Effects of pH on Algae Growth in Photobioreactors Rafael Martell, Karen Trejo, Chris Rodriguez Middleton High School Thursday, November 1, 2013

What is alga? Alga is a photosynthetic organism Alga is a photosynthetic organism Photosynthesis is 6CO 2 +6H 2 0->6O 2 +C 6 H 12 O 6 Photosynthesis is 6CO 2 +6H 2 0->6O 2 +C 6 H 12 O 6 Feeds off of waste water Feeds off of waste water Grows quickly and produces oils Grows quickly and produces oils Carbon Dioxide Oxygen

Why grow algae? Alga is cheap to grow, grows quickly, and is renewable Alga is cheap to grow, grows quickly, and is renewable We can use the oil that algae produces as a fuel source We can use the oil that algae produces as a fuel source If we gain enough oil, we can use algae instead of other pollutant and costly fuel sources If we gain enough oil, we can use algae instead of other pollutant and costly fuel sources The species of alga we grew was The species of alga we grew was Chlorella

Our Original Question How does the ratio of Nitrite to Ammonia affect algae growth?

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

Research Question for Phase 2 How does increasing and stabilizing the pH affect the growth of algae ()? How does increasing and stabilizing the pH affect the growth of algae (Chlorella sp.)?

Materials 3 3L Bottles Waste Water Test tubes Baking soda Syringes Air pump Tubing Gas flow meters Light meter

Methods We checked the amount of light being absorbed using a light meter in Klux We checked the amount of light being absorbed using a light meter in Klux We extracted 20mL of water + algae from the bioreactors using syringes We extracted 20mL of water + algae from the bioreactors using syringes 10mL was for testing the pH of the water 10mL was for testing the pH of the water The other 10mL was put in the drying oven so we could evaporate all of the water The other 10mL was put in the drying oven so we could evaporate all of the water We weighed the pans before and after so we could tell how much the algae weighed We weighed the pans before and after so we could tell how much the algae weighed

Why Test pH? pH is the level of acidity of a solution. pH is the level of acidity of a solution. CO 2 +H 2 O->H 2 CO 3 ->H + +HCO 3 CO 2 +H 2 O->H 2 CO 3 ->H + +HCO 3 The amount of carbon dioxide in the water, which is basically food for The amount of carbon dioxide in the water, which is basically food for the algae, can be found if the algae, can be found if you get the pH you get the pH The pH can show the overall The pH can show the overall health of the algae. health of the algae. Carbon DioxideHydrogen Ion Carbonic AcidBicarbonate

Data from phase 2 Stabilizing the pH made the algae grow faster

Conclusions According to our data, increasing the pH and stabilizing it improved the growth rate of algae According to our data, increasing the pH and stabilizing it improved the growth rate of algae This research is important because it showed that it is possible to grow algae quickly as a source of biofuel This research is important because it showed that it is possible to grow algae quickly as a source of biofuel The next thing we should do is measure the amount of oil produced by algae under different pH levels The next thing we should do is measure the amount of oil produced by algae under different pH levels After that we should be trying to maximize oil production After that we should be trying to maximize oil production