Processing of By-Products
Notable valuable substances can be recovered from the wash water from canning factories and from the pumpwater used to pump fish from vessels into the fish meal plant. In addition to recovering valuable substances, it is also important to reduce the waste water burden, water load and energy consumption in the process. GEA Westfalia Separator decanters play a key role in treating wash and pump water – in both economic and ecological terms.
Fish canneries produce relatively large amounts of waste water with a high biological load. The cost for the disposal of waste products is correspondingly high. GEA Westfalia Separator has launched a process engineering concept to solve this problem in a contemporary way. When cans containing preserved fish products are filled and then sealed, small quantities of oil or dressing overflow which have to be rinsed off with hot water before packing. A few milliliters per can are sufficient to consume an immense total quantity of wash water. Many companies have therefore already installed flotation systems in which solids and oil float to the surface attached to bubbles formed by air which has been blown in. This fat-containing sludge has hitherto been disposed of at significant cost.
GEA Westfalia Separator goes one step further and treats the sludge containing oil and solids.
Treatment of canning wash water
In the first step, the sludge is brought to high temperature in a tank – using heat recovery to save energy. This coagulates the proteins and releases the oil. A 3-phase decanter separates the sludge into oil, solids and water. The water phase, which still contains a certain amount of solids, is first used on the counter-current principle to pre-heat the product, but then flows back into the flotation tank again. The oil recovered can be polished in a separator and sold as a raw material to the paint industry, for example. The rinsing water, free of oil and solids, is now no longer highly polluted with biological material and can be disposed of much more cheaply.
Treatment of fish pump water
Pumps are frequently used to unload ships. Water is added to enable the fish mass to be pumped. If fresh water is used, as is usual especially in Europe, the pump water should be recirculated for as long as possible to keep the quantity of fresh water as low as possible.
Suspended solids are separated in the GEA Westfalia Separator 2-phase decanter and passed to the fish meal production line.
Pump water process using fresh water
This reduces fresh water consumption and increases productivity. This process is a closed loop, since at the end of the pumping phase, the remaining pump water is also fed into the fish meal process. This avoids waste water and simultaneously minimizes losses.
If seawater is used, a 3-phase decanter separates the flotation sludge into water, oil and solids. Whilst the water is returned to the sea, the fish oil is pumped into a storage tank. The solid phase also goes to the fish meal production line. In addition to the higher yield of fish oil and fish meal, the centrifuges contribute to reducing biological pollution in the waste water here too.