C« biomass

Significant differences in net photosynthetic assimilation of carbon dioxide are apparent between C, C, and CAM biomass species. One of the principal reasons for the generally lower yields of C biomass is its higher rate of photorespiration if the photorespiration rate could be reduced, the net yield of biomass would increase. Considerable research is in progress (ca 1992) to achieve this rate reduction by chemical and genetic methods, but as yet, only limited yield improvements have been made. Such an achievement with C biomass would be expected to be very beneficial for foodstuff production and biomass energy appHcations. 

Figure 7.5 Changes in (a) PolyP content, (b and c) PolyP-metabolizing enzymes activities, and (c) biomass and production of chlortetracycline during growth of the low-producing strain of Strepto-myces aureofaciens 2209 (Kulaev et al., 1976). (a) (1) total acid-insoluble PolyP (2) PolyP extracted with hot perchloric acid (3) salt-soluble PolyP (b) (1) polyphosphate kinase (centre scale) (2) 1,3-diphosphoglycerate-polyphosphate phosphotransferase (right-hand scale) (3) PolyP glucokinase (left-hand scale) (c) (1) biomass (2) chlortetracycline (3) exopolyphosphatase with PolyP29o (4) pyrophosphatase (5) tripolyphosphatase.

Webb, C., Biomass Holdup in Immobilized Cell Reactors, Chap. 8 in Process Engineering Aspects of Immobilized Cell Systems, pp. 117-133. Instn. Chem. Engrs. (London), 1986. Weber, G., New Lift Technique, Oil Gas J., IS (1952). 

Absolute rates were obtained by multiplying specific rates by total nitrogen biomass. Total nitrogen biomass was calculated from C biomass using a C N of 6.6. 

FIGURE 3.3 Biochemical pathway from carbon dioxide to glucose for C, biomass. (Net process 5 ATP, 2 NADPHj, 4 Fd VCOj assimilated.)... 

Run number T Riser ( C) T Combustor ( C) Biomass Fluidizing Vapor flow-rate air residence (kg flow-rate time (ms) itiaffh) (kg/h) Total liquids Mass yield balance (%wt on maf closures feedstock) (%) ... 

Almost all feedstocks of interest have such properties that they do not flow readily through cither pipes or shell of a conventional heat exchanger without distribution problems. Afler a number of alternatives had been considered it was concluded that the most adequate way of preheating is direct injection of hot water. In Fig. 3 this is done in vessel V where a stream of hot recycle water is mixed with the feed. A special way of contacting achieves efficient heat and mass transfer. It has been verified in our experiments that at 200-250°C biomass feedstocks of different origin, including wood chips, arc softened and form a pastc-like substance [7,8]. The... 

FIGURE 8 A pan-European field experimenl (a) Overall log-linear reduction of above ground biomass with the simulated loss of plant species richness, (b) Linear reduction with the loss of functional group richness within species richness levels, (c) Biomass patterns at each site (displayed with species richness on a log. scale for comparison with panel (a)) (Hector et al., 1999). 

Batch reactors were used for the SAA pretreatment. For low temperature operation up to 80 °C, biomass was soaked with 15% ammonia in screw-capped laboratory glass bottle and kept in an oven. For runs above 80 °C, stainless steel reactors (1.375 in. ID><6 in. 1) were used. For com stover, 60 °C temperature was used with 12 h soaking time and 1 8 solid to liquid ratio. For HL and LL hybrid poplar, the temperature of 150 °C was employed with 24 h soaking time and 1 10 solid to liquid ratio. 

Laboratory (4) and Process Development Unit (5,6) studies originally conducted at the Universite de Sherbrooke, and now conducted jointly with the private industry at Universite Laval, province of Quebec, have led to the conclusion that thermal decomposition under reduced pressure is an attractive approach for the conversion of biomass into chemicals and fuels products. The process uses a multiple-hearth furnace for wood pyrolysis. This approach is characterized by a low pressure and a short residence time of the vapor products in the rciactor. When compared with conventional, atmospheric pressure carbonization, vacuum pyrolysis has the potential to significantly enhance the yields of organic liquid products with respect to solid and gaseous products. The pyrolysis oils (biooils) obtained from this process can be deoxygenated into transportation fuels upon further upgrading (7). Specialty as well as commodity (Pakdel, H. Roy, C. Biomass, in press) chemicals can also be extracted from the pyrolysis oil product. 

Characterization of the low molecular weight carboxylic acids was successfully achieved following benzylation technique developed in our laboratory (Pakdel, H. Roy, C. Biomass, in press). Formic and acetic acids as decomposition products of cellulose and hemicellulose were the major constituents of pyrolysis oils (15). 

Perlack, R.D, Wright, L.L.,Turhollow, A.F., Graham, R.L., Stokes, B.J. Erbach, D.C. Biomass as feedstock for a bioenergy and bioproducts industry the technical feasibility of a billion-ton annual supply. DTIC Document, 2005. 

Table 5.122 Adhesion parameters (c = biomass growth constant, = adhesive force,...

Shah, N., Dunnet, A., Adjiman, C. Biomass to heat supply chains applications of process optimization. Process Safety and Environmental Protection. 85 (5), 419—429, 2007. 

Figure 9.2 Morphologies of (a) fiber bundles with silica body, (b) fibers attached with parenchyma cells, (c) biomass after pretreatment, and (d) residues from enzymatic hydrolysis. The images were kindly provided by Dr. Hao Liu from the State Key Laboratory of Pulp and Paper Engineering at South China University of Technology.

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