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Supporting Information
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Comparison of the transport and deposition of
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Pseudomonas aeruginosa under aerobic and anaerobic
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conditions
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Huixin Zhanga, Hongbo Zengb, Ania C. Ulricha, Yang Liua*
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a
Department of Civil and Environmental Engineering
University of Alberta, Edmonton, AB T6G 2W2, Canada
b
Department of Chemical and Materials Engineering
University of Alberta, Edmonton, AB T6G 2V4, Canada
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*Corresponding author: Department of Civil and Environmental Engineering, University
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of Alberta, 3-095 Markin/CNRL Natural Resources Engineering Facility, 9105 116
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Street, Edmonton, Alberta, T6G 2W2, Canada. Tel: (780) 492-5115; E-mail:
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yang.liu@ualberta.ca
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1.
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To better understand the mechanism controlling the observed PAO1 transport and
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deposition behaviors in column experiments, the DLVO theory was used to estimate the
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total interaction energy as the bacterial cells approaching a glass bead in each condition.
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The total interaction energy, including the sum of van der Waals forces and electrostatic
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double layer interactions, was determined by modeling the microbial cell-glass bead
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system as a sphere-plate interaction [Redman et al., 2004; Tufenkji and Elimelech, 2004].
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The electrostatic double layer interaction energies (ΦEDL) were calculated using the
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expression derived by Hogg et al. [Hogg et al., 1966]:
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Φ𝐸𝐷𝐿 = 𝜋𝜀0 𝜀𝑟 𝑎𝑝 {2𝜓𝑝 𝜓𝑐 𝑙𝑛 [1−exp⁡(−𝜅ℎ)] + (𝜓𝑝2 + 𝜓𝑐2 )𝑙𝑛[1 − exp⁡(−2𝜅ℎ)]}
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where ε0 is the dielectric permittivity in a vacuum, εr is the relative dielectric permittivity
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of water, ap is the microbial radius, κ is the inverse Debye length, h is the separation
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distance between the microorganism and the collector surface, and ψp and ψc are the
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surface potentials of the microbial cell and bead collector, respectively. The retarded van
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der Waals attractive interaction energy was calculated based on [Elimelech and Omelia,
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1990; Gregory, 1981]:
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Φ𝑉𝐷𝑊 = −
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where A is the Hamaker constant of the interacting media (microorganism – water – glass
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bead) and λ is the characteristic wavelength of the dielectric (assumed to be 100 nm). A
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value of 4.16 × 10-21 J was used for the Hamaker constant implying an attractive van der
Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations
1+𝑒𝑥𝑝(−𝜅ℎ)
𝐴𝑎𝑝
6ℎ
[1 +
14ℎ −1
𝜆
]
(S1)
(S2)
2
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Waals interaction as a microbial cell approaches a glass bead-water interface [Chen and
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Walker, 2012; Israelachvili, 2011; Lerner et al., 2012].
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References
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