Experimental Analysis on Bioflocculation Sediment Architecture

Sediment flocculation is very important for cohesive sediment dynamics. The bioflocculation of sediment induced by biological activity has attracted more and more attention over the last decades. In order to accurately understand the formation mechanism and structural characteristics of bioflocculation sediment, firstly, the micro-morphology of bioflocculation sediment in water environment should be visualized and its flocculating structure should be analyzed, so as to lay a foundation for further related research. Bioflocculation sediment has a small particle size, which is in the order of micron, and there is organic matter-biofilms on the surface and between the particles, whose main component of 85-90% is water. Therefore, the characteristics of sediment, microorganisms and their metabolites should be taken into account. Appropriate instruments and equipment should be used to observe bioflocculation sediment in situ, which couldn't be dried, carbon plated, etc. This paper uses a newly developed field kit and correlative microscopy to bridge the resolution gap between sediment particles and biological activities as well as its metabolic products-biofilm, so as to better understand the role of polymeric material biofilm in floc ultrastructure and outward flocculation behavior of bioflocculation sediment. The flocculation structure of bioflocculation sediment was observed by means of environmental scanning electron microscopy and confocal laser scanning microscopy. A more intuitive understanding of its internal micro-environment and external behavior characteristics was obtained, and the great role of microbial activities and their metabolites in the structure and adhesion characteristics of bioflocculation sediment was revealed. This will help to improve the understanding of bioflocculation sediment dynamics and its environmental effects in nature. The research showed that bioflocculation sediment was composed of complex networks of biofilm and appeared to be of complicated physical flocculation structures. The biofilm embedded particles and permeated the void space, representing the dominant physical bridging mechanism of the sediment flocculation and contributed to the extensive surface area, architecture characteristics and mechanical properties.