Marina Arnaldos, responsable de desalación de desalación y nuevas tecnologías de ACCIONA Agua, presentó la ponencia “Advanced oxidation processes to recover reverse osmosis cleaning waters for irrigation purposes” en la conferencia anual que la asociación europea de desalación ha celebrado en Roma entre los días 22-26 de mayo de 2016.

1. ACCIONA Agua. Tu socio en el ciclo del agua
ADVANCED OXIDATION PROCESSES
TO RECOVER REVERSE OSMOSIS
CLEANING WATERS FOR IRRIGATION
PURPOSES
EDS International Conference, 23rd May 2016, Rome (Italy)
M Arnaldos, S Jiménez, B Corzo, MM Micó, E Ferrero, T de la Torre & JJ
Malfeito

2. ACCIONA Agua. Tu socio en el ciclo del agua
INDEX
1. Introduction
2. Materials and Methods
3. Fenton Results and Discussion
4. Photo Fenton Results and Discussion
5. Conclusions

3. ACCIONA Agua. Tu socio en el ciclo del agua INTRODUCTION: BACKGROUND
NORMAL SEAWATER
ALGAE BLOOM
• Building Blocks
• Low Molecular Weight Acids
• Neutral Substances of Low
Molecular Weight
• Biopolymers
• Humic substances
• Polysaccharides (mainly)
BIOFOULING
ORGANIC FOULING
Different
Compounds
Algal EPS

4. ACCIONA Agua. Tu socio en el ciclo del agua INTRODUCTION: PROBLEM AND APPROACH
Current approach in Reverse Osmosis Process: Alkaline chemical cleanings with cycles
of pumping of permeate water and soaking
Compound Concentration
(mg/L)
Starch 7.37
EDTA 200
Sodium Lauryl Sulfate 150
Total Organic Carbon (TOC) 134.5
Chemical Oxygen Demand (COD) 414
REUSE OF WATER FOR IRRIGATION PURPOSES THROUGH TREATMENT
WITH ADVANCED OXIDATION PROCESSES!!

5. ACCIONA Agua. Tu socio en el ciclo del agua INTRODUCTION: RELEVANT LEGISLATION
• European and Spanish legislation: no limits for organic matter for reuse purposes
• Environmental Protection Agency (EPA) of the US recommends concentrations below
10-30 mg/L of BOD
• SLS is toxic and could be contemplated in wastewater discharge legislation
(2013/39/UE Directive) and regional regulation on sea discharge (MAH7285/2007)
(max. level accepted 6 mg/L).
Parameter Units EPA RD 1620/2007
limit
E.coli CFU/100 mL 10 100
Suspended Solids mg/L - 20
Turbidity NTU 2 10
Conductivity dS/m - 3
Sodium Adsorption Ratio SAR - 6
pH mg/L 6-9 6-9
BOD mg/L 10 -
Fe mg/L - 5

6. ACCIONA Agua. Tu socio en el ciclo del agua MATERIALS AND METHODS
• Experimental Design carried out using STATGRAPHICS
software: response surface design
• Doses covered:
- Bench scale: 1L reactors
- Times: 45, 157 and 300 min (Fenton) and 20, 60 and 157 min
(Photo Fenton)
• Total Organic Carbon (TOC) measurements: Sievers InnovOx
laboratory TOC analyzer (GE Analytical Instruments)
Fenton
• H2O2: 2000-8280 ppm
• Fe+2: 100-16500 ppm
Photo Fenton
• H2O2: 800-1200 ppm
• Fe+2: 40-600 ppm
• Solarbox 3000: 290-800 nm and
250 W/m2

7. ACCIONA Agua. Tu socio en el ciclo del agua FENTON RESULTS AND DISCUSSION
• Asymptotic behavior on TOC removal after 157 minutes of
reaction
• This time is selected as sufficient for Fenton reaction in RO
cleaning waters

8. ACCIONA Agua. Tu socio en el ciclo del agua FENTON RESULTS AND DISCUSSION
Standardized Pareto at t=157 min
Standardized Effect
Estimated Response Surface
- Optimal concentrations: above
4000 ppm of peroxide
- Maximum TOC removal: 67%
- Simultaneous high doses of
peroxide and iron
- Effect of peroxide to iron
ratios not as significant

9. ACCIONA Agua. Tu socio en el ciclo del agua PHOTO FENTON RESULTS AND DISCUSSION
0
20
40
60
80
100
120
140
160
0 50 100 150 200
TOCeffluent(ppm)
Reaction Time (min)
Exp 1
Exp 4
Exp 5
Exp 6
• Asymptotic behavior on TOC removal after 60 minutes of
reaction
• Faster reaction rates as compared to Fenton reaction

10. ACCIONA Agua. Tu socio en el ciclo del agua
Diagrama de Pareto Estandarizada para TOC (ppm) 60 min
0 1 2 3 4
Efecto estandarizado
BB
B:H2O2/Fe2+ (w)
AB
AA
A:H2O2 (ppm)
+
-
- Optimal concentration of
peroxide: 1500 ppm
- Maximum TOC removal: 76%
- Significant effect of
peroxide
concentrations
- No effect of iron doses
Standardized Pareto at t=60 min
Estimated ResponseSurface

11. ACCIONA Agua. Tu socio en el ciclo del agua CONCLUSIONS
It is feasible to remove organic matter from RO cleaning
wastewaters through AOPs: suitable for onsite reuse!
Fenton requires high concentrations of hydrogen peroxide
and iron, with maximum TOC removals of 67% achievable
Photo Fenton requires lower hydrogen peroxide
concentrations, presents higher reaction rates and reaches
TOC removals of 76%
Photo Fenton was the most adequate process solution
Further research: photo catalysis with nanostructured
titanium dioxide