3.3. Process water reuse, without specific additional treatments
(cascade configuration)
By reason of above reported constraints, there is no possibility
to recover the WWTP effluent because its quality is not compatible
with any utility requirements. In addition, it should be outlined
that WWTP effluent can be subjected to quality changes due to
malfunctioning or other unpredictable causes: a decrease in
WWTP efficiency can in fact dramatically increase the concentrations
of suspended solids and other pollutants in the effluent, with
serious drawbacks on the functionality of the WtE plant. Besides,
process water from bottom ash quenching and flue gas cleaning
utilities are scaling and highly contaminated. The only flows that
can be reused as such are cooling and boiler waters that are, as a
matter of fact, heated potable water.
Fig. 2 represents the most efficient cascade configuration for
process water reuse without additional treatments, in which cooling
and boiler waters feed the bottom ash quenching and the flue