The single most significant component of solid waste produced annually is cardboard. Though there have been great strides in its recycling efforts over the years, cardboard waste is still staggering. This is primarily attributed to people who think cardboard recycling only entails finding an alternative use for the cardboard in their surroundings.
There are many steps involved in expert waste cardboard recycling to come up with new products and hence reduce landfill. As such, it is essential to collect your waste cardboard and drop it a sorting centre from where it will undergo this recycling process.
Here are the primary stages involved in the processing of the cardboard into usable raw materials:
Pulp Cleaning and Screening
After making a pulp using chemicals and water with the sorted cardboard, the mixture is passed through screens containing holes to remove impurities. These holes generally filter out small contaminants. Heavy contaminants require spinning of the pulp in large cone-shaped cylinders. The centripetal force created throws out the heavy contaminants and settles light ones at the cone’s centre from where they are removed.
This involves the removal of ink from the cardboard’s fibres. At this stage, glue residue and adhesives that hold the cardboard are also removed. De-inking involves shredding and use of chemicals. Water is used to remove light ink particles while large ones are removed through flotation, which uses air bubbles.
Colour Stripping, Refining and Bleaching
The final processing stage involves beating the pulp to separate individual cardboard fibres. Addition of colour stripping chemicals is undertaken for coloured cardboard to strip it of the dye, thus generating brown paper. This can be bleached with hydrogen peroxide, carbon dioxide or oxygen to make white recycled paper.
After these processing stages, the paper pulp is cleaned and used to produce new paper. These stages guarantee that the recycled cardboard is safe for re-use. As such, processing forms a vital part of cardboard recycling.