The problem being solved: Harmful algal blooms (HABs, which are overgrowths of algae in water) are a widespread environmental threat with an economic impact of more than $2 billion per year. HABs reduce oxygen levels in water and block sunlight below the surface, which affects the plants and animals that live in the water and other animals that depend on those species for food. Some HABs also release toxins. HABs are challenging to address because they can span hundreds of square miles, and when HABs are removed physically the resulting algal mass becomes waste that is difficult to manage.  

The technology solution: TThe U.S. Army Corps of Engineers Engineer Research and Development Center (USACE ERDC) developed the Harmful Algal Bloom Interception, Treatment and Transformation System (HABITATS) in collaboration with several partners. HABITATS collects and removes HABs using a fence-like skimmer, cleans and adds oxygen to the water, and converts the waste into products like biocrude oil and fertilizer. The conversion process involves hydrothermal liquefaction (HTL), which uses high temperatures and pressures to break down algae, toxins and other organic waste. 

The tech transfer mechanisms: Early development and testing of HABITATS in 2019 were assisted by an Interagency Agreement with Pacific Northwest National Laboratory and engineering firm AECOM’s response to a Broad Agency Announcement. A 2020 Cooperative Research Agreement (CRA) with the University of Illinois at Urbana-Champaign helped ERDC scale the technology using a trailer-mounted HTL conversion system developed by the university. In 2021, ERDC acquired a shipboard environmental remediation platform from Elastec through an equipment contract and adapted it to create a floating HABITATS module for open-water use. 

The impact: HABITATS is currently in pilot testing; modules are expected to be available for stakeholders in September 2023. In a five-day test in 2020, HABITATS cleaned more than 200,000 gallons of water, yielding 700 gallons of algae paste that was converted into 20 quarts of biofuel. At full scale, a single module of HABITATS is expected to be able to treat two million gallons of contaminated water per day—meaning that a contained body of water like a marina could be cleaned within a week. More extensive waterways could be treated in months using multiple modules. Turning the byproducts of the process into renewable, secure fuel will add to the technology’s positive environmental impacts.