Flotation of PAH contaminated dredged sludge

The applicability of dissolved air flotation to remediate contaminated sediments of "Overschie" (Rotterdam) and "Petrol Harbor" (Amsterdam) is studied. Several flotation reagents (Diesel Fuel, Montanol, Aerophine, Aerofroth) are applied to enhance the flotation efficiency. The physical chemical characteristics of the different particles in the presence of surfactants are investigated by contact angle measurements. In the absence of reagents a one step batch flotation experiment removes around 85% of PAHs from both sludges. The remaining tailings contain 92% and 83% of the total mass for the Overschie and the Petrol Harbor sludge, respectively. When reagents are added the efficiency of the process decreases. The remaining tailings contain only 80 to 60% of the total mass, whereas the PAH removal is not substantially enhanced and in some experiments even dramatically reduced