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Assessing the performance of cold climate natural wetlands in the treatment of
domestic wastewater effluents in northern Canada
Gordon Balch‡, Brent Wootton‡, Colin Yates†, Sven Jørgensen¥ and Annie Chouinard§
‡Centre for Alternative Wastewater Treatment, Fleming College, Lindsay †Faculty of Environment, University of Waterloo, Waterloo
¥ Water Research Laboratories, ASP, Væløse, Denmark § Civil Engineering Queen’s University, Kingston
Alberta Onsite Wastewater Management Association: 2015 Conference and Trade ShowSaturday, March 7th, 2015, Edmonton, Alberta
2
Focus• Wetlands are providing a
treatment benefit• Assessment tools are available• Wetlands could be part of a
hybridized wastewater treatment strategy
3
Background
• CCME guidelines• Present and future
challenges for lagoon systems
• Tundra wetlands exist downstream of lagoons
Pond Inlet – sewage lagoon
Paulatuk– sewage lagoon
4
Question: do wetlands provide treatment?
• Anecdotal evidence• Answer hampered by– Lack of knowledge – Lack of standardized
testing– Inability to predict
response to changing conditions Ulukhakt
uk
Carbon Interactions
DC = dissolved carbonPC = particulate carbonDIC = dissolved inorganic carbonDOC = dissolved organic carbon
Kadlec & Wallace 2008
Principal components of the nitrogen cycle in wetlands (Docstoc, 2013)
Phosphorus cycling processes: Dissolved inorganic phosphorus (DIP); dissolved organic phosphorus (DOP); particulate organic phosphorus (POP); particulate inorganic phosphorus (PIP); inorganic phosphorus (IP) (Reddy, 2008)
8
Question
How well do wetlands perform in a cold climate?
9
Treatment ProcessesSuspended Solids Phosphorus
sedimentation matrix sorption
filtration plant uptake
Nitrogen Soluble Organics
ammonification aerobic microbial degradation
nitrification anaerobic microbial degradation
denitrification Pathogens
plant uptake sedimentation
matrix absorption filtration
ammionia volatilization natural die-off
Metals predation
adsorption and cation exchange UV irradiation
complexation and precipitationexcretion of antibiotics from plant roots
plant uptakemicrobial oxidation / reduction
Temperature Dependent
10
Wetland Surveys 2009-2012
• Phase 1: Arctic Summer
• Phase 2: Rapid Assessment Protocol
• Phase 3: Data Analysis and Tool development
Wetland Surveys
i. Arctic Summer (inlet, outlet)– Seasonal trend–No pretreatment or pretreatment
(facultative lakes or lagoons)– Lagoon decants / exfiltration– Performance (BOD5, TAN, TSS,
microbial, etc.)– Calibration of SubWet 2.0 rate
coefficients for Northern conditions
11
0
50
100
150
200
250
300
350
Influent
Arviat, NunavutB O D 5 m g
-
L
Sampling Dates
0
5
10
15
20
25
30
35
40
45
InfluentEffluent
Coral Habour, NunavutTo ta
l A m m on ia
Ni tr og en
m g -
L
Sampling Dates
14
Wetland Surveys
ii. Intensive Sampling– Rapid, intensive testing (2-4 days)– Sampling stations along transects
cBOD5 TKN TAN TSS
15
Wetland Community cBOD5 cBOD5 % m3/d
Size (ha) Infl Effl Red122 day summer
u.d. Baker Lake 466 6 99 500
17 Gjoa Haven 133 2 98 356
10 Coral Harbour 181 14 92 287
9.5 Repulse Bay 385 25 93 197
7.8 Arviat 130 16 85 703
7.3 Ulukhatok 94 5 95 121
6.1 Taloyoak 80 25 69 257
5.0 Chesterfield Inlet 221 14 94 107
3.7 Whale Cove 40 21 47 245
2.1 Edzo 26 2 92 325
1.5 Paulatuk 40 2 95 102
0.87 Fort Providence 60 32 47
0.58 Pond Inlet 70 50 29 312
• Unusual (large)
• No pre-treatment• Large vol, size
• Pre-treatment
• Large vol, size• Pre-treatment
• Good Pre-Treat• Recalcitrant
• Decant event• Small wetland
• Small wetland• Large slope
Influ
ent
PI9
PI8
PI7
PI6
PI5
PI4
PI3
PI2
PI1
0
10
20
30
40
50
60
70
80
90
100
%FSS %VSS
Sample Location
Per
cen
t C
omp
osit
ion
Composition of Total Suspended SolidsPond Inlet
Influent Efflluent0
20
40
60
80
100
120
140
160
180
TSS
Influ
ent a
Influ
ent b
T1S2
T7S3
T8S1
T8S4
T10S
1
T10S
2
T10S
4
T11S
10
10
20
30
40
50
60
