The Oberlin College Living Machine (LM) is a wastewater treatment facility designed to model the functional processes of nutrient removal in wetlands The LM recycles all of the wastewater in the environmental studies building. The primary goals of the

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Temporal, Seasonal, and Spatial Patterns in Water
Quality Indicators in a Wetland-based Wastewater
Treatment System Systems Ecology (ENVS316) 06
Oberlin College, Ohio Molly Danielsson, Elyse
Perruchon, Matthew Thayer

• Introduction
• The Oberlin College Living Machine (LM) is a
  wastewater treatment facility designed to model
  the functional processes of nutrient removal in
  wetlands The LM recycles all of the wastewater in
  the environmental studies building. The primary
  goals of the wastewater treatment are removal of
  nutrients (nitrogen and phosphorus), organic
  matter, and pathogens to prevent eutrophication
  in downstream bodies of water and harm to human
  health. Fecal coliform (FC) are a group of
  bacteria used as an indicator of pathogenic
  contamination in water and are measured to show
  whether microbial populations are being minimized
  by the LM.
• The LM is a more complex system than conventional
  wastewater treatment facilities because it
  utilizes microbial and plant communities that
  develop synergistically over time. We looked at
  FC and nutrient levels in the LM from the past
  three school years because the efficiency of the
  ecological processes in the LM is expected to
  reflect temporal, seasonal, and spatial patterns.
  
• Hypotheses
• As microbial communities become more adept at
  processing nutrients over time, we expect to see
  decreasing concentrations of nutrients in the LM
  Effluent from 2004 to 2006.
• The Oberlin College schedule results in increased
  LM flow in spring and fall and decreased flow
  during summer and winter breaks. Thus, we expect
  a seasonal cycle of increased nutrients
  throughout the LM system during fall and spring
  semester.
• Nutrients are removed by metabolic processes that
  vary in function and location in the LM. We
  expect NH4 to peak in the anaerobic tanks, and
  NO2- and NO3- to peak in the first aerobic tanks
  and decrease in the marsh due to ammonification,
  nitrification, and denitrification. PO43-
  concentrations should remain constant throughout
  the LM until it is sequestered in the marsh by
  positively charged gravel. Cl- concentrations are
  expected to remain unchanging throughout the LM
  system because it is an inert ion.

• Conclusions
• Nutrient trends in the LM Effluent do not show
  the clear temporal patterns we expected.
• Nutrient concentrations generally show seasonal
  patterns, increasing during school and decreasing
  between semesters. Patterns in NO3-
  concentrations are unexpected, as NO3- continues
  to increase in LM Effluent during winter break
  and spring semester 2006. We hypothesize that
  changes in the denitrification process
  responsible for metabolizing NO3- are causing
  increased Effluent concentrations of NO3-.
  Changes in denitrification could be caused by
  unfavorable conditions in the marsh such as low
  carbon supplies or the presence of oxygen.
• Nitrogen trends agree with our spatial
  hypotheses. PO43- follow the same pattern as
  NO3-, whereas we expected concentrations to
  remain constant until reaching the marsh. Cl-
  decreases throughout the LM unlike our
  hypothesis. As expected, FC levels decrease
  throughout the LM.
• Future Studies
• Further analysis of temporal patterns should
  include data from a longer time period.
• Further study should work to elucidate the
  relationship between phosphate and nitrate
  biochemical processes to maximize removal of both
  nutrients

• Methods
• We used Dionex Ion Chromatography to measure
  concentrations of NO2-, NO3-, PO43-, SO42-, and
  Cl- in samples taken weekly from the LM tanks
  between Fall 2004 and present. We measured NH4
  concentrations with an Orion Ammonium Probe.
• Fecal coliform levels were determined with a FC
  detector test bi-weekly between 2004 and 2006.
  Most of our FC data was for AN1, CA1, Effluent,
  and Post UV.

1.00
Cl
PO4
0.80
NO3-
SO4
NO2
0.60
0.40
0.20
0.00
9/20/2004
3/20/2005
9/20/2006
6/20/2005
9/20/2005
3/20/2006
6/20/2006
12/20/2004
10/20/2006
12/20/2005
Sample Date
Nutrient concentrations in LM Effluent between
2004 and 2006. Discontinuous lines represent
unsampled time periods. Results nutrient
concentrations decrease during school breaks and
increase upon student return. NO3- continues to
increase over winter break in 2006, while other
nutrients remain stable throughout the year.
Key Ion and Fecal Coliform Levels by LM Tank
1.00
0.80
0.60
Concentration (scaled to maximum value)
0.40
0.20
0.00
AN1
CA1
OA1
OA2
OA3
Clarifier
Marsh
Effluent
Post UV
Living Machine Flow Diagram AN1 AN2
CA1 CA2 OA1 OA2 OA3
Toilet Clarifier Post UV
Effluent Marsh
LM Tank
FC and nutrient levels represent median values of
data sets from school years 2004 through 2006.
Results NH4, Cl-, SO42- and FC concentrations
were highest in AN1. NO2-, NO3- and PO4 peak in
CA1. All variable decrease through subsequent
tanks except for NO3- and PO43-, which have
smaller peaks in OA3.