an american university constructed wetland
DESCRIPTION
An American University Constructed Wetland. Achieving the Green Dream By: Sara Schwartz. What is a Constructed Wetland?. Wastewater treatment system based on ecological systems found in natural wetlands Able to control the wetland to meet certain treatment standards - PowerPoint PPT PresentationTRANSCRIPT
An American University Constructed Wetland
Achieving the Green Dream
By: Sara Schwartz
What is a Constructed Wetland?Wastewater treatment system based on
ecological systems found in natural wetlandsAble to control the wetland to meet certain
treatment standards Vegetated submerged bed: water flows through
media (gravel) instead of being exposed to the air
Basic Components
Pre-treatment tank: solids settle hereCells containing plants and mediaPlants: roots act as substrate for bacteria which
digest organic matter ex. Bulrush, Cattail Media: usually gravel, acts as filter for
suspended solidsLiner: type of plastic or rubberInlet and outlet drains: help regulate water flowIndoor filters: increase clarity, decrease
particulateStorage tank
Water FlowStorage tank trickle filter (cylindrical tank with
plastic media and air, different bacteria hosted
and treats different contaminants), one of two top
cells, sand filter, third cell, 1/3 to sand filter and
2/3 back to trickle filter to repeat process
Inside: 2 different sized micron filters UV filter
sock filterpressure tankstoilets
Commonly Asked Questions
Are they reliable? What do they treat?Performs many of same functions as conventional wastewater
treatment, acts as filter and a sink for sediment and precipitates, recycles and transforms nutrients, treats total suspended solids, biochemical oxygen demand, nitrogen, metals, toxic organics
Does it smell?May have odors by inlet pipes, but overall not a problem
because water remains below the surface of the media
What about bugs?No pools of standing water exposed to air, so not a
problem
Nitrogen Removal
Commonly Asked QuestionsHow long do they take to become fully
operational?Sidwell took about 1.5 years, need more than one growing season
to reach proper plant density, and 3 to 6 months for microbial biomass to establish in media
How much effort is needed for operation and maintenance?
About one day a week for labor, monthly or weekly inspection of weirs, weekly sampling of water, control panel provides constant feedback for technicians
How long do they last?Estimated to last 15 years but systems vary What happens in the winter?System still works but transformation and removal of nitrogen may
occur at slower rate
Our WetlandLocation: front lawn
Beeghly-unused, natural slope, visible to visitors, proximity to science classes
Capacity: treat about 300 gallons a day from bathrooms (small system), requires about 300 square feet, lawn is 14,700 square feet
Would wait for extension to be built
CostsUpfront: EPA estimates $20 per ft2, AU
wetland=$6000, lots of factors including aesthetics but with other filters and piping NSI says
$64,540.88
Maintenance: about 6% of total cost, paid annually, $360, NSI says a couple thousand a year, energy costs minimal
Funding options: DDOE $986,000 in grants for LID/green infrastructure, Chesapeake Bay Trust grants, EPA grants for green infrastructure
Benefitsslow the flow of storm water and decrease sewage
overflows into D.C. rivers reduce our use of the D.C. water supply, reduced Sidwell
Friends Middle School’s use of the water supply by 93%
decrease the university’s water bill by reusing treated water for toilet flushing, take in less water and put out less water, thus decreasing those charges on our water bill
could help us gain up to 9 LEED credits, also give us more
points for our STARS report and contribute to our status as a leading green school
Benefitseducational outreach possibilities for Chemistry,
Biology, Water Resources, Ecohydrology, Sustainable Cities, and more (checking nitrogen, pH, dissolved oxygen, etc.).
research opportunities for professors such as Dr.
MacAvoy studying movement of nutrients, and the new professor specializing in water.
noticeable feature on campus tours and therefore a
good example of how AU is working to be sustainable the construction of a wetland would not impact the
extension of the Beeghly building
Next StepsReceive quote from Natural Systems International-said water from lab sinks would be okay, cleaning supplies
down drain more of a concern, look for mop sinks in maintenance closets
-could design it to get nitrogen out so can use for irrigation- Not easy to re-plumb toilets, maybe just use for extension
More research: better estimate of wastewater (see number of students in classes, faculty profile, how much will come from extension), effect of reduction of students in summer, see how much space available for indoor filters
Submit to Facilities Management, Office of the Architect, District Department of Health