Biomineral Flocculation of Kaolinite and Microalgae: Laboratory Experiments and Stochastic Modeling

Abstract

The transportation of cohesive sediments has attracted great attention for decades due to the significant influences of sediments on various coastal and offshore engineering (e.g., siltation, dredging, seawall foundation treatment, and riverbed morphology) and environmental (e.g., pollutant transport, phytoplankton photosynthesis, and coastal wetland sustainability) issues (Coats et al., 1989;Edmonds & Slingerland, 2010;Sun et al., 2021;Teisson, 1991). It is a challenge to precisely predict the dynamic processes of cohesive sediments because they exist in the form of flocs (clusters) rather than single particles, which further controls the size and the settling velocity (

Viscosity of Cohesive Sediment‐Laden Flows: Experimental and Empirical Methods

“…Using similar materials and the experimental setup, Zhu et al. (2017, 2022) observed that the viscosities of kaolinite suspensions exhibited the same trend of increasing and then reaching a plateau with sediment volume concentration. Nevertheless, some differences in absolute viscosity values were observed between their findings and those of this study, which may be attributed to the variances in sediment size, and/or sample preparation, and/or experimental conditions.…”

“…These organic matters can interact with sediment particles and flocs, potentially altering their structural properties and thus influence the rheological properties of the flow. It is widely known that organic matter can act as a biological glue that facilitate flocculation and promote the formation of biofilm, which consists of microbial communities embedded in EPS, can further modify sediment properties (Deng et al., 2019; Droppo, 2009; Fettweis et al., 2022; Zhu et al., 2022). In particular circumstance such as in the environment abundant of biomass (e.g., wetland, tidal creek, and mangrove area) or during the algal bloom period, the biological effects may become the significant factor influencing flocculation and the rheological behavior of the sediment‐water mixture compared to the hydrodynamic conditions.…”

“…Similar results were also recorded in the experiments conducted by De Wit (1996), who explored the viscosity of the remoulded kaolinite suspensions, supporting the fundamental role of sediment volume concentration in determining fluid viscosity. Using similar materials and the experimental setup, Zhu et al (2017Zhu et al ( , 2022 observed that the viscosities of kaolinite suspensions exhibited the same trend of increasing and then reaching a plateau with sediment volume concentration. Nevertheless, some differences in absolute viscosity values were observed between their findings and those of this study, which may be attributed to the variances in sediment size, and/or sample preparation, and/or experimental conditions.…”