The potential of using a combined fungal and enzyme treatment system to remove detrimental dissolved and colloidal substances from TMP/newsprint mill process waters

The main objective of this thesis was to assess the potential of using a combined fungal and enzyme system as an internal treatment “kidney” to control the build up of detrimental dissolved and colloidal substances present in a TMP/newsprint mill process water. Some specific objectives were achieved as a result of this study.; A clear knowledge of the composition of a “typical” TMP process white water gave us a better understanding of the influence that the DCS components had on paper properties and it also helped in the design of an appropriate treatment technology. These included mill white waters collected from a typical TMP/newsprint mill and “model” recycled white waters (one to five times recycled white waters) made in the PAPRICAN pilot plant. A comprehensive protocol was established to analyze each of DCS components present in the different white water samples and to determine the various physical properties of each of the white water samples. By examining the physical properties of the handsheets prepared by using these different white waters, it was recognized that the properties of the papersheets formed in the white water were not only influenced by the different chemical natures of the white water DCS components, but also by their physical form (i.e. dissolved or colloidal).; The major detrimental components present in the white water were shown to be lignin and lipophilic extractives. Thus, the next objective of the study was to screen various fungi for their activities against these substances and to find a suitable strain that could carry out effective fungal and enzyme treatment of the white waters. As anticipated, the fungi utilized a small portion of the white water from the main stream which was cooled to 30°C before feeding into a bioreactor to produce enzymes present within the fungal culture filtrate (FCF). More importantly, many of the enzymes required to break down the DCS substrates could then be released into the white water.; Over twenty fungal strains were screened through a two step-process. From the two screening steps, the white-rot fungus Trametes versicolor showed both the highest growth on white water and highest activity against the DCS components present in the TMP white water. Therefore, this fungus was selected for further study. (Abstract shortened by UMI.)...