AM1 (keynote)-Stinso.. - Illinois Water Environment Association

Sustainable Nutrient Removal & Recovery
Presented by:
Beverley Stinson, Ph.D
National Wastewater Practice Leader, AECOM
Illinois WEA
September 9th 2014
Eutrophication due to excessive nutrient
discharge is a global problem
•
Fundamentally impacting issues such as:
–
–
–
–
–
Water security
Public health
Economic and community growth
Tourism
Environmental aesthetics and quality of life
While the environmental, social and economic benefits of
nutrient management are extensive, they come at a price….
•
•
Conventional Biological Nutrient
Removal (BNR) processes rely on
anaerobic, anoxic and aerobic
microbes to remove N&P from
wastewater
Nutrient Management at
Wastewater Treatment Plants
results in increased:
– Energy demand
Activated-sludge
– Chemical
demand
Aeration
55.6%
– Space
– Carbon footprint
– Greenhouse gas emissions.
•
Increased Capital & Operating
Costs & Complexity
Conventional BNR processes require significant
aeration energy typically accounting for half the
electrical demand at a plant.
Agenda:
01 Challenges Ahead – P, N and Energy Removal / Recovery
02 Strategies for P Removal & Recovery
03 Strategies for N Removal
P removal
N removal
01 - Challenges Ahead
The Road to Sustainable and Efficient Nutrient Management
1.
2.
3.
A-Stage
Biosolids
B-Stage
– Maximize carbon capture
– Maximize energy recovery
– Minimize carbon & energy demand for N & P removal
3
1
2
3
Fundamentals of Nitrification - Denitrification
Heterotrophic Denitrification
Autotrophic Nitrification
1 mol Nitrate
(NO3- )
Aerobic Environment
Anoxic Environment
40% Carbon
25% O2
1 mol Nitrite
(NO2- )
1 mol Nitrite
(NO2- )
60% Carbon
75% O2
100% Alkalinity
1 mol Ammonia
(NH3/ NH4 +)
½ mol Nitrogen Gas
(N2 )
+
Oxygen demand 4.57 g / g NH 4-N oxidized
Carbon demand 4.77 g COD / g NO-3-N reduced
Biological Phosphorus Removal
Key Ingredient for
PAO Growth
Phosphorus
Accumulation
Organisms
(PAOs)
Phosphorus Removal Mechanism
BOD : TKN
Ratio
Carbon
Management
is Key for Successful
Nutrient Management
• Need at a least 6:1 rbCOD : NH3-N for effective TN removal
• & more for BioP - rbCOD / P > 15
• Many plants do not have this
• Need to supplement rbCOD or VFA
• Influent cBOD : TKN = 6.9
• Activated Sludge Influent cBOD : TKN = 4.2
01 Challenges Ahead
P-Removal /
Recovery
• Bio-P requires anaerobic
zones & VFA
• Fermentation
• Denitrifying PAOs
• Struvite precipitation
• Chemical polishing
N-Removal /
Recovery
• Conventional
Denitrification requires
anoxic zones & rbCOD
• Deammonification
Energy
Recovery
• Carbon capture
• Digestion / CHP
• Co-Digestion
02 - Strategies for Phosphorus
Removal & Recovery
02 Lower Effluent P
More Infrastructure Investment
Chemically P Removal
Bio-P
• RAS Fermentation
• Denitrifying PAOs
Sidestream Phosphorus Management
• Struvite Management
• Sludge Dewaterability
Tertiary Polishing
Processes
02 Lower Effluent P
More Infrastructure Investment
Chemically P Removal
Bio-P
• RAS Fermentation
• Denitrifying PAOs
Sidestream Phosphorus Management
• Struvite Management
• Sludge Dewaterability
Tertiary Polishing
Processes
Basic Principals of Phosphorus Removal
Key to P Removal
1. Convert Sol P to particulate P
2. Remove particles
3. Remove colloidal material
Soluble non-reactive
Phosphorus will define
the minimum effluent TP
Phosphorus Removal - Chemical Vs. Biological
Many factors must be considered:
• Where is the carbon most cost effective?
– To off-set methanol for TN reduction
– To off-set Iron or Alum salts for TP reduction
• Amount and type of chemical
• Space
• Ease of operation
• Quantity & quality of sludge & biosolids cake
• Recycling of phosphorus
• Cost – Capital and Operating
Chemical Molar Dose Ratios
•
•
•
•
•
•
1 -2 Molar ratios for 80-90% removal (<1mg/l)
4 - 6 Molar ratios for effluent P 0.1 to 0.05 mg/L soluble P concentrations
6 – 10 molar ratio for effluent Phosphorus < 0.05 mg/L
Ratios are higher with PAC
Tertiary chemical treatment required for values less than 0.15 mg/l
Durham OR used 170 mg/L Alum to reach 0.07 mg/L.
Blue Plains 370 mgd –
Multi-Point Chemical Addition for TP < 0.18 mg/l
•
When we have TN & TP limits – need Carbon for both
•
At Carbon Constrained Plants can be more cost effective to reserve the
inherent WW carbon for TN reduction & use Ferric for TP Reduction
Blue Plains 370 mgd – Multi-Point Chemical Addition
for TP < 0.18 mg/l
Multi-point Chemical addition very effective at Blue Plains
Chemically Enhanced Primary Treatment (CEPT)
• Over 60% TP removal with 7 mg/l as Fe
• Reduces load on activated sludge –
• Reduces VFA demand for Bio-P
• Reduces O2 & sludge production
• Gets carbon to fermenters for VFA production
Shallow Bed Anthracite Filtration
Blue Plains (370mgd),Washington DC
• Leopold Shallow Bed filters
• Effluent TP<0.18 mg/l
At Carbon Limited Plants - Chemical P Management
Often More Cost Effective
•
•
Effluent TP averaged < 0.05 mg/l
Apply about 9.6 mg/l as Fe (7.1mg/l in PSTs + 2.5mg/l in secondary clarifiers)
0.25
0.20
0.15
Ave.
