Flotation and remediation of contaminated sludge and soil

摘要

Flotation, traditionally applied in mineralogy, has been used more recently in wastewater treatment, soil and sediment remediation and paper de-inking. The latter types of application may differ from mineral separation by the fact that the particles that should be floated are often partially hydrophobic and this will have consequences for the use of collectors and frothers. It is shown that the effect of collector and/or frother addition on the Gibbs energy of particle-bubble (PB) attachment differs for high-energy and low-energy surfaces. With low-energy surfaces collector and frother addition will, in general, impair PB attachment and improve PB detachment. To illustrate the effects in practice, results on the remediation of three sandy sludges contaminated with soot and/or coal-tar particles with a high concentration of poly aromatic hydrocarbons are presented. The focus is on sludge flotation because large quantities of contaminated harbor sludge or polluted soil require treatment and remediation by flotation is a potential alternative for classification. The results show that in two of the three cases studied collector addition has a negative effect.