Biological effects on incipient motion behavior of sediments with different organic matter content
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SEDIMENTS, SEC 4 • SEDIMENT-ECOLOGY INTERACTIONS • RESEARCH ARTICLE
Biological effects on incipient motion behavior of sediments with different organic matter content Yongchao Zhou 1 & Xinyu Yao 1 & Yueqi Gu 1 & Dong Qian 1 & Yao Tang 2 & Yiping Zhang 1 & David Z. Zhu 3 & Tuqiao Zhang 1 Received: 31 October 2019 / Accepted: 13 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose The organic content in urban sewer sediment can significantly influence sediment erosion behavior because of biological activity. In this experimental study, the erosion behavior of sediments with different organic content was investigated to develop a mathematical relationship between the critical shear stress and biological activities. Materials and methods Before testing, sediment samples were incubated under two environmental conditions: aerobic conditions with high biological activities and sterile conditions with low biological activities. With different incubation periods, samples were subjected to the scouring test in an open channel flume, by which the incipient motion of sediments was determined. Results and discussion Experimental results show that the sediment erosion resistance is simultaneously subject to the strengthening and the weakening effect induced by the biological activity, which is dependent on the incubation period and organic content. For low organic content sediment (volatile solids content < 4%), the biological activity can strengthen the sediment erosion resistance and increase τc, while τc of higher organic content sediment is distinctly reduced. Conclusions The biological activity can both strengthen and weaken the sediment erosion resistance. The strengthening effect is attributed to the biofilm formation in the biological activity, whereas the weakening effect is due to the sediment volume expansion by the gas bubble formation. These effects depend on the incubation period and organic content within sediments, which can be used to predict the incipient motion of sediments by modifying the biological influence coefficient. Finally, Shields curves were modified to account for the biological activity. Keywords Biological activity . Erosion behaviors . Organic content . Real sewer sediments
1 Introduction Responsible editor: Sabine Gerbersdorf Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11368-020-02807-9) contains supplementary material, which is available to authorized users. * Yao Tang [email protected] 1
Key Laboratory of Drinking Water Safety and Distribution Technology of Zhejiang Province, Zhejiang University, Hangzhou, China
2
MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, College of Civil Engineering and Architecture, Center for Hypergravity Experimental and Interdisciplinary Research, Zhejiang University, Hangzhou 310058, China
3
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada
Sediment deposition in urban drainage systems can cause a series
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