TSS
TP
TSP
Influent
5.7
0.13
0.05
Effluent
0.6
0.05
0.03
Removal
5.1
0.08
0.02
% Removal
90%
62%
39%
Plant Effluent TP mg/L
TSP
0.10
0.05
0.00
1/1/09 3/3/09 5/3/09 7/3/09 9/2/09 11/2/09 1/2/10 3/4/10 5/4/10 7/4/10 9/3/10 11/3/10 1/3/11
02 Lower Effluent P
More Infrastructure Investment
Chemically P Removal
Bio-P
• RAS Fermentation
• Denitrifying PAOs
Sidestream Phosphorus Management
• Struvite Management
• Sludge Dewaterability
Tertiary Polishing
Processes
Phosphorus Removal - 1985
PO4
PO4
Poly P
Poly P
PHB
PHB
CO2 + H2O
VFA
Anaerobic Conditions
Oxygen
Aerobic Conditions
Biological Phosphorus Removal
Key Ingredient for
PAO Growth
Phosphorus
Accumulation
Organisms
(PAOs)
Phosphorus Removal Mechanism
Carbon Management is Key for
Successful Nutrient Management
Short-chain Volatile Fatty acids are Essential for BPR
Kelowna, Canada WWTP
Kelowna 1980 – 5 Stage Bardenpho
Anaerobic Anoxic
15 %
Preliminary
Treatment
20 %
Aerobic
30 %
Anoxic Aerobic
15 %
Primary
Clarifier
Storm Flows
Primary
Sludge Flow
@ 4% of Q
Recycle @ 6– Q
RAS @ 70% - Q
Primary Sludge
Primary
Sludge
Thickener
/ Fermenter
Thickener
20 %
Secondary
Clarifier
Dual Media
Filters
UV Disinfection
DAF
Thickener
Sludge
Handling
Steps to Optimize the Bio-P Process
• Performance and reliability can be enhanced with the
following:
1. Increase volatile fatty acids (VFAs)
2. Optimize anaerobic, anoxic and aerobic volumes
3. Control nitrates
4. Additional monitoring and/or automation
Fermenters Enhance Bio-P Performance
• Fermenter configuration
– Primary sludge is pumped to the
fermenters
– Fermenters store and thicken the
sludge
– VFA production is based on time
and temperature
– Operation based on target SRT
Primary
sludge
Fermenters
Overflow
(VFAs)
Fermented
primary sludge
Fermenter Design SRT
Fermenter SRT vs VFA Production
Acetic Acid
200.0
mg/L
150.0
Acetic
31%
Propionic
37%
Other
17%
100.0
Valeric
4%
50.0
Butyric
11%
Fermentate characteristics
0.0
0
1
2
3
4
5
6
7
8
time - days
9
10
11
12
13
14
15
Interim Steps to Maximize P Removal
•
Increase VFAs using activated primary
clarifiers
– High hydraulic loading rate / small footprint
– Sized for average flow
– Run deep sludge blanket for fermentation
Jasper, Alberta, Combined
Primary Clarifier / Fermenter
Primary Effluent
Influent
Mixed
Secondary
Primary
Anaerobic
Fermented
primary
sludge
Effluent
Aerated
Aerobic
RAS
WAS
Fermenters Can be converted GT, PSTs, Clarifiers or ?
Location
Design Features
Janesville WWTP, WI
2 fermenters, 40ft dia
Westbank
2 fermenters, 10 m dia
WEWPCC, Winnipeg
2 fermenters, 10 m dia
Kelowna
2 converted secondary clarifiers
Fort Mac
2 new fermenters, 17 m dia
Banff
Conversion of two existing sludge storage/thickeners, 10 m dia
Jasper
1 new primary clarifier with sludge fermentation incorporated into
the tank.
Summerland
1 new primary clarifier with sludge fermentation incorporated into
the tank.
Lake Country
1 new primary clarifier with sludge
fermentation incorporated into tank.
Brisbane
2 new fermenters, 15 m dia
Sault Saint Marie
1 new fermenter, 15 m dia
Phosphorus Release and VFA Uptake in Anaerobic zone
25.00
soluble P
NO3 + O2
VFA
mg/L
20.00
15.00
10.00
5.00
0.00
0
6
12
18
time - minutes
24
30
Phosphorus Release With and Without VFA
with
and
Primary Phosphorus
Release
25.00
without
VFA Phosphorus Release
Secondary
mg/L
20.00
15.00
soluble P
NO3 + O2
VFA
10.00
5.00
0.00
0
6
12
18
24
30
36
tim e - m inutes
42
48
54
60
Fermentate VFA
Fermenter VFA
Primary
Effluent
Primary
Effluent
Anaerobic
Anaerobic
• VFA to PE
• Step-feed PE
Anoxic
Anoxic
RAS
Return Sludge
66QQ
recyle
IR
Fermenter VFA
Phosphorus Release
3 cells - 21% of Bioreactor
Secondary Clarifier
Fermentate VFA
P Release
Configuration:
Smaller Anaerobic Zones
• 3 cell = 21% of
Bioreactor
25 mg/L
25 mg/l
OP
Removal
%
o-PO4 removal
80%
80%
Anoxic
Anaerobic
Anaerobic
Anoxic
• 2 cell = 14% of
18 mg/l
2 cells - 14% of Bioreactor
18 mg/L
Bioreactor
Primary
Effluent
Primary
Effluent
Secondary Clarifier
RAS
85%
85%
Return Sludge
66QQ
recyle
IR
Fermentate VFA
Fermenter VFA
Anaerobic
• 1cell = 7% of
Bioreactor
Anoxic
Anaerobic
Anoxic
Primary
Effluent
Primary
Effluent
1 cell - 7 % of Bioreactor
Secondary Clarifier
RAS
Return Sludge
Q recyle
66 Q
IR
10-12 mg/l
10 - 12 mg/L
90%
90%
Fermenter VFA directly to Anaerobic Zone
Fermentate
VFA
Fermenter
VFA
P Release
OP
P release Removal
%
Anoxic
Anaerobic
Anaerobic
Anoxic
Primary
Effluent
Primary
Effluent
cell - =7 %7%
of Bioreactor
• 1 1cell
of
Bioreactor
Secondary Clarifier
RAS
Return Sludge
66QQrecyle
IR
10 - 12 mg/L
90%
10-12 mg/l