70
80
90
100%FSS %VSS
Sample Location
Per
cen
t C
omp
osit
ion
Composition of Total Suspended Solids Ulukhaktok
Influent effluent0
500
1000
1500
2000
2500
3000
TSS
18
Predictive Tools
• Rules of thumb (sometimes also called scaling
factors)
• Regression equations and loading charts
• Simple first order kinetic models (e.g., k – C* model)
• Variable - order, mechanistic or compartmental models (e.g., SubWet 2.0) and sophisticated 2D and 3D models (e.g., HYDRUS, WASP, TABS-2, STELLA)
19
Campbell and Ogden 1999
As =
𝑄(ln −ln𝐶𝑜)𝐶𝑒 ∙ 𝐾𝑡 𝑑
∙ 𝑛Where: As = surface area of the wetland Q = flow, in m3/day Co = influent BOD (mg/L) Ce = effluent BOD (mg/L) Kt = temperature – dependent rate constant d = depth of bed medium n = porosity of bed medium
Kt = K20 θ(T-20)
Where: K20 = rate constant at 20°C Θ = theta, the temperature correction factor set at 1.06 T = temperature of the water in °C
20
Alberta Model 2000
A =0.0365𝑄 𝑥𝑙𝑛 𝐶𝑖−𝐶∗𝐶𝑒−𝐶∗
𝑘Where:
A = area (ha) k = aerial rate constant @ 20°C, m/yr Q = design flow (m3/d) Ci = influent concentration (mg/L) Ce = effluent concentration (mg/L) C* = wetland background limit (mg/L)
21
Comparison of 1st Order Kinetic Model with SubWet 2.0
• Campbell & Ogden predicts that a BOD5 reduction from 205 to 11 mg L-1 can be accomplished in a wetland 0.25 hectares in size
• The Chesterfield Inlet wetland can accomplish this level of treatment BUT wetland size is 5 hectares
• Campbell & Ogden greatly over estimates treatment efficiency of wetland
22
Predictive tools – SubWet 2.0
• 16 rate coefficients• 25 differential equations• Easily obtained input parameters• Ability to calibrate to site
conditions• Models BOD5, Ammonium,
Organic Nitrogen, Nitrate and Total Phosphorus
• Easy to use• Available as free-ware
• Calibrated to 11 individual tundra treatment wetlands
Nunavut: Arviat, Coral Harbour, Gjoa Haven, Pond Inlet, Repulse Bay, Whale CoveNTW: Edzo, Fort Providence, Paulatuk, Taloyoak, Ulukhaktuk
16 Rate Coefficients
Range 0.05-2.0
% Derivation of Simulation from Measured
Nunavut NTWBOD5 Ammonium Total
PhosphorusBOD5 Ammonium Total
Phosphorus
Arviat 18 7 2 Edzo 8 15 9Coral Harbour 5 14 8
Fort Providence 79 57 56
Gjoa Haven 2 3 12 Paulatuk 30 10 1
Pond Inlet 5 4 4 Taloyoak 15 2 9Repusle Bay 5 4 4 Ulukhaktuk 5 16 11Whale Cove 64 10 34
• Provides the lagoon operator the ability to forecast how the wetland will respond
• Forecast future capacities and needs
25
Calibration of Problematic Sites for BOD5
Before Calibration After Calibration
CommunityMeasure
dSimulate
d % DiffSimulat
ed % Diff
Whale Cove 21 8.6 64 21 0.5
Paulatuk 2 13 30 1.9 0.3
Fort Providence 32 9.8 79 34 6.4
26
Summary Report
• 380 pages• Provides
background to studies
• Overview of wetlands
• Interpretation of the data
• All raw data appended
• Predictive tools• User manual for
SubWet 2.0
27
cawt.ca
28
SubWet published literatureChouinard, A., Balch, G.B., Wootton, B.C., Jørgensen, S.E. and Anderson, B.C., 2014. Modelling the performance of treatment wetlands in a cold climate. In Advances in the Ecological Modelling and Ecological Engineering applied on Lakes and Wetlands . 1st Edition. Jørgensen, S.E.; Chang, N.B.; Fuliu, X., Eds. Elsevier: Amsterdam, Netherlands
Chouinard, A., Yates, C.N., Balch, G.C., Jørgensen, S.E., Wootton, B.C., Anderson, B.C., 2014. Management of Tundra Wastewater Treatment Wetlands within a Lagoon/Wetland Hybridized Treatment System Using the SubWet 2.0 Wetland Model. Water, 6(3):439-454 Yates, C. N., Wootton, B. C., and Murphy, S. D., 2012. Performance assessment of Arctic tundra municipal wastewater treatment wetlands through an Arctic summer. Ecological Engineering, 44(0), 160-173
Huang, J.J., Gao, X., Balch, G., Wootton, B., Jørgensen, S.E., Anderson, B. 2014. Modelling of vertical subsurface flow constructed wetlands for treatment of domestic sewage and stormwater runoff by subwet 2.0. Ecological Engineering 74:8-12.
