When the pulp fibres are diluted large quantities of water are required. The water requirement is currently satisfied by using the water from successive working processes (from under the flat board) as well as water that has not yet entered the productive process. This also a considerable saving of pulp fibres because the waste water contains large quantities of suspended fibres and other matter. There is also a considerable reduction in the drainage water, seeing that the water is reused in the production cycle. The waste water collected during production, before being put back into the process, is first treated using a drum thickener and then an external flotation unit.
The thickener drum separates the most prestigious fibres - which are sent to the machine container – from the fibre remains, which are then sent to the floater unit for a second chmical and physical recovery process.
The floater produces two types of output through separation:
A first stage, made up from clarified water is used the spraying and pulping of the paper.
A second stage, made up of “mud”, consists in a fraction of reused water with a high content of waste and impurities, destined to be discarded and a fraction of water that will be sent back to the plant container.