90%
8-12 mg/l
8 - 12 mg/L
95%
> 95%
• VFA to PE
Anaerobic
Fermentate
FermenterVFA
VFA
• 1 cell = 7% of
Bioreactor
Anoxic
Anaerobic
Anoxic
Primary
Effluent
Primary
Effluent
• VFA to
1 cell - 7 % of Bioreactor
Anaerobic zone
Secondary Clarifier
RAS
Return Sludge
Q recyle
66 Q
IR
Protect Anaerobic Zone from Nitrates –
Increase Internal Recycle Rates & Step-feed to Anoxic Zones
Anaerobic
Fermentate
FermenterVFA
VFA
Primary
PrimaryEffluent
Effluent
Anoxic
Aerobic
RAS Rate
100% to 125% Q
to Secondary
Effluent
Nitrates = 8 mg/l
10%
10%
90%
90%
Clarifier
Secondary Clarifier
RAS
Return Sludge
2 Q Recycle
2Q Internal Recycle
Anaerobic
Fermenter
VFA
Fermentate
VFA
Primary
PrimaryEffluent
Effluent
Anoxic
Aerobic
RAS Rate
90% Q
to Secondary
Effluent
Nitrates = 6 mg/l
50%
50%
50%
50%
RAS Rate
100 to 125% - Q
Effluent Nitrates = 8.0 Mg/L
Clarifier
Secondary Clarifier
RAS
RAS
Return Sludge
4 Q Recycle
4Q Internal Recycle
Anaerobic
Anoxic
Aerobic
Fermentate
FermenterVFA
VFA
Primary
Effluent
Primary Effluent
10%
10%
90%
90%
Secondary Clarifier
RAS
Return Sludge
recycle
6Q6 Q
Internal
Recycle
RAS Rate
90% - Q
Effluent Nitrates = 6.0 Mg/L
RAS Rate
70% Q
to Secondary
Effluent
Nitrates = 4.5 mg/l
Clarifier
Effluent Nitrates = 4.5 Mg/L
RAS Rate
70% - Q
Anoxic Zone need balanced NOX, COD & HRT to prevent
Phosphorus Re-Release
5
Insufficient Nitrates with Excess COD
Secondary P Release
4
3
Anoxic Zone
Aerobic Zone
2
1
0
0
15
30
time - minutes
45
60
Denitrifying PAOs – excess nitrates & insufficient COD
•
•
•
•
•
Observed increased occurrence of denitrifying PAOs
(Accumulibacter)
Some DPAOs can use Nitrate and others can use
Nitrite along with stored carbon to remove Phosphorus
DPAOs are considered to be less efficient than aerobic
PAOs i.e. require more COD / P removed with slower
rates
But they may still may be highly efficient overall
Effluent Nitrates were lower (3 mg/l vs 10 mg/l) in
system when DPAOs were highly active. (same influent &
effluent COD and TP in both systems)
PO4
Poly P
PHB
CO2 + H2O
NO3 or NO2
Anoxic Conditions
Courtesy of April Gu – Publication Pending
Phosphorus Release in Secondary Clarifier
in Secondary Clarifier
5.00
mg/L
4.00
3.00
soluble P
NO3 + O2
2.00
1.00
0.00
0
6
12
18
24
30
36
tim e - m inutes
42
48
54
60
Effects of Long SRT & HRT in Aerobic zones
Ammonia and Nitrates
with a Long SRT
6
NH4
5
NO3
3
2
1
time - minutes
24
0
22
0
20
0
18
0
16
0
14
0
12
0
10
0
80
60
40
20
0
0
mg/L
4
Kelowna modified to “3 Stage Westbank Configuration”
or RAS Fermentation Configuration
5 Stage Bardenpho
Fermenter VFA
Primary Effluent
Secondary Clarifier
Return Sludge
Anaerobic
Anoxic
Aerobic
Aerobic
Anoxic
6 Q Recycle Flow
3 - Stage Westbank
RAS 3Fermentation
Configuration
Stage Westbank
Anaerobic
Anoxic
Aerobic
Fermenter VFA
Primary Effluent
Secondary Clarifier
Return Sludge
Fermentate
to Secondary
Clarifier
6 Q Recycle Flow
RAS
• Reduced tank volume by 33%
• More reliable performance
• Much simpler configuration
• No step feed of PE
• No fermentate feed to each tank
• Just a sidestream RAS fermentation tank
Aerobic
to Secondary
Clarifier
mg/L
Kelowna Effluent Phosphorus 1990 to 1997
• Effluent TP = 0.23 mg/l
• No Chemical
• No Filtration
0.75
Ortho-P
Construction
Total-P
0.50
0.25
0.00
Dec-97
Sep-97
Jul-97
Apr-97
Jan-97
Oct-96
Aug-96
May-…
Feb-96
Nov-95
Sep-95
Jun-95
Mar-95
Jan-95
Oct-94
Jul-94
Apr-94
Feb-94
Nov-93
Aug-93
May-…
Mar-93
Dec-92
Sep-92
Jul-92
Apr-92
Jan-92
Oct-91
Aug-91
May-…
Feb-91
Nov-90
Sep-90
Jun-90
Mar-90
Jan-90
Optimal Nutrient Removal Process Configuration Includes
a common RAS Fermentation Tank
Operate all 4 Gravity
Thickeners as Fermenters
Fermentate to Anaerobic
Bio-P conditioning tanks
Convert Anaerobic Zones
to Anoxic Zones
Eliminate Acetic Acid
Addition & Storage
Convert Tanks to Anaerobic
RAS Fermentation tanks
02 Lower Effluent P
More Infrastructure Investment
Chemically P Removal
Bio-P & RAS Fermentation
• Denitrifying PAOs
Sidestream Phosphorus Management
• Struvite Management
• Sludge Dewaterability
Tertiary Polishing
Processes
Efficient TSS Capture is Critical in Both Chemical
and Biological Phosphorus Removal
0.1 mg/L Total Phosphorus
Requires Very Low Effluent TSS
0.5
Phosphorus in Effluent TSS (mg/L)
Phosphorus Content from a Biological
Phosphorus Removal Plant and
Conventional Plant Differ
0.4
0.3
0.2
0.1
0
0
1
2
3
4
5
6
7
8
9
10
TSS in Effluent (mg/L)
For Conventional Systems
For Bio-P Systems
Filters After Clarifiers Help
Range of Compact Add-on TP Reduction Technologies
Lower than 0.2 mg/l;
•
Filters – deep bed, dual media etc.
