Agricultural by-products and wastes

West, L., Pomerleau, T., Matusheski, N., Ludwing, C., Hestekin, J., Crowley, C., and K.N. 2008. Production of Glucosinolates from Agricultural By-Products and Waste. United States of America Patent Application US 2008/0311276A1. 

The list of plants, by-products and waste materials that can potentially be used as feedstock is almost endless. Major resources in biomass include agricultural crops and their waste by-products, lignocellulosic products such as wood and wood waste, waste from food processing and aquatic plants and algae and effluents produced in the human habitat. Moderately dried wastes such as wood residue, wood scrap and urban garbage can be directly burned as fuel. Energy from water-containing biomass... 

Mining and processing phosphate ores redistribute and its decay products among the various products, by-products and wastes of the phosphate industry. Effluent discharges into the environment as well as the use of phosphate fertilizers in agriculture and of by-products in the building industry are possible sources of exposure to the public (Lardinoye et al., 1982 Nash, 1987). 

The exposure pattern, or chain of relationships between radioactivity in agricultural products and radiation dose and health effects (risk) in humans, is schematically presented in Fig. 3.1. The actual radionuclides present in some phosphate fertilizers (including by products and wastes) contribute to the radiation exposure of a population (Fisher et al., 1979 Fitzgerald and Sensitaffar, 1978 Phillip et al., 1978). 

Expansion of production. The a priori limited) supply of products from the agricultural and forestry primary production can be expanded only by an expansion of production. This is possible by a more intensive production i.e. higher yield per hectare) and/or a production on land not used on a commercial basis so far. For the latter option the needed land areas in Europe are available (see above). In contrast to that, emerging competitions about residues, by-products and waste can not be met by an expansion of the agricultural and forestry primary production or only to a very limited extent. 

Steam turbines are an even older technology, providing power for over 100 years. Most utility power is produced by steam turbines. The steam turbine generator depends on a separate heat source for steam, often some type of boiler, which may run on a variety of fuels, such as coal, natural gas, petroleum, uranium, wood and waste products including wood chips or agricultural by-products. 

The removal of metal ions from waste aqueous solutions is of importance to many countries of the world both environmentally and for water re-use. The application of low-cost sorbents including carbonacceous materials, agricultural products and waste by-products has been investigated [1], Several researchers employing wide variety techniques have attempted removal of metal ions from contaminated water bodies. Majorities of these are adsorption on various surfaces. In recent years, agricultured by products have been widely studied for metal removal from water. These include peat [2], pine bark [3], banana peat [4], peanut shells [5], sawdust [6] and leaves [7]. 

Pentoses contained in hemicellulose are used to produce furfural, a useful industrial chemical, used as a solvent for resins and waxes and in petrochemical refining. It is also used as a feedstock for a range of aromatic substances (it has an almond odour) including preservatives, disinfectants and herbicides. Furfural can be converted to furfuryl alcohol and used to make resins for composite applications with fibreglass and other fibres. These are of interest in the aircraft component and automotive brake sectors. Furfural is commercially derived from acid hydrolysis of waste agricultural by-products, such as sugarcane bagasse, com cobs and cereal brans. Around 450 000 tonnes is produced by this method per year. 

The cellulose-to-ethanol process has five basic steps as shown in Figure I. They are feedstock handling and pretreatment, enzyme production, yeast production, simultaneous saccharification/fermentation (SSF) and ethanol recovery. Cellulose is the most abundant organic material on the earth. It is annually renewable, and not directly useful as a foodstuff. It is a polymer of glucose linked /8-1,4 as compared with the a-1,4 linked polymer starch which by contrast is easily digestible by man. There are three basic classes of potential cellulose feedstocks. These are agricultural by-products, industrial and municipal wastes, and special crops. The availability of these materials in the U.S. is shown in Table I. For economic reasons, we are concentrating our efforts on those materials that are collected for some other reason. 

Marshall, W.E. and Champagne, E.T. 1995. Agricultural by-products as adsorbents for metal-ions in laboratory prepared solutions and in manufacturing waste water. J. EnvimtL Sci. Health A 30 241-261. 

The market demand is also essential for the economics of butanol fermentation. It is expected that after biobutanol is adapted as a liquid fuel, the demand will astonishingly increase. Nonetheless, butanol is even more important as a chemical feedstock rather than as a fuel (Mascal, 2012). So, development of novel feasible industry routes for butanol-derivative products could significantly increase the market demand for butanol, and thus draw closer to the commercial production of biobutanol using the biological fermentation process. Furthermore, the recovery and utilization of the fermentation by-products (nutritional waste stream, cell biomass, CO2, and H2) can also contribute substantially to the economics of biobutanol production. For example, H2 can be used as a clean energy source, while the nutritional waste stream and cell biomass can be used for some agricultural purposes after proper treatment processes. 

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