From wastewater to renewable energy

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by Kirk Davis
June 06, 2012
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From wastewater to renewable energy

A team of ASU grad students is working with the Arizona Center for Algae Technology and Innovation to clean up the environment while creating clean, renewable energy.


Full transcript

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Joshua Wray, Ph.D. candidate, life sciences:  This project investigates the use of waste waters in order to make an algae culture media suitable for commercial production of algae for bio‑fuel.

Milton Sommerfeld, co-director, AzCATI:  The advantages of using waste water is the fact that you are using nutrients that are going to be disposed off. In this case, you have the algae use those nutrients to grow, develop more bio‑mass, and ultimately bio‑fuels. Otherwise, the nutrients would simply be put in landfills or end up in ground water or lakes or streams.

Emil Puruhito, M.S. candidate, engineering:  The research on algae has many potentials mainly focus on people with a biology background. However, with recent research and development, there is a need of more broad disciplines involved.

Sommerfeld:  The project involved three graduate students from different disciplines: Horticulture, Molecular Biology, and Mechanical Engineering.

Wray:  Growing up on a farm in Missouri, I've always been interested in growing things. I've just recently had more of an interest in bio‑fuels and micro algae presents so many opportunities.

Puruhito:  I have to understand that I deal with living organisms here. I cannot put sort of equipment that can damage some of the algae cells.

Wray:  The process starts off with aeorbic digestion. Here we used a five gallon bucket to release the nutrients from the waste water. We scaled it to a thousand liter digester batches where we were able to develop swine, poultry, municipal sludge, and ag runoff for use in an algae culture media.

After we're done with that and we have a media ready, we have the preparation of innoculants so a single colony will be streaked across. We do this to ensure that we're using one strain and we know what strain we're using. We can take single colonies and pluck them off into the dish and use it to start small amounts of innoculant in test tubes. In this stage, it will go on to a larger tube. Finally, it will go to a 2x2 panel and eventually we will take it out to the field site.

What starts off as a single algae colony on a petri dish is eventually formed into trillions of workers that work cleaning phosphorus, ammonia, and nitrates from waste waters.

Puruhito:  The next stage after algae culture is the algae dewatering process. Here we've chosen a strain that can be settled within a day. The results from there are is the final effluent and it's slow in nitrate, phosphate, and ammonia. Back here is a sample of the algae that's been dewatered.

Wray:  This bio mass was freeze dried, however solar drying may be employed on a commercial scale. After harvesting and drying, we bring the bio mass in here. We put the bio mass in with an excess of methanol in the presence of a catalyst. It'll end up a crude product that looks similar to this. That can be further purified into a clean diesel product.

Sommerfeld:  I think what is surprising to me is the fact that they were able to look at multiple types and get differential results. Not all waste waters give you the same type of algae growth.

Wray:  I can see the entire process to be commercially viable. Industry will take an interest in this when you can affordably produce bio diesel.

Sommerfeld:  What's exciting about it is students from different areas of science and engineering coming together and using their own unique capabilities to grow something that produces products that are very important from the standpoint of energy sustainability.

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