•
ACTIFLO
- Kruger, Inc.
•
Densadeg
- Infilco Degremont, Inc.
•
AquaDAF
- Infilco Degremont, Inc.
•
Blue PRO
- Blue Water Technologies, Inc.
•
CoMag
•
DynaSand D2 Dual Filtration System - Parkson
•
Ultrafiltration Membranes e.g. GE ZeeWeed 1000
- Cambridge Water Technology
ACTIFLO Syracuse, NY Operational Data (80 / 126 mgd)
April – December 2006 Daily Operating Conditions
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Apr-06
Effluent Total P
Average Influent FLow
130
120
110
100
90
80
70
60
50
40
30
20
10
0
May-06
Jun-06
Aug-06
Date 2006
Sep-06
Nov-06
Dec-06
Average Daily Flow (MGD)
Total Phosphorus (mg/l)
Influent Total P
Cloth Disk Filters
• Low head Loss
• Small Footprint
Westbank 2011 – Experiments
Pre- Anoxic Anaerobic Anoxic
Preliminary
Treatment
Primary
Clarifier
3%
70% of Q
7%
20 %
Aerobic
70 %
Recycle @ 6 – Q
Test #2
Alum
50 mg/L
Test #1
PAC - 40 mg/L &
Polymer - 0.5 mg/L
Secondary
Clarifier
Cloth Filters
30% of Q
Primary
Sludge Flow
@4%of Q
RAS @ 70%- Q
UV Disinfection
Primary
Sludge
Thickener
DAF
Thickener
Sludge
Handling
Tertiary P Polishing – Kelowna Tot. P & Tot. Sol. P
0.25
No
Alum
Al / Tot Sol P dose
@ 5:1
Bioreactor #1 - Drain
Al / Tot Sol P dose @ 10:1
Alum = 40 mg/L
Al / Tot Sol P dose @
13:1
Alum = 55 mg/L
Bioreactor #2 - Drain
Bioreactor #1 - Fill
0.20
Total P - mg/L
Tot. Sol. P
0.15
0.10
0.05
0.00
Tot. P
PAC Addition (40 mg/l) + Polymer (0.5 mg/l)
Prior to 5µ &10µ Cloth Filters
0.4
0.37
0.35
Filtered - No PAC
Filtered - PAC
0.3
Secondary Clarifier –
no filter
Total P - mg/L
0.25
0.45 um filter paper
0.2
5 um Filter Cloth
0.21
0.15
0.16
10 um Filter Cloth
0.14
0.1
0.08
0.05
0.06
0.05
0
0
1000
2000
3000
4000
Total Particle Counts
5000
6000
7000
8000
Banff 2002 – 3 Stage BNR
Pre- Anoxic Anaerobic Anoxic
Preliminary
Treatment
Primary
Clarifier
3%
90% of Q
7%
20 %
Aerobic
70 %
Recycle @ 6 – Q
Alum
10 – 20 mg/L
Secondary
Clarifier
Dual Media
Filters
10% of Q
Primary
Sludge Flow
@ 4% of Q
RAS @ 60 - 70% -
UV Disinfection
Primary
Sludge
Thickener
DAF
Thickener
Sludge
Handling
Banff Effluent Total Phosphorus with 10 mg/l Alum
1.500
Effluent Total Phosphorus - Monthly Average
Start Biological
Phosphorus
Removal
Regulatory Limit
1.0 mg/L
TSS mg/l
1.000
0.500
Contract Limit 0.15 mg/L
0.000
Month
Eff TP
Eff TP Leadership Limit
EFF TP Regulatory Limit
02 Lower Effluent P
More Infrastructure Investment
Chemically P Removal
Bio-P & RAS Fermentation
• Denitrifying PAOs
Sidestream Phosphorus Management
• Struvite Management
• Sludge Dewaterability
Tertiary Polishing
Processes
Nutrient “Merry-Go-Round”
Effluent
Influent
WAS
RAS
Gravity Belt
Thickening
Primary Sludge
• 1% of Total Plant Influent Flow
• Rich in Nitrogen & Phosphorus
Dewatering
• 15 to 40% of the Total Plant TN load
• Up to 50% TP load
• Often returned in slug loads – not equalized
• Ammonium Conc. 800 to 2,500 mg-N/L
• Temperature 30 - 38 C
• Alkalinity insufficient for complete
nitrification
• Poor in rbCOD (rbCOD :TKN = 0.4 :1)
Centrate
Phosphorus &
Ammonia Rich
TP = 15%
Recycle
Biosolids
Phosphorus in Centrate Recycle Stream and Biosolids
Effluent
TP =30%
Influent
TP = 100%
WAS
TP = 35%
RAS
Gravity Belt
Thickening
Primary Sludge TP = 35 %
TP=20%
Dewatering
Centrate
Phosphorus &
Ammonia Rich
TP = 15%
Recycle
Biosolids
Phosphorus Content of Centrate will Increase with Bio-P
Effluent
TP =3 %
Influent
TP = 100%
WAS
TP = 62 %
RAS
Gravity Belt
Thickening
Struvite
Problems
Primary Sludge TP = 35 %
Iron salts e.g.
