Decolourization of recycled paper by biotechnological methods

Abstract

This project is done in collaboration with the “Grup de recerca en Enginyeria Paperera (Celbiotech)” of the Universitat Politècnica de Catalunya (UPC), which investigates new methods for deinking recycled fibres, using biotechnological methods and ozone. The main objective is to increase the use of fibres recycled from coloured paper. One of the main problems of this raw material is the presence of contaminants, such as colourants, which hinder its potential and causes the obtained product to loss part of its value. A big inconvenience of using recycled fibres from the disintegration of coloured paper as raw material is that the type of colourant used is unknown. Therefore, parameters based on measuring the optical properties of the paper sheets where used to determine the efficiency of the colour elimination sequences. The first part consisted in applying different enzymatic stages (laccasemediator system) and a bleaching chemical agent to the red/black recycled fibres for determining the efficiency of eliminating colour in the dough. Afterwards, different biotechnological agents (enzymes) and chemical treatments will be applied to the red recycled fibres using a combination of mediators and doubling the dose of mediator used in the red fibres in order to determine which treatment gives the best results. Later on, we will apply a selected colour elimination sequence to the red and black recycled fibres, with the aim of determining the best biochemical sequence. At the same time, studies with another oxidizing agent (ozone) will be done in order to determine if the enzymatic stages can substitute the ozone stage. Last part of the project consists in doing physical test to determine if the paper has lost any of its properties after the treatments. The enzymatic activity of the effluents will be calculated as well in order to determine which mediator performed better and the possibility of recirculating these effluents will be studied.