Future challenges and solutions

Between 1960 and 2010, the global consumption of fish rose from 9.9 kg per capita to 18.6 kg per capita. The Food and Agriculture Organization of the United Nations (FAO) assumes that this trend will continue. By 2020, an additional 23 million tons of fish will be needed each year just to meet the demands of the current per capita consumption. As the supply of fish cannot be sustainably increased through fishing, the rising demand must be met through aquaculture. Aquaculture is hugely dependent on the availability of high-quality feeds in the quantities required (FAO, 2012). However, this presents aquafeed manufacturers with the challenge of achieving higher production capacities.

Nowadays, commercial aquafeed is predominantly manufactured using extrusion. This continuous process allows huge quantities to be produced. Single screw extruders reach their capacity limits at a throughput rate of around 15 t/h, whereas even higher throughput rates can be achieved with twin screw extruders. Coperion is a pioneer in the development of co-rotating and closely intermeshing twin screw extruders and has already designed numerous large-scale plants with screw diameters up to 420 mm and throughput rates of up to 100 t/h in different areas of application.

However, the maximum throughput rate on its own is not significant. It is also important to ensure that the selected extrusion system can manufacture a wide range of recipes to the desired quality. With its modular design, our ZSK twin screw extruder is extremely versatile. Its process section and the screw configuration can be individually designed to the process task.

With our new test lab for food and feed extrusion applications in Stuttgart, Germany, we offer aquafeed manufacturers a testing area that is well equipped to meet extrusion needs. The test lab is fitted with a ZSK Mv PLUS twin screw extruder with 43 mm screw diameter and some appropriate plant periphery. A considerable number of customers make use of the test lab to develop and optimize processes and recipes on a small scale, thereby acquiring reliable data for the scale-up to production scale.

Customers from the aquafeed industry have already been able to achieve throughput rates of more than 500 kg/h on the ZSK 43 Mv PLUS extruder with the desired product characteristics. These high throughput rates are primarily down to the high free volume in the process section of the ZSK Mv PLUS series. In a scale-up to a ZSK Mv extruder with 248 mm screw diameter that has already been built, this would correspond to a throughput rate of more than 40 t/h. Within the same tests it was possible to inject more steam directly into the process section compared to a set-up including a preconditioner.