Constructed Wetlands and
Wastewater Treatment
Scott Stine
SWES 574
Types of Constructed Wetlands

Surface Flow Wetlands (SF)
– similar to natural wetlands
– free floating, emergent, and submerged
plants are used

Subsurface Flow Wetlands (SSF)
– water flows below surface of support media
– emergent plants that are tolerant of water
saturated soils are used
Wastewater Treatment Uses



Additional Secondary Treatment
Tertiary Treatment
Onsite Wastewater Treatment
– alternative to municipal sewage treatment
– used in animal feeding operations
Microorganisms

Bacteria
– Coliforms, Enterococci, C. perfringens

Viruses
– Coliphage

Parasites
– Cryptosporidium, Giardia
Removal Processes


Most processes are enhanced by
vegetation
Processes include:
– Filtration
– Adsorption
– Predation
– UV light
– Sedimentation
SSF vs. SF


What are the objectives of the
constructed wetland?
Some considerations:
– SSF remove pathogens more efficiently
than SF
– SF allow more biodiversity and habitats
– SSF minimize pests such as mosquitoes
Concerns

Some bacteria are able to reproduce on
some plant surfaces
– Enterococci

Spore forming pathogens may be
released by precipitation
– Cryptosporidium
– Giardia