Effluent Contamination
Release of pigments or dyes from printed labels or packaging into the hot wash water during the recycling process. When wash bath bleed occurs, the dissolved colorants contaminate the wash water and can stain the unprinted recycled plastic flakes or paper fibres in the same batch. This discoloration reduces the brightness and value of the recycled material, which limits its use to lower-value, dark-coloured products.
Inks Separation
Inks formulated for recyclable packaging must remain attached to the substrate or, if detached, must remain insoluble and rise to the surface of the bath where they can be skimmed off. Standard inks often dissolve or disperse in the alkaline wash solutions used in PET recycling plants, which causes the wash water to turn dark and carry dissolved pigments. The selection of non-bleeding ink chemistries and water-insoluble binders prevents this staining of the recycled flakes.
This separation performance is evaluated using standardized laboratory wash tests that measure the color change of the wash water.
Process Mitigation
Recycling facilities use flocculants and advanced filtration systems to remove dissolved dyes from the wash bath, but these treatments increase operational costs and chemical consumption. Utilizing inks that comply with non-bleeding standards reduces the need for water treatment and maintains the purity of the recycled polymer. This compliance ensures high-quality raw materials for the circular economy.
