New aquaculture wastewater treatment system helps the aquaculture industry meet increased supply

The demand for fish is increasing with global population. The aquaculture industry continues to adapt and innovate to increase supply. But with new approaches, better management of water is required to ensure long term production and to protect our oceans and land. Arvia’s Nyex technology can be applied to address various problems, including removing off-flavour compounds, lice control and persistent micropollutant removal.

The food shortage that aquaculture can help solve

In the next few years, the world may run out of food. Stark fact but true.  The UN thinks so and organised a Food Systems Summit in September 2021 to be viewed from the perspective of its sustainable development goals.

One of the areas of food production that is growing in popularity and could be one of the solutions to the problem is aquaculture – mainly (but not exclusively) the farming of fish.

According to the Norwegian Institute of Marine Research, fish is not only a source of omega 3 fatty acids and protein (as is well-known)  but also contains important essential micronutrients – mainly vitamins A, B12, and D as well as calcium, iron, iodine, iron, and selenium.   Rather than adding these supplements to other foods they argue that the increased consumption of fish would basically do the job for you.

The growth of aquaculture

So it would appear that the increase in farmed fish is good for everyone. Well not quite, as fish farming has come in for some criticism  recently for its practices and reportedly the amount of antibiotics and other chemicals being used to keep the fish healthy and parasite-free.

But as a fast growing industry, there are bound to be pain points in its progression and at Arvia we believe we can contribute to its continued, safe growth.

Since 1980, the global amount of wild-caught fish for the oceans has remained constant at around 70 – 90 million tonnes per annum. But in the same period, farmed fish has grown fast and is projected to reach an output of 109 million tonnes by 2030 with a yearly value approaching US$50bn.

This therefore, is big business and notwithstanding the issues with both RAS and off-shore aquaculture, there’s no stopping it now.

Aquaculture methods

Fish are farmed either onshore – that is to say, in land-based (RAS) growing environments (often indoors) that mimic ‘wild’ conditions – or offshore, in large nets or containments placed in the sea.

In the latter case, these nets are normally grouped together in deep water so the current washes away the inevitable sinking debris from a large concentration of fish.

Both have advantages and disadvantages, and both can hugely benefit from the sort of water treatment that Arvia’s Nyex™ systems can deliver.

Nyex Rosalox™ advanced water treatement

The revolutionary Nyex Rosalox™ products produced by Arvia are the result of many years advanced research into water treatment – and specifically how to remove recalcitrant organic compounds, EDCs and COD from wastewater down to parts per million levels. They can also remove tastes, colour, turbidity and odours (like geosmin.)

Nyex Roasalox™ is based around our unique and patented Nyex™ media. Utilizing the advantages of both adsorption and electrochemistry techniques, our reactors will often outperform other treatments in reducing recalcitrant organic compounds to extremely low levels. They do this without needing chemical dosing, without creating any toxic sludge and only requiring minimal top-ups of media annually.

Combining the best of two technologies

Using this unique combination of the two most effective techniques, our systems have a small footprint, don’t use a massive amount of power and contain no moving parts so they’re ideal for remote or challenging locations like ships and barges. Lifting spent material, chemicals and waste off ships requires docking time at high expense, whereas Nyex Rosalox™ requires greatly reduced replacement of parts and generates zero waste.

Nyex Rosalox™ works in one continuous process: pollutants are adsorbed by the Nyex™ media. A charge passed through the media forms hydroxyl radicals which completely oxidises the pollutants to gas and water, whilst at the same time, reactivates the Nyex media. So unlike GAC, our media doesn’t degenerate and require replacement and unlike ozone-based oxidation systems, no potentially dangerous chemicals are used.

Where a Nyex reactor can be used

Our plant can be harnessed as part of comprehensive treatment train and is suitable for retrofitting into existing installations. Each reactor is essentially plug and play so scaling up is just a question of adding more reactors in parallel.
As they require minimal maintenance, virtually no top-ups, and no chemical dosing, there is never really a need to take a Nyex™ reactor off-line, cutting out the risk of operator error. And as one large fish producer knows full well, taking filtration plant off-line for maintenance can be a costly business when dealing with a high value salmon harvest.

Why Nyex Roasalox™ is ideal for offshore aquaculture

With offshore aquaculture, stock may need to be rid of sea lice mechanically and this involves fish being moved into tanks where various processes are used to remove the lice including heating the water.

Alternative methods involve dousing in H2O2 but the use of hydrogen peroxide is criticised by consumers as causing damage to the fish, and also results in reduced yield and product quality.
Water from this process will need treatment before it can be discharged and whilst GAC (granular activated carbon) is often used, it involves the complete replacement of this media. This is something that must be done on a regular basis and is extremely challenging from a barge or tender.

Nyex Rosalox™ on the other hand, needs minimal tops ups and little maintenance and is ideally suited to rugged, remote locations, having no moving parts and no requirement to dose with potentially dangerous chemicals. That makes it ideal for use at sea.

Why Nyex™ is also highly suitable for RAS facilities

RAS (recirculating aquaculture systems) facilities tend to use stock ideally suited to the specific environment. There are however various issues with what is a ‘closed’ system; water needs to constantly circulate and be monitored carefully.

There is a constant risk of losing a lot of stock through lapses in biosecurity and often fish are treated with antibiotics or other medicines to counteract the threat of organic build-up. However APIs from these products will need to be removed from the water to avoid microbial resistance building up. Our Nyex™ systems are ideally suited to removing many APIs and EDCs down to parts per trillion levels.

Additionally, fish grown in an RAS may be susceptible to geosmin and other compounds that produce off-flavours. Although not harmful or toxic, this will certainly reduce the value of the harvest. Again, Nyex™ is excellent at the removal of this.

The advantages of Nyex™-based systems are clear: no time offline for replenishment, no need to remove sludge and no chemical dosing required. Plus minimal maintenance and low operator intervention needed because there are no moving parts and virtually no consumables – just a yearly top-up of media (1 – 3% by volume.)

Conclusion – giving water a second chance

Arvia’s Nyex™ systems are some of the most advanced water treatments systems available, allowing many companies to approach ZLD (zero liquid discharge) status.
Whether offshore or RAS, it’s ideal for inclusion in the treatment train in many aquaculture environments. We are already working with several organisations in this field worldwide, so have built up plenty of useful operational experience over the last few years.
To arrange a conversation with a water treatment scientist who’ll be able to get to grips with your particular water treatment challenge, call or mail us today.