Project Description

The RAZone project has been initiated by the Norwegian company, Normex for improving the efficiency and safety of ozone in the management of water quality in land based aquaculture including Recirculation Aquaculture Systems (RAS). The research work of the project is funded by the European Union’s FP7, managed by REA – the Research Executive Agency. In addition to Normex, four other equipment suppliers, two fish rearing companies and three research institutions participate in the project that will run until the end of 2014.

Land based aquaculture comprises hatchery, nursery and on growing operations. In order to try and maintain good biosecurity, these facilities are largely dependent on best management practice including the ability to provide high quality water conditions. Water to the farm can either be supplied on a flow-through basis, being used just once before being discharged or recycled several times. Flow-through systems causes production problems as the ability to control disease is vastly reduced while any uneaten food and faeces is released directly to the environment. Recycling the water using RAS technology involves processing the effluent water from the fish tanks and returning the purified water back to the production units. In the hatchery and nursery sectors, application of proper water quality control has significant economic benefits to the producer.

RAS technology is gaining increasing interest in Europe and internationally due to its recognised advantages. These include flexibility in site selection; reduced water usage; lower effluent volumes and most importantly reduced disease outbreaks and improved environmental control while also optimizing animal welfare. The EU wishes to increase and diversify aquaculture production while substituting seafood imports and RAS technology is considered to be critical in supporting this goal. However, to encourage its uptake, greater efficiencies in terms of the performance of different components of water treatment technology and t reduction of heir associated operational costs are required.

As stocking densities and levels of water re-use increase in RAS, waste products can accumulate rapidly and control of the environment within the production system becomes more complex. Conventional means of solids removal, such as micro screening filtration and sedimentation address the removal of coarse solids, but not the removal of fine particulates that can make up 50-70% of particulate substances in the water, whereas membrane filtration such as ultrafiltration and reverse osmosis are too costly to operate. Similarly, bacterial nitrification in bio filters removes dissolved ammonia and nitrites, but not other dissolved organic wastes which can reduce the quality of farmed fish for market while also destroying the stability of water as well as populations micro-flora that are required for optimum growth conditions in the production system.  If the organic loading in a RAS farm increases, optimum bio filter operation declines, resulting in system instability, increased exposure of stock to elevated bacterial numbers and eventually elevated ammonia and nitrite levels. The result is reduced stock performance and an increasing potential for disease outbreaks.

Today, ozone introduced to RAS via protein skimmers is a key tool in processing the farm water to remove impurities and has been demonstrated to positively impact fish production in RAS. Even though ozone has contributed to significant improvement in purification of recirculated water and creating improved water quality environment in RAS, its application hashowever become a costly component of RAS operation due to poorly designed equipment for ozone feeding, inefficient configuration of skimmers and lack of controlled ozone dosage combined with poor understanding of the ozonation process. This may result either in avoidance of ozone technology altogether or limited application to achieve desired aims. Furthermore, the installation of poorly designed ozonation technology can affect the health of farm staff. Data from experiencedusers of protein skimmers indicate that up to 2/3 of ozone produced may be lost in ill-designed ozone feeding systems resulting in a financial loss of €10-12K per month in some RAS farms producing up to 1000 tonnes per year. In addition, there have been several high profile commercial failures of RAS both in EU and other parts of the globe due to sub-standard ozonation technology.

The RAZone technology will redress the current limitations in application of ozone technology in the aquaculture sector through development of improved ozone delivery and dispersion technique, floc separation, control of the ozonation process for optimum ozone dosage and cost effective application of the technology while also improving our understanding of the impact of ozone on water chemistry and livestock. This will be achieved through development of a novel ozone delivery system that maximizes efficiency of mass gas transfer to water with efficient and even dispersion.  Moreover, RAZone provides an innovatively configured reaction chamber that significantly enhances floc separation resulting in improved clarity of the water entering the production system, which SOA skimmers cannot attain; and a process control unit that enables intelligent optimization of the ozonation process to avoid insufficient separation of pollutants or overdosing of ozone that is harmful to the stock. The RAZone project will thus provide a solution to a major bottleneck to the expansion of RAS technology both in Europe and globally.