Table 1: Physical and physicochemical characteristics of sewage sludge.

ParameterValue in dry
sewage sludge (SS)
Limit value in dry SS (according to
Italian Legislation
Lgs D. 99/1992)

Colour 7.5Y 2/1
Moisture content (%)11.8
Total OM (%)a42.3
Oxidizable OC (%)a21.9≥20.0
pH (H2O)7.64
EC (dS m−1)4.10
C : N ratio6.12
CaCO319.8
CHA/CFAn.d.
Total Kjeldahl Nitrogen TKN (%)a3.21≥1.50
P2O5 (%)a1.91≥0.40
K2O (%)a0.21
CEC (cmol(+) kg−1)n.d.
Pb (%)a49.0750
Cd (%)a5.2120.0
Ni (%)a24.0300
Zn (%)a10572500
Cu (%)a2161000
Hg (%)a 5.1010.0
Cr+6 (%)a1.20

Values on a dry matter basis; data are mean values, .