Browsing by Author "Li, Zhongyuan"

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    CFD modelling of particle shrinkage in a fluidized bed for biomass fast pyrolysis with quadrature method of moment
    (Elsevier, 2017-05-08) Liu, Bo; Papadikis, Konstantinos; Gu, Sai; Fidalgo, Beatriz; Longhurst, Philip J.; Li, Zhongyuan; Kolios, Athanasios
    An Eulerian-Eulerian multi-phase CFD model was set up to simulate a lab-scale fluidized bed reactor for the fast pyrolysis of biomass. Biomass particles and the bed material (sand) were considered to be particulate phases and modelled using the kinetic theory of granular flow. A global, multi-stage chemical kinetic mechanism was integrated into the main framework of the CFD model and employed to account for the process of biomass devolatilization. A 3-parameter shrinkage model was used to describe the variation in particle size due to biomass decomposition. This particle shrinkage model was then used in combination with a quadrature method of moment (QMOM) to solve the particle population balance equation (PBE). The evolution of biomass particle size in the fluidized bed was obtained for several different patterns of particle shrinkage, which were represented by different values of shrinkage factors. In addition, pore formation inside the biomass particle was simulated for these shrinkage patterns, and thus, the density variation of biomass particles is taken into account.
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    Co-occurrence of PFASs, TPHs, and BTEX in subsurface soils: impacts on native microbial communities and implications for bioremediation
    (Elsevier, 2025-02-15) Zhang, Zhuanxia; Liu, Zeliang; Coulon, Frederic; Luo, Gubai; Wang, Qing; Gao, Xinyu; Li, Zhongyuan; Song, Xin
    This study investigates the co-occurrence of per- and polyfluoroalkyl substances (PFASs), petroleum hydrocarbons (TPHs) and benzene, toluene, ethylbenzene, and xylene (BTEX) and their effects on the indigenous microbial communities in soils at a contaminated site with a history of petroleum refinery operations. PFASs concentrations were in the range of 5.65–6.73 ng/g, and fluorooctane sulfonate (PFOS) and perfluorobutane sulfonic acid (PFBS) were the dominating compounds. No significant difference was observed in the PFASs concentration profiles between the site and background locations, indicating that PFASs detected in the soil samples were mainly contributed from non-point sources, due to the long-distance transport of PFASs in the region. The concentrations of TPHs and BTEX ranged from 227 to 72,360 mg/kg and 0.06–2109.77 mg/kg, respectively, mainly contributed by the historical refinery activities. The presence of PFASs, TPHs, and BTEX significantly impacted soil microbial community diversity and abundance, altering microbial compositions and enriching bacteria with higher resistance or metabolic capabilities against contamination. Strong correlations were observed between TPHs and its degraders such as Pseudomonas, Azoarcus, and Polaromonas. Significant positive relationship between PFASs and Trichlorobacter implied the potential defluorination capabilities of Trichlorobacter, warranting further investigation. Moreover, the higher energy metabolism including carbon, nitrogen and sulfur metabolisms and higher abundance of metabolic enzymes for alkane, cyclohexane and toluene in the refinery site revealed the potential occurrence of natural biodegradation of contaminants with indigenous microbial community. These findings highlight the complexity of sites contaminated with a mixture of traditional and emerging contaminants, providing valuable insights into the potential for biodegradation of mixed contaminants and underscoring the need for integrated approaches in environmental remediation strategies. This study contributes to understanding the ecological impacts of co-occurring contaminants and emphasizes the importance of considering multiple contaminant types in environmental risk assessments and remediation efforts.