Algae-Based Wastewater Treatment: A Sustainable Solution with Enhanced Efficiency

Algae have emerged as a promising solution for removing nutrients such as phosphorus and nitrogen from wastewater, leveraging their natural ability to absorb these elements. However, the widespread adoption of algae-based wastewater treatment systems has been hindered by challenges related to system footprint, mass transfer efficiency, and the difficulty of maintaining optimal growth conditions for algae.

Gross-Wen Technologies (GWT), based in Slater, Iowa, has developed an innovative solution to these challenges with its Revolving Algal Biofilm (RAB) system. By reorienting algal biofilms vertically onto a conveyor belt, the RAB system maximizes algae surface area and optimizes the gas-liquid interface, addressing key engineering obstacles.

“One of the biggest challenges in algae systems is efficiently delivering CO2 to the algae and removing oxygen from the system,” explains Martin Gross, CEO and co-founder of GWT. “By increasing surface area, we enhance gas exchange, making it faster and no longer a limiting factor for productivity.”

Algae growth rates in traditional water-treatment systems are often constrained by the difficulty of achieving the right balance of light, water, and CO2. Gross notes, “Most algae systems rely on microscopic cells suspended in liquid, which makes it hard to deliver light effectively. In our system, we bring the algae out of the liquid, creating more surface area for light exposure and ensuring more efficient delivery of both light and CO2.”

The vertical design of the RAB system also optimizes space utilization, requiring a smaller footprint compared to conventional horizontally oriented algae systems. Additionally, the system allows for the easy harvesting of nutrient-rich algae, which can be processed into a solid biomass and sold as fertilizer, creating a valuable byproduct.

The largest application of the RAB system to date is at a food waste treatment facility in Pasco, Washington. This 4-million-gallon-per-day system processes water from anaerobic digesters, preparing it for safe discharge. GWT has also recently secured a new patent in collaboration with the Metropolitan Water Reclamation District of Greater Chicago, focusing on the use of RAB technology for enhanced removal of total dissolved solids (TDS) from wastewater.

This breakthrough in algae-based wastewater treatment not only addresses environmental challenges but also offers a sustainable and economically viable approach to water management. As the technology continues to evolve, it holds significant potential for broader adoption in the wastewater treatment industry.