Applying a logistic growth equation to model flocculation of sediment in the presence of living and dead organic matter

Frontiers in Marine Science

Marine Science

Zhirui Deng¹  Claire Chassagne²  Zeinab Safar² 

[1] Guangdong Research Institute of Water Resources and Hydropower, Guangdong Engineering Laboratory of Estuary Hydropower, Guangzhou, China;Section of Environmental Fluid Mechanics, Department of Hydraulic Engineering, Delft University of Technology, Delft, Netherlands;

关键词: logistic growth;    flocculation;    population balance equation;    clay;    EPS;    microalgae;   

DOI  :  10.3389/fmars.2023.1227849

 received in 2023-05-23, accepted in 2023-07-10,  发布年份 2023

来源: Frontiers

【 摘 要 】

In the present study, we aim to parameterize a flocculation model, based on a logistic growth equation, by conducting laboratory experiments. The flocculation experiments are performed using two types of natural sediments and different flocculating agents: salt (monovalent and divalent), extracellular polymeric substances, and living and dead microalgae Skeletonema costatum. It was found that the median size of flocs (D50) did not exceed the Kolmogorov microscale when salt-induced flocculation was performed (in the absence of organic matter), which is in line with previous studies. Flocs with organic matter reach sizes that are larger than the Kolmogorov microscale, and both their growth and steady-state size are salinity-dependent. In particular, divalent salts are shown to promote flocculation of sediment to organic matter. The logistic growth model can be used to study either the evolution of a class volume concentration as function of time or the change in size of a given class as function of time. The fine particle volume concentration decreases in time, whereas the coarse particle volume concentration increases, during the flocculation process. The mass balance between the two classes as defined by Chassagne and Safar (Modelling flocculation: Towards an integration in large-scale sediment transport models. Marine Geology. 2020 Dec 1;430:106361) is estimated.

【 授权许可】

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