Improving the Drainage of Recycled Paper Pulp Using Enzymes

10 May 1999

in 1999

Mean Green Recycling Machine – Edmond Lascaris

Recycling wastepaper is good for the environment but it could be better. Ed is using enzymes from fungi to make recycling greener.

Many people think that recycling wastepaper is good for the environment, and it is. However, the collection and reprocessing of wastepaper consumes a lot of energy, which inevitably contributes to carbon dioxide emissions. Enzymes, those special secretions from bacteria and fungi, can reduce energy consumption significantly, by making the process more efficient.

This project began as a joint venture between the CRC for International Food Manufacture and Packaging Technology, Visy Paper the Australian owned paper recycling giant and Swinburne University of Technology. Visy Paper was interested in making the process of paper recycling greener and more productive than current technologies permitted. Rather than apply chemicals, some of which are difficult to handle and potentially toxic, it was decided to use enzymes. Enzymes are special secretions obtained from bacteria and fungi that have the ability to selectively break down larger molecules. They are nature’s own nano-machines.

Australian wastepaper has a relatively high starch content. Starch is widely used in the paper manufacturing process because, just like “clag”, small amounts help to glue paper fibres together to produce a stronger and cost competitive paper sheet. When wastepaper is mixed with water the starch that coats the fibres once again turns to “clag”. These gooey fibres retain water like a sponge and slow down the drainage and drying processes on a paper-recycling machine. If enzymes chew up the starch the paper-recycling machine speeds up without any additional energy costs. A global patent now protects this novel treatment process.

Other enzymes give the recycled fibres a close shave. Just as a piece of rope frays with wear and tear, so too do recycled paper fibres.

Enzymes rapidly break down the frayed components of paper fibres (termed fibrils) because, unlike the larger parent fibre, they are “bite size”. Shorn fibres also contribute to better drainage on a paper-recycling machine.

This work culminated in several large-scale industrial experiments performed in one of the Visy Industry wastepaper recycling machines in Melbourne. During one trial the 8-hour, 24-hour and monthly paper production records were broken. Because more recycled paper was produced at no additional energy cost, a considerable saving was achieved.

These outcomes steadfastly place Australia at the forefront of recycling paper technologies. And more importantly, this work takes us all one step closer to averting the Green House Effect.

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