Fish farming (also known as aquafarming) is a rapidly-growing industry, estimated to bring in revenues of over 253.9 billion USD within the next five years. Across the world, fish farming accounts for approximately half of the fish consumed annually, which also helps preserve wild species from the effects of overfishing. However, the growing popularity of aquafarming has also increased the volumes of wastewater generated every day, which can cause harm to the environment if not managed properly.
What is aquaculture wastewater and is it toxic?
Aquaculture (fish farming) wastewater is generated during every stage of the farming process and often contains high levels of nutrients such as nitrogen and phosphorus; organic matter and solids such as algae and bacteria; and other chemical pollutants. Although some of these elements exist in nature, high levels can become toxic, which is why effective wastewater treatment is especially important.
If left untreated and discharged into the environment (especially larger bodies of water), wastewater from fish farming can cause eutrophication – a process where excessive nutrients in the water lead to an overgrowth of algae, which in turn depletes oxygen levels and causes the death of fish and other aquatic organisms. The result is what’s known as a “dead zone” and it can take decades to recover – in fact, the Gulf of Mexico has the largest man-made dead zone in the world and it’s estimated that recovery will take a minimum of 30 years.
The negative impacts of untreated wastewater from any industry can be detrimental, and this is especially true for fish farming wastewater due to the way organic matter can quickly spread and affect large bodies of coastal water. This is why proper wastewater treatment and management is necessary to help protect aquatic life and ensure more sustainable fish farming practices.
How do you maintain good water quality in aquaculture?
As we’ve seen, maintaining good water quality in aquaculture is essential not only for the health and growth of the fish but also for the overall sustainability of the industry and its environment. Poor water quality can lead to a variety of issues, including disease outbreaks, decreased growth rates, and even death of fish. Therefore, implementing effective water quality management practices is crucial for aquaculture farmers.
One of the most important steps in maintaining good water quality is regular testing: testing the pH of the water, abundance of oxygen, and levels of ammonia and nitrites present in the water can help quickly identify emerging issues and assist farmers in taking corrective action. (Speak to our team about our wastewater testing solutions and ongoing monitoring options with the LAT Unit.)
Another key step is to remove uneaten food and fish waste from the water – if the site is left unclean, stale food, supplements, and waste can contribute to the buildup of organic matter and create an environment for harmful bacteria to thrive. This can lead to disease outbreaks and other issues that can negatively impact fish health. For this reason, many fish farmers will use natural and synthetic chemicals to regulate the quality of the aquaculture site, however, these chemicals must be removed as part of the wastewater treatment process.
It’s also important to ensure fish have sufficient space to live and grow – overcrowding can lead to increased stress on the fish, which has been shown to make them more susceptible to ailments as well as encouraging the faster spread of disease through close contact. This in turn makes wastewater treatment more difficult as infective bacteria and viruses can spread and evolve very quickly.
Additionally, monitoring the water temperature is also crucial for maintaining good water quality as different fish species have different temperature requirements, and maintaining the appropriate temperature range is important for disease-free, healthy growth.
How do you manage wastewater in aquaculture?
Traditionally, aquaculture wastewater is managed through constructed wetlands which mimic the processes which occur in natural wetlands; settling ponds to separate solids from liquids; or biological filtration which breaks down harmful bacteria.
However, effective wastewater management for modern aquaculture sites usually requires specialised infrastructure and more resources to cope with the large volumes of wastewater as varied types of pollutants may be present and traditional methods of treatment can be less efficient.
The best course of treatment will also depend on a few factors including the location of the site and its proximity to the land, as well as the direction of water flow and types of waste present in the wastewater itself. Our team at LAT Water will be able to run tests to determine the wastewater composition and this will help determine the optimum configuration for your LAT Unit to ensure maximum clean water recovery and provide additional options for byproducts and wastewater recycling – adding further value to the supply chain and helping your process become more sustainable.
A single LAT Unit is capable of treating very large quantities of water and in one case study, delivered a 48% reduction in operational costs and a 70% reduction in energy use as it utilises waste heat as an energy source and recirculates this through the system to reduce overall energy requirements. This is particularly important for aquaculture sites as many usually operate at lower temperatures and the need for additional, costly infrastructure is therefore minimised.
Contact The LAT Water Team
Learn more about our aquaculture wastewater solutions by contacting our team on +44 (0)1635 635900 or by emailing info@latwater.com.
Meet us later this month at The World Biogas Expo 2023 at the NEC in Birmingham on the 29th – 30th of March. We’ll be available on both days of the conference at stand D205. Download our corporate brochure for more details and to find out more.
