(in lingua inglese)
• UMT process displayed a reduction of ecotoxicity only after the 1st mesophilic step of digestion. Ecotoxicity increased after the 2nd thermophilic step.
• The toxicity exerted by the Canadian biosolids was considerably lower than that of the European samples even after enhanced stabilization processes. The toxicity of sludge seems to be more related to the source than to the treatment, with “source” meaning the origin (and thereby contamination) of the wastewater from which the sludge was produced. This was confirmed by some tests on mixed sludge (AA process) which was much more ecotoxic than secondary sludge.