Fish Farm to Utilise Waste Water for Oyster Production

​The CNC fish farm project has decided to expand the facility with yet another sustainable initiative. The facility will produce trout and later salmon – but the plan is also to utilise the wastewater from the fish to produce oysters.

On behalf of the client, Cape Nordic Corporation, Gråkjær Aqua is well under way with the design of the processing plant for the huge large-scale fish-production facility near Cape Town in South Africa. In the first phase, the fish-production facility will be able to produce 1,800 tons of sea trout a year. In the first delivery, the facility will produce sea trout, but it will be constructed in such a way that will also be able to produce salmon in the future. The fish facility will contain a hatchery, first feeding, fry, a pre-smolt unit, a smolt and post-smolt unit, and a delivery tank and will have the capacity to grow fish from eggs to a final slaughter weight of about 5.2 kg. And now CNC also plans to produce oysters.

Thinking innovatively and sustainably – expanding to include oyster production
The fish production facility is to be expanded so as also to incorporate oyster production.  The production will be an integral part of the Integrated Multi-Trophic Aquaculture (IMTA) set-up in the plant. The IMTA principle implies that one species finds niche food in the residual waste generated from other species. In other words, the oysters produced in the facility will live off the residual waste of the fish in the wastewater. The wastewater includes, for example, fish slurry, which will be utilised and converted into fertiliser, feed and energy. When the facility is completed and operational, CNC expects an annual output of 3.5 million oysters.

This means that CNC’s concern for the environment in the project scales new heights, given that they will be utilising even the smallest resource in the waste water, thereby creating added value: not merely for their own business, but also for the environment.

Erik B. Rasmussen, Danish Director of CNC, says about the project: “Oyster production is a good business initiative, since the expanded fish production facility will enable us to produce a much-coveted, high quality product. The production will also generate even more local jobs, which will benefit the local community in the area.”

Most of the energy in the fish farming plant will also come from recyclable energy. 85% of the energy for the large-scale fish production facility will come from a sustainable wind energy system located centrally in relation to the production. Furthermore, the limited amount of bio-waste from production will be used as fertiliser on the farmland that surrounds the plant.

CNC must take credit for their innovative thinking vis-à-vis food production and the environment. That is why the project is being subsidised by the government of South Africa via DTI (The Department of Trade and Industry) for realising this innovative project.

“The CNC project is pioneering and the first of its kind to receive recognition in the form of such a large subsidy,” explains Erik B. Rasmussen. The grant amounts to 30 million rand during the construction phase.


The impact of the partnering agreement

Gråkjær and CNC decided to enter into a partnering agreement. That means that the client and the turnkey contractor will jointly optimise budget, quality, schedules and construction process.

The effect of this form of collaboration is clearly evident in the initial stage of the project.  In practice, this means that every week there is a project meeting for the purpose of clarifying the status of the project and determining its progress.  In addition, from time to time there are workshops, also attended by the subcontractors. Jens Jensen, Business Developer of Gråkjær Aqua says: “We are two teams (i.e. CNC and Gråkjær), who, while sitting opposite each other, are actually on the same side of the table. We optimise the process together. In a project like this, involving the construction of a huge fish farm in South Africa, there are a huge number of process and system solutions, based on parameters such as quality, temperature, local conditions etc., which must be decided upon and taken into account. We look at everything from every possible angle so as to arrive at the very best solutions, which suit this particular type of fish production and the wishes of CNC. Thereby we ensure that everything is well thought out and that each party leaves a meeting with peace of mind, because we have both been involved in the decision-making.

The project is running according to plan. Right now, there is a lot of on-site activity including drilling of boreholes for water supply, soil investigations and analyses of the general conditions on and around the construction site. Currently, the CNC project team are working intensively on environmental approval and authorities processing. This is all expected to be in place by summer 2019 so building can commence in February 2020.

See also

16.5.2018 Gråkjær signs contract with Cape Nordic Corporation

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High tech smolt facility makes a big impression

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Early Involvement and Matching of Expectations

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Gråkjær A/S, Fabersvej 15, DK-7500 Holstebro  ·  Tlf. +45 96 13 55 55  ·  graakjaer@graaakjaer.dk