To effectively manage detrimental algal blooms, controlling phosphorus levels is essential. Limited research has been conducted on utilizing algal biomass, particularly blue-green algae, for developing materials that can extract phosphate from water. Recently, scientists have addressed this issue by converting cyanobacterial biomass into specialized materials capable of removing harmful phosphorus from aquatic environments. The materials developed in their research achieved over 99% phosphorus removal efficiency. With additional enhancements and scaling, this approach shows potential as a valuable method for addressing nutrient pollution.
As harmful algal blooms (HABs) proliferate globally, there is an urgent need for research to tackle this escalating problem. Investigations conducted in Italy, China, and the Atlantic basin indicate a significant prevalence of elevated nitrogen-to-phosphorus ratios in many water bodies, emphasizing the importance of phosphorus in these blooms. This situation underscores the necessity for improved phosphorus management techniques to combat HABs and safeguard our ecosystems.
Recently, there has been a surge of interest in creatively repurposing harmful algal biomass into beneficial products, such as bioplastics, biofertilizers, and biofuels. Researchers have begun exploring the conversion of algal biomass into materials that can aid in cleaning up various contaminants, including heavy metals, rare earth elements, dyes, and even capturing CO2 and toxic volatile organic compounds from the atmosphere.
However, there has been limited exploration into how algal biomass, particularly cyanobacteria, can yield materials aimed at removing phosphate from water.
Now, a team from Florida Atlantic University’s College of Engineering and Computer Science has filled this void by transforming cyanobacterial biomass, typically considered a hazardous waste, into specially designed adsorbent materials capable of extracting detrimental phosphorus from water. Adsorbent materials attract and retain molecules or particles—such as gases, liquids, or dissolved solids—on their exterior surface. This contrasts with absorbents, which incorporate substances deeply into their structure.
To create chemically modified activated carbon adsorbents for phosphate removal, researchers sourced cyanobacterial biomass from Lake Okeechobee in Florida, processing it through a swift and energy-efficient microwave heating process. To enhance the removal of phosphorus, the researchers tested adsorbent materials modified with lanthanum chloride or zinc chloride. Lanthanum, a metal within the rare-earth element group, is relatively plentiful. Both compounds serve multiple purposes, including environmental remediation, industrial processing, and chemical manufacturing, and prior studies have shown no health risks from using lanthanum for phosphorus removal.
The findings of the research, published in the journal Algal Research, indicate that adsorbents treated with lanthanum chloride effectively removed over 99% of phosphorus, even at initial phosphorus concentrations as high as 20 milligrams per liter. The most effective material could be synthesized in as little as three minutes, achieving 90% phosphorus removal efficiency with only 0.2 grams per liter of contaminated water and 30 minutes of contact time. This material also showed strong performance in environments with natural organic matter, selectively targeting phosphorus.
The research suggests that lanthanum-modified algae-based adsorbents could reduce HABs by extracting phosphorus from water. This is effective due to the formation of a compound, LaPO4.H2O (rhabdophane), which captures phosphorus in a permanent manner.
“Our results indicate that lanthanum-modified algae-based materials could serve as an effective solution for phosphorus removal and prevention of harmful algal blooms on a larger scale,” stated Masoud Jahandar Lashaki, Ph.D., the study’s lead author, assistant professor, and director in FAU’s Department of Civil, Environmental and Geomatics Engineering. “By utilizing readily available waste materials like algal biomass, along with lanthanum, which has strong phosphorus-binding properties, we have created an adsorbent that targets and diminishes excessive phosphorus in water. Phosphorus significantly contributes to harmful algal blooms that can result in toxic water conditions, loss of aquatic life, and serious economic implications for industries like fishing and tourism.”
The study’s results highlight the potential of this innovative method to confront one of the most urgent challenges in managing water quality. With further adjustments and potential for scalability, this technique could become vital for combating nutrient pollution and maintaining global aquatic ecosystems.
“Our team’s research emphasizes the high efficacy of these materials in phosphorus elimination across various concentrations. This strategy offers a sustainable and cost-effective solution to mitigate eutrophication—the phenomenon where excessive nutrients, predominantly phosphorus, stimulate harmful algae growth in lakes, rivers, and coastal regions,” remarked Stella Batalama, Ph.D., dean of FAU’s College of Engineering and Computer Science. “Implementing lanthanum-modified algae-based materials in areas susceptible to harmful algal blooms could significantly lower their incidence, enhancing water quality, protecting ecosystems, and ensuring safe water for both human use and wildlife.”
The co-authors of the study include Vithulan Suthakaran, a civil engineer and doctoral student at FAU’s College of Engineering and Computer Science; Ryan Thomas, an environmental engineer and FAU alum; Mitchell Guirard, another environmental engineer and FAU graduate; and Daniel Meeroff, Ph.D., professor and dean of undergraduate studies in FAU’s Department of Civil, Environmental and Geomatics Engineering.
This research and publication were developed under Project INV12 and financially supported by the Florida Department of Environmental Protection (FDEP) under the guidance of the Blue-Green Algae Task Force. The research team is currently pursuing a Phase-II grant ($590,527; INV45) from FDEP to explore the scalability of their proposed approach.
