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RAS Connector Series: The Roundtable recap

September 21, 2021  By Jean Ko Din

Photo: JLH Consulting

Highlights from the RAS Connector Series’ second virtual event

Technology meets biology

New developments and innovations are popping up in the industry constantly. On Sept. 14, RAStech editor, Catarina Muia, moderated a roundtable discussion with Innovasea VP Greg Beckman; Freshwater Institute (FI) research director Christopher Good; Alpha Aqua COO Ramon Pérez; and AKVA group research and development (R&D) director Siri Tømmerås.

Water quality and biosecurity are among the industry’s most important developments, according to the group. Topics, such as the regulated use of peracetic acid in aquaculture, improved biosecurity protocols and increased automations, have greatly improved RAS operations overall. But panelists agreed, there’s still much learning to do.


“What we’re lacking is the time to develop all these things at the same time,” said Pérez. He added that the industry must prioritize developing R&D rather than rushing to build large facilities throughout. “We need to walk before we run,” he said.

Beyond the technical advancements in operations, panelists agree that the most valuable resource in RAS facilities are the experienced aquaculturists. In theory, everything can be automated but it can’t replace a pair of eyes from an experienced fish farmer.

Feed challenge

Formulating fish feed that’s both nutritious and safe to use in a RAS tank isn’t easy! Jason Mann, director of nutrition at Riverence Trout Farms, gets to the meat of the matter with Steven Backman, product manager and veterinarian at Skretting; David Brock, aquaculture nutritionist at Rangen Foods; and Marc Turano, nutrition and technology lead of Cargill Aqua Nutrition – North America.

Panelists agreed that RAS feeds optimizing fish nutrition and minimum feed conversion are priorities in developing the right formulation. Turano added that RAS feeds also have to consider the “second stomach” that is the recirculating system, understanding its interaction with biofilters, piping and other stages in the system. “We can’t afford many failures in these touchy systems,” said Brock.

The biggest challenge of commercial feed production is consistent product. Backman said he puts a lot of pressure on Skretting’s supply chain managers to make sure raw materials are available.

Mann asked the group if they see RAS diets and conventional diets converge, in terms of cost per ton, however, the panelists remain skeptical. Turano said it’ll always be a challenge, with limited volumes, and to figure out how to navigate the different demands of different farms. “I know it’s not something producers want to hear and we don’t like to say it but it’s still a niche market.”

Waste management

Ed Aneshansley and Christine Lepine attempt to clean up the misconceptions of waste management at their live roundtable. David Kuhn, associate professor of food science and technology at Virginia Tech, was moderator of this session. Together, the three experts discussed why water treatment shouldn’t be an afterthought in a RAS facility.

“I think if RAS wants to gain the trust of local communities, to expand into areas that have tighter discharge regulations, and even as we see RAS farms get into larger sizes, it’s going to be really important to develop technologies to find best-fit solutions,” said Lepine, research associate at FI.

She indicates that while compost hasn’t been popular in RAS waste removal, there are plenty of potential nutrients to utilize. When it comes to denitrification, Aneshansley, CTO at HTL Sustainable Foods Inc., was asked if anaeorobic digestion of sludge is part of that process. He replied that anaeorobic digestion is a separate process offsite.

“A drum filter’s discharge is relatively low in solids, less than one per cent. Running this through an anaerobic digester, would require de-watering the sludge stream to 8 to 12 per cent solids,” Aneshansley said. “Additional technology must be added to facilities to produce a product suitable for anaerobic digesters.”

The ins and outs of off-flavour

Geosimin and methyl-isoborneol (MIB) are well documented as the culprits of off-flavour in RAS fish. Andrea Dietrich, professor of civil and environmental engineering, and food science and technology at Virginia Tech, looked at how the industry is mitigating the musty taste.

Panelists included Steve Atkinson, founder of Taste of BC Aquafarms; John Davidson, research scientist at FI; Niels O. G. Jørgensen, associate professor at University of Copenhagen; and Raju Podduturi, research scientist at Atlantic Sapphire.

Davidson shared that one of FI’s recommended depuration standard of procedure is to simplify the design. “You want to have systems that are free of high surface-area aeration media as it can provide excess surface area for these microbial biofilms to accumulate on,” said Davidson.

RAS technology doesn’t currently allow operators to detect and empirically measure off-flavour levels in tanks, so panelists agree that depuration is the most reliable solution. Podduturi added there are also other compounds that contribute to off-flavour. He said his research has found terpenes in fish feed and phytoplankton that may also be contributing to the off-flavour in fish.

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