It’s easy to associate algae as being a nuisance. Noticing slimy green algae building up on the sides of your crystal blue pool might have you rushing to remove it. But before you prepare to scrub it away, let’s take a moment to consider how algae could actually benefit our water, particularly in wastewater treatment.

Microalgae are single-cell algae species that can survive individually or in clusters. They are among the most important groups of organisms on the planet because they produce approximately half of the atmospheric oxygen on earth, while also consuming vast amounts of greenhouse gas carbon dioxide. Microalgae play an important role in absorbing excess nitrogen and phosphorus in natural water systems while absorbing carbon dioxide. Thus, a mass culture of microalgae represents a viable approach to wastewater treatment.

As wastewater treatment technologies become more necessary for our future, we will need to find solutions that are not only sustainable but also cost-effective. With over 33 years of experience in algae research and development, Dr. Peter Lammers, chief scientist of Algae Testbed Public-Private Partnership (ATP3), has recently begun a pilot project in Gilbert that focuses on using algae for wastewater treatment. Lammers gave us further insight on the benefits of using algae for wastewater treatment as well as an overview of his current research project in an interview which begins below.

Interview with Peter Lammers:

Why use algae for wastewater treatment? How long have researchers been considering algae for wastewater treatment?

Researchers have been considering algae for wastewater treatment for quite some time. William J. Oswald was one of the first researchers to propose this in the 1950s. Algae benefit wastewater treatment by producing oxygen that allows aerobic bacteria to breakdown organic contaminants in the water and taking up excess nitrogen and phosphorus in the process. It is also a sustainable and affordable alternative to current wastewater treatment practices.

What’s new in this field today is our use of a different type of algae from Yellowstone National Park that likes high temperatures and is very stable and low pH values—about the same pH levels as Coca Cola. Pathogens (biological agents that causes disease) die pretty rapidly under those conditions. Therefore, wastewater treated by this method would require less chemical disinfectant. This platform represents a new paradigm in the use of algae for wastewater treatment.

What drew you to your research and development of your pilot project? Why focus on wastewater treatment?

There are several reasons but the main one being that current wastewater treatment is energy intensive and expensive. The lack of wastewater treatment in underdeveloped regions is also a major public health issue. There is now an opportunity to utilize sunlight prevalent in the desert that directly creates net energy production, fertilizer extraction, and clean water available to repurpose to other applications.

We use algae that like warm water because when we grow algae in wastewater placed in plastic reactors the water heats up just like the air in a greenhouse. The algae perform the wastewater treatment by removing nitrogen, phosphorus, and dissolved organic carbon. Those growth conditions destabilize harmful bacteria while yielding more energy-rich biomass than current treatment systems. Current sewage facilities’ electricity bills can account for up to 60% of waste water treatment practices (WWTP) operation costs today. The use of algal systems could ultimately eliminate these bills, while benefiting the industry by extracting fertilizer nutrients in the process.

Can you explain the direct health benefit for people and for the environment? How much cleaner will the water be?

Given climate change and drought in the Southwest, the idea of repurposing water at several different levels is very much a part of our future. Once the nutrients have been removed from the wastewater, we would need to adjust the pH back to neutral and preform a final disinfection. After this process, the treated water could be discharged as gray water for agriculture, landscaping or golf courses. In the future, we could even go through additional purification to recycle wastewater into drinking water. This process has already been developed and deployed in San Diego.

What do you anticipate for your project in Gilbert?

We’re starting a small pilot scale research project located at the Greenfield Road Water Reclamation Plant. We plan to operate there for a year to determine the rate of carbon, nitrate, and phosphorous removal and seasonal variations associated with those rates. We’re continuing to investigate the costs for the reactor platform fabrication and operations, and how to get the highest level of performance from the Yellowstone algae strain, known as Galdieria suphuraria. Another major goal is to reduce the land area required for large scale wastewater treatment. We would like to achieve something close to 12 acres per million gallons treated per day.

Here at AzCATI, it’s a process of continuous improvement. We will be working together with researchers such as ASU LightWorks’ Bruce Rittmann and Cesar Torres on electrochemical pH shifting to save energy and reduce salt formation. We’re excited to continue developing this project into the future.

Conclusion of Interview.

Here in the Southwest, securing clean water will continue to be an important issue to address. Designing a sustainable, energy yielding wastewater treatment process for our desert environment is a very realistic possibility that could be utilized in other hot arid regions of the world with similar problems with limited water supplies. Lammers’ vision of creating a treatment process using algae not only directly benefits our needs for repurposed clean water, but also creates a more energy efficient solution from current treatment processes. The algae used in the wastewater treatment process will also provide opportunities for fertilizer extraction, a growing industry in the development of sustainable products.

As we move forward, innovation that promotes a resilient and equitable energy future will continue to grow more important. ASU LightWorks supports projects like these that address society’s grand energy challenges. To learn more about Lammers’ project as well as other projects we support, please visit our website by clicking here.

In recent news, LightWorks' Bruce Rittmann and two of his colleagues from the China University published an article about transitioning from costly wastewater treatment to resource recover from "used water" in Nature News and Commentary. The focus is on domestic wastewater, where we can change the paradigm from a cost liability into a source of revenue for municipalities. As one paragraph mentions, this paradigm also applies to other streams of organic wastes. Read the full article here.

Written by Gabrielle Olson, ASU LightWorks