Manuel Garcia-Perez

Separation, hydrolysis and fermentation of pyrolytic sugars to produce ethanol and lipids

This paper describes a new scheme to convert anhydrosugars found in pyrolysis oils into ethanol and lipids. Pyrolytic sugars were separated from phenols by solvent extraction and were hydrolyzed into glucose using sulfuric acid as a catalyst. Toxicological studies showed that phenols and acids were the main species inhibiting growth of the yeast Saccharomyces cerevisiae. The sulfuric acids, and carboxylic acids from the bio-oils, were neutralized with Ba(OH)(2). The phase rich in sugar was further detoxified with activated carbon. The resulting aqueous phase rich in glucose was fermented with three different yeasts: S. cerevisiae to produce ethanol, and Cryptococcus curvatus and Rhodotorula glutinis to produce lipids. Yields as high as 0.473 g ethanol/g glucose and 0.167 g lipids/g sugar (0.266 g ethanol equivalent/g sugar), were obtained. These results confirm that pyrolytic sugar fermentation to produce ethanol is more efficient than for lipid production.

DSC studies to evaluate the impact of bio-oil on cold flow properties and oxidation stability of bio-diesel.

This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect.

Recent developments in fast pyrolysis of ligno-cellulosic materials

Pyrolysis is a thermochemical process to convert ligno-cellulosic materials into bio-char and pyrolysis oil. This oil can be further upgraded or refined for electricity, transportation fuels and chemicals production. At the time of writing, several demonstration factories are considered worldwide aiming at maturing the technology. Research is focusing on understanding the underlying processes at all relevant scales, ranging from the chemistry of cell wall deconstruction to optimization of pyrolysis factories, in order to produce better quality oils for targeted uses. Among the several bio-oil applications that are currently investigated the production and fermentation of pyrolytic sugars explores the promising interface between thermochemistry and biotechnology.

Yeast fermentation of carboxylic acids obtained from pyrolytic aqueous phases for lipid production.

The presence of very reactive C1-C4 molecules adversely affects the quality bio-oils produced from the pyrolysis of lignocellulosic materials. In this paper a scheme to produce lipids with Cryptococcus curvatus from the carboxylic acids in the pyrolytic aqueous phase collected in fractional condensers is proposed. The capacities of three oleaginous yeasts C. curvatus, Rhodotorula glutinis, Lipomyces starkeyi to ferment acetate, formate, hydroxylacat-aldehyde, phenol and acetol were investigated. While acetate could be a good carbon source for lipid production, formate provides additional energy and contributes to yeast growth and lipid production as auxiliary energy resource. Acetol could slightly support yeast growth, but it inhibits lipid accumulation. Hydroxyacetaldehyde and phenols showed high yeast growth and lipid accumulation inhibition. A pyrolytic aqueous phase with 20 g/L acetate was fermented with C. curvatus, after neutralization and detoxification to produce 6.9 g/L dry biomass and 2.2 g/L lipid.

Fermentation of levoglucosan with oleaginous yeasts for lipid production

This paper reports the production of lipids from non-hydrolyzed levoglucosan (LG) by oleaginous yeasts Rhodosporidium toruloides and Rhodotorula glutinis. Enzyme activity tests of LG kinases from both yeasts indicated that the phosphorylation pathway of LG to glucose-6-phosphate existed. The highest enzyme activity obtained for R. glutinis was 0.22 U/mg of protein. The highest cell mass and lipid production by R. glutinis were 6.8 and 2.7 g/L, respectively from pure LG, and 3.3 and 0.78 g/L from a pyrolytic LG aqueous phase detoxified by ethyl acetate extraction, rotary evaporation and activated carbon. This corresponded to a lipid yield of 13.5 wt.% for pure LG and only 3.9 wt.% for LG in pyrolysis oil.

Slow pyrolysis of poultry litter and pine woody biomass: Impact of chars and bio-oils on microbial growth

Accidental or prescribed fires in forests and in cultivated fields, as well as primitive charcoal production practices, are responsible for the release of large amounts of gases, char and condensable organic molecules into the environment. This paper describes the impact of condensable organic molecules and chars resulting from the slow pyrolysis of poultry litter, pine chips and pine pellets on the growth of microbial populations in soil and water. The proximate and elemental analyses as well as the content of proteins, cellulose, hemicellulose, lignin, and ash for each of these bio-materials are reported. The yields and some properties of char and condensable liquids are also documented. The behavior of microbial populations in soil and water is followed through respiration studies. It was found that biological activity was highest when aqueous fractions from poultry litter were applied in water. Cumulative oxygen consumption over a 120-h period was highest in the aqueous phases from poultry litter coarse fraction (1.82 mg/g). On average the oxygen consumption when oily fractions from poultry litter were applied represented 44 to 62% of that when aqueous fractions were applied. Pine chip and pine pellet derived liquids and chars produced respiration activity that were an order of magnitude lower than that of poultry litter liquid fractions. These results suggest that the growth observed is due to the effect of protein-derived molecules.

