Biofilm effects on size gradation, drag coefficient and settling velocity of sediment particles

Shang, Qi; Fang, Hongwei; Zhao, Huazhang; He, Guojian; Cui, Zhenghui

doi:10.1016/s1001-6279(14)60060-3

Cited by 42 publications

(24 citation statements)

References 36 publications

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“…Growing attention has been paid to how SPM dynamics changes in the presence of a biological phase in addition to the mineral phase. The consistent finding throughout the recent literature is that although generally larger in size, biomineral aggregates are subject to higher drag and have lower excess density than mineral aggregates because of their lower capacity dimension, and thus, their settling velocity is not substantially different from mineral aggregates (Maggi, 2013(Maggi, , 2015Maggi, Manning, & Winterwerp, 2006;Maggi & Tang, 2015;Shang et al, 2014;Tan et al, 2012;Tang & Maggi, 2016). It is noteworthy that earlier experiments have also shown a high variance in biomineral SPM geometric properties such as size L and capacity dimension d (Tang & Maggi, 2017), thus suggesting that the heterogeneity is particularly high relative to our current NGUYEN ET AL.…”

Section: Introductionsupporting

confidence: 63%

Optical Measurement of Cell Colonization Patterns on Individual Suspended Sediment Aggregates

2017

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Microbial processes can make substantial differences to the way in which particles settle in aquatic environments. A novel method (OMCEC, optical measurement of cell colonization) is introduced to systematically map the biological spatial distribution over individual suspended sediment aggregates settling through a water column. OMCEC was used to investigate (1) whether a carbon source concentration has an impact on cell colonization, (2) how cells colonize minerals, and (3) if a correlation between colonization patterns and aggregate geometry exists. Incubations of Saccharomyces cerevisiae and stained montmorillonite at four sucrose concentrations were tested in a settling column equipped with a full‐color microparticle image velocimetry system. The acquired high‐resolution images were processed to map the cell distribution on aggregates based on emission spectra separation. The likelihood of cells colonizing minerals increased with increasing sucrose concentration. Colonization patterns were classified into (i) scattered, (ii) well touched, and (iii) poorly touched, with the second being predominant. Cell clusters in well‐touched patterns were found to have lower capacity dimension than those in other patterns, while the capacity dimension of the corresponding aggregates was relatively high. A strong correlation of colonization patterns with aggregate biomass fraction and properties suggests dynamic colonization mechanisms from cell attachment to minerals, to joining of isolated cell clusters, and finally cell growth over the entire aggregate. This paper introduces a widely applicable method for analyses of microbial‐affected sediment dynamics and highlights the microbial control on aggregate geometry, which can improve the prediction of large‐scale morphodynamics processes.

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Section: Introductionsupporting

confidence: 63%

Optical Measurement of Cell Colonization Patterns on Individual Suspended Sediment Aggregates

2017

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“…It is known that biofilms will colonize sediment and exert significant effects on the size gradation, bulk density, and surface properties, which all influence the settling velocity of the sediment particles. Previous studies showed that the biosediment size could be 1–2 orders of magnitude larger than the primary particles due to the biofilm growth, expressed as [ Shang et al ., ]

D_{f} = d_{50} true(1 + \frac{a}{d_{50}^{m}} f (N) true)

where D f (mm) is the median diameter of biosediment; d 50 (mm) is the median diameter of the clean sediment; and a and m are parameters. The function

f (N)

is the nutrient limiting factor, particularly

f (N) = 0

with no nutrient (no biofilm growth), and

f (N) = 1

with abundant nutrient.…”

Section: Methodsmentioning

confidence: 99%

“…The biosediment settling velocity

ω_{f}

(m/s) can be derived from the following formula suggested by Shang et al . []

ω_{f} = {[\frac{g D_{f}^{1.754} υ^{- 0.754}}{47.52} \frac{(ρ_{f} - ρ_{w})}{ρ_{w}}]}^{0.803}

where

ρ_{f}

and

ρ_{w}

are the density of biosediment and water in kg/m 3 , respectively;

g

is the gravitational acceleration in m/s 2 ;

D_{f}

is the median diameter of biosediment in m; and

υ

is the coefficient of kinematic molecular viscosity in m 2 /s.…”

Section: Methodsmentioning

confidence: 99%

“…Sediment provides an excellent substratum for microorganism colonization and the formation of biofilms has been found ubiquitously distributed in aqueous ecosystems [ Righetti and Lucarelli , ; Gerbersdorf et al ., ]. The development of biofilms can influence sediment properties (e.g., architecture, density, morphology, and size gradation) [ Gibbs , ; Droppo and Petticrew , ; Zhao et al ., ; Fang et al ., ; Shang et al ., ] and their transport processes [ Gerbersdorf et al ., ; Vignaga et al ., ; Fang et al ., ; Malarkey et al ., ; Fang et al ., ], as well as sediment associated contaminant transport [ Paterson et al ., ; Förstner et al ., ], which is critical to the aquatic environment. Therefore, enhancing our understanding of the interrelations between flow and biosediment transport is conducive to the operation of the TGR.…”

Section: Introductionmentioning

confidence: 99%

“…Then, the architecture and rheological properties of biosediment were illustrated [ Zhao et al ., ; Fang et al ., ], which were essential for sediment physical properties such as morphology, porosity, and density. Furthermore, the methods for computing size gradation, density, settling velocity, and critical erosion velocity for biosediment were also proposed [ Fang et al ., ; Shang et al ., ], and the bed form dynamics and transport characteristics for biosediment were studied by flume experiments [ Fang et al ., ]. Therefore, the previous studies on biofilm effects on sediment properties and transport characteristics make it possible to establish a sediment transport model with an integrated view of the biofilm effects.…”

Section: Introductionmentioning

confidence: 99%

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Modeling sediment transport with an integrated view of the biofilm effects

Fang

Lai

Cheng

et al. 2017

Water Resources Research

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Most natural sediment is invariably covered by biofilms in reservoirs and lakes, which have significant influence on bed form dynamics and sediment transport, and also play a crucial role in natural river evolution, pollutant transport, and habitat changes. However, most models for sediment transport are based on experiments using clean sediments without biological materials. In this study, a three‐dimensional mathematical model of hydrodynamics and sediment transport is presented with a comprehensive consideration of the biofilm effects. The changes of the bed resistance mainly due to the different bed form dynamics of the biofilm‐coated sediment (biosediment), which affect the hydrodynamic characteristics, are considered. Moreover, the variations of parameters related to sediment transport after the biofilm growth are integrated, including the significant changes of the incipient velocity, settling velocity, reference concentration, and equilibrium bed load transport rate. The proposed model is applied to evaluate the effects of biofilms on the hydrodynamic characteristics and sediment transport in laboratory experiments. Results indicate that the mean velocity increases after the biofilm growth, and the turbulence intensity near the river bed decreases under the same flow condition. Meanwhile, biofilm inhibits sediment from moving independently. Thus, the moderate erosion is observed for biosediment resulting in smaller suspended sediment concentrations. The proposed model can reasonably reflect these sediment transport characteristics with biofilms, and the approach to integration of the biological impact could also be used in other modeling of sediment transport, which can be further applied to provide references for the integrated management of natural aqueous systems.

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