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

35th

Assembly District

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$1,364,739

Amount Spent

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Active

Project Status

Project Update

Experiments for nitrogen removal in the 1000 L pilot scale raceways were used to guide operational modifications and optimizations of the full-scale raceway system, resulting in lower total nitrogen in the effluent later into the fall and early winter than in previous years. In 2022 and 2023, research focused on achieving total nitrogen limits < 10 mg/L in the effluents of the full-scale facility particularly in winter months. Over the course of the last three years the optimization of the RNEW® process resulted in a 10-25% increase in nitrogen removal and was able to decrease the amount of aeration needed by 15%. The ultrafiltration pilot studies concluded and the results indicate that tangential filtration, while consistent at producing a high-quality treated effluent regardless of feed quality, was not an economically viable option for polishing secondary-treated effluent from a heavily loaded conventional pond system. Further research into the use of crossflow membranes operated in dead-end configuration with intervals of high-flow crossflow flushes may be warranted as a low-cost alternative to outside-in membranes (which require air scouring). Modeling of this process is nearly complete and operational guidelines for use in future process and facility designs were developed.

The 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 reduced treatment performance in winter months and this project is researching methods to maximize performance year-round.

Project Innovation

This project will advance the RNEW(r) (Recycle Nutrients Energy and Water) process, which will overcome the seasonal limitation 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. RNEW(r) is suitable for both small and large communities and industries. Besides application in new facilities, aspects of the RNEW(r) process can be used in retrofits. The technological and scientific knowledge being advanced by this project are 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 separation for recovery of energy, fertilizers, and reclaimed water.

Project Benefits

This project will advance the science and engineering of algae wastewater treatment systems, to enable California wastewater plants to reduce net electricity consumption while improving plant performance and lower overall costs. The RNEW® technology has a projected 50% lower electricity consumption and 50% lower annualized capital and operating costs than the conventional activated sludge process. RNEW® can produce water that meets California's Title 22 recycled water standards.

Consumer Appeal

Consumer Appeal

The project seeks to improve the cost effectiveness of RNEW(r), to expand availability of recycled water and lower peak demand on the electrical grid.

Lower Costs

Affordability

The RNEW(r) technology has a projected 50% lower electricity consumption and 50% lower annualized capital and operating costs than conventional activated sludge.

Environmental & Public Health

Environmental Sustainability

If widely adopted, the estimated annual greenhouse gas emissions reduction for all cities within the San Joaquin Valley (with a population >100,000) is ~47,000 mt CO2eq per year.

Key Project Members

Dr. John Benemann

Dr. John Benemann

Chief Executive Officer
MicroBio Engineering Inc.
Shelley Blackwell

Shelley Blackwell, M.S.

Senior Scientist
MicroBio Engineering Inc.
John Coyne

John Coyne

Senior Environmental Engineer
MicroBio Engineering Inc
Dr. Tryg Lundquist

Dr. Tryg Lundquist

Professor
California Polytechnic State University, San Luis Obispo

Subrecipients

Rocket

Cal Poly Corporation

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Match Partners

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MicroBio Engineering, Inc.

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