February 2010, Vol. 22, No. 2

Bridging the Gap Between Algae and Wastewater

News

The idea of using algae to treat wastewater is not new, but what is new in the past year or so is a redoubled effort by both the wastewater and algae industries to come together to make the practice more common and more beneficial. This effort is being driven in large part by algae’s potential as a feedstock for biofuel production.

The Water Environment Federation (WEF, Alexandria, Va.) Algae Working Group met Oct. 14 at WEFTEC®.09 in Orlando, Fla., to discuss the progress made in the past year to bring these two groups together.

“The whole goal is to get the communities talking together, and they are,” said Steve Gluck of Dow Chemical Co. (Midland, Mich.), who leads the working group. He added that at recent meetings with the two groups, representatives from the algae community have demonstrated a much greater understanding of how wastewater treatment works.

 

Why Algae?

Algae technologies have been used throughout the world for centuries, according to Stephen Lyon, a senior scientist at Johnson Diversey (Sturtevant, Wis.). Lyon has been studying algae-based wastewater treatment since 1982.

The resurgence of interest in algae technologies now, Lyon said, is due in part to the understanding that we live in a finite world with no single answer to our water and energy problems.

Growing algae while treating wastewater could help solve two problems at once. The two driving forces behind conventional wastewater treatment technologies are cost and discharge requirements, Lyon said. Algae-based wastewater treatment plants have the potential to produce a high-quality effluent with a significantly lower energy cost, he noted. Further, revenue generated by the biofuel and greenhouse gas credits also will help lower operations and maintenance costs, he said.

From a biofuels standpoint, algae makes more sense than land-based crops, Lyon said. The higher percentage of oil in a crop, the better for biofuel production. Some strains of wild-type algae have percentages 10 to 20 times greater than corn or soybeans on a dry weight basis, Lyon said. Moreover, algae doesn’t force a choice between growing food or fuel crops on agricultural land.

“Given the proper conditions of light and temperature, algae can be cultured throughout the year,” Lyon said. “Depending on the strain of algae, it can double its biomass in as little as 2 days.”

 

How Does Wastewater Fit?

Right now, the algal biofuel industry is beginning pilot projects nationwide, Gluck said. However, the pilot-scale biofuel projects that are burgeoning now are not engaging the wastewater industry.

The projects are being bolstered by $85 million from the American Recovery and Reinvestment Act for the development of algae-based biofuels and advanced, infrastructure-compatible biofuels. At press time, the U.S. Department of Energy, which is in charge of dispersing these funds, had not yet released which organizations and companies would receive the funds.

However, to scale up these projects to a commercial scale will require two things that the wastewater industry has: water and nutrients.

There are approximately 56 algae-biofuel companies in the United States and probably a similar number scattered throughout the world, Lyon said. All of these companies will have great demands for water and nutrients. With the exception of one or two companies and a few academic research programs, none of these companies has said where they will get their water and nutrients.

Additionally, the wastewater industry brings to the table a wealth of knowledge of handling large volumes of water and solids, methane-based cogeneration, and dewatering technologies, Lyon said.

 

Challenges?

One logistical and two technological challenges stand in the way of algae-based biofuels.

On the logistics side, algae-based wastewater treatment plants require a significant amount of land for algae-growth basins, Lyon said. The algae then uses sunlight and the nutrients in the wastewater to grow. Most large-scale plants — 190,000 to 1.1 million m3/d (50 to 300 mgd) — are located in or on the border of large urban areas. For these situations, such a system is not practical, Lyon said. The ideal candidate for a conversion would be a rural, overburdened wastewater treatment plant in the U.S. Sunbelt, he explained.

The two technological challenges are how to harvest the algae and extract its oil most efficiently, Lyon said. To date, few research programs have addressed these issues, he said. Making matters more complex, the harvesting and dewatering technologies vary depending on the strains of algae.

“Until these technical issues are resolved, the experiments will remain at the bench,” Lyon said.

Communication

However, the basic hurdle of communciation stands between the wastewater and algae industries, Lyon said. “The day-to-day vocabulary in both fields is very different,” he said. “Both sides need to have some of their key representatives acquire the other’s language.”

To this end, WEF’s Algae Working Group is trying to bridge the gap and bring algae experts into wastewater arena, Gluck said.

“Our intent was to educate our community [the wastewater community] on what is going on in the algae arena and get the algae folks tuned into what our community can provide,” Gluck said.

For example, next year, the group hopes to invite such groups as the Algal Biomass Organization (ABO; Preston, Minn.) to bring their knowledge and know-how to meetings such as WEFTEC. Similarly, last year, the working group organized a session at the ABO meeting to educate algae professionals on wastewater topics.

Gluck stressed that WEF’s Algae Working Group is not seeking to be a leader or an educator on algae technologies.

“The wastewater community is not the community to say, ‘This is how you grow algae,’” Gluck said. “But the waste-water community does have some skill sets and technologies that overlap and certainly some understanding of the scale of doing this.”

 

— Steve Spicer, WE&T

© 2010 Water Environment Federation. All rights reserved.