Ferric Chloride
TP=45%
Dewatering
Centrate
Phosphorus &
TP = 17%
Ammonia Rich
TP = 52%
Recycle
TP= 35%
Biosolids
Alternative Phosphorus Plan
Effluent
TP =3%
Influent
TP = 100%
WAS
TP = 62%
RAS
Anaerobic Gravity Belt
Zone for OP & Thickening
Mg Re-release
Mitigates
Struvite
Problems
Primary Sludge TP = 35 %
Phosphorus
Rich Recycle
TP=45%
TP = 45%
Recovered as
Valuable
Fertilizer
Dewatering
Centrate
Ammonia Rich
Recycle
TP = 17%
Biosolids
TP = 45%
Ostara – Controlled Struvite Precipitation
Recovers P & N as Crystal Green®
Mg2+ + NH4+ + PO43-
MgNH4PO4.6H2O
• slow release fertilizer
• produced without GHG emissions
Typical performance;
• 75% P recovery & 15% N recovery
• Reduced recycle of P and NH4
• Reduced VFA / Carbon demand in BNR plants
• Reduced aeration & alkalinity for NH4-N removal
• Numerous full scale installations – proven process
Enhanced Nutrient Recovery – Food Security
•
Until recently believed that there was less than 100 years of phosphorus reserves
•
China recently imposed doubled tariffs on phosphorus exports
•
Price of Phosphate rock has soared over past couple of years
•
USGS recently revised its estimates to predict 400 years of reserves remaining
•
Phosphorus is key to Food Security – Water / Food / Energy Nexus
Phosphorus production – 90% in 5 regions. Source IFDC.
Theories as to why EBPR Sludge is Difficult to Dewater
•
•
•
•
•
One dominant theory by Matt Higgins revolves around Divalent Cation Bridging
Theory (DCBT)
Monovalent / Divalent (M/D) Cationic balance is upset in EBPR sludge
digestion due to the formation of struvite
Optimal M/D balance <10 for bio-flocculation & thus good settling & dewatering
PO4+ released reacts with the Mg2+ and NH4+ to form struvite (MgNH4PO4.6H2O)
Leaves excessive K+ (and Ca2+) which pushes the M/D ratio up
PO4
Poly P
Poly P
PHB
0.34 mol
Ca2+
Mg2+
PO4
0.26 mol K+
Mg2+
CO2 + H2O
Oxygen
Activated Sludge Aerobic Conditions
K+
WAS EBPR Sludge in
Anaerobic Digestion
NH4+
Bio-P Sludge Dewaterability Issues and Mitigation
Strategies
•
Higher M/D Cationic Ratios and soluble PO4-P result in poor bio-flocculation
and poor cake solids
Higgins et.al 2014
WasStrip / Phosphorus Recovery can also Enhance Dewaterability
Effluent
TP =3%
Influent
TP = 100%
WAS
TP = 62%
RAS
Anaerobic Gravity Belt
Zone for OP & Thickening
Mg Re-release
Mitigates
Struvite
Problems
Primary Sludge TP = 35 %
Phosphorus &
Mg Rich Recycle
TP=45%
TP = 45%
Recovered as
Valuable
Fertilizer
TP = 45%
Dewatering
Centrate
Ammonia Rich
Improves
Recycle
Dewaterability
TP = 17%
Biosolids
AirPrex / AirPrex MgPlus
•
•
•
•
•
Struvite precipitation after digestion
Multi-stage reactors with CO2 stripping to increase pH & form MAP
Berlin Water Works patent in 2001
Pollution Control Services GmbH licensed process in 2006
Proposed benefits
– Significant improvement in the sludge dewatering
– Significant increase in cake solids (3-4%)
– Reduction of OP recycle by 80 - 90%
– Avoid uncontrolled struvite formation
03- Strategies for N Removal
03 Lower Effluent N
More Infrastructure Investment
Sidestream RAS Reaeration
Sidestream Deammonification
Mainstream Deammonification
Tertiary Polishing
Processes
Fundamentals of Nitrification - Denitrification
Heterotrophic Denitrification
Autotrophic Nitrification
1 mol Nitrate
(NO3- )
Aerobic Environment
Anoxic Environment
40% Carbon
25% O2
1 mol Nitrite
(NO2- )
1 mol Nitrite
(NO2- )
60% Carbon
75% O2
100% Alkalinity
1 mol Ammonia
(NH3/ NH4 +)
½ mol Nitrogen Gas
(N2 )
+
Oxygen demand 4.57 g / g NH 4-N oxidized
Carbon demand 4.77 g COD / g NO-3-N reduced
Fundamentals of Nitritation - Denitritation
Autotrophic Nitritation
Heterotrophic Denitrification
1 mol Nitrate
(NO3- )
Aerobic Environment
25% O2
Anoxic Environment
40% Carbon
•
25% reduction in Oxygen
•
40 % reduction in Carbon demand
•
40% reduction in Biomass production
1 mol Nitrite
(NO2- )
1 mol Nitrite
(NO2- )
60% Carbon
75% O2
100% Alkalinity
1 mol Ammonia
(NH3/ NH4 +)
½ mol Nitrogen Gas
(N2 )
Oxygen demand 3.42 g / g NH+4-N oxidized
Carbon demand 2.86 g COD / g NO-3-N reduced
Fundamentals of Deammonification
Partial Nitritation
Aerobic Environment
1 mol Nitrate
(NO3- )
ANAMMOX Deammonification
Anaerobic Ammonium Oxidation Autotrophic
Nitrite Reduction
40% Carbon Strous et. al. 1999)
(New Planctomycete,
• > 60% reduction in Oxygen
NH4+ + 1.32 NO2- + 0.066 HCO3- + 0.13 H+
• Eliminate demand for supplemental carbon
0.26 NO3- + 1.02N2 + 0.066 CH2O0.5N0.15 + 2.03 H2O
25% O2
• 50% of the alkalinity demand
0.57 mol NO2-
Partial Nitritation 40% O2
50% Alkalinity
1 mol Ammonia
(NH3/ NH4 +)
0.44 mol N2+ 0.11 NO3Oxygen demand 1.9 g / g NH+4-N oxidized
Overall Benefit of Deammonification Processes
•
Eliminates need for carbon - Available for energy recovery
•
Significant reduction in energy demand possible
•
Reduction in alkalinity demand
Typical Energy Demand Ranges
7
kW-hr / kg N removed
6
5
4
3
2
1
0
Nitrification /
Denitrification
Nitritation /
Denitritation
Deammonification
(a.k.a. ANAMMOX)
03 Lower Effluent N
More Infrastructure Investment
Sidestream RAS Reaeration
Sidestream Deammonification
Mainstream Deammonification
Tertiary Polishing
Processes
Novel Sustainable Centrate/Filtrate Management Options
Nitrogen
Removal
Focus
Centrate / Filtrate Management Options
Biological
Nitrification / Denitrification
& Bio-augmentation
Nitritation / Denitritation
Deammonification
Physical-Chemical
Ammonia Stripping
• Steam
• Hot Air
• Vacuum Distillation
Ion-Exchange
• ARP
“Struvite” Precipitation
• MAP Process
