Improved ethanol production from the slurry of pretreated brewers' spent grain through different co-fermentation strategies.

The aim of this work was to bioconvert all sugars in BSG into ethanol using a process scheme that includes the enzymatic hydrolysis of the whole slurry resulting from the pretreatment of BSG with phosphoric and sulfuric acid using previously optimised conditions, followed by the co-fermentation of the mixed sugars. More than 90% of the sugars in raw BSG were recovered in the pretreatment and the subsequent enzymatic hydrolysis of the whole slurry. The co-fermentation of the enzymatic hydrolysates with Escherichia coli was then compared with that the co-culture of Scheffersomyces stipitis and Saccharomyces cerevisiae, which resulted in lower ethanol production. The co-fermentation strategy with a single microorganism (E. coli) when BSG was pretreated with phosphoric acid resulted into the highest ethanol concentration, 39 g/L, which means that 222 L of ethanol can be obtained from a ton of BSG without detoxification requirements.

Biorefinery based on olive biomass. State of the art and future trends.

With currently more than nine million hectares, olive tree cultivation has spread worldwide, table olives and olive oil as the main products. Moreover, a number of by-products and residues derived from both tree cultivation and the process of industrial olive oil production, most having no practical applications, are obtained yearly. This paper reviews the research regarding these by-products, namely biomass from olive tree pruning, olive stones, olive pomace and wastewaters obtained from the process of olive oil production. Furthermore, a wide range of compounds has been identified and can be produced using a broad definition of the term biorefinery based on olive tree biomass. As an example, this paper reviews ethanol production as one of the main proposed applications, as well as research on other value-added products. Finally, this paper also assesses recent technological advances, future perspectives and challenges in each stage of the process.

Development of a process for the production of L-amino-acids concentrates from microalgae by enzymatic hydrolysis.

A process for the production of l-amino-acids concentrates from microalgae biomass by enzymatic hydrolysis has been developed. The process includes pre-treatment for cell-disruption, enzymatic hydrolysis and final separation by centrifugation. Thermal and mechanical cell-disruption methods have been tested, selecting mechanical disruption using bead milling for 30 min. The enzymatic hydrolysis was done using the commercial enzymes Alcalase and Flavourzyme. Maximum hydrolysis was obtained for biomass concentrations under 270 g/l and previous additional treatment with Viscozyme, reaching a 42% hydrolysis. Repeated reaction steps increased the hydrolysis from 42% (4h) with a single step to 59% (8h) after two successive steps. Further increase of the number of steps had a meagre impact on the global yield. The process widens the portfolio of products that can be obtained from microalgae biomass and is a new possibility to enhance the economic viability of microalgae-based biofuels production processes.