THE brightly coloured sticky notes that many an office worker could not live without are an expensive nightmare for paper recycling plants. The same goes for envelopes, address labels and any paper with glue or gum on it. The residue on all these 鈥渟tickies鈥�, simply blocks up the recycling works. But enzymes are coming to the rescue.
Jim Fitzhenry from Buckman Labs in Memphis, Tennessee, says tiny particles of glue inside recycling machinery gums up the works.
Traditionally, recyclers tackle the problem with heavy-duty solvents that can be damaging to the environment. But since May, Fitzhenry鈥檚 team has been carrying out trials using harmless esterase enzymes that attack the sticky residues. The enzymes unclog gummed-up recycling machinery while it is working, avoiding the need for expensive stoppages.
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The team aren鈥檛 yet revealing the source of their enzymes, but say they work by catalysing a reaction that breaks the chemical bonds in adhesives such as polyvinylacetates. They do this by cutting the larger globules down to size at the same time as reducing their tackiness. The worst stickies have globules bigger than 0.1 millimetres across. Globules smaller than this are much less of a problem, and tend to nestle away harmlessly in recycled fibres.
In pilot tests, the team has been getting encouraging results. By avoiding stoppages, one plant has already boosted paper production by 50 tonnes per day.