Huang, J.J., Gao, X., Balch, G., Wootton, B., Jørgensen, S.E., Anderson, B. 2014. submitted. The comparison of first-order model and dynamic model for the modelling of free water subsurface constructed wetlands: SubWet 2.0 and WASP 7.5.
Jørgensen, S.E.; Gromiec, M.J. Mathematical models in biological waste water treatment—Chapter 7.6. In Fundamentals of Ecological Modelling, Volume 23, 4th Edition: Applications in Environmental Management and Research ; Jørgensen, S.E., Fath, B.D., Eds.; Elsevier: Amsterdam, the Netherlands, 2011; pp. 1–414. Yates, C.N., Wootton, B.C., Jørgensen, S.E., Murphy, S.D., 2013. Wastewater Treatment: Wetlands Use in Arctic Regions. In Encyclopedia of Environmental Management. Taylor and Francis: New York Yates, C., Balch, G.B., Wootton, B.C., Jørgensen, S.E., 2014. Practical Aspects, Logistical Challenges, and Regulatory Considerations for Modeling and Managing Treatment Wetlands in the Canadian Arctic. In: Advances in the Ecological Modeling and Ecological Engineering applied on Lakes and Wetlands. 1st Edition. Jørgensen, S.E., Chang, N. B. and Fuliu, X., Eds. Elsevier, Amsterdam, The Netherlands, 560 pages Yates, C.N., Balch, G.C., Wootton, B.C., Jørgensen, S.E., 2014. Exploratory Performance Testing of a Pilot Scale HSSF wetland in the Canadian Arctic. In Advances in the Ecological Modelling and Ecological Engineering applied on Lakes and Wetlands . 1st Edition. Jørgensen, S.E.; Chang, N.B.; Fuliu, X., Eds. Elsevier: Amsterdam, Netherlands Yates, C.N., Balch, G.C., Wootton, B.C., Jørgensen, S.E., 2014. Framing the Need for Application of Ecological Engineering in Arctic Environments. In Advances in the Ecological Modelling and Ecological Engineering applied on Lakes and Wetlands . 1st Edition. Jørgensen, S.E.; Chang, N.B.; Fuliu, X., Eds. Elsevier: Amsterdam, Netherlands
29
Coral Harbour
Northern Wastewater Strategy
Hybridized approach (lagoons + wetlands)
30
Common Challenges
• Cold temperatures lower treatment rates in lagoons
• Long HRT required• Accumulation of sludge can decrease
lagoon’s design capacity• Population growth• Need to release effluent earlier than
desired• Treatment targets not achieve
31
Wetlands Provide Additional Treatment
However: Current Regulatory Challenges• Wetlands considered “receiving
environment”• Until now, lack of proof in Wetland
performance• Considered “black box”, no predictive ability• No point of control• How and what should be sampled, where to
analyze (sample shelf life issues)
32
• Designate wetlands as part of treatment train (protect and preserve for future)
• SubWet and interpolated mapping open the “black box”
• Survey protocols have been developed and proven to work
Challenges can be overcome
33
SubWet as a Predictive Management Tool
Scenarios:• Need to decant early – what volume, conc can be
released before wetland treatment is overwhelmed• Decant practices (time of year, frequent/small volumes
versus less frequent/larger volumes or exfiltration versus scheduled decants
• SubWet to predict treatment capacity to meet future population growth
• Applicable to industrial sites requiring domestic sewage treatment
• Help regulators better predict treatment capacities of municipalities
34
Concluding Remarks
• Wetlands do provide treatment benefit
• Sampling protocols and predictive tools exist
• Consideration of a hybridized approach should be considered
35
Concluding Remarks
• Demand for decentralized treatment likely to increase
• Demand for specialized treatment to off-load burden to centralized systems may increase
• May see greater need for advanced treatment systems for Nitrate and Phosphorous in relationship to source water protection
Acknowledgements