1. Factors Affecting Algal Growth
By: Sarah Perez

2. Research Question
Which of 13 different silicate samples will, when in the presence of algae, yield the most algal growth over a set period of time?
How will algal growth be affected when grown in different pH’s?

3. Background Information
All that is necessary for algae to sustain life is water, CO2, and nutrients (nitrogen,etc.)
One of fastest growing plants in world
Great potential for an alternative energy source
50% of its mass is oil
Biofuel: can produce gallons of oil per acre compared to gallons of oilseed crops
AACT plant

4. Background: AACT Photo Bioreactor: grows algae
Anaerobic Bioreactor: converts algal biomass into fuel for power generation and fertilizer
Organic Carbon Engine: uses biomass to produce syngas, biochar, and bio-oil. Residual heat and CO2 that is created is recycled back in GPH system to grow algae

5. Procedure: Silicate Test
3 different trials testing 2 different factors
SILICATE TRIALS:
Independent Variable: 13 different silicate samples
Dependent Variable: amount of algal growth
Controlled Variables: amount of water (3 L), amount of algae to start (100 ml), amount of fertilizer (50 ml), amount of light (plant light, 18 hrs on, 6 off), amount of silicate (1.2 ml)
Two trials conducted, lasting three weeks each
Did not use CO2 tank for second trial

6. Procedure: pH Test pH TRIAL:
Five different pH’s tested with two of each pH
3, 5, 7, 9, 11
Independent Variable: pH
Dependent Variable: amount of algal growth
Controlled Variables: water (3 L), amount of algae to start (100 ml), amount of light
1 trial lasting 3 weeks
Did not use CO2 tank or fertilizer

7. Ranked subjectively by 2 people
Data: Silicate Trial 1
MOST
Mash control
CO2 control 11 8 9 5 3
Ranked subjectively by 2 people

8. Ranked subjectively by 2 people
Data: Silicate Trial 2
MOST
Control 12 9 8 10 7 6 3 2
Ranked subjectively by 2 people

9. Data: pH Trial MOST pH 11 (#1) pH 9 (#1) pH11 (#2) pH 9 (#2) pH 5 (#2)
LEAST

10. Comparison: Silicate Trials
Sample 12
Sample 13

11. Sample 1
Sample 4

12. Sample 8
Sample 3

13. Conclusion: Silicate Samples
In the silicate sample trials, there were inconsistencies between the results of which sample produced the most algal growth. The samples that yielded the most and least algal growth, however, were uniform in both experiments. Samples 12 and 13 were consistently in the top 3; therefore, it can be concluded that when algae is in the presence of silicate samples 12 and 13, it will grow more than when in the presence of samples Likewise, samples 1 and 4 yield the least algal growth.

14. Conclusion: pH Trial
I have only conducted 1 test, so my results are not definite. The results of my one test offer the conclusion that algae grows better in higher pH’s, specifically 9 and 11, and less in lower pH’s. I would need to run more tests to confirm these results, however.

15. Improvements: Silicate Trials
Same controlled variables for all 3 tests
CO2 tank
mash
More accurate method for measuring amount of starting algae
More precise way of comparing algal growth at end of trials

16. Improvements: pH Trial
I could have conducted one or two more identical trials to strengthen my results
Tested more pH’s (even numbers)
More accurate way of comparing algal growth at end of trial
Better way to measure starting amount of algae

17. Acknowledgements
I would like to thank AACT, and specifically Robin Kelson and Makena Johnson, for helping with the setup of these trials and giving us a tour of their facility. It was a really great experience and I am so glad I was given the opportunity to work with this innovative company.

18. References
"Algae Basics - Benefits of Algae." Algae Basics - Benefits of Algae. N.p., n.d. Web. 13 Jan
"Smithsonian National Museum of Natural History." Algae Research / Department of Botany, National Museum of Natural History, Smithsonian Institution. Smithsonian Museum, Web. 12 Jan
“Information about Why Algae Grow in Lakes." Information about Why Algae Grow in Lakes. Access Washington, n.d. Web. 12 Jan