Solidification effect of river bottom sediments after flocculation via different composite flocculants
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RESEARCH ARTICLE
Solidification effect of river bottom sediments after flocculation via different composite flocculants Linzhu Sun 1 & Yunyun Zheng 1 & Xiaoniu Yu 1,2 Received: 11 July 2020 / Accepted: 12 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The main problem in the reduction of river bottom sediments is to solve the dewatering of the rive sediments. The reduction of river bottom sediments is usually dehydrated by natural air drying and requires more time and economic costs. Different proportions of composite flocculants and curing agents have been developed to the reduction of river bottom sediments according to the requirements of the project. Two or more flocculants were mixed with the rive sediments. Therefore, anionic polyacrylamide (PAM), polyaluminum chloride (PAC), polysilicate aluminum ferric (PSAF), and iron perchloride (IC) were selected for flocculation of river sediments. Through the sedimentation column test, the relationship between sedimentation amount and time was plotted, the turbidity value and pH value of the supernatant filtration supernatant were detected, and the flocculation effect of different flocculants was evaluated to obtain suitable groups of composite flocculants. The optimum ratio of two types of polyacrylamide with a molecular weight of 18 million and 23 million was 3:7. The turbidity of the supernatant of water could well be reduced by adding polysilicate aluminum ferric. Finally, the 6 groups of composite flocculants were determined according to the sedimentation and the turbidity value of the supernatant. The relative water content was maintained at about 60% before and after flocculation. At the same curing age, the compressive strength increased as the amount of curing agent increased after flocculation. At the same curing agent dosage, the overall solidification effect was reduced with increase of curing time after flocculation. Keywords River bottom sediments . Flocculants . Turbidity value . Flocculation effect . Solidification effect
Introduction The water in the sludge is in the form of bound water (Wang et al. 2019; Liang et al. 2020). The flocculation method of the river sediments is to discharge bound water between soil particles. The bound water is also called free water and exists between the flocs, which can be extruded from the flocs by mechanical dewatering (Wang et al. 2019). The flocculation agent can be used to encapsulate the colloid, solute, or particles suspended in the Responsible Editor: Philippe Garrigues Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-11242-9) contains supplementary material, which is available to authorized users. * Xiaoniu Yu [email protected]; [email protected] 1
College of Civil Engineering and Architecture, Wenzhou University, Wenzhou 325035, China
2
School of Environment, Tsinghua University, Beijing 100084, China
solution into a flocculent precipitate (solid-water separation), and can function as a purifying solution (Zhai et al.
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