Improving Energy Efficiency and Performance of Wastewater Recycling
This project’s intent is to test and demonstrate, the controlled operation of intensive high-rate algal ponds for year-round wastewater treatment. This includes low-cost harvesting of the algal biomass by a combined algal settling and membrane
MicroBio Engineering, Inc.
Recipient
San Luis Obispo, CA
Recipient Location
17th
Senate District
30th
Assembly District
$1,394,862
Amount Spent
Active
Project Status
Project Update
The project was completed in 2025 and the Final Report has been posted on the CEC’s website. The advancements made over the course of this project set raceway pond technology on a trajectory to provide a nature-based solution for municipal wastewater treatment that is particularly well suited for rural communities in need of conventional pond upgrades to meet lower nutrient discharge limits. This solution uses less electricity with lower associated GHG emissions than traditional alternatives. Additionally, raceway ponds can be operated in a manner to use less electricity during periods of peak demand, freeing up electricity for essential functions during such periods.
Beyond the initial reduction in electricity demand when compared to conventional treatment, optimization of the raceway pond process decreased the amount of aeration needed by 15% over 3 years. Because of the ability to provide treatment with limited use of aeration, the electricity consumption of raceway ponds is much lower than a facility of the same size using activated sludge would be. When factoring in the optimizations developed over the course of this project, implementation of raceway ponds could result in up to a 66% reduction in annual energy use for a wastewater treatment facility. Based on the data collected, the savings in energy consumption for a 0.6 million gallons per day (MGD) facility like the Delhi County Water District (CWD) Wastewater Treatment Plant (WWTP) (used for this project) was projected to be about 700,000 kWh annually.
View Final ReportThe Issue
Standard wastewater treatment methods have high power demands and are not efficient in their handling of nutrients. Algal-based wastewater treatment has the potential to simultaneously lower costs and improve process sustainability. Algal-based treatment can reduce and shape power use while also recycling nutrients and producing biofuel feedstocks from wastewater. However, algal-based wastewater treatment has historically been shown to reduce treatment performance only in winter months. This project researched methods to maximize performance year-round.
Project Innovation
The project advanced raceway pond technology, to minimize the seasonal limitations of current wastewater treatment pond processes and incorporate two-stage algae biomass harvesting by settling and filtration. The products resulting from this process are unrestricted reuse water and biomass that can be used to generate biofuels, fertilizers, and bioplastics. Raceway ponds can be suitable for both small and large communities and industries. In addition to applications in new facilities, aspects of raceway pond processes can be used in retrofits. The technological and scientific knowledge advanced by this project is the controlled operation of intensive high-rate algal raceway ponds for year-round wastewater treatment. This included low-cost harvesting of the algal biomass by a combined algal settling and membrane separation. The harvested algae biomass can then be anaerobically digested for recovery of energy, or converted into biofertilizers or other bioproducts. Following filtration the reclaimed water is suitable for unrestricted agricultural irrigation.
Project Goals
Develop a low energy intensity wastewater treatment (WWT) process to reduce the electrical demand of WWT in California.
Develop a low-cost WWT technology so disadvantaged communities can upgrade facilities to meet discharge requirements.
Ensure that the WWT technology is robust for all seasons, reliable and can meet discharge limits year-round.
Project Benefits
This project advanced the science and engineering of algae wastewater treatment systems to enable California wastewater plants to reduce net electricity consumption while improving plant performance and lowering overall costs. The raceway pond technology has been shown to use 66% less electricity on average and is projected to have 50% lower annualized capital and operating costs than the conventional activated sludge process. The raceway pond technology can produce water that meets California's Title 22 recycled water standards.
Affordability
Affordability
Raceway ponds on average have 66% lower electricity consumption and are projected to have 50% lower annualized capital and operating costs compared to conventional activated sludge.
Environmental Sustainability
Environmental Sustainability
If widely adopted, the estimated annual greenhouse gas emissions reduction for all cities (populations greater than 100,000) within the San Joaquin Valley would be roughly 47,000 metric tons of CO2 equivalent per year.
Reliability
Reliability
The project sought to improve the cost effectiveness of raceway pond technology to expand availability of recycled water and lower peak demand on the electrical grid.
Key Project Members
Dr. John Benemann
Chief Executive Officer
MicroBio Engineering Inc.
Shelley Blackwell, M.S.
Senior Scientist
MicroBio Engineering Inc.
John Coyne
Senior Environmental Engineer
MicroBio Engineering Inc
Dr. Tryg Lundquist
Professor
California Polytechnic State University, San Luis Obispo
Subrecipients
Cal Poly Corporation
Match Partners
MicroBio Engineering, Inc.
