Biological Pulping-その原理と技術上の問題点-
1980 年 34 巻 12 号 p. 761-768
詳細
1980 年 34 巻 12 号 p. 761-768
In current view of energy saving, the studies on biological pulping become more attractive in people of pulp industry.
The origin of biological pulping is natural degradation of lignin by a white rot fungus, which remains white cellulose in the decayed trees or logs in forest. While the last several years, researches of biodegradation of lignins and of these applications have been increased, and an international seminar on lignin biodegradation in US-Japan Cooperative Science Program 1978 was held at the U. S. Forest Products Laboratory, Madison. The proceedings of that seminar provide many fundamental principles for biological pulping.
Suitable microorganisms, culture conditions and enzymic mechanisms for accelerating degradation of lignin are important and outlines of the recent relative reports are reviewed.
It is noticeable that degradation of lignin by white rot fungus goes forward with consumption of co-substrates ; cellulose, hemicellulose or the other carbon sources. The requirement of co-substrates for biodegradation of lignin is one of problems for practical biological pulping.
Eriksson and Vallander studied on biomechanical pulping. They have a mutant strain of the white rot fungus, Sporotrichum pulverulentum, which produce no cellulase. The strain of the fungus is applicable for pretreatment of thermomechanical pulping and their studies showed that about 30% energy could save at the pulp production from chips of birch, rotted for 12 days by the fungus.
Of the white rot fungi, there are the fungi having bleaching ability. Using several these fungi and edible mushroom fungi, an investigative study was carried out to estimate properties and yields of the biochemical pulps in our department. The pulps were made from rotted chips of Quercus serrata by SCP or KP digesting method. Our study showed that the yields of the pulps decreased by 410%, but the brightness increased. The properties of the biochemical pulps were almost equivalent with control chemical pulps and some of the pulps rather increased the strength.
These studies on the biological pulping suggest that good quality of pulps ; increasing strength and brightness, may be produced under energy and chemical savings.
An important technological problem on the biological pulping is how to cultivate the fungus in a mass of wood chips with homogenious and rapid growth of the mycelia. A device for mass cultivation is proposed, and needs of fundamental researches on the biological pulping are discussed and emphasized.