• Reduction in energy & chemical demands – more sustainable
• Perceived increase in operational complexity
Nutrient
Recovery
Focus
RAS Reaeration
PST
Thickener /
Fermenter
Activated Sludge
RAS
Reduce Effluent
Effluent TN even at short
SRT and HRT
WAS
RAS Re-aeration /
Bioaugmentation
Compatible with PAO
Bioaugmentation also
Digestion /
CHP
Centrate
• 1% Plant Influent Flow
• Rich in Nitrogen & Phosphorus
• 15 to 25% Plant Influent TN load
• Ammonium Conc. 800 to 2,500 mg-N/L
• Centrate TP = 200-800 mg/L (up to 70% TP)
• Temperature 30 - 38 C
• Alkalinity insufficient for complete nitrification
• Insufficient carbon for denitrification
Dewatering
Beneficial
Reuse of
Biosolids
Plant without Bio-Augmentation Integration
• Winter TN Removal Varied from 43% - 80%
• Avg. 60%
Stinson et al., “ Evaluation and Optimization of a Side Stream Centrate
Treatment System Integrated with a Secondary Step-Feed Process”, WEF / IWA
Specialty Nutrient Conference, Baltimore 2007
Plant with Bio-Augmentation Integration
• Winter TN Removal Varied from 60% - 90%
• Avg. 75%
Stinson et al., “ Evaluation and Optimization of a Side Stream Centrate
Treatment System Integrated with a Secondary Step-Feed Process”, WEF / IWA
Specialty Nutrient Conference, Baltimore 2007
Operational Benefits - NYCDEP 26th Ward WPCP
HRT < 4.5 Hrs, SRT < 5 -8 days,
Temp. as low as 12°C
Peak Wet Weather Flows 2-4 ADWF
“Nitrifier Incubator” enhanced
Operational Reliability
Enhanced winter performance
Mitigated storm washout impacts
Mitigated centrate inhibition impacts
26th Ward WPCP – 85 mgd
Mitigated air limitations
Off-Loaded 30% TKN Load
Oxidized 70-95% Centrate TKN
Denitrified in main plant anoxic zone using wastewater COD
>70% TN Removal Plant-Wide
Effluent TN 5-8 mg/l
RAS Reaeration Experience
•
21 Plants Czech Republic
Influent
•
4 Plants Sweden
•
5 Plants USA
Primary
3 New York City DEP WPCPs (<85 mgd)
Activated
Sludge
Effluent
RAS
RAS
Reaeration
Dewatering
Centrate
Appleton, WI (15 mgd)
Denver MWRD Hite Plant
•
Final
Clarifiers
Harrisburg, PA - HPO Plant in construction (30 mgd)
Anaerobic
Digestion
Appleton Wisconsin Overview
•
15 MGD facility (1994
upgrade)
•
RAS reaeration is first pass of
Three Parallel
Aeration Passes
aeration tank
•
RAS reaeration operates at
6,000 mg/L TSS
•
MLSS is 3,000 in three
aeration passes
RAS Reaeration Pass
•
SRT 5-7 days
•
Influent NH4-N 15 – 20 mg/l
•
Effluent NH4-N 0.2 – 2 mg/l
Appleton Wisconsin Overview
Data from 2004/2005 when plant was operated at lower SRTs
Month Flow, mgd Temp, oC SRT, days Inf. NH4-N, mg/L Eff. NH4-N, mg/L
Oct-04
10.3
20.9
6.4
19.2
0.33
Nov-04
11.2
21.2
7.2
16.8
0.15
Dec-04
12.6
17.1
6.8
14.3
0.18
Jan-05
11.9
17.1
6.6
17.0
0.70
Feb-05
12.7
17.8
5.9
17.1
0.92
Mar-05
13.9
17.2
5.7
16.5
1.31
Apr-05
13.9
12.9
5.2
15.0
1.39
May-05
12.8
20.2
5.6
16.8
2.61
Jun-05
11.7
25.0
5.5
18.0
1.56
Jul-05
10.0
25.9
6.1
18.7
1.47
Aug-05
10.0
25.6
6.1
18.9
0.44
Sep-05
9.4
24.6
6.0
18.7
0.22
Average
11.7
20.5
6.1
17.3
0.94
Prague Czech Overview
•
•
•
•
21 plants in Czech Republic Operate RAS Reaeration
Prague - 83 MGD facility operating RAS reaeration of centrate
10 day SRT (including regeneration), 12 days with secondary clarifiers
Influent:
• BOD = 121 mg/L
• TN = 44.5 mg/L
•
•
•
Ammonia & TN Reduction
Limited footprint
Practices CEPT to maximize
nitrification volume
Prague Czech Overview
•
•
RAS Reaeration tanks only
receive 40% of RAS
4 Reaeration tanks (38ft deep)
Anoxic/Oxic/Oxic/Anoxic
• Regeneration HRT
3.8 hrs total
2 hours aerobic
• No carbon addition
• No pH control
• Plant Effluent
3.7 mg/L NH4-N
19.8 mg/L TN
03 Lower Effluent N
More Infrastructure Investment
Sidestream RAS Reaeration
Sidestream Deammonification
Mainstream Deammonification
Tertiary Polishing
Processes
Sidestream Nutrient Management
PST
Activated Sludge
Effluent
Reduce
Effluent TN
by 20%
WAS
RAS
Thickening
Digestion /
CHP
Centrate
Sidestream
Nitrogen
Treatment
Phosphorus
Recovery
Dewatering
Beneficial
Reuse of
Biosolids
Challenges of Sidestream Deammonification
• Low Growth Rate
approx. 10 day doubling time at 30 C
<10 day has been reported (Park et. al - 5.3 - 8.9 days)
SRT (>30 days)
• Sensitive to;
•
•
•
•
Nitrite
Toxic- irreversible loss of activity based on
concentration & exposure time
NH4+ : NO2- ratio 1 : 1.32
DO - reversible inhibition
Free ammonia (<10 -15 mg/l)
Temperature >30 C preferred
pH (neutral range)
Sidestream Nitritation – NOB Repression
• Control
– Elevated NH3-N concentrations
– Elevated temperature (30-35 deg C)
– Low SRT (1-2 days)
– Low DO (~0.5 mg/L)
• NOB Repression Mechanisms
– Free NH4 –N inhibition of NOB > AOB
– Nitrous acid inhibition of NOB > AOB
– AOB max growth rate > NOB max
growth rate at high temp
– AOB DO affinity > NOB DO affinity
(perhaps only at high temp)
Operational Experience
•
DEMON® Suspended Growth SBR
– 15 Operational /11 in Construction
– York River, VA, Alexandria, VA, Blue Plains, DC
•
Cleargreen® Suspended Growth SBR
– 3 Pilots / 3 WWTPs in Design
•
Terra-N Hybrid Suspended and Attached
– 4 Operational Facilities (Germany)
•
DEMON®, Cleargreen, Terra-N
Anita®MOX Attached Growth MBBR
– 4 Operational / 2 Start-up
– James River, VA & South Durham, NC
•
ANAMMOX® Upflow Granular
– 11 Operational facilities (4 WWTPs / 7 industrial)
– 9 in Design / Construction (2 WWTPs / 7 Industrial)ANITATM MOx MBBR
ANAMMOX® Upflow
Granular Process
Comparative Summary of Deammonification Processes
Suspended
SBR
(DEMON®)
Attached
MBBR
(ANITATM Mox)
Granular
Single-Stage
(AMAMMOX®)
kg N
/m3/day
0.7 – 1.2
0.7 – 1.2
IFAS > 3.2 ?
