Waste biomass residues, agricultural

Recurring feedstocks are those that are produced as wastes from other activities. They are usually considered as nuisance wastes that require significant costs and resources for control and disposal. These include paper sludge, municipal solid waste (fiber fraction), conventional forestry waste wood, agricultural residues etc. (21,37). Estimates of the availability vary widely for industrial and agricultural residue, however this type of waste is estimated to amount to around 300 million dry metric tons of per year (26). The quantity of municipal waste is also very large. It is estimated that in the United States every member of the population disposes of over four pounds of solid waste containing over two pounds of ceilulosic biomass each day. 

Biomass. Biomass is simply defined for these purposes as any organic waste material, such as agricultural residues, animal manure, forestry residues, municipal waste, and sewage, which originated from a living organism (70—74). 

One of the most promising substrates for future production of microbial biomass is the ceUulose contained in agricultural residues such as wood pulp, sawdust, feed-lot waste, com stover, rice huUs, nut sheUs, and bagasse, aU of which contain ceUulose as the principal carbon source. CeUulose contents range from 90% in cotton to 15—20% in dicotyledon leaves. Wood residues and grasses contain mixtures of ceUulose, hemiceUulose, and lignin. The major... 

The gasification process can use a variety of biomass resources, such as agricultural residues and wastes, or specifically grown energy crops. The technologies for gasifying... 

These systems offer the opportunity to produce hydrogen from renewable resources in the mid-term (five to ten years). Using agricultural residues and wastes, or biomass specifically grown for energy uses, hydrogen can be produced using a variety of processes. 

Waste biomass, such as peanut shells or bagasse (the residue from sugarcane), tends to be the most cost-effective source, but the ultimate supply is limited. Even in a country with as much arable land as the United States, a large fraction of agricultural land would need to be devoted to biomass production if that were to serve as the major source of transportation fuel. 

Wood is one of our most important renewable biomass resources. Unlike most biomass sources, wood is available year roimd and is more stable on storage than other agricultural residues. In the United States, wood residues from industrial by-products totaled 60.8 x 10 metric tons in 1993 (73). Increasingly, residues are incorporated into manufactured wood products and are used as a fuel, replacing petroleum, especially at wood-industry plants (73) some is converted to charcoal but most is used in the pulp and paper industry. Residues are also available for manufacturing chemicals, generally at a cost equivalent to their fuel value (see Fuels FROM BIOMASS Fuels from waste). 

Another large source of renewable carbon supplies is waste biomass. It consists of a wide range of materials and includes municipal solid wastes (MSW), municipal biosolids (sewage), industrial wastes, animal manures, agricultural crop and forestry residues, landscaping and tree clippings and trash, and dead biomass that results from nature s life cycles. Several of these wastes can cause serious health or environmental problems if they are not disposed of properly. Some wastes such as MSW can be considered to be a source of recyclables... 

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