Meeting biological and engineering challenges during scale-up of biopulping

Biopulping, defined as the treatment of ligoncellulosic materials with lignin-degrading fungi prior to pulping, is an environmentally friendly process that can increase mill throughput by 30%. The process reduces the electrical energy requirement by at least 30% and also improves paper strength properties during mechanical pulping. Over a period of ten years, we established the economic feasibility of biopulping at a pilot scale after meeting both biological and engineering challenges. We identified a fungus, Ceriporiopsis subvermispora that performs biopulping very effectively on different types of wood and reduced its amount of inoculum to a commercially attractive range. We also established that a brief atmospheric steaming decontaminates the wood chip surfaces, and allows the fungus to perform biopulping. Methods for decontaminating wood chip surfaces, cooling the chips after steaming, and inoculating them with the fungus on a continuous basis were developed Methods were also developed to maintain the optimum growth temperature and moisture in the chip pile so that the fungus could perform biopulping effectively and uniformly. An economic analysis was also performed which looks very attractive, and the process appears to fit well into a mill's woodyard operations.