The Leaching Behavior of Toxic Metals in Petroleum Sludge After Thermal Treatment

Abstract

Petroleum sludge contains high concentration of hydrocarbons and heavy metals, which are hazardous to the environment and human health. In this study typical petroleum sludge samples collected from crude oil tank were thermal treated by burning and melting, respectively. The leaching behavior of seven target heavy metals including Cr, Ni, Cu, Zn, As, Cd, and Pb from the solid residue were comparatively studied with that from municipal sewage sludge according to the toxicity characteristic leaching procedure. Scanning electron microscopy and X-ray diffraction analysis were carried out to investigate the morphology and crystalline composition. Results showed that total concentrations of target metals in petroleum sludge were relatively lower comparing with those in sewage sludge except for Cu, Cd, and Pb. Leached concentrations of Cu, As, and Pb from petroleum sludge increased dramatically after burning and were higher than those from sewage sludge. The leached concentrations after melting were decreased substantially except for Cr and Ni whose leaching concentrations were unaffected by thermal treatment for the studied samples.

Keywords:

• petroleum sludge
• heavy metal
• melting
• leaching characteristic
• morphology