Alternatives for the Management of Industrial Forest Waste: Energy, Bioethanol, and Cellulose Pulp

Modern kraft pulp mills generate solid waste of 1–2% of incoming debarked wood. Given the size of these plants, with an annual production capacity of at least 1000,000 tons, each plant generates 20,000–30,000 dry tons of waste per year. The largest current use of these residues is for combustion in biomass boilers for steam and power generation. However, the conversion of biomass into biofuels and chemicals is gaining interest due to increasing demands for energy, limited sources of fossil fuels, and growing concerns about the environmental impact of greenhouse gas emissions. This chapter shows the laboratory-scale results of the use of eucalyptus wood wastes to obtain cellulose pulp by alkali pulping reinforced with hydrogen peroxide to obtain alkaline peroxide mechanical pulp or cellulosic bioethanol. Based on the results, an industrial-scale techno-economic analysis of the processes is presented and compared with current alternatives for energy generation

Bioprocess intensification for isopropanol, butanol and ethanol (IBE) production by fermentation from sugarcane and sweet sorghum juices through a gas stripping-pervaporation recovery process

Producción CientíficaButanol and isopropanol are important commodity chemicals with a variety of applications. One of the main obstacles for biobutanol production by IBE (isopropanol–butanol–ethanol) fermentation is the intensive energy consumption for product recovery by conventional distillation due to low butanol titer in fermentation broth caused by butanol toxicity to cells. In the present study, butanol production by batch IBE fermentation coupled to an in situ gas stripping-pervaporation process to recover the butanol is proposed using Clostridium beijerinckii DSM 6423 and a mixture of sugarcane-sweet sorghum juices as substrate. Gas stripping was used to continuously remove butanol from the fermentation broth, followed with pervaporation to further concentrate butanol. The strategy used allows alleviating butanol inhibition and to recuperate a condensate containing high butanol concentration (559 g/L). A kinetic model describing butanol production by IBE fermentation was developed. Kinetic parameters and experimental data were used to estimate the energy consumption of the sugarcane-sweet sorghum IBE production process. It was found that although the IBE production process showed less energy consumption (15%) than the butanol production process by ABE (acetone-butanol-ethanol) fermentation, a substantial improvement is still necessary for the process to be energetically/economically attractive.Agencia Nacional de Investigación e Innovación (ANII), Uruguay ( FSE 102720