treatment plants. It may be deposited in landfills, in the sea
(ocean disposal), under the ground, or (to a certain extent)
in the air as a consequence of incineration. In addition,
sludge can be used (recycled) in various ways, including its
use as fertilizer, as a soil conditioner in farmland, in forests,
and in home gardens, as well as in concrete and in
bituminous mixes in buildings and roads (Ødegaard et al.,
2001). Oceanic disposal of sludge is currently forbidden.
Landfilling of sludge has hitherto been an inexpensive
method of disposal, but in the future, the use of landfills
will have the lowest priority in the waste-handling
hierarchy (i.e., waste minimization first, then reuse;