C. Godínez

Process design and economic analysis of a hypothetical bioethanol production plant using carob pod as feedstock

A process for the production of ethanol from carob (Ceratonia siliqua) pods was designed and an economic analysis was carried out for a hypothetical plant. The plant was assumed to perform an aqueous extraction of sugars from the pods followed by fermentation and distillation to produce ethanol. The total fixed capital investment for a base case process with a capacity to transform 68,000 t/year carob pod was calculated as 39.61 millon euros (€) with a minimum bioethanol production cost of 0.51 €/L and an internal rate of return of 7%. The plant was found to be profitable at carob pod prices lower than 0.188 €/kg. An increase in the transformation capacity of the plant from 33,880 to 135,450 t/year was calculated to result in an increase in the internal rate of return from 5.50% to 13.61%. The obtained results show that carob pod is a promising alternative source for bioethanol production.

A Box–Behnken Design-Based Model for Predicting Power Performance in Microbial Fuel Cells Using Wastewater

Although modeling is regarded as a useful tool to understand the performance of microbial fuel cells (MFCs), the number of MFC models remains very low compared with the number of experimental works available in the literature. Moreover, there are very few MFC modeling attempts dealing with the use of wastewater as fuel in these devices, which is essential for the practical implementation of MFCs since the potential of this technology lies in the two-fold benefit of wastewater treatment and bioenergy generation. In this work, a four-factor three-level Box–Behnken design was developed to model the electrochemical power generation in two-chamber MFCs using wastewater as fuel. The optimum values of temperature, external resistance, feed concentration and anodic pH that maximized power output were investigated. Optimum conditions were found at T = 35°C and R = 1 kΩ, corresponding to a maximum power density of 0.88 W·m−3, while feed concentration and pH did not show statistical significance in the ranges studied. Thus, a Box–Behnken design-based model as empirical approach could provide an effective tool for the optimization study of MFC systems.

Ionic Liquids/Supercritical Carbon Dioxide as Advantageous Biphasic Systems in Enzymatic Synthesis

Ionic liquids/supercritical carbon dioxide (ILs/scCO2) biphasic systems have recently proved as interesting clean alternatives to classical organic solvents in enzymatic synthesis. The success of IL/scCO2 biphasic systems is based on the fact that ILs provide an adequate microenvironment for the catalytic activity of the enzyme, while supercritical carbon dioxide acts as extracting phase, making possible the easy recovery of the products. This new methodology avoids the use of volatile organic solvents and hence is considered as a green technology. In this chapter, the properties of ionic liquids/supercritical carbon dioxide biphasic systems for enzymatic applications have been examined.