%. This finding suggests that water washing is a promising technology for recycling solvent used in TPH extraction from contaminated soils