1. Kassim Olasunkanmi Badmus Ninette Irakoze Leslie Petrik
Treatment of textile wastewater using combined Hydrodynamic cavitation, Fenton process and Nano zero valent Iron
Kassim Olasunkanmi Badmus
Ninette Irakoze
Leslie Petrik

2. Oxidizing and reducing agents
Textile wastewater contains both organic and inorganic chemical substances used in the complex processes of textile production.
Wastewater
Organic
Organic acids
Thickeners
Dyes
Detergents
Textile auxiliaries
Finishing agents
Inorganic
Oxidizing and reducing agents
Acids
Alkalis
Salts

3. Dyes are the dominant content of textile wastewater
Complex organic dyes are toxic chemicals with documented biological effect on animals (Akhtar et al. 2016)

4. Conventional Treatment of Textile Wastewater
Method
Example
Advantages
Disadvantages
Physical treatment
Filtration, Sedimentation, Precipitation, Adsorption.
Turbidity and colour removal
Amenability for further treatment
Inexpensive
Low efficiency
Microorganism cannot be removed.
Chemical treatment
Coagulation, Flocculation,
Ion exchange, Chemical disinfection.
Improved microbial quality
Efficient
Physical removal
Generation of toxic chemical intermediates
Use of expensive chemical
Require further treatment for solid waste removal.
Biological treatment
Active filtration, Riverbank filtration, Membrane bio reactor and Soil aquifer treatment.
Effective for COD and turbidity removal
Need skilled man power
Ineffective for colour removal.
Toxic intermediates (Cripps et al. 1990).

6. Cavitation is a Non-chemical
Ultrasonic
Hydrodynamic

7. NZVI is a red-ox agent and good source of Fenton catalyst

8. Combined AOP using FP, NZVI and HC can result in efficient mineralization of persistent organic pollutants in textile wastewater . Orange II sodium salt (OR2) is a representative azo dye. HC
NZVI FP

9. Objectives of the studies
Single AOPs
Determination of the optimum condition for degradation of OR2 in HC
Focus on pH and initial concentration
Combined AOPs
Investigation of the degradation effect of HC and FP in combined AOP.
Investigation of the degradation effect of HC and NZVI in combined AOP.
Results
Discussion of the best combined AOP on the degradation effect
Proposal for the reaction pathway

10. Experimental method
Find the optimum pH for degradation of OR2 in HC at 300 kPa in-let pressure
Find the optimum concentration for degradation of OR2 in HC at 300 kPa in-let pressure
Apply the optimum conditions for degradation of OR2 in HC
Combine FP [10 ppm H202/ 200 mg Fe (2+)] with the HC at 300 kPa in-let pressure, pH 2, 10 ppm OR2
Combine NZVI (20 mg/ L) with HC at optimum conditions in the degradation of OR2

11. First order kinetic degradation of OR2 in hydrodynamic cavitation jet-loop at varied initial contaminant pH (Initial concentration and pressure are 10 ppm and 300 kPa respectively).

12. pH 2 was confirmed as the optimum for the generation of OH radicals in an ultrasonicator in our previous experiment. Badmus et. al., 2016

14. % degradation per 60 minutes
First order rate constant (k) and extent of degradation of OR2 at varied contaminant concentration using HC at pH 9.4, 300 kPa inlet pressure
Concentration (ppm)
% degradation per 60 minutes
k X 10-3 min-1 R2 5 21
4.15
0.988 10 16
3.12
0.991 20 13
2.92
0.972

16. C Ξ cavitation, F Ξ Fenton, N Ξ green nano zero valent iron (gNZVI) CF Ξ combined cavitation and Fenton, CN Ξ combined cavitation and gNZVI while CNF Ξ combined cavitation, gNZVI and Fenton.

18. FT-IR spectrograph of OR2 and degraded products after an hour treatment time at the optimized conditions showing the peculiar peaks at (cm-1)

19. FT-IR spectrograph of OR2 and degraded products after an hour treatment time at the optimized conditions of combine AOP showing the presence of new peaks

20. Conclusion
The single AOP is ineffective in mineralization of Azo dyes.
Combination of HC, FP and NZVI can result in efficient degradation of Azo dyes.
NZVI and HC represent a green replacement for Fenton oxidation in a AOP system.
NZVI and HC was successfully combined for the first time in the treatment of wastewater containing OR2.
The rate and extent of degradation is significantly high.
The method is recommended for tertiary stage of textile wastewater treatment.

21. Recommendation for further studies
LC-MS analysis should be done to elucidate the complete degradation pathway.
COD and BOD test should be done to determine the biodegradability of the resulting compounds.
Daphnia magna test should be done to estimate the toxicity of the resulting products.
The pH range of activity should be investigated in combine AOP using H.C and NZVI

22. Acknowledgment Prof. Leslie Petrik ENS (staff and students) Royal Society of chemistry/ Dalton Division UWC

23. References
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Cripps, C., Bumpus, J.A. & Aust, S.D., Biodegradation of azo and heterocyclic dyes by Phanerochaete chrysosporium. Applied and Environmental Microbiology, 56(4), pp.1114–1118.
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