INFLUENCE OF STABILIZED-DEWATERED SLUDGE ADDITION ON SOLID-PHASE CLEAN-UP OF A SOIL CONTAMINATED BY PHENOLIC COMPOUNDS

摘要

The purpose of this work was to investigate the effect of stabilized-dewatercd sludge on the performances of a solid-phase biological treatment applied to a soil contaminated with phenolic compounds. To this aim, a soil sample was artificially contaminated with either phenol or 3-chlorophenol, with concentrations of 1 and 0.5 g kg~(-1) of soil, respectively. Each contaminated soil sample was treated with a solid phase process, performed in three different operating conditions: without any addition; with addition of nutrients; with addition of nutrients and stabilized-dewatered sludge, obtained from a domestic wastewater treatment plant. The results obtained clearly indicated that the use of stabilized-dewatered sludge greatly reduced the time for complete removal of both phenol and 3-chlorophenol. Besides, the microorganisms concentration was higher in the sludge-amended soil with respect to other samples. This behavior could be a consequence of the carbon and energy sources contained in the sludge, even if the sludge could also offer a source of phenols-degrading microorganisms. On the contrary, the simple addition of nutrient did not notably affect the solid phase treatment under the studied conditions. Based on these results, it was shown that the use of stabilized-dewatered sludge may represent an efficient and economical way for accelerating solid-phase treatments, since it is produced worldwide and in large quantities as residue of domestic wastewater plants.