Chemical Techniques for Sediment Treatment
Type:
Presented during:
WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.
Authors:
A. Boisson
Abstract
"Every year, millions cubic meters of sediments are dredged around the world. Sediments, once considered like a waste, are now more and more used as a resource. There are existing projects using sediments as raw material for concrete or brick production, for submarine dike construction, etc ... When dredged material is contaminated by pollutants (like heavy metals, HAP, PCB, ...), a treatment is necessary to eliminate or to stabilize contamination. For this, polymers can be used to improve treatment and to help re-use of sediments. Polymeric dithiocarbamates are known for their excellent chelation properties. They are commonly used in the water treatment to treat heavy metal in water and also for fly ash stabilization. In the dredging industry, dithiocarbamates are an interesting new chemical technique to treat sediments due to their ability to insolubilize and stabilize heavy metals. Flocculants are used in the dredging industry for more than 50 years. Polymers are typically used for better solid liquid separation, shorter drying time and reduced land requirement for sediment treatment. New innovations in polymers have improved flocculant properties. As an example, with structured polymers, it is possible to improve polymer and sludge mixing, to increase drainage and flocs resistance to shearing forces. Laboratory tests made for Capurro harbour dredging project in Uruguay illustrate well these polymer properties improvements. When sediment treatment is required in a dredging project, the use of polymers brings and environmental benefits. With increasing pressure for sediment reuse, we believe that the dredging industry will find more and more interest in polymers use."
Keywords: polymer, chelating agent, sediment reuse, sediment treatment, flocculation, heavy metal, stabilization