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RASTECH24: Fish waste as RAS’s second harvest

The conversion of aquaculture waste products has been creating a growing buzz in the recirculating aquaculture system (RAS) space for several years now. However, while several fish farm operations have implemented a variety of waste conversion strategies into their operation, the aquaculture industry is still playing catch up with its terrestrial counterpart.

On the second day of the RASTECH 2024 Conference and Trade Fair in Charlotte, N.C., a panel of RAS experts discussed research, initiatives and technologies that are pushing the envelope on transforming aquaculture waste into sustainable by-products and potential revenue streams.

The session: Unlocking fish waste as a resource and profit stream was chaired by Jason Danaher, senior biologist at the Florida-based Aquatic Equipment and Design Inc.

Danaher’s presentation which was title “Fish with a Side of Green: Partnering for a Greener Tomorrow” discussed some of the encouraging results of his experiments in the use of geotextile bags and lower cost burlap bags to dewater nutrient-rich aquaculture effluents to produce soil enrichment products for agriculture uses.

Danaher said partnerships are critical in pushing development further.

In her presentation the “Green Solution in Blue Food Production,” Megan Sorby, founder of Pine Island Redfish, spoke about her company’s journey in raising red drum in a 150-acre RAS facility in an island in Florida.

The project also involves developing a strategy for recovering aquaculture waste for use as a mitigation tool in coastal restoration and growing vegetable species in the highly saline soil of Pine Island.

“We set out to do a proof-of-concept on how we can address this issue in a sustainable way,” she said. “…How can we use that waste product, make it a profit stream and still contribute to the sustainable circularity in the sector.”

Today, Sorby is growing California Sunfire, Sea Purslane and Red Mangrove using wastewater from the RAS facility. The company is still exploring possible uses for the plants. Sorby said there are possibilities in using the plants for protein production or even carbon capture.

In his presentation, “Using Everything but the Swoosh”, John Holder, co-founder, and director of technology for Goldriver Aquafarms, discussed how RAS facilities can regulate the large amounts of sludge they produce.

Holder spoke about RAS-centered technologies developed by Goldriver Aquafarms from small waste dryers, rotary presses, and the company’s large equipment for solids removal.

Trevor Gent, sales manager for technology at Alumichem Technologies, discussed the water treatment chemicals and systems produced by the Denmark-based company. Gent also spoke on how environmental regulations impact the development of such tools.

Alumichem develops a wide variety of wastewater treatment for different industries. The company’s aquaculture targeted solutions include chemical for the removal of solids, nitrogen, phosphorous and heavy metals as well as solutions for low-cost sludge handling and conversion into various resources.

Todd Deligan, general manager for the North America operations of Salmon Evolution, made a case for rehabilitating the image of sludge and wastewater. (Photo: Jean Ko Din, RAStech Magazine)

Todd Deligan, general manager for the North America operations of Salmon Evolution, made a case for rehabilitating the image of sludge and wastewater.

In his presentation “Wasting an Opportunity! It’s Time to Rebrand,” Deligan said, “Let’s not use the word sludge, it’s terrible.”

The concept of treating effluents and recycling solid waste has always been a part of Salmon Evolution’s environmental sustainability strategy, according to Deligan.

He also noted that a perceptions and knowledge regarding aquaculture waste products have change a lot.

“Thirty years ago, nearly everything was classified as waste. Today, 94 per centof a salmon is used as a valuable product…recently useful and commercially available iron was found to be an ingredient in fish blood,” said Deligan. “Let’s talk about what we call waste from a values creation point.”