The greatest challenge in paper recycling is removal of polymeric ink and coating. It was suggested that the most difficult raw material for deinking is the mixed office wastepaper especially the papers that had gone through photocopiers and laser printers.
Traditional deinking processes involve the use of large quantities of chemicals. Not only is this expensive, it causes pollution to the environment due to the excessive use of chemicals. Environmental friendly technology that exploits enzymes (biological molecules) potential has been the focus of many researches that look for lower operational cost and minimal environmental impact in paper deinking processes.
Enzymatic treatment can achieve similar effect as chemical treatment. It can even improve the deinking results without affecting the physical properties in the final paper product. Application of enzyme stable in alkaline environment has been shown in other research to be effective in increasing the brightness and reduced the ink counts of recycled paper.
A research project conducted by Universiti Malaysia Sarawak and Sarawak Forestry Corporation reported the use of a crude enzyme preparation for the enzymatic deinking of mixed office paper. The enzyme material was prepared by growing endoglucanase (enzyme use for the enzymatic treatment) producing Bacillus licheniformis BL-P7 in a liquid culture media containing sago pith waste and rice husk.
The enzymatic effect was compared to the conventional chemical treatment. The enzymatic deinking process was reported to produce better deinking effects on the mixed office paper compared to conventional chemical methods. Ink detachment from the paper fibre was facilitated by the enzymatic modification of the fibre surfaces. Furthermore, the process proved to be more effective for the removal of larger ink particles. Also, properties such as brightness, air permeability, tensile, and tear were enhanced in the handsheets preparation of the recycled mixed office paper.
Researchers : Hashimatul F.H., Hairul A.R., Andrew Wong H.H., Awg A.Sallehin A.H. (all of Universiti Malaysia Sarawak)
Nigel Lim P.T. (Sarawak Forestry Corporation)