1.4 – 2.0
%
~90% NH3-N
~85% TN
~90% NH3-N
~85% TN
~90% NH3-N
~85% TN
kW hrs/
kg N
removed
1.0 – 1.3
1.2 – 1.75
1.0 – 1.3
Start-up
1-2 months with
Cyclone &
30% Seeding
~5 mo w/
2% seeding
1 mo
w/ seeding
Sensitivity /
Flexibility
pH & DO Control
NO2 < 5 mg/l
Pre-settling
DO control
Tolerates elevated
DO & NO2 well
DO control
Tolerates
elevated NO2
Volumetric
Loading Rates
Performance
TN Removal
Energy Demand
DEMON® Sequencing Batch Reactor – Energy Demand
•
Strass undertook many energy efficiency activities
•
With the introduction of DEMON® it became a net energy producer 2015
2002
2003
2004
2005
2006
2007
2008
81%
84%
95%
108%
105%
109%
124%
Nitritation /
Denitritation
Deammonification
Co-Digestion
Net Energy
Producer
%
Mainstream
Deammonification
175%?
Operational Cost Savings
$8.5M / yr (methanol,
alkalinity, sludge processing
8 year payback
Risk Mitigation for effluent TN
Sidestream
Treatment
20,200
lbs /day
NH3-N
Mainstream
Treatment
105,000
lbs/day
TKN
03 Lower Effluent N
More Infrastructure Investment
Sidestream RAS Reaeration
Sidestream Deammonification
Mainstream Deammonification
Tertiary Polishing
Processes
The Road to Sustainable and Efficient
Nitrogen Management
1.
2.
3.
A-Stage
Biosolids
B-Stage
– Maximize carbon capture
– Maximize energy recovery
– Minimize carbon & energy demand for N & P removal
3
1
2
3
Challenges for Mainstream Deammonification
vs. Sidestream Deammonification
•
Lower influent & effluent nitrogen concentrations
– Lack of free ammonia & low nitrous acid inhibition of NOB
– Reduced competitiveness of the AOB to outcompete the NOB at lower N
concentrations
•
Lower and more variable operating 1temperatures
•
Specific growth rate
(1/d)
AOB
– Slow growth rate of the Anammox
0.8
– Relative growth rates of NOB > AOB at Temperatures < 15-17°C
0.6
NOB
Higher carbon to nitrogen ratios - OHO
will compete with;
0.4
– AOB for oxygen under aerobic conditions
0.2
– anammox for the nitrite under anoxic conditions.
0
– anammox for organic substrate (certain
0 anammox
1 can denitrify
2 using organic
3
4
acids (Kartal et al. 2007).
Ammonia (AOB) or nitrite (NOB), mg-N/L
Zone 3 complete nitrification
Anthonisen et al. 1976
Chandran & Smets, 2005
Do’s and Don’t’s of Deammonification
1 mol Nitrate
(NO3- )
1. AOB Growth & Retention
2.
Anammox Growth &
Retention
0.57 mol
NO2-
Ordinary
Heterotrophs
(OHO)
40%
Carbon
1 mol Nitrite
(NO2- )
60%
Carbon
3. Control OHO Activity
AnAOB /
Anammox
4.
Limit NOB Growth
1 mol Ammonia
(NH3/ NH4 +)
0.44 mol N2+ 0.11 NO3-
Approaches to Mainstream Nitrite Shunt / Deammonification
Small
Flocculant
&Suspended
Growth
Anammox
Granules
e.g. Activated
Sludge Systems
•
•
•
•
•
•
•
•
Large
Anammox
Granules
e.g. granular
sludge
systems
Hybrid
Suspended &
Attached
Growth
e.g. IFAS
Increasing diffusivity or mass transfer resistance
• Delft Technical
DC Water, USA
University / Paques /
HRSD, USA
WSHD – Dokhaven,
AIZ Strass/ARA Consult, Austria
Netherlands
Glarnarland/Cyklar-Stulz, Austria
• ELAN Process –
Changi WRP, Singapore PUB
Bejing Technical University, China Santiago de Compostela
& Aquialia
Beijing Drainage Group, China
Harbin IT, China
• Veolia Water, France
Attached
Growth
Biofilm
e.g. RBC,
MBBR,
Biofilter
• Ghent University RBC
• Veolia Water, France
Two-Stage Approach
to Mainstream Deammonification
Nitrite shunt
Anammox Polishing
Small Flocculant
&Suspended
Growth AOB
Attached Growth
e.g. activated sludge
Suspended Growth
Nitrite Shunt
anammox
e.g. MBBR
Post MBBR
Anammox Polishing
HRSD Pilot Concept - Operating Very Successfully
WERF Mainstream Deammonification Project
3 different sites and scales
DC Water
WWTP Strass
HRSD
Engineering Control Mechanisms were Tested at Pilot Scale
– resulting in the successful removal of over 85% of the nitrogen
Recipe for Mainstream Deammonification
•
AOB & Anammox Bioaugmentation from sidestream
•
Anammox Retention in Mainstream
•
Intermittent high DO “transient anoxia”
– At high DO AOB grow faster than NOB
– NOB seem to have a delayed response as they move from anoxic to aerobic zones
•
Maintain residual ammonia > 2 mg/l
– Ensure max ammonia oxidation rates so AOB outcompete NOB for DO
– Ammonia based aeration control (AVN controller by HRSD)
•
Rapid transition to anoxia
– DO must be scavenged quickly to avoid a “low” DO environment
– Step-feed to anoxic zones to deplete DO quickly
– CEPT by-pass to enhance soluble COD as needed
•
Aggressive SRT Control
– Lower SRT results in selective washout of NOB at warmer temperatures
Changi Water Reclamation Plant (WRP)
Warm Climate Full Scale Mainstream Deammonification Demonstration
•
•
•
•
•
•
•
Full scale demonstration was based
upon successful strategies proven
at pilot scale
Changi - largest WRP in Singapore:
800 000 m3/day.
