esTech Engineering, Inc. and Utah State University’s Sustainable Waste-to-Bioproducts Engineering Center (SWBEC) are jointly engaged in developing processes for more efficient harvesting of algae from municipal wastewater and other nutrient-rich sources, and researching its conversion into products that are much higher-value resources compared to conventional applications such as for energy usage or livestock feed.
The open-pond lagoon system used by SWBEC is part of the City of Logan, Utah, Wastewater Treatment Facility, which is also a partner in SWBEC, along with WesTech Engineering, Inc., a leading engineering firm and manufacturer of water and wastewater treatment processes for municipal and industrial applications, based in Salt Lake City, Utah.
The 460-acre lagoon, that treats municipal wastewater for Logan City, has enough nutrients to produce 30 tons dry weight of algae per day from April through October. The algae growth, aided by natural sunlight, can be harvested daily for use in SWBEC’s research programs.
“Our interest is in technologies that can have a positive impact on social conditions, as well as economically self-sustaining on a long-term basis,” said Rex Plaizier, CEO of WesTech. This is what drew us to the research that SWBEC has been engaged in, and why we elected to partner with them.”
SWBEC commissioned WesTech in 2010 to design an algae growth reactor, which, to their knowledge, was the world’s first rotating algae biofilm reactor (RABR). This was based on a concept of algae biofilm developed by the Utah State Biological Engineering Department. The biofilm rector was designed for harvesting large amounts of algae, with applications to large-scale open-pond lagoons, and raceway engineered systems.
“Algal biofilm systems in wastewater treatment have emerged as an alternative to suspended algal growth systems, because of the ease of biomass harvesting and reduced costs in downstream processing,” said Dr. Ronald Sims, Utah State University Professor, and Co-Director of SWBEC. “Research studies at Utah State demonstrate that algal biofilms grown using the RABR are very effective in removing nitrogen and phosphorus nutrients from wastewater.”
The first RABR was installed at as part of SWBEC’s Algae Test & Evaluation Facility at the City of Logan lagoons. It was developed as a field-scale site where outdoor research and testing is conducted, utilizing phototrophic algae-based engineered systems for algal biomass production and water quality improvement.
“We piloted the idea of biofilm reactors in our laboratory,” added Dr. Sims. “But designing and manufacturing a full-scale biofilm system, and putting it into operation within a 460-acre lagoon, was something totally different. That is where WesTech first brought its expertise to SWBEC. Since then we have had a continuing partnership.”
The full-scale RABR is contained within a 14,500-liter tank. Additionally, three pilot-scale RABR systems are operating within a tank of over 4,000 liters, as well as two .25-acre open-pond raceway bioreactors, each having a capacity of over 150,000 liters. Each of these systems is capable of supplying and discharging required water, and is instrumented to record photosynthetically-active radiation, temperature, dissolved oxygen and pH readings.
The field laboratory is designed for on-site testing of nutrients, algae growth conditions, algae concentrations, and algae yield, as a percentage of dry weight. Nutrient samples, specifically nitrogen and phosphorus, can be processed within minutes utilizing a continuous sample processing system.
The facility includes two greenhouses that provide specific research needs such as laboratory scale algae growth tests and/or biomass drying. The site also is equipped with two 26 x 24 foot buildings designed for harvesting algae biomass, performing bench-scale studies for algae growth, and harvesting and utilizing the algae biomass within two 1000 gallons each anaerobic digesters.
Once the algae are harvested, SWBEC’s Algae Processing and Products Facility, located on the campus of Utah State University at Logan, researches algae processing – from biomass production using open-pond raceways and rotating algae biofilm reactors, to chemical, biological, and thermal pretreatment, to the production of bioproducts.
This uniquely designed facility utilizes five outdoor stations for pilot- and full-scale testing. The site houses a greenhouse outfitted with growth systems situated for algae growth, harvesting and evaluation.
Subsequent to algae processing, SWBEC has established a fermentation laboratory, designed to enable the optimization of bioproducts produced by fermentation technologies. The lab has the capacity to produce these products on a large scale. One of the purposes of the laboratory is to generate substantial quantities of bioproducts for commercialization and scale-up performance data.
The laboratory houses two 10-liter fermenters with carbon dioxide and oxygen off-gas analyzers. For large-scale fermentations, the lab utilizes a 125-liter fermentation system, and for cell and product recovery the lab is equipped with several sizes of centrifuges. The capabilities of this fermentation laboratory enable scale-up optimization of fermentation bioproducts that can be grown and analyzed under a variety of growth conditions for maximum product yield and quality.
Waste-based bioenergy, bioplastics, and other bioproduct technologies developed through the unique SWBEC partnership provide new alternatives for addressing sustainable waste treatment and bioenergy production.
— by Floyd Griffiths, Lead Process Engineer, WesTech Engineering, Inc.
For more information, contact Dr. Ronald Sims, Professor, Co-Director of the Sustainable Waste-to-Bioproducts Engineering Center (SWBEC), Department of Biological Engineering, Utah State University; 4105 Old Main Hill, Logan, UT 84322-4105; Telephone 435-797-3156; Email firstname.lastname@example.org; www.swbec.usu.edu.