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Energy and water: wastewater treatment
Lorna Fitzsimons Matthew Horrigan, Edelle Doherty, Greg McNamara, Thomas Phelan,
Dr. Eoghan Clifford, Dr. Yan Delaure and Dr. Brian Corcoran
Presentation overview
• The energy- water nexus
• Energy requirements for water treatment
• Overview of current EPA funded project
• Future work and conclusions
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Desalination
3 Sources: Adapted from www.desaldata.com and http://www.ges.co.il/
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Source: Hager-Elsasser Website
Water purification technology Energy (kWh/m3) Reference
Brackish water RO (core process) 1 (Semiat 2008)
Seawater RO with Energy recovery (core process) 2.2 to 2.7 (Semiat 2008, Macedonio, Drioli 2010)
Seawater RO (all auxiliary requirements) 5 to 7 (Blank, Tusel et al. 2007, Macedonio, Drioli 2010)
MSF 16 to 20 (Darwish 2007, Mabrouk, Nafey et al. 2010)
MSF (all auxiliary requirements) 38.5 to 125 (Blank, Tusel et al. 2007)
MED 14 (Mabrouk, Nafey et al. 2010)
MED (all auxiliary requirements) 32 to 122.5 (Semiat 2008)
Ultra-Pure Water RO (all auxiliary requirements) 9.55 to 10.24 (Hu, Wu et al. 2008, SEMI 2005)
Project overview: Improving resource efficiency in wastewater treatment plants
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Source: http://www.rpsgroup.com
Description of work carried out to date
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Characteristic Plant E Plant F
Plant G Plant H
Treatment Technology AS AS AS AS
Influent Characteristics Municipal domestic
Wastewater only Municipal domestic
Wastewater only Municipal domestic
Wastewater only Municipal domestic
Wastewater only
Tertiary Treatment
Nutrient reduction and phosphorous removal
Nutrient reduction and phosphorous removal
Nutrient reduction and phosphorous
removal
Nutrient reduction and phosphorous removal
Design Capacity 12000 p.e. 12000 p.e. 600 p.e. 600 p.e.
Organic loading 8649 p.e. (2012) 5853 p.e. (2012) 604 p.e. (2012) 673 p.e. (2012)
Test Frequency Monthly Monthly Monthly Bi - Monthly
Characteristic Plant A Plant B Plant C Plant D
Treatment Technology Activated sludge with P
removal PFBR (Biofilm) AS AS
Influent Characteristics Wastewater, imported
sludge & landfill leachate Municipal wastewater
with storm water
Municipal domestic Wastewater only
Wastewater and imported sludge
Tertiary Treatment Sand filtration
None Nutrient reduction and phosphorous removal
Design Capacity 24834 p.e. 750 p.e. 186000 p.e. 50000 p.e. Organic loading 22440 p.e. (as of 2010) 422 p.e. 175000 p.e. 35743 p.e.
Test Frequency Monthly 3 times per year
24 hour (Real time monitoring)
24 hour
Energy audit: Plant D versus Plant E
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• Average energy use: 1381 kWh/day • 1 Blower on VFD running 24 hours a day (2 standby)
• Sludge drying infrequent during trial period
28%
7%
18% 4%
16%
27%
Energy usage: Plant E
Blowers
Foul pump
Recirculation
SR pumps
SludgebuildingOther
69%
16%
8%
3%
1% 3%
Energy usage: Plant D
Blowers
Other
Effluent pumps
Centrifuge
Centrifuge pumps
Grit blower
• Average energy use: 1895 kWh/day • 3 Blowers on VFDs running 24 hours a day • Effluent Pumps significant contributor
Conventional Aeration systems
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Plant G Plant E Plant D
Plant F
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0 50000 100000 150000 200000
kWh
/p.e
. ye
ar o
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nt
to
pla
nt
Plant size (p.e.)
Plant F
Plant E
Plant D
Plant G
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1
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0 20000 40000 60000 80000 100000 120000 140000 160000 180000 200000
kWh
/kgB
OD
to
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o p
lan
t
Plant size (p.e.)
KPIAdvisor & KPICalc – Toolkit Overview
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Progress overview
LCA progress overview
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0
50
100
150
200
250
Total Electricity Lime(CaO)
Ferricchloride
Transport
Glo
bal
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min
g P
ote
nti
al [
kg C
O2
-E
qu
iv.]
GWP per BOD
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50
100
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Glo
bal
War
min
g P
ote
nti
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kg C
O2
-
Equ
iv.]
GWP per volume of Influent
Plant D
Plant E
Plant F
Plant G
0% 20% 40% 60% 80% 100%
Plant D
Plant E
Plant F
Plant G
GWP
Electricity
Lime (CaO)
Ferric chloride
Transport
Sodium hydroxide
Conclusions and future work
• The energy-water nexus requires joined up thinking and a holistic approach
• Benchmarking energy requirements – no ‘one-size fits all’ simple metric
• Future work: small-scale wastewater treatment plants (design and optimisation)
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