Effects of pH on Effects of pH on Algae Growth in Algae Growth in PhotobioreactorsPhotobioreactorsRafael Martell, Karen Trejo, Chris Rafael Martell, Karen Trejo, Chris

RodriguezRodriguez

Middleton High SchoolMiddleton High School

Thursday, November 1, 2013Thursday, November 1, 2013

What is alga?What is alga?

Alga is a photosynthetic organismAlga is a photosynthetic organism Photosynthesis is 6COPhotosynthesis is 6CO22+6H+6H220-0-

>6O>6O22+C+C66HH1212OO66

Feeds off of waste waterFeeds off of waste water

Grows quickly and produces oilsGrows quickly and produces oils

Carbon Dioxide Oxygen

Why grow algae?Why grow algae?

Alga is cheap to grow, grows quickly, Alga is cheap to grow, grows quickly, and is renewableand is renewable

We can use the oil that algae produces We can use the oil that algae produces as a fuel sourceas a fuel source If we gain enough oil, we can use algae If we gain enough oil, we can use algae

instead of other pollutant and costly fuel instead of other pollutant and costly fuel sourcessources

The species of alga we grew was The species of alga we grew was Chlorella

Our Original QuestionOur Original Question

How does the ratio of Nitrite to How does the ratio of Nitrite to AmmoniaAmmonia affect algae growth?affect algae growth?

DataData

•50/50 grew the best so our group is using this ratio for phase 2

Research Question for Research Question for Phase 2Phase 2

How does increasing and stabilizing How does increasing and stabilizing the pH affect the growth of algae the pH affect the growth of algae ((Chlorella sp.)?)?

MaterialsMaterials

•3 3L Bottles•Waste Water•Test tubes•Baking soda

•Syringes•Air pump•Tubing•Gas flow meters•Light meter

MethodsMethods

We checked the amount of light being We checked the amount of light being absorbed using a light meter in Kluxabsorbed using a light meter in Klux

We extracted 20mL of water + algae from We extracted 20mL of water + algae from the bioreactors using syringesthe bioreactors using syringes

10mL was for testing the pH of the water10mL was for testing the pH of the water The other 10mL was put in the drying oven The other 10mL was put in the drying oven

so we could evaporate all of the waterso we could evaporate all of the water We weighed the pans before and after so We weighed the pans before and after so

we could tell how much the algae weighedwe could tell how much the algae weighed

Why Test pH?Why Test pH? pH is the level of acidity of a solution.pH is the level of acidity of a solution. COCO22+H+H22O->HO->H22COCO33->H->H+++HCO+HCO33

The amount of carbon dioxide in the The amount of carbon dioxide in the water, which is basically food forwater, which is basically food for

the algae, can be found if the algae, can be found if you get the pHyou get the pH The pH can show the overallThe pH can show the overall health of the algae.health of the algae.

Carbon Dioxide Hydrogen IonCarbonic Acid Bicarbonate

Data from phase 2Data from phase 2

Effects of pH on Algae

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8-Oct 10-Oct 12-Oct 14-Oct 16-Oct 18-Oct 20-Oct 22-Oct 24-Oct

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alg

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Control

pH

•Stabilizing the pH made the algae grow faster

ConclusionsConclusions According to our data, increasing the pH and According to our data, increasing the pH and

stabilizing it improved the growth rate of stabilizing it improved the growth rate of algaealgae

This research is important because it showed This research is important because it showed that it is possible to grow algae quickly as a that it is possible to grow algae quickly as a source of biofuelsource of biofuel

The next thing we should do is measure the The next thing we should do is measure the amount of oil produced by algae under amount of oil produced by algae under different pH levelsdifferent pH levels

After that we should be trying to maximize oil After that we should be trying to maximize oil productionproduction