The sewage sludge was taken from different sewage plants (Mezzocorona and Rovererto, Italy and Paris, France). The blend material was air-dried at ambient temperature, further dried at 105 oc after crushing the lumps and !arge aggregates, and passed through a large Retsch hammer mill, equipped with tungsten carbide tools and a circular sieve with 2 mm aperture. The obtained powder was passed over a 125 µm sieve and the fraction > 125 µm discarded. The fraction < 125 µm was homogenized for 2 weeks in a mixing drum. In order to test the completeness of mixing, 10 subsamples were taken at different positions in the mixing drum for bulk homogeneity testing. Each bottle contain ca. 40 g. keywords: environmental material , biosolids , trace elements , heavy metals |
