Solindus Experimental Dredged Material Treatment Platform: a Versatile Solution for Sediment Treatment and Clay Flocculation
Type:
Presented during:
WODCON XX: "The Art of Dredging" - 2013, Brussels, Belgium
Authors:
Brequel H, Gineys N, Urbain F, Couturier F, Duchadeau A
Abstract: Treatment by mineralurgical processes of dredged material is often proposed due to the relative simplicity of physical-chemical principles involved, reasonable investment and operating costs and reduced environmental impact. Unfortunately, return on experience is usually missing and prevents industrial operators from investing in such processes. The Solindus project aims at providing such data by building and operating one experimental semi-industrial platform for sediment treatment. It will be used as a technical demonstrator for industrials dealing with sediments. As a result of the treatment, 5 fractions (gravel and miscellaneous, coarse sand, fine sand, silt and clay) are obtained. The important issue is the clarification of the clay fraction before dewatering, especially when its characteristics can vary from one sample to another, as it is usually the case in Wallonia, depending on the dredged locations. Moreover, the presence of pollutants (metallic species and/or organic compounds) can affect the behavior of the dredged material towards the flocculants. At laboratory scale, a protocol was set up in order to choose the more efficient reagent for different samples of sediments. Depending on the sample, it could vary from cationic to anionic species, with various ionic strengths and molecular weights. On the platform, it is not possible to have in stock several flocculants so the opposite approach was preferred, id est to have one chemical that can be used for the various sedimentary materials encountered so far. One amphoteric polymer has been selected, tested at the laboratory scale and used at the platform. Amphoteric polymers carry simultaneously cationic, non ionic and anionic sites. As a consequence they can cope with high sediment variations. Combining simple physical processes with specific chemicals has been the key to operate successfully the semi-industrial platform whatever the sediment composition.
Keywords: sediment treatment, clay flocculation, dewatering, amphoteric polymers