Tropical climate: sewage
temperature between 28-32 °C
Five basins with cyclical anoxic/
aerobic zones.
Feeding: 20% of primary effluent to
each anoxic zone
Total SRT: 5 days with 2.5 day SRT
for aerobic and anoxic
HRT: 5.7 hours
Changi’s Positive Performance Provided Proof of Concept
144 m
Basin 6 (Of f line)
Zone 4
Anoxic
• Observe significant
portion of the ammonia
converted to nitrite as
opposed to nitrate
indicating robust NOB
suppression
• Observe concomitant
reduction in ammonia &
nitrite in anoxic zones
indicating reliable
anammox activity
• Full scale
demonstration of
mainstream
deammonification
Zone 3
Anoxic
Basin 1
Zone 4
Anoxic
Aerobic
Zone
Zone 3
Anoxic
Basin 2
Zone 4
Anoxic
Aerobic
Zone
Zone 3
Anoxic
Basin 3
Zone 4
Anoxic
Aerobic
Zone
Zone 3
Anoxic
Basin 4
Zone 4
Anoxic
Aerobic
Zone
Zone 3
Anoxic
Basin 5
Zone 4
Anoxic
Aerobic
Zone
Zone 3
Anoxic
Aerobic
Zone
50 m
Zone 2
Anoxic
Zone 2
Anoxic
Zone 2
Anoxic
Zone 2
Anoxic
Zone 2
Anoxic
Zone 2
Anoxic
Zone 1
Anoxic
Zone 1
Anoxic
Zone 1
Anoxic
Zone 1
Anoxic
Zone 1
Anoxic
Zone 1
Anoxic
RAS
To SST
PE
Basin 6 under maintenance
Inlet of anoxic zone
Sampling Point
Ammonia
Nitrite
Nitrate
Strass WWTP, AustriaCold Climate Full Scale Mainstream Deammonification Demonstration
•
•
•
•
•
•
•
First Cold climate Demonstration
A-B type plant
Temp 10-12°C range
A-Stage - ½ day SRT High Rate
Activated Sludge with 65% carbon
capture for energy recovery
B-Stage - Carousel type aeration
tank providing high DO transient
anoxia (DO 0-1.7 mg/L).
Sidestream DEMON for AOB &
Anammox Bio-Augmentation
Cyclones for mainstream anammox
retention
Full Scale Cold Climate Success - Strass WWTP, Austria
- Deammonification performance was better & more reliable than
nitrogen
nitrogenconcentration
concentration(mg
(mgN/L)
N/L)
the conventional BNR process resulting in less nitrogen to the river
25
2010/2011NO3-N
NO3-N effluent
effluent
2010/2011
2010/2011 NO2-N
NO2-N effluent
2010/2011
effluent
2011/2012 NO3-N
2011/2012
NO3-Neffluent
effluent
2011/2012 NO2-N
2011/2012
NO2-Neffluent
effluent
Conventional BNR
Effluent Nitrogen 2010
20
15
Mainstream Deammonification
Effluent Nitrogen 2011
10
5
0
1-Dec
1-Dec
11-Dec
31-Dec
21-Dec
30-Jan
31-Dec
29-Feb
10-Jan
30-Mar
20-Jan
29-Apr
30-Jan
29-May
Benefits of AOB-AMX granules?
105
Principle One Step ANAMMOX®
FISH picture:
Mari Winkler
Principle One Step ANAMMOX®
O2
NH4+
NO2N2
NH4+
NH4+
2 NH3 + 1.7 O2
1.14 NO2- + 0.86 NH3
0.88 N2 + 0.24 NO3-
NO3-
Mainstream Granular Sludge Pilot –
Dokhaven WWTP / Delft TU/ Paques / WSHD
• Upflow system
• Biomass segregation in
granule
• NOB out competed due to
space in larger granules
• Selection criterion
NOB, Anammox, AOB
Key Messages
•
Sidestream systems offer a lot of opportunity for both N& P management
Phosphorus Take-Aways
– RAS Fermentation for P removal
– Controlled struvite formation for P sequestration / recovery
– WasStrip / Ostara combination for improved dewaterability of Bio-P sludge
– Denitrifying PAOs may offer opportunities for efficient N&P reduction
– Cyclones for Bio-P granulation exciting concept
– Cyclones also seem to enhance SVIs in winter so lower effluent TSS and hence TP
and TKN
Nitrogen Take-Aways
– RAS Reaeration & Nitrifier Bioaugmentation effective & easy to install
– Sidestream deammonification systems proven and effective– compact & bijou
•
Deammonification for mainstream promising
– Offers potential to redirect carbon for energy recovery or Bio-P
– Design so as not to preclude this opportunity in the future
– Granular mainstream anammox also promising – smaller footprint, lower capital cost
Beverley Stinson Ph.D
Global Wastewater Practice Leader
[email protected]
917-355-3169

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