NEW TECHNOLOGY FOR PAPERMAKING - COMMERCIALIZING BIOPULPING

Biopulping is defined as the treatment of wood chips with lignin-degra ding fungi prior to pulping. Fungal pretreatment prior to mechanical p ulping reduces electrical energy requirements during refining or incre ases mill throughput, improves paper strength, reduces the pitch conte nt, reduces cooking time for sulfite pulping, and reduces the environm ental impact of pulping. Our recent work involved scaling up the biopu lping process toward the industrial level, investigating both the engi neering and economic feasibility of the technology. We envision the pr ocess to be done in either a chip-pile or silo-based system for which several factors need to be considered: the degree of decontamination, a hospitable environment for the fungus, and the overall process econo mics. Currently, treatment of the chips with low-pressure steam is suf ficient for decontamination. Furthermore, a simple, forced ventilation system can be used to maintain the proper temperature, humidity, and moisture content throughout the chip bed, thus promoting uniform growt h of the fungus. The pilot-scale vial resulted in the successful treat ment of 4 tons of wood chips (dry weight basis), with results comparab le to those on a laboratory scale. For mechanical pulping, a 2-week tr eatment results in approximately 30% energy savings, which, considerin g the additional equipment and operating costs, results in on overall savings of US$ 10-20 per ton of pulp in a chip-pile system. Larger 40- ton vials were also successful with energy savings and paper propertie s comparable with the laboratory scale.