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Fermentation medium and oxygen transfer conditions that maximize the xylose con...

The xylose conversion to ethanol by Pichia stipitis was studied. In a first step, the necessity of supplementing the fermentation medium with urea, MgSO4 × 7H2O, and/or yeast extract was evaluated through a 23 full factorial design. The simultaneous addition of these three nutritional sources to the fermentation medium, in concentrations of 2.3, 1.0, and 3.0 g/l, respectively, showed to be important to improve ...

Ethanol production from xylose by pichia stipitis NRRL Y-7124 in a stirred tank...

The ethanol production by Pichia stipitis was evaluated in a stirred tank bioreactor using semidefined medium containing xylose (90.0 g/l) as the main carbon source. Experimental assays were performed according to a 22 full factorial design to evaluate the influence of aeration (0.25 to 0.75 vvm) and agitation (150 to 250 rpm) conditions on ethanol production. In the studied range of values, the agitation incre...

Technological trends, global market, and challenges of bio-ethanol production

Ethanol use as a fuel additive or directly as a fuel source has grown in popularity due to governmental regulations and in some cases economic incentives based on environmental concerns as well as a desire to reduce oil dependency. As a consequence, several countries are interested in developing their internal market for use of this biofuel. Currently, almost all bio-ethanol is produced from grain or sugarcane....

A study on chemical constituents and sugars extraction from spent coffee grounds

Spent coffee grounds (SCG), the residual materials obtained during the processing of raw coffee powder to prepare instant coffee, are the main coffee industry residues. In the present work, this material was chemically characterized and subsequently submitted to a dilute acid hydrolysis aiming to recover the hemicellulose sugars. Reactions were performed according to experimental designs to verify the effects o...

The influence of initial xylose concentration, agitation, and aeration on ethan...

Rice straw hemicellulosic hydrolysate was used as fermentation medium for ethanol production by Pichia stipitis NRRL Y-7124. Shaking bath experiments were initially performed aiming to establish the best initial xylose concentration to be used in this bioconversion process. In the sequence, assays were carried out under different agitation (100 to 200 rpm) and aeration (V flask/V medium ratio varying from 2.5 t...

Production, characterization and application of activated carbon from brewer’s ...

Different types of activated carbon were prepared by chemical activation of brewer’s spent grain (BSG) lignin using H3PO4 at various acid/lignin ratios (1, 2, or 3 g/g) and carbonization temperatures (300, 450, or 600 °C), according to a 22 full-factorial design. The resulting materials were characterized with regard to their surface area, pore volume, and pore size distribution, and used for detoxification of ...

Avaliação do processo de bioprodução de etanol a partir de xilose pela levedura...

A produção de etanol pela levedura Pichia stipitis foi avaliada em reator de bancada sob diferentes condições de aeração e agitação em meio semi-sintético contendo xilose (90,0 g/L) como principal fonte de carbono. Os ensaios foram realizados segundo um planejamento fatorial 2² variando-se a aeração (0,25 a 0,75 vvm) e a agitação (150 a 250 rpm). Dentro da região de transferência de oxigênio estudada, o fator d...

Kinetic behavior of ethanol production by Pichia stipitis under high xylose con...

Activated carbon production from brewer’s spent grain lignin

Activated carbons are adsorbents that are industrially used in multiple processes for product separation and purification, and for the treatment of liquid and gaseous effluents. Despite its frequent use in the water and waste industries, activated carbons remain an expensive material. In view of the high cost and the tedious procedures for the preparation and regeneration of activated carbons, there is a contin...

Inhibitory action of the toxic compounds present in lignocellulosic hydrolysate...

Lignocellulosic materials represent an abundant and inexpensive source of sugars which can be microbiologically converted to industrial products. However, hydrolysis of lignocellulosic materials for sugars recovery always goes together with the formation of by-products that inhibit the fermentation process. Such by-products include acetic acid, phenolic compounds such as syringaldehyde, ferulic acid, p-hydroxyb...