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Gary M. Scott, Ph.D.
Faculty of Paper and Bioprocess Engineering
Empire State Paper Research Institute
State University of New York, College of Environmental Science and Forestry
The biopulping process, using a lignin-degrading fungus as a pretreatment to pulping, was scaled-up to near industrial levels. Past consortia research work has demonstrated the technical feasibility of this technology on a laboratory scale. The current scale up work was completed by a team consisting of myself, two microbiologists, and an engineering professor to do the process economics. The process design is either for chip piles or a silo-based system for which several factors needed to be considered. These factors included the necessary degree of decontamination of the wood chip surface, maintaining a hospitable environment for the fungus to be effective, and the overall process economics. A brief, low-pressure steaming of the chips was found to be sufficient for the decontamination, thus reducing the energy requirements in this step of the process. Furthermore, a simple, forced ventilation system was designed and used to maintain the proper temperature, humidity, and moisture content throughout the chip bed, thus promoting uniform growth of the fungus. The end result of the process, for mechanical pulping, was that a 2-week treatment saves 25 to 30% or more electrical energy at the refiner, which, considering the additional equipment and operating costs, results in an overall saving of $9 to $20 per ton of pulp in a chip-pile based system. This cost savings does not include other benefits listed previously that biopulping also confers, including the environmental benefits. The process has been successfully demonstrated by treating 4 tons of chips (at a rate of 12 tons/day) in an indoor pile and by treating 40 tons of chips (at a rate of 40 tons/day) in an outdoor chip pile. Much of the current and future funding for this work has been through various companies and granting agencies, indicating the wide-based support for this research.
Biopulping with the white-rot fungus Ceriporiopsis subvermispora has been shown to be very effective at the laboratory scale. Although technically and economically feasible, this particular fungus has two major drawbacks in its use for biopulping. First, it is generally limited to the temperature range of 27 to 32oC, thus requiring sufficient cooling air to maintain this condition. Second, it produces a fair amount of aerial hyphae, which restricts the air flow, causing increased pressure drop and ventilation costs. The white-rot fungus P. subserialis has several advantages. The fungus was identified as producing similar energy savings to that produced by C. subvermispora. However, it grows at in a temperature range of 27 to 39oC. In addition, the lack of aerial hyphae would significantly reduce the pressure drop when ventilating the pile to remove the heat. The combination of the wider temperature range (which reduces the volume of air that is needed) and the less aerial hyphae (which produces less pressure drop) significantly reduces the cost of aeration while producing the same benefits. The optimization and use of this fungus are expected to increase the economic benefits of the biopulping process by reducing the capital and operating costs of the process.
A professional video on the biopulping process is available, as are numerous scientific papers. The technology has been exclusively licensed to Biopulping International, a Wisconsin-based company that has taken the lead in commercializing biopulping technology and supporting further research at FPL and the State University of New York. The principles of this company are promoting this technology worldwide and have developed an extensive technology package which includes the patent licensing arrangements, supply of fungal inoculum, design and supply of appropriate equipment, and most important, technical knowledge.
Dr. Masood Akhtar|
Chief Executive Officer
Dr. Ross E. Swaney|
Department of Chemical Engineering
University of Wisconsin
Copyright 2003, Gary M. Scott. All rights reserved.