Treatment Wetlands
Presented by:
Scott Wallace, P.E.
Scott.Wallace@naturallywallace.com
(612) 802-2329

References for Wetland Design
Water Environment Research
Foundation (WERF)
• Small Scale Constructed Wetland
Systems (Wallace & Knight,
2006)
Treatment Wetlands 2 nd Edition
• (Kadlec & Wallace, 2009)

Types of Treatment Wetlands
• Surface Flow (SF)
• Horizontal Subsurface Flow (HSSF)
• Vertical Flow (VF)
• Sludge Dewatering Reed Beds
• Intensified Wetlands
– Aerated (cold climates)
– fill-and-drain (warm climates)
– reactive media (ammonia, phosphorus, etc)
– industrial wastewaters

Surface Flow Wetlands
Kadlec & Wallace, 2008

Surface Flow Wetlands
Champion Paper, Pensacola Florida

Horizontal Subsurface Flow
Wetlands
Wallace & Knight, 2006

Horizontal Subsurface Flow
Wetland
Wildflower Meadows: 90-person treatment system

Vertical Flow Wetland
IWA, 2000

Vertical Flow Wetland
Rousillon, France

Sludge Dewatering Reed Bed
Skovby, Denmark: 8000-person treatment wetland
Kadlec & Wallace, 2008

Main Treatment Mechanisms
• Adsorption of dissolved-phase hydrocarbons
• Microbial degradation of organic compounds
• Settling of particulate compounds
• Oxidation and reduction of nitrogen compounds
• Precipitation of metals
• Use of intensification methods (aeration and reactive medias to accelerate treatment)

Natural vs. Mechanical Systems
LEAST Energy and O&M Needs
Natural Systems
Intensified
Wetlands
MOST Area Requirements
MOST
Mechanical
Treatment
Systems
LEAST

Climate Range of
Treatment Wetlands
Wellsville, New York
Northern Sahara,
Libya

Casper, Wyoming
Casper

BP – Casper, Wyoming Refinery
• Operated 1912 to 1991
• 37,000 m 3 of LNAPL recovered to date
• Extensive smear zone due to river flooding
• 50 to 100 years to remediate site
• High mountain west: -35 o C

BP – Casper Wyoming Refinery

HSSF Wetlands
SF Wetlands
Casper Reuse Plan

Full-Size System from Pilot Data
Wallace & Kadlec, 2005

Casper Intensified Wetland Cell

Casper System Construction

Casper Wetland Construction

Casper Benzene Data 2004 - 2006
Benzene effluent at Outfall 001 consistently below detection levels
<0.01 mg/L

Rosebel Gold Mine
Project
Site

Cyanide Removal
Cyanide Levels from Reclaim to TWSP
1,00
0,90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
S-05 M-06 O-06 A-07 N-07 J-08
Month-Year
D-08 J-09 J-10 A-10 F-11
Reclaim Cyanide
TWSP Cyanide
Permit WAD Cyanide

Iron Removal
Iron Levels from Reclaim to TWSP
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
S-05 M-06 O-06 A-07 N-07 J-08
Month-Year
D-08 J-09 J-10 A-10 F-11
Reclaim Iron
TWSP Iron
Permit Iron

Multi-Stage Treatment Processes
• Wetlands are typically multi-stage treatment systems
– Process Chemistry
– Site Topography
Compania Minera
Antamina, Peru

Conclusions
• Treatment wetlands are already being used in North America, South America, Europe,
Asia and Australia
• Surface flow, horizontal subsurface flow, vertical flow, and intensified wetlands are all being used
• Use of wetlands for treatment wetlands is increasing on two major fronts:
– Range of applications in different industries
– Construction of wetlands in different geographic regions

Treatment Wetlands
Thank you for your time