In the pet and fish food sectors, the term "wet extrusion waste" is defined as the solid or pasty matter which is produced when the extruder starts and stops,  as well as the samples of kibble and flour taken from the system during production. The disposal of this type of waste is normally entrusted to specialized companies in specialized treatment centers. The amount of waste produced on a daily basis depends on the type and productivity of the extruder, the operator's ability to manage the system and the number of start-ups due to change of formula, shape, colour, etc. For example, if each stop/start-up of a 6/7 ton/h extruder generates a quantity of waste of 80 <100 kilos, there is subsequently an economic loss of about €25 <45. Given an annual production of 30,000 tons in batches of 12,000 kg, 2,500 start-ups will be performed, leading to an overall loss of €62,000 < 112,000.

CRISTIANO TORRE Engineering has developed a system which is able to perfectly recycle all the waste and therefore recover this cost in full.

In our wet extrusion waste recycling machine, waste is loaded manually or automatically into a treatment tank; water is added according to a specific formulation; the blend will be ground by means of a variable speed 'cowles' disperser and then the mixture obtained will then be gradually transferred into the preconditioner upstream of the extruder during normal production, by means of a variable speed volumetric pump. The dissolution formula, the dispersion process, the maintenance of the density and the flow of the mixture to the preconditioner are all automatically  managed by a microprocessor equipped with a weighing system and a flow meter. The flow rate of the pump is adjustable allowing the constant unaltered  maintenance of the quantity of water necessary for the process of extrusion independently from the quantities of solids added for disposal. The tank is automatically washed at the end of each disposal cycle. Given that operating an extruder is a source of environmental pollution due to the content of waste waters (MES, DCO, DBO5) , our system guarantees a solid reduction in pollution and, as a consequence, substantial cost savings.

The operating results are:

• THOROUGH GRINDING AND HOMOGENEOUS DISPERSION

• ABSENCE OF RESIDUAL PRODUCTS

• NO INTERFERENCE WITH OPERATION OF EXTRUDER

• NO ORGANOLEPTIC ALTERATION OF PRODUCT