PHOTO BY U.S. ARMY CORPS OF ENGINEERS

During testing of the U.S. Army Engineer Research and Development Center’s Harmful Algal Bloom Interception, Treatment, and Transformation System (HABITATS) at Lake Okeechobee, Florida, water is removed from the collected material, resulting in a concentration of the algae biomass.

been limited by costs and challenges with managing the resulting large quantities of algae biomass. The research at ERDC is being performed alongside other complimentary HAB-focused projects funded and managed through the USACE Aquatic Nuisance Species Research Program (ANSRP), which is also managed at ERDC. The ANSRP is the primary research and development program for addressing invasive and nuisance aquatic species that affect navigable waters, infrastructure, and associated water resources. “The ANSRP supports HAB research on early detection, prevention, and management, with scalable technologies as a key research piece, to reduce the occurrence and impact of HABs to USACE and the nation’s waterways,” said Christine VanZomeren, Ph.D., acting ANSRP program manager. In July 2019, ERDC scientists tested the HABITATS at Lake Okeechobee, Florida. The goal of the research was to develop and demonstrate a scalable capability to remove algae, algae-entrained nutrients, and potential algal toxins from large bodies of water. Additionally, scientists hoped to develop resource recovery methods that enable efficient and safe management of the resulting biomass while destroying any potential toxins. The HABITATS approach intercepts concentrated algae in bodies of water; filters and cleans the water source while further separating the algae; transforms the highly concentrated algae sludge into useful products, such as biofuels; and destroys potential harmful toxins. A dissolved air flotation process was successfully demonstrated for high throughput concentration of the algae that resulted in clean water output. Samples of concentrated

algae were sent to the Department of Energy’s Pacific Northwest National Laboratory for conversion to biocrude oil using a high throughput hydrothermal liquefaction process, also destroying any potential toxins in the sludge. “The HABITATS research project is developing a capability to remove and efficiently dispose of large quantities of algal biomass and entrained nutrients, which may someday help protect ecosystems and communities from HAB events,” said Martin Page, Ph.D., material engineer at the ERDC’s Construction Engineering Research Laboratory and HABITATS project manager. “By recovering resources in the process, the positive environmental impacts are achieved with reduced operations’ costs and footprint. Those aspects are key to developing a truly scalable tool that can be used by stakeholders as part of a broader strategy to mitigate HABs.” Results of the HABITATS study are published in an ERDC technical report, dated January 2020. The HABITATS project managers continue to collaborate with federal, state, and local agencies, as well as academic institutions and other key stakeholders on HAB research in an effort to minimize duplication of effort, maximize efficiencies, and ultimately save resources. In 2020, the HABITATS research team began working to optimize the integration of the HABITATS components in order to develop final design criteria for this innovative approach. The team will be working at pilot scale in Florida and New York, testing land-based systems and also building a shipboard mobile HABITATS prototype. This foundational research will support the transfer of the technology to stakeholders for consideration as one of many important tools in the fight against HABs. n 135