contrast, metal concentrations in soil leachate increased,
possibly due to colloidal transport of Zn precipitates
and Cu transport in the dissolved fraction.
However, hydrochar (poplar-derived) is not suitable
for metal immobilization. Conversion of sewage sludge
into biochar is a potential way to manage these
wastes, because the use of sewage sludge biochar and
sewage sludge may have different effects on soil biochemical
properties as indicators of soil quality (Hossain
et al., 2010). Microbial biomass C, soil respiration,
net N mineralization, and enzyme activities showed a
different response to the treatments of sewage sludge
biochar and unpyrolyzed sewage sludge with higher
quality after sewage sludge biochar treatment (Paz-
Ferreiro et al., 2012).