The significant reduction of water usage in paper manufacturing is based on an increasing rate of circular water usage in paper production. At sites which use predominantly recovered paper, the water circuits are often partially or completely closed. Despite the advantages associated with the resource protection, some adverse effects can be observed caused by an increasing accumulation of dissolved, colloidal and suspended material in the process water. This comprises in addition to hampered quality of the product also side effects like increased cleaning efforts caused by agglomeration and deposition of material on paper manufacturing aggregates. The potential to release substances to the aqueous phase during disintegration has so far not been considered in the method PTS-RH 021:2012 evaluating the recyclability of packaging products.
PTS-method PTS-RH 025:2022 has been developed to determine and evaluate the contaminants which are released upon disintegration to the aqueous phase. It is used for the quantification of dissolved, colloidal and suspended substances in the filtrate of a fibre suspension following standard disintegration in the lab scale. After the filtration of the fibre suspension, the water is vaporized, followed by a gravimetric determination of the residues. For an optional qualitative assessment of the filtrate the chemical oxygen demand (COD) is measured. The assessment of the sample is based on the comparison with reference values.
The revised Cepi Recyclability Laboratory Test Method for recycling in standard mills, Version 2 (2022) includes the described method and parameters.
The new PTS method is available at Papiertechnische Stiftung (PTS) as of now, please send an inquiry to firstname.lastname@example.org.