Phosphorous Remediation of Various Water Samples With Duckweed

1
Phosphorous Remediation of Various Water Samples
With Duckweed
Wilnely Rivera, Amber Stangroom, Richard Tia, and
Mark Troutt
Introduction This experiment answered two
questions What are the phosphorus levels of
various water samples? and How effective is
duckweed in the remediation of these samples?
These questions were asked so that we could
determine not only how effective duckweed is at
removing phosphorus but also to see how great a
need there is for phosphorus remediation. The
following results, we believe, accurately answers
the first of these questions. The following
duckweed results may not be entirely accurate and
cannot be taken fully at face value.
Conclusions Only the pond water sample showed a
significant decrease in phosphorous levels. All
of the other samples showed an increase in the
amount of phosphorous. There could be several
reasons for this. One explanation is that the
caps on the BOD bottles were too tight and no air
could get in, disrupting normal gas exchange.
That would cause the duckweed to die and release
phosphorous. Another reason why only the pond
water showed positive results could be because
the duckweed was raised in the pond water and
became adapted to its specific oxygen and
nutrient levels. This could cause it to flourish
in the pond sample and die in the tap and well
water. Also, some human error could have caused
the results. A pond water sample had to be thrown
out because the device used to filter out the
duckweed had a backup of tap water which mixed
with the sample. The same thing could have
happened to our other samples without being
noticed. Based on the research by other people
on this subject the results after the experiment
disagreed with that of the other people, who
performed a similar experiment using duckweed. In
the experiment, the phosphorous levels of the
different water samples were raised after the
duckweed was left in them for a few days, while
in other experiments the phosphorous levels were
lowered.
Results No duckweed Duckweed

• Procedure
• Collect different water samples (pond, well,
  tap, etc.)
• Measure absorbance level to figure out
  phosphorus concentration
• Add duckweed to samples
• Wait five days for remediation to occur
• Filter out the duckweed from the water
• Measure absorbance again

Figure 1. Graph of change in absorbance.
When testing the phosphorous levels of various
water sources we were quite surprised with the
results we got. For our experiment we used three
main water sources which were tap,well, and pond
water. Out of the water samples tap had the
highest phosphorous levels. That was a shock,
because in most places tap water is the most
fasted way to get water. Thats a problem because
we need to take better care of our water sources.
We performed a experiment in which we added
duckweed to the samples. The results we got from
the experiment weren't that great because intead
of decreasing the phosphorous level , the
duckweed actually increased the phosphorous
levels. The only good result we had was from the
pond water. it decreased the phosphorous levels
from 0.179 to 0.042.
When testing the phosphorous levels of various
water
References "Application of Duckweed in Treating
Municipal Wastewater." Foundation for Water
Research. Apr. 1993.21Dec.2007lthttp//www.fwr.org/
wsaa/wsaa151.htmgt.
Figure 3. Duckweed, The Remediator.