Page 228 - Industrial Wastewater Treatment, Recycling and Reuse

202 Industrial Wastewater Treatment, Recycling, and Reuse

Precipitator
Polyelectrolyte
Fenton NaOH
reactor
H SO H O
2 4 Settling tank
2 2
Waste Treated
water water
pH 7 pH 7
Iron
sludge
Fe (III)

O Fe(II) / Fe(III)
2
Electrolysis H SO
cell 2 4
pH 1
Dissolution
tank
H O
2
Figure 4.7 Ex situ electro-Fenton layout.

the Fered Fenton process, the conversion takes place in the reactor, in the
ex situ process, the sludge post-neutralization stage is again acidified to the
necessary pH and then passed through an electrochemical cell where the
ferric is converted to ferrous. Thereafter, this ferrous salt is reused in the pro-
cess for reaction. This Fenton sludge recycling has been reported in the past
(Swinnen et al., 1999). A typical process schematic is shown in Figure 4.7.
Othervariantsoftheelectro-Fentonprocesscanbefoundintheliterature,
but the two mentioned in this chapter are possible commercially viable pro-
cessoptionsthatcanbeusedinindustriesatthesmall,medium,andlargescale.

4.5 FENTON CATALYTIC REACTOR ADVANCED
OXIDATION TREATMENT
The Fenton process generally is not an ideal choice for treatment of high-
volume wastewater because of the limitations associated with it, as discussed
earlier. The Fenton catalytic reactor aims to address the limitations of the
classical Fenton process using a special reactor design wherein the exhausted
ferrous catalyst gets converted into a heterogeneous catalyst that further aids