Forest product waste

More recently, interest has developed in the use of enzymes to catalyze the hydrolysis of cellulose to glucose (25—27). Domestic or forest product wastes can be used to produce the fermentation substrate. Whereas there has been much research on alcohol fermentation, whether from cereal grains, molasses, or wood hydrolysis, the commercial practice of this technology is primarily for the industrial alcohol and beverage alcohol industries. About 100 plants have been built for fuel ethanol from com, but only a few continue to operate (28). 

CBPC matrix composites can incorporate a high volume of industrial waste streams such as fly ash, mineral waste such as iron taUings and Bayer process residue from the aluminum industry (red mud), machining swarfs from the automobile industry, and forest product waste such as saw dust and wood chips. Table 14.1 lists some of these waste streams and potential products or applications. 

R. Kat2en Associates, Chemicals from Wood Wastes, U.S. Department of Agriculture Forest Products Laboratory, Madison, Wise., Dec. 14,1975. 

Wastes or By-products as Raw Materials. By far the largest volume of natural products for industrial use, aside from the forest products, are wastes or by-products of food processing (qv). The largest use of these wastes is as animal feeds. Because they are used rather than becoming a disposal problem, they are considered to be chemurgic products. 

Grain that is usable as food or feed is an expensive substrate for this fermentation process. A cheaper substrate might be some source of cellulose such as wood or agricultural waste. This, however, requires hydrolysis of cellulose to yield glucose. Such a process was used in Germany during World War II to produce yeast as a protein substitute. Another process for the hydrolysis of wood, developed by the U.S. Forest Products Laboratory, Madison, Wisconsin, uses mineral acid as a catalyst. This hydrolysis industry is very large in the former Soviet Union but it is not commercial elsewhere. 

Forest products industries know that temperature increases in piles of sawdust and bark. In pulp and paper mills, self-heating develops in amassed tree chips. Paper rolls stacked hot tend to self-heat, as occasionally do stored bales of waste paper. The wood-base panel products particleboard, hardboard, and fiberboard self-heat after being stacked too hot in the factory. Where in structures the framing lumber, wood-base panels, and lignocellulosic insulation is heated by items such as steam pipes, temperatures tend to rise above that of the heat source. 

Wood biomass involves trees with cotranercial stracture and forest residues not being used in the traditional forest products industries. Available forest residues may appear to be an attractive fuel source. Collection and handling and transport costs are critical factors in the use of forest residues. Although the heat produced from wood wastes is less than that from oil or gas, its cost compared to fossil fuels makes it an attractive somce of readily available heat or heat and power. The most... 

Baking and food processing Brewing and fermentation Forest products Detergents Specialty chemicals Waste treatment... 

Raphael Katzen Associates, "Chemicals from Wood Waste, Forest Products Laboratory, U.S. Forest Service, Madison, Wisconsin, 1975. 

Use renewable feedstocks Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are often made from agricultural and forest products or are the wastes of other processes depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined. Another advantage of renewable feedstocks is that often the oxidation state of the feedstock is often close to that of the desired product. This simplifies and reduces the number and extent of chemical transformations necessary in a synthetic pathway. 

If this method proves to be commercially feasible, a renewable and abundant waste product of forest products manufacture could replace expensive petrochemicals. Additionally, use of an inexpensive waste product from processing of forest products could materially reduce adhesive costs and expand opportunities for manufacture of structural materials from low-quality wood. This benefit is particularly important since the difficulty in producing large, strong, structural members from timber resources of declining quality is growing exponentially with time. The cost-benefit ratios of replacing PRF resins with extracts from conifer barks are, therefore, quite favorable in a honeymoon system. 

Waste materials Forest products Energy crops... 

Liu, M.S., Serenius, R., "Fluidized Bed Solids Waste Gasifier", Forest Products Journal 26a, 56-59, 1976. 

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