 "Photo: Brandon Tan/Poly Post")
Researchers at Cal Poly are attempting to turn wastewater into biodiesel and cattle feed by using certain types of algae.
Marcia Murry, a biologist who is working on the experiment, is looking for algae with high percentages of lipids, which are fats. The lipids undergo a reaction and then are turned into biodiesel.
"We're looking at the growth rates [of the algae], and then we're going to take these mixed cultures and add a dye that's specific for lipid that's fluorescent," said Murry. "We'll be able to pick out those that have very high lipid concentration and pull them out individually."
Murry's grant is not just environmentally friendly; it also can help to rid the environment of harmful carbon dioxide.
"The gist of our grant is to couple this process of growing algae to clean up wastewater and animal wastes and take away those nutrients and get a product from it that [we can use]," said Murry. "We also want to accompany it with methane digestion where you take horse manure, for instance, and put it in a methane generator and it breaks it down into nutrients. All the carbon that's in there gets turned into methane and carbon dioxide."
The methane can be used for energy, and the carbon dioxide will be pumped into the algae ponds.
Normally, the excess carbon produced by methane generators is pumped into the atmosphere, where it contributes to global warming.
"For instance, there's a big methane digester out in Chino that handles a lot of farms," said Murry.
"They're just blowing their CO2 out, and they have to pump their residual nutrients all the way to Orange County to do this. That's an operation that we'd like to be involved with. We'd like to use those nutrients to grow algae and then pump in CO2 for photosynthesis."
The algae do not just produce biodiesel. The residuals left after the lipids are extracted can be used as a high-energy cattle feed, which makes the process lucrative as well as environmentally friendly, according to Murry.
"One of the other things we're doing is with the residue of the algae," said Murry. "We're making very high-protein, high-lipid cattle feed from it. That has a very high profit margin. It's basically an integrated system. We're using waste to generate products."
The scientists are using wastewater from some of the different animal farms on campus to search for different algae forms that will produce more of the fats that are to be used as biodiesel.
After they obtain the water, they put some nutrients in it and put them under the light to see what will grow. The algae samples are tested every other day to see how high the lipid concentration is.
A higher concentration of fats makes a better biodiesel. Murry has one pure strain that produces 85 percent lipids, but she doubts that the concentration can be replicated outside the laboratory.
Murry explained that conditions outside the laboratory can yield unpredictable results.
She did an experiment at Berkeley when she was a graduate student that did not turn out as expected.
"We set up these outdoor ponds, using algae to treat wastewater," said Murry. "Being good researchers, we put two ponds next to each other so we could have replicates with exactly the same algae and all the conditions were identical. Three days later, we had two entirely different groups of algae growing. There's just no control over it."
According to the grant's abstract, the study will help Cal Poly reduce its carbon footprint by reducing greenhouse gas emissions.
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