Ultrasound sludge lysis: heavy metals stability enhancement

摘要

Heavy metals in sludge are of great concerns worldwide due to their high toxicity. The toxicity of heavy metals strongly depends on their stability in the sludge. This study investigated the stability of typical sludge heavy metals (As, Cd, Cr, Cu, Ni, Hg, and Pb) during ultrasonic sludge treatment process. Results showed that sonication enhanced the stability of sludge heavy metals, which was beneficial for sludge disposal and reclamation. Content of stable fractions increased and content of unsteady fractions decreased after 15-min sonication at 2.0 WmL(-1). The stability of each heavy metal in sludge was significantly different during sonication. For arsenic, unsteady fractions decreased from 94 to 9% and stable fractions increased from 0 to 68% after 15-min sonication; for mercury and lead, stability showed little change due to the high residual fraction. Sonication changed the stability order of heavy metals in sludge. In the untreated sludge, the stability order was As