Bagasse

Abstract: Various agricultural residues, such as corn fiber, corn stover, wheat straw, rice straw, and sugarcane bagasse, contain about 20–40% hemicellulose, the second most abundant polysaccharide in nature. The conversion of hemicellulose to fuels and chemicals is problematic. In this paper, various pretreatment options as well as enzymatic saccharification of lignocellulosic biomass to fermentable sugars is reviewed. Our research dealing with the pretreatment and enzymatic saccharification of corn fiber and development of novel and improved enzymes such as endo-xylanase, β-xylosidase, and α-l-arabinofuranosidase for hemicellulose bioconversion is described. The barriers, progress, and prospects of developing an environmentally benign bioprocess for large-scale conversion of hemicellulose to fuel ethanol, xylitol, 2,3-butanediol, and other value-added fermentation products are highlighted.

Abstract: Advances in industrial biotechnology offer potential opportunities for economic utilization of agro-industrial residues such as sugarcane bagasse. Sugarcane bagasse, which is a complex material, is the major by-product of the sugar cane industry. It contains about 50% cellulose, 25% hemicellulose and 25% lignin. Due to its abundant availability, it can serve as an ideal substrate for microbial processes for the production of value-added products. Attempts have been made to produce from bagasse substrate protein-enriched animal feed, enzymes, amino acids, organic acids and compounds of pharmaceutical importance, etc. Often, a pre-treatment process has resulted in improved substrate utilization by the microbes. Application of solid-state fermentation technology could be an attractive possibility for such bioconversions. This article reviews the recent developments on processes and products developed for the value addition of sugarcane bagasse through the biotechnological means. Emphasis has been given on more recent developments of the past 8–10 years.

Abstract: Physical processing or pretreatment of lignocellulosics concerns the ultrastructural modification of materials such as wood, straw and bagasse. The substrates produced can be subsequently converted by chemicals. The various pretreatment options will be discussed in the light of the ultrastructural, polymeric and chemical modifications that are obtained. The processes can be classified as follows: (i) steam; (ii) aqueous; and (iii) organosolvolysis treatments. All of these have their antecedents in the thermomechanical processes developed by the pulp and paper or fibreboard industries. Sequential application of thermomechanical technology leads to fractionation of the substrate into the major polymeric fractions: cellulose, hemicellulose and lignin in varying degrees of modification. A number of pretreatment concepts are now at a commercial scale and are being applied to produce foodstuffs from lignocellulosics for use by ruminant animals. The same techniques are being piloted in the energy and chemicals from lignocellulosics field.

Abstract: This work presents the evaluation of energy balance and GHG emissions in the production and use of fuel ethanol from cane in Brazil for 2005/2006 (for a sample of mills processing up to 100 million tons of sugarcane per year), and for a conservative scenario proposed for 2020. Fossil energy ratio was 9.3 for 2005/2006 and may reach 11.6 in 2020 with technologies already commercial. For anhydrous ethanol production the total GHG emission was 436 kg CO 2 eq m −3 ethanol for 2005/2006, decreasing to 345 kg CO 2 eq m −3 in the 2020 scenario. Avoided emissions depend on the final use: for E100 use in Brazil they were (in 2005/2006) 2181 kg CO 2 eq m −3 ethanol, and for E25 they were 2323 kg CO 2 eq m −3 ethanol (anhydrous). Both values would increase about 26% for the conditions assumed for 2020 mostly due to the large increase in sales of electricity surpluses. A sensitivity analysis has been performed (with 2005/2006 values) to investigate the impacts of the huge variation of some important parameters throughout Brazilian mills on the energy and emissions balance. The results have shown the high impact of cane productivity and ethanol yield variation on these balances (and the impacts of average cane transportation distances, level of soil cultivation, and some others) and of bagasse and electricity surpluses on GHG emissions avoidance.

Abstract: An inexpensive and effective adsorbent was developed from bagasse fly ash, obtained from a sugar industry, for the dynamic uptake of lead and chromium. Lead and chromium are sorbed by the developed adsorbent up to 96-98%. The removal of these two metal ions up to 95-96% was achieved by column experiments at a flow rate of 0.5 mlmin(-1). The adsorption was found to be exothermic in nature. The adsorbent was successfully tried for the removal of lead and chromium from wastewater in our laboratory. The developed system for the removal of two ions is very useful, economic, rapid, and reproducible.