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Data Worksheet for Biofuel from Algae

Introduction

Plankton Power, a biofuel company, wants to build a machine that maximizes indoor algae growth so that they can make a profit selling algae as biofuel. To facilitate the engineering process they have been conducting research on machine prototypes to determine the optimal conditions for algae growth. Below is a list of research questions they are attempting to answer:

  1. What intensity of light (3400 lumens, 2300 lumens, 1800 lumens) is best for algae growth?
  2. What species of algae (Scenedesmus, Selenastrum, or Spiropgyra) grows best in the machine?
  3. What temperature range (22°C-23°C or 24°C-25°C) is best for algae growth?
  4. What amount of light (12 hours/day or 24 hours/day) is best for algae growth?
  5. What concentration of fertilizer maximizes algae growth?
  6. What ratio of nitrogen: phosphorus: potassium for fertilizer is best for algae growth?

Researchers measured algae growth indirectly by collecting data on the turbidity of the samples. Turbidity is a measure of the cloudiness caused by solid particles suspended in a liquid. If these particles are too tiny to see with the naked eye, they stay suspended, discoloring the liquid. In these experiments. algae discolored the water solution growth medium green.A greater concentration of algae made a greener solution as determined by cross-referring the turbidity data below with microscope cell counts (see Data Collection Methods Handout for a complete explanation as to how the data in the tables below was determined).

Predictions

Predict the answer for each of the five research questions listed above. Be sure to explain your predictions.

A) What intensity of light (3400 lumens, 2300 lumens, 1800 lumens) is best for algae growth?

B)What species of algae (Scenedesmus, Selenastrum, or Spiropgyra) grows best in the machine?

C)What temperature range (22°C-23°C or 24°C-25°C) is best for algae growth?

D) What amount of light (12 hours/day or 24 hours/day) is best for algae growth?

E)What concentration of fertilizer maximizes algae growth?

Data Tables

Key

Genus / SCE = Scenedesmus / SES = Selenastrum / SPI = Spirogyra
Fertilizer Solution, MiracleGro:Water / FS1 = 1 Tbsp: 1 Gallon / FS2 = / FS3 =

Experiment #1

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Algae Sample / Description / Light / Change in
Turbidity (ml)
A / 100 ml SCE
400 ml Water / 24 hours
1900 Lumens / -19.5
B / 200 ml SCE
300 ml Water / 24 hours
1900 Lumens / -22
C / 100 ml SCE
400 ml FS1 / 24 hours
1900 Lumens / -21.5
D / 200 ml SCE
300 ml FS1 / 24 hours
1900 Lumens / -25.5
E / 100 ml SCE
400 ml FS2 / 24 hours
1900 Lumens / -30.5
F / 200 ml SCE
300 ml FS2 / 24 hours
1900 Lumens / -18.5
G / 100 ml SCE
400 ml FS3 / 24 hours
1900 lumens / -39.5
H / 200 ml SCE
300 ml FS3 / 24 hours
1900 lumens / -28.5
I / 100 ml SCE
400 ml Water / 24 hours
2300 lumens / -31.5
J / 100 ml SCE
400 ml FS1 / 24 hours
3400 lumens / -35.0
K / Narrow Bottle
100 ml SCE
400 ml FS2 / 24 hours
3400 lumens / -43
L / Narrow Bottle
100 ml SCE
400 ml FS3 / 24 hours
3400 lumens / -43.5
M / Narrow Bottle
200 ml SCE
300 ml Water / 24 hours
3400 lumens / -32
N / Narrow Bottle
200 ml SCE
300 ml FS1 / 24 hours
3400 lumens / -27
O / Narrow Bottle
200 ml SCE
300 ml FS2 / 24 hours
3400 lumens / -29
P / Narrow Bottle
200 ml SCE
300 ml FS3 / 24 hours
3400 lumens / -29
Q / Narrow Bottle
100 ml SCE
400 ml Water / 24 hours
3400 lumens with reflector / -51
R / Narrow Bottle
100 ml SCE
400 ml FS1 / 24 hours of
3400 lumens with reflector / -46
S / Narrow Bottle
100 ml SCE
400 ml FS2 / 24 hours of
3400 lumens with reflector / -46.5
T / Narrow Bottle
100 ml SCE
400 ml FS3 / 24 hours of
3400 lumens with reflector / -48.5

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Experiment #2

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Algae Solution / Description / Light
(Lumens) / Temperature / Change of Turbidity (ml)
A / 100 ml SEC
400 ml FS2 / 3400
12 hours / 22ºC Lights off
23 ºC Lights on / -7
B / 100 ml SEC
400 ml FS2 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / -14
C / 100 ml SEC
400 ml FS2 / 2300
12 hours / 22ºC Lights off
23ºC Lights on / -3
D / 100 ml SEC
400 ml FS2 / 2300
12 hours
Reflector / 22ºC Lights off
23ºC Lights on / -8

Experiment #3

Algae Solution / Description / Light / Temperature / Change in turbidity after 1 week (ml) / Change in turbidity from week 1 to week 2 (ml) / Total change in turbidity after 2 weeks (ml)
A / 5 ml SEC
500 ml FS2 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / -39 / -14 / -53
B / 5 ml SEL
500 ml FS2 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / -78 / -3 / -82
C / 5 ml SPI
500 ml FS2 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / 0 / 0 / 0

Experiment #4

Algae Solution / Description / Light
(Lumens) / Temperature / Change inturbidity after 1 week (ml)
A / 100 ml SCE
400 ml FS1 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / -35
B / 50 ml SCE
450 ml FS1 / 3400
12 hours
Reflector / 22ºC Lights off
23 ºC Lights on / -62
C / 100 ml SCE
400 ml FS1 / 3400
12 hours
Reflector / 24ºC Lights off
25ºC Lights on / -20
D / 100 ml SEL
400 ml FS1 / 3400
12 hours
Reflector / 22ºC Lights off
23ºC Lights on / -24
E / 50 ml SEL
450 ml FS1 / 3400
12 hours
Reflector / 22ºC Lights off
23ºC Lights on / -10
F / 100 ml SEL
400 ml FS1 / 3400
12 hours
Reflector / 24ºC Lights off
25ºC Lights on / -40

Analysis

Graph

Create a graph in the space provided to the right, illustrating the change in turbidity by its temperature, light, or concentration.

Analysis Questions

  1. Which species of algae had the highest total growth rate? Use the data from the tables above to support your answer.
  1. Were the growth rates of Scenedesmus and Selanstrum constant over the course of two weeks? What happened to growth rate after the first week?
  1. What factors might have affected the growth rate of algae during the second week of the experiment?
  1. What might have caused the Spiropgyrato show no change in turbidity? Does this mean the algae did not grow over the course of the two weeks?

a)Algae grow better under higher lumen light. Explanation: Different species prefer different light intensities for photosynthesis. This species of algae happens to prefer a high light intensity. Follow-up experiment: Would even higher intensity make for more photosynthesis and growth?

b)Algae grow better when surrounded by reflectors. Explanations: Reflectors reduce shadowing from nearby bottles and helps ensure the bottle receives more light. More light of course means more photosynthesis, which means more cell growth and division.