Wastewater Treatment Wetlands: Ecology and Design

1
Wastewater Treatment Wetlands Ecology and Design

• David Tilley
• Department of Environmental Science Technology
• University of Maryland, College Park
• www.enst.umd.edu/tilley
• dtilley_at_umd.edu

2
Educational Objectives

• What do they look like?
• What are their functions?
• How well do they perform?
• How are they designed?

3
Agriculture
Tidal Freshwater Wetlands
Swamp
Marsh
Nanticoke River, Delmarva Peninsula
4
Swamp
High Marsh
Low Marsh
5
Tidal Freshwater Marsh, Nanticoke River (Md)
6
(No Transcript)
7
Radiometric Measurements of Reflectance
(Nanticoke)
8
Tidal Fresh Marsh Mid-Autumn
9
Treatment Wetland Definition
US EPA Engineered or constructed wetlands that
utilize natural processes involving vegetation,
soils, and microbial assemblages to assist in
treating an effluent or other water source. (EPA
843-B-00-003)
10
Treatment Functions

• Nutrients Transform and sequester
• Suspended Solids Sequester as sediment
• Toxins (e.g. chlorinated organics, pesticides)
  anaerobic decomposition
• Heavy Metals Adsorb to organic matter,
  sequestered

11
Ecological Economic Functions

• Provide Wildlife Habitat
• Fish
• Birds
• Mammals
• Buffer natural water bodies from
• Flood pulses
• Pollution
• Eco-Tourism
• Low Cost Treatment Alternative
• Produce Wood for Harvest

12
Home to Endangered Species
Wetlands Mitsch and Gosselink (2000)
13
Wetland Effect on Flooding
Wetlands Mitsch and Gosselink (2000)
14
Port Aransas Waste-Water Treatment Facility
Birding Center
15
Activated Sludge
16
Port Aransas Birding Center
17
Boardwalk and Bird Viewing Platform
18
WasteWater Treatment Plant
19
BirdWatching
20
UM Dairy Farm Treatment Wetlands
21
(No Transcript)
22
Surface Flow Treatment Wetland
Milking parlor effluent, barn washwater
Wetland Cells
Solids Separator
2
4
Storage Tank
to vegetated filter strip
Treatment Lagoons
1
3
Crop irrigation
Loading 75 gal/cell/day
23
(No Transcript)
24
Sub-Surface Flow Treatment Wetland
Distribution System
Septic Tank
Collection System
Impervious Bottom
25
(No Transcript)
26
(No Transcript)
27
Anaerobic Zone Ecological Wealth Below
Water
Oxidized Soil
Depth
Reduced Soil
Redox Potential Oxygen
Mn4 Fe Sulfide
28
Arrowhead
Reed
Bulrush
Cat-tail
ArrowArum
29
Shrimp Farm Wetland Natural
RecirculatingFilter
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
Roseate Spoonbills
37
Spatial Analysis of Water Quality
38
Average total dissolved solids concentrations
(ppt) (with 95 confidence intervals) versus
wetland area (m2) for recirculation and harvest
periods
Vegetated area
39
Average pH (with 95 confidence intervals) versus
wetland area (m2) for recirculation and harvest
periods
40
Average dissolved oxygen concentrations (mg/l)
(with 95 confidence intervals) versus wetland
area (m2) for recirculation and harvest periods
41
Logarithmic plot for average total ammonia
concentrations (mg/l) (with 95 confidence
intervals) versus wetland area (m2) for
recirculation and harvest periods
42
Average nitrate concentrations (mg/l) (with 95
confidence intervals) versus wetland area (m2)
for recirculation and harvest periods
43
Logarithmic plot for average total phosphorus
concentrations (mg/l) (with 95 confidence
intervals) versus wetland area (m2) for
recirculation and harvest periods
44
Logarithmic plot of average Total Suspended
Solids concentrations (mg/l) (with 95 confidence
intervals) versus wetland area (m2) for
recirculation and harvest periods
45
Average Volatile Suspended Solids concentrations
(mg/l) (with 95 confidence intervals) versus
wetland area (m2) for recirculation and harvest
periods
46
Logarithmic plot of average Inorganic Suspended
Solids concentrations (mg/l) (with 95 confidence
intervals) versus wetland area (m2) for
recirculation and harvest periods
47
Average Chemical-Biological Oxygen Demand
concentrations (mg/l) (with 95 confidence
intervals) versus wetland area (m2) for
recirculation and harvest periods
48
Dissolved Oxygen
Treatment Wetland
Shrimp Ponds
49
Anaerobic Degradation of ToxinsBrominated-organi
cs (flame retardants)
Environ. Sci. Technol. 2002
50
Abstract
Environ. Sci. Technol. 2002
51
Dynamic Simulation of the Water Budget for a
Constructed Wetland
52
(No Transcript)
53
(No Transcript)
54
(No Transcript)
55
(No Transcript)
56
Hydraulic Loading Rate
HLR VOLUME FLOW per TIME per AREA HLR Flow
Rate/Wetland Area HLR Depth per Day Typical
Values for Wastewater Treatment -- 0.5 to 7
cm / day
57
Hydraulic Detention

• Design for Detention Time (t)
• t (Wetland Volume) / (Inflow Volume)
• Typical Values5 to 14 days

58
Chemical Uptake

• Design for Nutrient Removal

Ci
Co
59
Nitrate Removal Rate
60
Cropland Treatment Wetland Designs

• Go to pdf

61
Urban Stormwater Wetland Sizing based on Storm
Flow
62
Sizing contd
63
Sizing contd
64
Sizing contd
65
Wetland Construction Costs
66
Water Clean-up Wetlands v. Chemicals
(200 Million Gallons per Day)
67
The End