3.2. Legal and technical constraints
Legal constraints are related to the efficiency of the WWTP.
Water reuse implies a reduction of the total influent flow rate to
the WWTP and, as a consequence, of the wastewater discharged.
An increase of the concentration of pollutants that cannot be
removed by the WWTP (i.e. chloride and sulfate) is therefore implicit
in the final effluent, while the concentration of the other pollutants
should be evaluated as a function of the specific
characteristics of the treatment plant. Chloride and sulfate ions
showed high concentration values especially in process water
derived from bottom ash quenching and flue gas cleaning system,
as reported in Table 1. Considering the highest measured concentration
of chloride and sulfate, it was possible to calculate Fmax
and Qmin related to both anions. Assuming the most restrictive condition,
Qmin resulted in 165 m3 d1
; as a safety factor, a minimum