wastewater treatment by solar driven aops: design and applications

Sixto Malato, PhD ([email protected])Isabel Oller, PhD ([email protected])

CIEMAT- Plataforma Solar de AlmeríaTabernas (Almería), Spain

Wastewater treatment by solar driven AOPs: design and applications

1st Summer School on Environmental applications of Advanced Oxidation ProcessesUniversity of Salerno, Fisciano (Italy), June 15-19, 2015.

1. Central receiver technology

7. Solar furnaces

4. Parabolic-trough technology (DSG)

2. Parabolic dishes + Stirling engines3. Parabolic-trough technology (thermal oil)

8. Water desalination 9. Water treatment

1

1

3

10. Passive architecture 10

8

97

2

4

6. Linear Fresnel Collector

6

5. Parabolic-troughs (gas) + Molten Salt TES

5

Plataforma Solar de Almería-CIEMAT


3

1. Using solar photocatalytic and photochemical processes as tertiary treatment of theeffluents from secondary treatment of MWTPs, for production of clean water. For this, theremoval of both emerging pollutants and pathogens are investigated.

2. Using solar photocatalytic and photochemical processes for the remediation of industrialwastewaters contaminated with several types of pollutants and water reclaim for differentapplications.

3. Combining Advanced Oxidation Technologies with other water treatment techniques suchas nano- and ultra-filtration, ozonation, biological treatments, etc., for improving the watertreatment efficiency and reducing operating costs.

4. Assessment of photocatalytic efficiency of new materials under real solar light conditions, andtheir use in solar CPC reactors.

5. Using solar photocatalytic and photochemical processes for water disinfection. Severaltypes of contaminated water sources with a number of water pathogens are under study.

6. Developing new solar photo-reactors for different purposes (drinking water, water reclamation,irrigation, etc.), either water decontamination or water disinfection.

Research activities of STW Unit at PSA


Introduction.

Technical and engineering aspects of solar photo-reactors for

photocatalytic applications.

Solar photocatalysis as tertiary treatment for MWTPs effluents.

Solar reactors for water disinfection.

Outlook


(ng-μg/L)

Photochemical transformations

TRANSFORMATIONPRODUCTS

EMERGING CONTAMINANTS

• Until recently unknown

• Commonly use

• Emerging risks (EDCs,

antibiotics)

• Unregulated

WWTPs

INCOMPLETEREMOVAL

CONTINUOUS INTRODUCTIONINTO THE ENVIRONMENT

Introduction


Introduction


Compound OxidationPotential

Fluorine 2.23Hydroxyl radical 2.06Atomic Oxygen 1.78

Hydrogen Peroxide 1.31Peroxyradical 1.25

Permanganate 1.24Chlorine dioxide 1.15

Chlorine 1.00Bromine 0.80Iodine 0.54

Advanced Oxidation Processes (AOPs) are a source of hydroxyl radicals (OH )

“near ambient temperature and pressure water treatment processes which involve the generation of hydroxyl radicals in sufficient quantity to

effective water purification”

Nevertheless, technical applications are still scarce. Process costs may be considered the main obstacle to their commercial application.

Introduction


98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 140

1000

2000

3000

4000

5000

6000

7000

8000

9000

Num

ber o

f pub

licat

ions

Year of publication

PhotocatalysisSolar photocatalysis

source: www.scopus.com 2015

Introduction. Solar AOPs


Fe3+ activity, l540‐580 nm

0.2 0.4 0.8 1.0 1.2 1.40

200

400

600

800

1000

1200I, W/m

2m

O3 O2

O3

H2O

H2O

CO

H2O

0.60

200

400

600

800

1000

1200

Wavelength, µm

O3 O2

O3

H2O

H2O

2

H2O

TiO

2activ

ity, l3

90nm

Wavelength, µm



22

2

2h

2

OOe

HOHh

)he(TiOTiO

OH

TiO2/UVA (Carey et al., 1976)

Aquacomplexes Fe(III) + hѵ ●OH

(Mazellier et al., 1997a,b; Brand et al., 1998, 2000;

Mailhot et al., 1999)

Aquacomplexes Fe(II) + h ѵ ●OH (Benkelberg and Warneck,

1995)

Fe(III)-Fe(II)/UVA

H2O2 + h ѵ 2 ●OH for l<280 nm

(Goldstein et al., 2007)

H2O2/UVA

OHHFeOHFe 2h2

3

Photo-Fenton (several authors, early 90s)

OHOHFeOHFe 322

2

Fenton (J. Chem. Soc., 1894)



Linearly dependent on the energy flux but only ~5% of

the whole solar spectrum is available for TiO2 band-

gap.

