Shuangning Xiu

Swine manure/crude glycerol co-liquefaction: physical properties and chemical analysis of bio-oil product.

The aim of this work was to investigate the principal structural and physico-chemical changes of bio-oils associated with liquefaction of swine manure with crude glycerol and its key fraction, free fatty acids. Bio-oils have been obtained from liquefaction processes at 340 °C. They were subjected to various physico-chemical characterization methods. FTIR data indicated a reduction in aliphatic structures and an increase in more oxidized and, probably, more polycondensed aromatic components resulting from the addition of crude glycerol to swine manure. GC-MS data indicated that the addition of crude glycerol facilitated the esterification reaction in sub-critical water to convert organic acids contained in bio-oil into various kinds of esters. The dynamic viscosity of bio-oil decreased dramatically by adding crude glycerol into the swine manure.

Co-liquefaction of swine manure and crude glycerol to bio-oil: Model compound studies and reaction pathways

The reaction pathways of co-liquefaction of swine manure and crude glycerol to bio-oil (ester compounds) were investigated. Swine manure was hydrothermal treated (340 °C, 27.5 MPa, 15 min) with a number of model compounds in a high pressure batch reactor under inert atmosphere. The compounds were methanol, pure glycerol, mixture of pure glycerol, pure methanol and H(2)O, and commercial fatty acids (linoleic acid). The chemical composition of the bio-oil was analyzed by GC/MS. Glycerol, methanol and water showed synergistic effects on manure liquefaction, increasing the oil yield as high as 65%. A maximum oil yield of 79.96% was obtained when linoleic acid reacted with swine manure. Based on the results, the reaction pathways were proposed. Esterification reactions occurred not only because the crude glycerol have methanol, but also because methanol can be produced from hydrothermal reactions of glycerol.

Oil production from duckweed by thermochemical liquefaction.

Abstract Duckweed was treated over a temperature range 250–374°C, a retention time of 5–90 min, and a catalyst loading of 0–10 wt% by a high-pressure reactor. Operating temperature, retention time, and catalyst loading are all found to affect oil yield. The lower limit of reaction temperature for the production of heavy oil was found to be 260°C. The highest oil yields were obtained at 30% on an organic basis under the following conditions: reaction temperature of 340°C, retention time of 60 min, and operation without catalyst. The average heating value of the bio-oil product was estimated at 34 MJ/kg.

Pretreatment and Fractionation of Wheat Straw with Acetic Acid to Enhance Enzymatic Hydrolysis and Ethanol Fermentation

Abstract Acetic acid was used to pretreat and fractionate wheat straw. A 25% acetic acid solution at 160°C could remove all xylan and 26.2% of lignin in the wheat straw at a 10% solid concentration while recovering 94.2% of glucan. The glucan content of the pretreated wheat straw was 60.9% compared to 35.5% in the raw wheat straw. After the 6-day hydrolysis with a cellulase at a load of 15 FPU/g glucan, 67.6% of the glucan in the acetic acid-pretreated wheat straw was hydrolyzed into glucose, compared to 58.3, 26.0, and 24.4% for pure cellulose, wheat straw pretreated with hot water at 160°C, and raw wheat straw, respectively.

Effects of fertilizer application and dry/wet processing of Miscanthus x giganteus on bioethanol production.

The effects of wet and dry processing of miscanthus on bioethanol production using simultaneous saccharification and fermentation (SSF) process were investigated, with wet samples showing higher ethanol yields than dry samples. Miscanthus grown with no fertilizer, with fertilizer and with swine manure were sampled for analysis. Wet-fractionation was used to separate miscanthus into solid and liquid fractions. Dilute sulfuric acid pretreatment was employed and the SSF process was performed with saccharomyces cerevisiae and a cocktail of enzymes at 35°C. After pretreatment, cellulose compositions of biomass of the wet samples increased from 61.0-67.0% to 77.0-87.0%, which were higher than the compositions of dry samples. The highest theoretical ethanol yield of 88.0% was realized for wet processed pretreated miscanthus, grown with swine manure. Changes to the morphology and chemical composition of the biomass samples after pretreatment, such as crystallinity reduction, were observed using SEM and FTIR. These changes improved ethanol production.

Green biorefinery of fresh cattail for microalgal culture and ethanol production.

