1. Fenton Family - Advanced Oxidation
Technologies for Wastewater Treatment
SunKyoung Watech co., Ltd.
322, HWA SAN ONSAN ULJU ULSAN, KOREA

2. Conventional advanced wastewater treatment technologies
Coagulation: low COD removal, low sludge generation
Adsorption by GAC: high operating cost, activated carbon need be regenerated or wasted
Fenton‘s reaction: high sludge generation
O3 oxidation: high capital cost, residual O3 need be treated
Membrane separation: high capital cost, concentrate need be treated

3. AOP ⊙AOP (advanced oxidation processes): generating OH
→ Fenton’s reagent: H2O2 / Fe2+
→ Fenton-like reagent: H2O2 / Fe3+
→ Combination of O3 , H2O2 , and UV light
→ Combination of H2O2 ( or O3 ) and metal ions (e.g. iron salts)
→ Combination of UV light and semiconductors (e.g. TiO2)
→ electron beam
Commercialized industrial wastewater treatment technologies
Fenton, UV/O3

4. Comparison between oxidation potential for several oxidants

5. Introduction Fenton’s reaction H2O2 + Fe2+  OH + Fe(OH)2+
Fe(OH)2+ + OH-  Fe(OH)2+
Fe(OH)2+ +OH-  Fe(OH)3
                      
In 1894, Fenton found that Fe2+ improves the oxidation capability of H2O2 on tartaric acid
Substantial amount of ferric hydroxide sludge
Require solid/liquid separation and disposal
Let me now introduce the origin of this study. Advanced oxidation processes (AOPs) show potential for treating refractory compounds in waters and wastewaters. As you know, Fenton’s reagent is the combination of hydrogen peroxide and a ferrous salt. The primary oxidant in Fenton’s reagent is the hydroxyl radical (OH). Fenton’s reagent is an effective and simple oxidant of various types of organic contaminants. However, the drawback of Fenton’s method for destruction of organics is the production of substantial amount of ferric hydroxide sludge that requires further separation and disposal.
To solve this problem, the application of iron oxide as the heterogeneous catalyst in oxidizing organic contaminants deserves an in-depth investigation. In this study, a novel supported-FeOOH catalytic fluidized-bed reactor (FBR) was developed. The FBR was selected because of its high mass transfer efficiency and easy solid/liquid separation.

6. H2O2+Fe2+ → . OH+Fe (OH) 2+ →Fe(OH)3↓
Fenton’s method Fe(OH)3 sludge

7. List of refractory high-COD wastewater
Semiconductor / TFT-LCD: stripper, developer (TMAH), isopropanol
Film developing: developer (organic Ag)
Car manufacturing: resin, dye
Electroplating / printed circuit board: electroless Cu, electroless Ni, develop/strip solution
Chemical / petrochemical: solvent (toluene, benzene, acetone, chlorine-containing organics), resin, paint, polymer
Rinse water from air pollution control facility: scrubber, concentrator

8. Comparison of advanced treatment for refractory high-COD wastewater

9. List of refractory low-COD wastewater
Petrochemical
Chemical
Man-made fiber / textile
Dye
dyeing / finishing
PCB
Synthetic resin
Pharmaceutical
Leather
TFT-LCD

10. Comparison of advanced treatment for refractory low-COD wastewater
Items
Membrane
Separation
Activated Carbon Adsorption
Chemical Coagulation
Ozone Oxidation
Fenton Method
Fenton IV method
COD removal efficiency
（％）
90-95
20-75
20-50
30-60
65-85
70-90
Capital cost
（US $/m3）
60-140
60-200
Operating cost
(US $/m3)
(US $/kg COD)
4-10
3-11
1-4
7-10
3-7
2.5-4
Note
Concentrate must be treated
Activated carbon must be regenerated
Sludge must be treated
Wasted O3 must be treated
Sludge is reduced 70%, compared to Fenton method