75% of solar collector efficiency and 1% for the catalyst

means 0.04% original solar photons are efficiently used.

This is a rather inefficient process.

0.25 0.30 0.35 0.40 0.45

TiO2

Arb

itrar

yU

nits

Wavelength, µm

Solar Spectrum

0.25 0.30 0.35 0.40 0.45

TiO2

Arb

itrar

yU

nits

Wavelength, µm

Solar Spectrum

Mild catalyst working under mild conditions with mild oxidants.

As concentration of contaminants and water ionic strength increase: slow kinetics and unpredictable

mechanisms need to be solved.

TiO2 efficiency improved with the addition of powerful oxidants or when doped (with iron, nitrogen…)

to undertake practical applications.

Pure TiO2 can utilize only UV and new catalysts able to work with the visible component of the solar

spectrum are needed.

Introduction. Solar photocatalysis with TiO2


L Fe L][Fe hν L][Fe 2*33

HOHFe hνO)][Fe(H 232

OHFe hν[Fe(OH)] 22 RCOFehνR)][Fe(OOC 2

22

Sola

r ir

radi

ance

[W.m

-2.n

m-1

]

300 400 500 6000

500

1000

1500

2000

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Solar Spectrum

Fe3+

(0.25 mM, pH=2.8)

ε[M

-1.c

m-1

]Wavelength [nm]

Sola

r ir

radi

ance

[W.m

-2.n

m-1

]

300 400 500 6000

500

1000

1500

2000

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Solar Spectrum

Fe3+

(0.25 mM, pH=2.8)

ε[M

-1.c

m-1

]Wavelength [nm]

OHOHFeOHFe 322

2 OHFeOHFe 32

Introduction. Solar photo-Fenton process


Widely applied for wastewater treatment under different operating conditions.

Several aspects may also greatly contribute to market introduction upon achieving

maturity:

Catalysts based on immobilized iron. Heterogeneous photo-Fenton for working at

natural wastewaters pH.

Additives which enhance the process performance, either regarding kinetics or pH

operation range.

Optimization of treatment taking into account the wastewater specific characteristics.

Ways to minimize hydrogen peroxide consumption, which is the main factor regarding

operating costs.

Introduction. Solar photo-Fenton process


Introduction. Solar photocatalysis pilot plant


QUV (J l-1): cumulative UV energy during exposure time per unit of volume of treated water.

UV Dose (J m-2): UV energy received per unit surface during exposure time.

UV Energy (J): total UV energy received during exposure time.

, , ∙

∙

∙

Introduction. Evaluation and measurement of irradiance


Introduction.





Outlook


Technical and engineering aspects of solar photo-reactors

Concentrating or non-concentrating collectors

Sandia National Labs

(Albuquerque, USA)

developed in 1989 the first

solar facility for water

detoxification at pre-

industrial level based on

One-axis Parabolic Trough

Collectors (PTC).

These pilot plants were

the first step in the

development of the solar

technology.


CIEMAT, in 1990, erected the second at Plataforma Solar de Almería

(Spain), using 2-axis PTCs.

Initially, it consisted of two-axis HELIOMAN collectors with a total collector area of 384 m2.

It has been widely used during the 90s by manyEuropean research groups (supported by EU)resulting in a continuous contribution of newideas about the process and technology.




Concentrating or non-concentrating collectorsOne-sun (non-concentrating) collectors are cheaper than PTCs. An extensiveeffort in the design of small non-tracking collectors, has resulted in the testing of several different non-concentrating solar reactors.