Co-pyrolysis under vacuum of sugar cane bagasse and petroleum residue : Properties of the char and activated char products

Abstract Vacuum pyrolysis of sugar cane bagasse (5.7% moisture) at 500°C and 8 kPa yielded 19.4% charcoal, 34.2% pyrolytic oil, 27.8% water and light organic compounds and 17.6% gases. High surface area (∼1950 m 2 /g) activated carbon was obtained from the chars by steam activation. It was earlier observed that the properties of bagasse-derived pyrolytic oil (biofuel) can be improved by co-pyrolysing the bagasse with petroleum residue. The addition of petroleum residue affects the yields and properties of the pyrolytic char. It was shown by thermogravimetry that the formation of the bagasse char is almost complete when the pyrolysis of the major portion of the petroleum residue occurs. Products from the petroleum residue pyrolysis are deposited on the bagasse char, increasing its yield. According to surface spectroscopic results, the surface of the bagasse char is completely covered when the feedstock concentration of petroleum residue reaches 15%. At this concentration the char yield reaches a maximum (30%). Co-pyrolysis chars yield activated carbon with a lower surface area as compared to bagasse chars. However, since the activated carbons derived from the co-pyrolysis char still have high surface areas and the corresponding pyrolytic oil has good combustion properties, co-pyrolysis of bagasse with petroleum residue might be economically feasible.

Effect of biochar on leaching of organic carbon, nitrogen, and phosphorus from compost in bioretention systems.

Compost is used in bioretention systems to improve soil quality, water infiltration, and retention of contaminants. However, compost contains dissolved organic matter, nitrate, and phosphorus, all of which can leach out and potentially contaminate ground and surface waters. To reduce the leaching of nutrients and dissolved organic matter from compost, biochar may be mixed into the bioretention systems. Our objective was to test whether biochar and co-composted biochar mixed into mature compost can reduce the leaching of organic carbon, nitrogen, and phosphorus. There was no significant difference between the effects of biochar and co-composted biochar amendments on nutrient leaching. Further, biochar amendments did not significantly reduce the leaching of dissolved organic carbon, nitrate, and phosphorus as compared to the compost only treatment. The compost-sand mix was the most effective in reducing nitrate and phosphorus leaching among the media.

The role of biochar porosity and surface functionality in augmenting hydrologic properties of a sandy soil

This paper reports studies to elucidate the potential relationships between porosity and surface functionality of biochar and soil water retention characteristics. The biochars studied were produced from pine wood (PW), hybrid poplar wood (HP), and pine bark (PB) at temperatures of 350°C and 600°C. The resulting materials were then oxidized under air at 250°C to generate oxygenated functional groups on the surface. All biochar were thoroughly characterized (surface and bulk properties) and their hydrological properties measured in blends with Quincy sand. We prepared 39 microcosms for this study to examine the effect of biochar functionalities and porosity on the hydro-physical properties of Quincy sand. Each biochar was thoroughly mixed with the soil at 20gkg-1. The field capacity, wilting point, and total available soil moisture of the bio-char/Quincy sand mixtures were measured for both dry and wet ranges. The soil water potentials and soil water contents were fitted using the model of van Genuchten. Our results indicated that the amount of oxygenated functional groups on the surface of biochars clearly differentiated the biochars in terms of hydrophilicity, with the oxidized biochars being superior, followed by the low-temperature biochars, while the high temperature biochars possessed lowest hydrophilicity. As a result, oxidized biochars exhibited better wettability compared to unoxidized biochars, regardless their feedstock source. Significant correlation occurred between the total acidic functional groups on biochar surface and water contents at different matric potentials. Over a wide range of soil water potentials, oxidized biochar-soil mixtures held more water than the unoxidized biochar-soil mixtures except in the region between -0.1 and -5kPa of ψ, which is near saturation. Soil water contents at different matric potentials were significantly inter-correlated (P<0.01) and correlated with bulk densities of biochar-amended soil samples.

Determination of Kinetic Parameters of Thermal Degradation of Palm Oil Mill By-Products Using Thermogravimetric Analysis and Differential Scanning Calorimetry

Empty fruit bunches (EFB), fiber, and shell are the main solid residues produced during extraction of oil from oil palm (Elaeis guineensis Jacq.). Thermogravimetric (TG) and differential scanning calorimetric (DSC) analyses of these materials were carried out on samples as received and after solvent extraction. Presence of extractives and ash had a strong effect on the thermal behavior of EFB. Observed thermal degradation behavior was described using two analytical approaches. The first approach considered that biomass thermal degradation occurs in three consecutive steps, while the second approach used three independent reactions as the model. The shapes of the TG and DSC curves were used to identify the degradation steps. The thermal degradation activation energy (E) and pre-exponential factor (A) obtained by both approaches were very similar.