11. Fenton Family Technology
Fered-Fenton
Fenton (conventional)
FentonⅡ
Feox-Fenton
FentonⅣ
FBR-Fenton
COD (mg/L)

12. Fenton Family Technology
Fered-Fenton
Refractory wastewater
FBR-Fenton
Pretreatment
Non-refractory wastewater
Biological treatment
Advanced treatment: adsorption, Fenton…
effluent
Then I will introduce the application of Fenton family methods. The core techs are Fered-Fenton and FBR-Fenton methods. Fered-Fenton method is applied to treat the refractory wastewater which can inhibit or kill the microorganism of the activated sludge reactor if we have no further pretreatment. The effluent of Fered-Fenton reactor can feed into the biological treatment process because the biodegradability has been improved. FBR-Fenton method can replace the conventional advanced treatment unit such as activated carbon adsorption and Fenton method. The effluent of FBR-Fenton also can partly recycle back the biological process to upgrade the biodegradability. Combination of Fenton family methods and biological processes not only can reduce the operation cost of chemical but also upgrade the performance of biological processes.
Application for COD 50-50,000 mg/L of non-biodegradable wastewater

13. Fered-Fenton (Fenton III)
method

14. Fenton III (Fered-Fenton) process
Fered-Fenton: apply H2O2 and electrogenerated ferrous ion produced from ferric sulfate
Fered-Fenton reaction
Cathode：Fe3++e-→Fe2+
Solution:
H2O2+Fe2+ → . OH+OH-+Fe3+→╳Fe(OH)3↓╳
sludge reduction 80%
Peroxid-Chemie (German) patent：separated Fenton reactor and electrolytic reactor

15. Design principles of FentonIII
Cathode:Fe3++e-→Fe2+
H2O2+Fe2+ → . OH+OH-+Fe3+→╳Fe(OH)3↓╳
Faraday’s laws
n＝It ／ZF
1F=96500 Coul=26.8 Ah
Equivalent value =56/26.8
=2.08gFe/A.h

16. Fenton III (Fered-Fenton) process
Organics RH
H2O2
· OH
Oxidation
Products
CO2, H2O
< Major Reactions>
Fe2+ + H2O2 → · OH + OH- + Fe3+
Fe3+ + H2O2 → Fe2+ + HO2· + H+
Fe2+ + · OH → OH- + Fe3+
H2O2 + · OH → HO2· + H2O
Fe2+ + HO2· + H+ → Fe3+ + H2O2
Fe3+ + HO2· → Fe2+ + O2 + H+
pH 3~4

17. Rate constants for reactions
of OH radicals in acids
k (M1S1) dissociated form (B or B2)
k (M1S1) nondissociated form (HB)
Formate
Acetate
Oxalate
3.2109
8.5107
4.7107
1.3108
1.6107
1.4106
Buxton et al., 1988
These acids with dissociated form have higher rate constants than those with nondissociated form.

18. Comparison between Fenton and Fenton III method
On the degradability
of acetic acid

19. Example Hexamine Petrochemical wastewater (CH2)6N4 N H2C CH2 CH2 N CH2
Let me now introduce the origin of this study. Coagulation/flocculation is not only an important pretreatment process, but also an advanced treatment unit following the activated sludge system for solving the bulking problems.
As Taiwan’s new effluent standard in 1998 (SS < 30 mg/l) is stricter, we develope an on-line monitoring system for the coagulation/flocculation process in wastewater treatment plant. N N
CH2

20. Treatment of hexamine-containing wastewater by EF-Fere method
theoretic dosage
Fei = 5000 mg/l
cathode current
density =18 A/m2
initial pH = 1.71
The second topic is “...”.
Fig. 4 shows the relationships between PACl dosages and some coagulation indexes for the raw pulp wastewater. The maximum of Ratio occurs at 35 mg/l of PACl dosage. Further increasing the dosage to 100 mg/l, the supernatants turbidity maintain at the lowest levels (i.e. 20 NTU). It infers that 35 mg/l of PACl dosage is the optimal dosage to coagulate the raw pulp wastewater. In addition, the corresponding floc diameter and floc settling velocity also indicate that the same trend. This evidence conforms to Huang and Chen (1996) that the maximum of Ratio value is an effective index to determine an optimal PACl dosage.

