Page 283 - Materials Chemistry, Second Edition

266 Practical Design Calculations for Groundwater and Soil Remediation

= 26.9 moles of KMnO /m of aquifer
3
4
= (26.9 mole × 158 g/mole KMnO )/m of aquifer
3
4
= 4,250 g KMnO /m of aquifer = 4.25 kg KMnO /m of
3
3
4
4
aquifer
Stoichiometric amount of KMnO needed for the entire zone (40 m )
3
4
= (4.25 kg KMnO /m of aquifer) × 40 m 3
3
4
= 170 kg KMnO 4
(d) MW of sodium persulfate (Na S O ) = (23)(2) + (32)(2) + (16)(8) = 238
2 2
8
As shown in Table 5.3 and as discussed, the stoichiometric
requirement of sodium persulfate will be 1.5 times of that of
potassium permanganate.
Stoichiometric amount of Na S O (per m of aquifer)
3
8
2 2
= (3 moles of Na S O /2 moles of KMnO ) × (26.9 moles of
8
4
2 2
KMnO /m of aquifer)
3
4
= (40.35 moles Na S O /m of aquifer)
3
8
2 2
= (40.35 moles × 238 g/mole Na S O /m of aquifer)
3
2 2
8
= 9,600 g Na S O /m of aquifer = 9.6 kg Na S O /m of aquifer
3
3
8
2 2
8
2 2
Stoichiometric amount of Na S O needed for the entire zone (40 m )
3
8
2 2
= (9.6 kg Na S O /m of aquifer) × 40 m 3
3
2 2
8
= 384 kg Na S O 8
2 2
6.11 Advanced Oxidation Process
Advanced oxidation process (AOP) refers to an oxidation process assisted by
ultraviolet (UV) irradiation. In AOP, high-power lamps emit UV radiation
through quartz sleeves into impacted groundwater. An oxidizing agent, typ-
ically hydrogen peroxide, ozone, or a combination of these two is added. The
oxidizing agent is activated by the UV light to form hydroxyl radicals, which
have a very strong oxidizing power. These radicals destroy the organic COCs
in the impacted groundwater.
In a typical AOP, oxidizing reagents are often injected and mixed using
metering pumps and in-line static mixers. The groundwater then flows
sequentially through one or more UV reactors. The reactors are often consid-
ered as plug-flow type, and the reactions follow first-order kinetics. Equation
(4.24) describes the relationship among the influent concentration, effluent
concentration, retention time, and reaction rate constant for plug-flow reac-
tors. It is repeated here for the AOP reactors as:
C out −kV Q) − τk
(/
= e = e (6.39)
C in