The design of a robust one-sun photoreactor isnot trivial: weather-resistant, chemically inertand ultraviolet-transmissive. Also, flow in non-concentrating systems is usually laminar.



1 Sun CPCs



1,1,, ;

nnnnGnnUVnUV tttVAUVtEE

E, kJ L-1

Con

tam

inan

te, m

gL-

1

E, kJ L-1

Con

tam

inan

te, m

gL-

1

Experimental results evaluation and comparison



MAIN DISADVANTAGESMAIN ADVANTAGESPARABOLIC CONCENTRATORS

MAIN DISADVANTAGESMAIN ADVANTAGES

Chemically inertNo heatingLow cost

Laminar flow (low mass transfer)Direct & Diffuse radiation

High optical efficiency

NON CONCENTRATING PHOTOREACTORS

OverheatingLow Quantum efficiency (with TiO2)

Low optical efficiency

High cost (Tracking)Vaporization of volatile compounds Only Direct radiationTurbulent flow

MAIN DISADVANTAGESMAIN ADVANTAGESPARABOLIC CONCENTRATORS




Colina-Márquez , Machuca-Martínez , Li Puma. Env. Sci. Technol., 43, 2009

LVRPA* distribution in a CPC in sunny (a) and cloudy (b) day.

*LVRPA= local volumetric rate of photon absorption, W/m3

Considerations:• I Constant = 30 W/m2

• Direct/diffuse = Constant

• 75% UV trasmittance by clouds



Compound Parabolic Collectors (CPC)



Connections

(elbow joints)

Compound Parabolic Collectors (CPC)



Solar photocatalysis demonstration plants


Introduction.





Outlook


CHARACTERIZATION

29/62 Compounds with

higher contribution in MWTP

Effluent

LC-QLIT-MS/MS

AOPs for tertiary treatment. ECs


9.55.0

2.31.5

1.00.60

2000

4000

6000

8000

10000

12000

14000

16000

18000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Con

cent

ratio

n ( n

g/L)

Emerging ContaminantsO

3 (mg/L)

Ozonation475290

280175

10085

450I

2000

4000

6000

8000

10000

12000

14000

16000

18000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Emerging Contaminants

Con

cent

ratio

n (n

g/L)

t30W (m

in)

Mild Solar photocatalysis

with TiO2

2,281,12

0,560,050

2000

4000

6000

8000

10000

12000

14000

16000

18000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Con

cent

ratio

n (n

g/L)

Emerging Contaminants

Quv (K

J/L)

Mild Solar photo-Fenton

Bisphenol A Ibuprofeno Hidrochlorothiazide Diuron Atenolol 4-AA Diclofenac Ofloxacin Trimethoprim Gemfibrozil 4-MAA Naproxen 4-FAA EC <1000ng/L 4-AAA Caffeine Paraxanthine

) Water characteristics and Micro-

contaminants concentration change depending on the day

that were taken.



LC-MS chromatogram. Photo-Fenton.t = 0

t = 20 (t30W = 14) minLC-MS chromatogram. Ozonation.t = 0 t = 60 min



TiO2 based materials (immobilised, modified with graphene, several morphologies) and iron based materials like clays etc.

pH 3 pH 5 pH 7

New materials for solar photocatalysisapplications


Introduction.





Outlook


Comisión Nacional de Energía AtómicaLos Pereira, Tucumán, Argentina

Makerere University, Uganda

Solar reactors for water disinfection


Phytophtora after 5 h of solar exposure without TiO2.

Phytophtera after 5 h of solar exposure with TiO2.

Solar photocatalytic disinfection


0 1 2 3 4 510

100

1000

10000

100000

Fixed TiO2 (19,3 g/m 2)

Fixed TiO2 reused

C, C

FU

/mL

Q UV, kJ/L

Slurry TiO2 (50 mg/L)

No catalyst



Acknowledgments

Unidad de Tratamientos Solares de Agua (Solar Treatment of Water Research Group).

Plataforma Solar de Almería (CIEMAT).

http://www.psa.es/webeng/areas/tsa/index.php

wastewater treatment by solar driven aops: design and applications

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