The 13th IWA Leading Edge Conference on Water and Wastewater Technologies

DEVELOPMENT AND APPLICATION OF SUSTAINABLE MEMBRANE DESALINATION TECHNOLOGY: REVERSING WATER SCARCITY AND FAST FORWARDING TO THE FUTURE

FEASIBILITY OF FORWARD OSMOSIS FOR DESALINATION AND WATER RECLAMATION: APPLICATION EXAMPLE AT PILOT SCALE

BEATRIZ CORZO

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INDEX

Water Scarcity and Wastewater Reuse

Hybrid FO advantages

FO challenges

OFREA Project

Design

Demonstration plant

Cost evaluation

Conclusions

Acknowledgments

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WATER SCARCITY AND WASTEWATER REUSE

>3 Billion people will live under water stress in 2025 (Valladares et al., 2014)

Options:‒ Water desalination‒ Water reuse‒ Improve water efficiency

Can we compete using FO in water reuse for agricultural purposes?

A combination of the three is needed

Challenges for water reuse are both technological and economical: technologies that can assure safe water at a

competitive price are needed

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Water Recycling Guidelines: Depend on local context Mainly bacteriological parameters

E.coli Nematode eggs Giardia Criptosporidium

Others: Nutrients (N and P) Suspended solids Turbidity Dissolved salts Heavy metals Boron Harmful organic substances

WASTEWATER REUSE

Sand filtration/O3/AC/MBR/biological treatment/floculation….

MF/UF+RO (one or two passes)F+EDR+Disinfection+AOPsHybrid FO?

What water quality do we need?

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HYBRID FO ADVANTAGES

Multibarrier concept ‒ High permeate quality

Low and reversible fouling ‒ Less pretreatment ‒ Less chemical cleaning

Product water customization (e.g. boron removal, fertigation)

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FO CHALLENGES

Low flux (ICP & ECP) and expensive elements‒ Improvements in FO membranes:

# Thinner membranes with less tortuosity (S parameter) → less ICP and higher flux # More providers → lower prices

DS recovery is energy intensive.‒ Diluted DS has more osmotic pressure than feed water

DS replacement costs ‒ Reverse salt diffusion and incomplete DS recovery

Permeate quality ‒ DS content

No real data‒ Main studies are lab-scale, synthetic feed, short term and batch conditions. Realistic

studies are still needed → OFREA PROJECT

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OFREA PROJECT

According to a workshop on water reuse: (Optimizing water reuse in EU. Dec 2014)

‒ Water reuse in Spain: 35%‒ Region of Murcia: 98%

of wastewater is reused, mostly in agriculture.

The rest presents high salinity

Reuse Datebase (CEDEX). R. Iglesias, 2007

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OFREA PROJECT

FO-NF pilot plant is operating with real feed, continuous and long-term (> 1 year): Feed water: San Pedro del Pinatar 3 m3/h WWTP

effluent– Conductivity: 4-6 mS/cm – Boron: 1.2 ppm – SAR: 10.6

RD 1620/2007 limit:– Conductivity: 3 mS/cm – Boron: 0.5 ppm – SAR: 6

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OFREA PROJECT: PREVIOUS DESIGN

FO MEMBRANE SELECTION5 membrane brands tested with different configuration.

‒ TFC membrane showed the best performance.

‒ TFC was the selected for the demonstration plant.

Porifera membrane

was selected

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OFREA PROJECT: PREVIOUS DESIGNDS SELECTIONDifferent families. Different Van’t Hoff and diffusivity properties.

• High osmotic pressure obtained by formate• Conductivity must be carefully used as control variable

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OFREA PROJECT: PREVIOUS DESIGNDS SELECTION Dynamic test. Spiral wound commercial element. Asymptotic behavior is caused by internal concentration polarization. For 10 bar no significant differences.

KCOOH the best in terms of flux. Expensive. Compromise between CAPEX and OPEX. NF recovery method has been chosen.

Draw Solution

FOFlux

Reversal flux

losses

DS losses in permeate

Cost of product

Cost of replacement

Recovery method

HMWP + - - - - ++ - NFNaCl + + + - - - RO

HCOOK ++ + + ++ ++ ROMgSO4 - - - - - NFK4P2O7 + ++ ++ + ++ NF

- Low+ High

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OFREA PROJECT: DEMONSTRATION PLANT

The first and largest Hybrid-FO demonstration plant worldwide for

reclamation in agricultural purposes.

84 m2

30 m2

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OFREA PROJECT: DEMONSTRATION PLANT DATA

Stable operation of the FO (22% of loss of flux the first days)

NF permeability decreased due to fouling: ‒ Using an organic DS.‒ Using an inorganic DS

and increasing permeate flowrate. Silicates and gypsum presence.

Specific flux or permeability FO=Flux/(пDS – пfeed)

NF=Flux/(NDP)

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OFREA PROJECT: PERMEATE QUALITY

Stable permeate quality Low conductivity except

for initial NF membranes

B < 0.4 mg/L (>70% removal)

High quality for agricultural use!

A change in NF: savings in chemical consumption

but more energy is used

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OFREA PROJECT: COST EVALUATION

DS reposition and energy consumption

No chemical cleaning in FO membranes

(1) DS price is referred to a small-scale order(2) It is assumed 0.10€/KWh(3) NF Membranes fouled

NF HF

NF HR

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COST EVALUATION AND CONCLUSIONS

UF+RO€/m3

FO+NF€/m3

0.35-0.45 0.96

TERTIARY TREATMENT

LET’S GO DOWN THE PRICES! We demand:

An improvement in FO membranes permeability. To find a really cheap DS with ↑Van’t Hoff coefficient. To regenerate the DS with other systems: MD (waste heat or solar

energy)

LARGE SCALE PILOT SCALE

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CONCLUSIONS

FO-NF operated in the long term with real feed:‒ NF membrane was fouled with the organic DS and the first inorganic DS.‒ FO membrane is working with stable permeability. No fouling in the long-term.‒ High permeate quality (conductivity, SAR and boron are below legislation).

Costs‒ NF chemical cleaning is related to DS. No cleaning in FO membranes. ‒ No remineralization is needed.‒ Relevant costs due to low permeability of FO membranes, DS losses and DS

reconcentration energy.‒ To implement our new DS has decreased the prices relevantly.

Economic feasibility of hybrid FO is highly dependent on all these factors.IN A NEAR FUTURE COULD BE CHEAPER THAN CONVENTIONAL SYSTEMS!

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ACKNOWLEDGMENTS

The research leading to these results has received funding from the LIFE+ Programme of the European Commission (LIFE12/ENV/ES/000632 LIFE OFREA) and from La Generalitat de Catalunya (Industrial PhD program).

All my colleagues from Acciona Agua and Carme Sans from the University of Barcelona.