Production of Fair Average Quality (FAQ) fishmeal (63-65% protein) by indirect drying, residual heavy fuel (R500) powered. Data from one plant representing 8% of the total amount of anchovy processed into FAQ fishmeal (48 430 t/y out of 5.2 million t/y * 12%, in 2008-2010). The technology is common in the country for FAQ fishmeal production.

After arrival of the fishing vessel at the floating terminal, the fish is pumped out of the vessel’s hold and conveyed to the plant mixed with seawater in a proportion close to 1 m3 per t of fish. There the fish is separated from the mix of water, fish residues and blood (bloodwater) through a screw drainer. The drained bloodwater is processed in a rotating screen in order to remove the solid residues (flesh, scale, etc.) that are then conveyed to the “solid line” (described below), and the remaining water is processed first in an oil and solids separator and then in a flotation tank where oil is recuperated thanks to its positive buoyancy. The oil is conveyed to the “liquid line” (described below) whereas the remaining water is discharged at sea through a long underwater pipe (e.g. one-km long). In modern plants, the flotation process is accelerated by the release of fine air bubbles at the bottom of the flotation tank. The remaining bulk of the fish is then conveyed by a wire mesh conveyor belt to an automated weighting hopper and then released into large storage pits. From there fish is conveyed to a cooker using a conveyor, whereas additional bloodwater is processed into a specific trommel. There, a continuous cooking occurs by means of an internal rotary screw conveyor, at a temperature of 95 to 100°C in order to coagulate the proteins. The cooking process is indirect, thanks to steam-heated jacket surrounding the conveyor, but still generates odorous fumes. From the cooker the product is conveyed to strainer (or first to a pre-strainer and then to double helicoid press) that allows draining a mix of oil, protein (dissolved and suspended) and water from the solid mass, thanks to the previous cooking step. From the straining process starts the major separation between the liquid line (oily water or “press liquor") and the solid line (presscake), but with further bridging connections.
The processes in the liquid line consists in a further separation between oil, water and protein coming from different paths. The press liquor, along with the bloodwater, is first transferred by pipe to an oil and liquid separator (or decanter) which is a horizontal centrifuge. After two to three separation phases, the oil and liquid separator returns the remaining solid (sludge) to the solid line whereas the liquid goes to a vertical disk centrifuge. The centrifugation process allows further separation between fish oil and the aqueous phase named “stickwater”. Stickwater is concentrated in a multi-stage (two to four) evaporation unit, prior to enzyme addition aimed at reducing its viscosity. The unit must be cleaned at regular interval, usually using caustic soda, to maintain its thermal efficiency. This is because the evaporator tubes where steam circulates are quickly fouled. The final phase of the liquid line is oil polishing, which is carried out in special separators and facilitated by using hot water, which extracts impurities from the oil (resulting in additional stickwater) and thus ensures stability during storage. This phase ends with the transfer of the stickwater to the evaporation unit and with the pumping of the refined oil into storage.
The presscake along with the sludge from the oil and liquid separator is conveyed first to a wet mill and then to a rotating dryer. As indicated earlier, direct-fire dryers or indirect steam dryers can be used and will result in different qualities of fishmeal. The drying process also generates smells and particles, especially in the case of direct-fire dryers. The raw dry meal (“scrap”) first passes through a sieve to remove large extraneous material mostly collected during the purse-seining operation (wood, rope, plastic residues, etc.). Then the meal is pneumatically conveyed to a cyclonic tower to extract fish meal particles from the drying air. In the sampled plant of FAQ fishmeal, the air emission of the cyclone was processed in a scrubbing tower where water is pulverised in order to limit particles and odours emissions. The fishmeal is then milled in a dry mill. Follows a centrifuging purifier that allows a final elimination of small extraneous material. Finally anti-oxidant is added before automatic weighting and conditioning into plastic bags for distribution.
Steam is produced in a series of boilers and distributed throughout the plant by insulated pipes, forming close circuits in order to save energy. Steam condensate is also returned to the boiler through a piping systems.
The energy source in boilers is either natural gas when available or heavy fuel. In the past fish oil was recycled in boiler burners because its commercial value was very low.
Electricity from the Peruvian grid is used most of the time, except during peak hours (or power breakdowns) where it is supplied by a series of powerful electric generators fuelled by light fuel. This strategy is used to reduce production costs because self-generated energy is cheaper than the grid energy during peak hours.

Process diagram of FMFO production