Phytotoxicity and extractability of heavy metals from industrial wastes

The content, mobility and phytotoxicity of heavy metals in industrial wastes (sewage sludge, carbide residue, flotation tailings) have been determined by chemical characterization and biological test. Assessment of phytotoxicity and content of heavy metals in industrial wastes is important for screening the suitability for their land application or storage. The obtained information may provide a better understanding of environmental risks of heavy metals in wastes. Waste phytotoxicity was arranged in the following order: municipal sewage sludge > industrial sewage sludge > carbide residue > flotation tailings from Żelazny Most > flotation tailings from Gilów. High toxicity of sewage sludge can be caused by a high total content of metals and their forms soluble in 1 M HCl. As a result of waste acidification, zinc, chromium, nickel, and cadmium will be released into the environment from sewage sludge, whereas copper and lead will be released from flotation tailings. The study showed a strongly positive correlation between the content of Zn, Ni, Cr, Cd in waste and root growth and seed germination inhibition.