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Algae in Advanced Wastewater Treatment

Algae is often considered a harmful consequence of polluted water, but new technologies are finding ways to harness the power of algae to provide solutions to water quality challenges around the world. Algae-based water treatment takes advantage of the ability of algae to grow quickly and absorb pollutants under carefully controlled conditions. The approach is offering communities a sustainable, cost-effective and energy efficient way to treat wastewater from cities, farms and industrial settings. 

As these new technologies enter the market they are presenting water treatment plant operators, local water districts, agricultural operations and industrial water facilities new options that closely align with environmental, social, and corporate governance (ESG) goals as well as strict regional water quality requirements. 

Algae Brings ESG Advantages to Wastewater Treatment

Algae-based wastewater treatment can provide a natural, climate positive solution to municipal, industrial and agricultural customers. Among the most powerful potentials is these systems’ ability to remove nutrients like nitrogen and phosphorus very efficiently, even better than many standard bacterial and or chemical treatment processes. Nitrogen and phosphorus are facing new and more stringent discharge limits by regulatory bodies worldwide. They are also difficult to treat in traditional plants and often require energy intensive and costly chemical inputs.

Yet performance is not the only advantage using algae in water treatment; there are economic benefits as well. Algae-based treatment produces a valuable algal biomass that can be sold in a number of markets, creating a new revenue stream for treatment facilities. These markets include slow release organic fertilizer or as bio-based inputs for consumer products like bioplastics and foams. In contrast, bacterial or chemical processes produce a sludge that only adds a disposal cost to operations. 

Algal biomass can also serve as a potential carbon credit; for every ton of algae produced, about two tons of carbon dioxide can be captured from the atmosphere

Perhaps most importantly, algae-based wastewater treatment systems can use less energy than traditional biological treatment processes, which require huge air blowers to create an oxygen-rich environment to allow for bacterial treatment. 

From Innovation to Commercial Success

Why is algae-based water treatment attracting more interest? A number of technology innovations are making these applications successful in real-world settings. One of them has been introduced by ABO member Gross-Wen Technologies (GWT), based in Slater, Iowa. 

GWT’s patented Revolving Algal Biofilm (RAB) treatment system utilizes an algae biofilm to treat wastewater. As the algae grows on the biofilm, nutrients (N and P) are removed from the wastewater. The resulting algal biomass can be used to create a variety of products, and helps generate revenue to offset the operational costs of the system. 

Since first developed at the University of Iowa, GWT’s technology has has been shown to be a cost effective and sustainable option for municipal and industrial wastewater treatment. 

One installation is in GWT’s headwaters city of Slater, Iowa, a growing community located between two large economic hubs (Des Moines and Ames, IA). The city’s existing water treatment plant has been able to meet the demands of the community, but it is now facing more stringent permitting requirements for the discharge of nutrients and other pollutants. In exploring its options the city worked with GWT to evaluate algae-based water treatment and build a demonstration scale facility that could operate with the city’s existing aerated lagoon wastewater treatment plant.

That demonstration was an impressive success. It validated that GWT’s treatment system is an effective technology to retrofit an aerated lagoon to achieve nutrient removal, and was also shown to potentially over $1 million in capital expenses, as well as a great deal in personnel costs. 

The city is now pursuing a commercial-scale RAB facility, with plant upgrades expected to be completed in Q4 of 2022. The upgrades are expected to treat the city’s full flow of wastewater, and meet the new, more stringent effluent requirements placed on the facility. 

GWT’s innovative technology, and that of other algae-based water treatment options, can also be integrated into anaerobic digestion facilities and in many high strength wastewater industrial applications. This makes algae water treatment a unique approach for rural areas that have large water treatment needs but limited budgets. Algae is the cost-effective, nature-based solution to the kinds of challenges rural communities face. 

To date, GWT’s innovative technology has been deployed at pilot, demonstration and full-scale commercialization at municipal and industrial facilities throughout the upper Midwest (Iowa, Illinois, Wisconsin).  With this and other successes, GWT is poised for remarkable growth as it continues to expand its team and number of deployments across the United States. 

Of course, GWT is not alone in offering algae water treatment solutions, other providers include Clearas Water Recovery in the United States, and the LIFE ALGAECAN and MicroAlgae Biorefinery projects in Europe. 

What’s Next for Algae in Wastewater Treatment

There is an enormous opportunity to use this technology on a much larger scale.  There are 16,000 wastewater treatment facilities in the US alone, and many of them are facing increased pressures from new population growth and new water quality requirements. 

At the same time, nutrient loading in waterways is creating expensive ecological problems around the world. Too many nutrients from human activity can trigger harmful blooms of wild algae in waterways. These blooms can kill native species, disrupt local economies and have a significant human health impact as well.

The new water infrastructure that is needed to meet these challenges is often expensive for communities, farmers and businesses. They can also be time-consuming to install, and require new expertise to operate. That is not so much the case with many of the approaches that use algae. 

​​Algae-based wastewater treatment offers the most sustainable, cost-effective and energy efficient way to treat both municipal and industrial wastewater.  Algae is “nature’s way” of addressing nutrients and removing them from water.  As our world looks for sustainable, climate positive solutions, algae-based treatment is the means to the positive end point. 

In the end, what’s next for algae in wastewater treatment may be in the hands of the communities that are seeking solutions. There is still room for technological improvements, but with the successes we’ve seen so far, the most important decision will be how water treatment operators want to balance the need for clean water with economics and sustainability. 


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