Management and valorization of brines from desalination ...

Management and valorization of brines from

desalination plants in the Gulf

Dr. Philip Davies

Sustainable Environment Research Group,

Aston University, Birmingham, UK

Water and Energy Sustainable Innovation and Industry

University of Bahrain, 22-23rd April 2018

Outline

Desalination: Challenge of brine disposal

Approaches to valorising brine

Water-energy-food nexus

Conclusions

Deterioration in Gulf ecosystems

Salinity at highest level in 30 years

Correlates with Shatt Al-Arab river discharge

Diatom species decreased in coastal waters

(92 down from 243)

Less fish caughtSuboor Landings

year year

Salin

ity

Al-Said et al, Environ Monit Assess,

2017, 189-268

Challenge of brine disposal

Desalination continues to grow

Water output now 100 million m3/day

Brine output equals/exceeds water output:

×1 to ×2 for RO plant

×3 to ×8 for thermal plant

Elevated:

Temperature (+1 to +10°C)

Salinity (up ×2)

No safe limit for concentration of brine not to disturb ocean biota*

co

nstr

uctio

nw

ee

konlin

e

*Falkenberg & Styan,

Desalination 368(2015)3-

Maalouf et al., Desalination 333(2014)134- www.panresearch.com

Valorisation: what can we use brine for?

Nexus

LITHIUM for

ELECTRIC BATTERIES

REMOVAL of CO2

SPACE COOLING for

WATER EFFICIENT

CULTIVATION

Recovery of minerals from brine favoured by

high price and/or concentration

Concentration in seawater (mg/L)

Price (

US

D/k

g)

–2015 d

ata

Price increase

Increase concentration in seawater

Log

ana

tha

n e

t a

l., E

nv.

Sci –

Wa

ter

Re

s. &

Te

ch.,

2017

, 3, 37-5

3

Economically feasible

Economically

challenging

Lithium price hike

2015

Lithium price hike driven by battery demandLithiu

m d

em

and (

Li 2

CO

3)

kt

Electric

vehicles

Estimated Li availability from Gulf desalination

Gulf plants estimated to treat ~100 million m3 of seawater/day

@ 0.17 g/m3 and 50% recovery of Li⟶ 3000 tonnes Li per year

Compare world production 36 000 tonnes in 2015 (USGS)

Technologies to recover Li from seawater

Li adsorbed on MnO ion-

exchange resins, eluted by HCl

Resin prepared as granules

(mm size)

Slow process: requires large

amounts of resin for sufficient

residence time

150 days cycle time

~30 min residence time

Nishihama et al., Solvent Extraction and Ion Exchange,

29, 421- (2011)

Technologies to recover Li - membranes

Electrospun polysulphone mixed-matrix nanofibre dispersed

with particulate Li ion sieves

Residence time only ~2 min, faster cycle time ~ 12 h

Repeated eluted with HCl to increase Li concentration

Park et al, J. Membrane Science, 510 (2016) 141-

Cycle numberC

(m

g L

i+ L

-1)


Nexus

LITHIUM for

ELECTRIC BATTERIES

REMOVAL of CO2

SPACE COOLING for

WATER EFFICIENT

CULTIVATION

Remove CO2 and neutralise ocean acidity

Oceans getting more acidic because of CO2

Magnesium in brine can absorb CO2

1 m3 of seawater can absorb up to 4.8 kg of CO2

Reactions:

MgCl2 (aq) + 2H2O (l) → Mg(OH)2 (s) + 2HCl (aq)

Mg(OH)2 (s) + 2CO2(g) → Mg(HCO3)2 (aq)

RO plantBrine

treatment

1 m3

seawater

0.75 kg CO24.8 kg CO2

Mg(OH)2

OCEANS

• Absorb CO2

• Neutralise acidity

Anion exchange

membrane

Gas diffusion

anode

H. Xie, Y. Wang, W. Chu, Chinese Science Bulletin, 59 (2014) 2882-2889

VE o 50.0

Formation of magnesium hydroxide

eHClClH 2222 eHClClH 2222

Electrolysis to yield Mg(OH)2

Prototype at

Aston University

Electrolysis in flow-through mode

Freshwater

inputBrine from desal plant

Brine enriched with Mg(OH)2 to

ocean

Hydrochloric acid for

geological disposal

Electrical power input

Davies, Yuan, de Richter, Env. Science: Water Research and Technology – in press

Negative emissions from desalination

-10

-8

-6

-4

-2

0

2

4

6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

kg

CO

2e

mis

sio

n p

er

m3

ou

tpu

t

Carbon intensity kgCO2/kWh

With electrolysisGas Coal

Without electrolysis

Carbon intensity of

electricity kgCO2/kWh

kgC

O2

em

issio

ns p

er

m3

of w

ate

r out

RO plant powered by natural gas power plant absorbs 2.3 × amount of CO2 emitted.


Specific energy

consumption

SEC increased by

electrolysis process

Recovery ratio

around 0.7

minimises SEC

0

2

4

6

8

10

12

14

16

18

-8

-6

-4

-2

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1

Ene

rgy

pe

nal

ty G

J/tC

O2

Ne

t CO

2e

mit

ted

pe

r m3

of f

resh

wat

er o

utp

ut (

kg/m

3 )

or

SEC

kW

h/m

3

Recovery ratio, r

SEC

Net CO2

Energy penalty

Recovery ratio r

SEC

Net CO2

Energy

penalty



Nexus

LITHIUM for

ELECTRIC BATTERIES

REMOVAL of CO2

SPACE COOLING for

WATER EFFICIENT

CULTIVATION

Seawater Greenhouse

Brine is used to cool a greenhouse for crop production

Demonstrated in: Tenerife, UAE, Oman, Australia and Somaliland

Seawater Greenhouse: Somaliland, 2017

Desalination by Reverse Osmosis (RO) + photovoltaics

Wind ventilation

Low cost 1000 m2 shade net

Reject brine for cooling then salt production

Salt NaCl

Bitterns MgCl2

Evaporative cooling pad Cucumbers

Seawater Greenhouse: modelling & design

Summary findings:

Modelling using Computational Fluid Dynamics

8-58% reduction in land usage for brine disposal vs. evaporation ponds

Cool air 10-15 m downstream of pad

Validation against satellite data

Akinaga et al, Desalination 426(2018)135-

Key conclusions

Nexus

LITHIUM for

ELECTRIC BATTERIES

REMOVAL of CO2

SPACE COOLING for

WATER EFFICIENT

CULTIVATION

DESALINATION

Brines mostly

dumped today

– harmful not

valuable

Increasingly promising –

membrane recovery

Negative emissons

but high SEC

Seawater Greenhouse:

Innovative approach for water

saving and improved food

security in arid countries.

High-recovery desalination complementary to brine valorisation

Acknowledgements

Innovate-UK and Department for International Development

(Agri-Tech Catalyst Programme)

Seawater Greenhouse Ltd

University of Bahrain

Thank you for listening!

Management and valorization of brines from desalination ...

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