Green biorefinery represents an appropriate approach to utilize the fresh aquatic biomass, eliminating the drying process of conventional bioenergy-converting system. In this study, fresh cattails were homogenized and then filtered, whereby cattails were separated into a fiber-rich cake and a nutrient-rich juice. The juice was used to cultivate microalgae Chlorella spp. in different media. In addition, the solid cake was pretreated with the sonication, and used as the feedstock for ethanol production. The results showed that the cattail juice could be a highly nutritious source for microalgae that are a promising feedstock for biofuels. Sugars released from the cattail cake were efficiently fermented to ethanol using Escherichia coli KO11, with 8.6-12.3% of the theoretical yield. The ultrasonic pretreatment was not sufficient for pretreating cattails. If a dilute acid pretreatment was applied, the conversion ratio of sugars from cattails has the potential to be over 85% of the theoretical value.

Biorefinery Processes for Biomass Conversion to Liquid Fuel

The development of products derived from biomass is emerging as an important force component for economic development in the world. Rising oil prices and uncertainty over the security of existing fossil reserves, combined with concerns over global climate change, have created the need for new transportation fuels and for the manufacture of bioproducts to substitute for fossil-based materials. The United States currently consumes more than 140 billion gallons of transportation fuels annually. Conversion of cellulosic biomass to biofuels offers major economic, environmental, and strategic benefits. DOE and USDA predict that the U.S. biomass resources could provide approximately 1.3 billion dry tons of feedstock for biofuels, which would meet about 40% of the annual U.S. fuel demand for transportation (Perlack et al., 2005). More recently, in January 2010, U.S. President Barack Obama delivered a request during his State of the Union speech for Congress to continue to invest in biofuels and renewable energy technology. Against this backdrop, biofuels have emerged as one of the most strategically important sustainable fuels given their potential to increase the security of supply, reduce vehicle emissions and provide a steady income for farmers. Several biorefinery processes have been developed to produce biofuels and chemicals from the initial biomass feedstock. Of all the various forms energy can take, liquid fuels are among the most convenient in terms of storage and transportation and are conducive to the existing fuel distribution infrastructure. This chapter comprehensively reviews the state of the art, the use and drawbacks of biorefinery processes that are used to produce liquid fuels, specifically bioethanol and bio-oil. It also points out challenges to success with biofuels in the future.

Uses of miscanthus press juice within a green biorefinery platform.

This study assesses some uses of nutrient-rich juice mechanically extracted from freshly harvested Miscanthus x giganteus (MxG) as part of a green biorefinery system. The juice was used for culturing Saccharomyces cerevisiae and lactic acid bacteria. MxG juice was further used as substrate for fermentation to produce lactic acid using Lactobacillus brevis and Lactobacillus plantarum. The results show that MxG juice was a highly nutritious source for the cultivation of bacteria. Higher concentrations of MxG juice used as culture media, resulted in higher cell growth both aerobically and anaerobically. The highest ethanol yield of 70% theoretical and concentration of 0.75g/100ml were obtained from S. cerevisiae cultivated with 90% (v/v) MxG juice media and used for miscanthus solid fraction fermentation. 11.91g/L of lactic acid was also successfully produced from MxG juice through SSF.

Co-liquefaction of swine manure with waste vegetable oil for enhanced bio-oil production

ABSTRACT Waste vegetable oil was co-liquefied with swine manure to determine the bio-oil potential in this study. The result shows that co-liquefaction of waste vegetable oil with swine manure can improve the bio-oil production and decarboxylation of waste vegetable oil. The weight ratio of swine manure to waste vegetable oil exerted a great effect on both the yield and quality of the bio-oil. The optimum weight ratio of swine manure to waste cooking oil was 1:3, where a maximum oil yield of 80% was obtained with higher calorific value up to 38 MJ/kg.

Separate Hydrolysis and Fermentation of Untreated and Pretreated Alfalfa Cake to Produce Ethanol

The use of lignocellulosic biomass to produce biofuel will add value to land and reduce emissions of greenhouse gases by replacing petroleum products. Valuable co-products derived from fractionation of alfalfa (Medicago sativa) give the resulting fibrous fraction an economic advantage as a feedstock for ethanol production. Freshly harvested alfalfa was dewatered using centrifugation and filtration, whereby alfalfa is separated into a fiber-rich cake and a nutrient-rich juice. Alfalfa solids was pretreated with alkaline soaking (1, 4, and 7 %) at room temperature to evaluate the effects on cellulose digestibility. The production of cellulosic ethanol from alfalfa fibers were investigated by this work using separate hydrolysis and fermentation (SHF). Results show the alkali pretreatment was able to effectively increase cellulosic digestibility of alfalfa solids. A maximal glucose yield of 61 % was obtained with filtered solids with 1 % NaOH pretreatment. The filtration process resulted in a solid fraction with a higher cellulose digestibility, which leads to a higher ethanol production.