21. Treatment of hexamine-containing wastewater by EF-Fere method
Hexamine  formaldehyde  formic acid (formate) CO2
NH4+ NO3-
(trace)
The second topic is “...”.
Fig. 4 shows the relationships between PACl dosages and some coagulation indexes for the raw pulp wastewater. The maximum of Ratio occurs at 35 mg/l of PACl dosage. Further increasing the dosage to 100 mg/l, the supernatants turbidity maintain at the lowest levels (i.e. 20 NTU). It infers that 35 mg/l of PACl dosage is the optimal dosage to coagulate the raw pulp wastewater. In addition, the corresponding floc diameter and floc settling velocity also indicate that the same trend. This evidence conforms to Huang and Chen (1996) that the maximum of Ratio value is an effective index to determine an optimal PACl dosage.

22. Comparison experiments
The second topic is “...”.
Fig. 4 shows the relationships between PACl dosages and some coagulation indexes for the raw pulp wastewater. The maximum of Ratio occurs at 35 mg/l of PACl dosage. Further increasing the dosage to 100 mg/l, the supernatants turbidity maintain at the lowest levels (i.e. 20 NTU). It infers that 35 mg/l of PACl dosage is the optimal dosage to coagulate the raw pulp wastewater. In addition, the corresponding floc diameter and floc settling velocity also indicate that the same trend. This evidence conforms to Huang and Chen (1996) that the maximum of Ratio value is an effective index to determine an optimal PACl dosage.
A: H2O2 /Fe3+
B: H2O2 /Fe2+
C: direct electrolysis

23. Feature of Technique
① Using the Fenton reaction dispose of wastewater to compose anode of stick type and cathode of matrix type using the up-flow type electrolyzer of cylinder type . Fenton reaction tank and the up-flow type electrolyzer of cylinder type are continuous circulation advanced oxidation system
the up-flow type electrolyzer of cylinder form composed anode of stick type (Titanium DSA) and cathode of matrix type (STS316)
It compares in cathode and the surface area is few relatively. Therefore high price minimizes of using the Titanium DSA
Equally, electrolyzer changes from lower part of up-flow type electrolyzer to top part
Are composed with Matrix type, the inside and the outside of cathode structure states cathode, smooth moving of waste water between cathodes

24. Anode rod
Cathode screen

25. Control flow chart Continuous Feed Flow
Batch Feed Flow
pH control Tk
Electrolytic reactor
Fe3+
Clarifier
Neutralization Tk
Coagulation Tk
Case 1 (Use to coagulant at other WWTP)
First Time
Second Time
Case 2 (Reuse of Fe in process)
Case 3 (Use to coagulant at other WWTP)
Case 4 (Batch Feed Flow process)
Reaction Tk

26. Case Study (Fenton III)
Solvent vessels-washing wastewater
from a semiconductor plant
Components : isopropyl alcohol, acetone,
monoethanoamine and phenol
COD＝11000mg/L
Flowrate=1m3/day (batch mode)

27. Case Study (Fenton III)
pH<2
Mixing with
NaOH,
pH>7
Discharge
Mixing with H2SO4
pH＝1.5～2
Iron sludge dissolves
Solvent vessels
Wastewater
Equalization
tank
Electrolytic
tank
Effluent
Buffer tank
The effluent also can be applied as the coagulant directly.

28. Case Study (Fenton III)
Batch
Influent
After Fenton III reaction
After coagulation
COD(mg/L)
CODr(%) 1
10982
352
96.8
295
97.3 2
10806
303
97.2
272
97.5 3
23800
986
95.9
892
96.3 4
18367
561
96.9
511
Influent
After coagulation
After 8 hrs of Fenton III reaction
After 22.5 hrs of Fenton III reaction