Nídia S. Caetano

Parametric study of a brewery effluent treatment by microalgae Scenedesmus obliquus

This work analyses the potential of using microalgae Scenedesmus obliquus (So) for a brewery wastewater treatment and biomass production. The chemical oxygen demand (COD), total nitrogen (TN) and total carbon (TC) was followed in time, and the influence of light exposure, light intensity and culture aeration was studied. Results show that the most adequate conditions for cultivating So in this effluent are the aerated cultures, exposed to a 12h period of daily light, at 12000 Lux intensity. At these conditions it is obtained a maximum of 0.9 g of dry biomass per liter of culture, after 9 days, for a maximum reduction of 57.5% and 20.8% of COD and TN, respectively, after 14 days, and 56.9% of TC, after 13 days, corresponding to the final values of 1692 mg O(2)/L COD, 47 mg N/L TN, and 1mg C/L TC.

Sustainability and economic evaluation of microalgae grown in brewery wastewater

This article evaluates the sustainability and economic potential of microalgae grown in brewery wastewater for biodiesel and biomass production. Three sustainability and two economic indicators were considered in the evaluation within a life cycle perspective. For the production system the most efficient process units were selected. Results show that harvesting and oil separation are the main process bottlenecks. Microalgae with higher lipid content and productivity are desirable for biodiesel production, although comparable to other biofuels feedstock concerning sustainability. However, improvements are still needed to reach the performance level of fossil diesel. Profitability reaches a limit for larger cultivation areas, being higher when extracted biomass is sold together with microalgae oil, in which case the influence of lipid content and areal productivity is smaller. The values of oil and/or biomass prices calculated to ensure that the process is economically sound are still very high compared with other fuel options, especially biodiesel.

Effect of the Culture Nutrients on the Biomass and Lipid Productivities of Microalgae Dunaliella tertiolecta

Effect of the Culture Nutrients on the Biomass and Lipid Productivities of Microalgae Dunaliella tertiolecta Teresa M. Mata*, Ricardo Almeida, Nidia S. Caetano LEPAE – Laboratory for Process, Environmental and Energy Engineering, Faculty of Engineering, University of Porto (FEUP), R. Dr. Roberto Frias S/N, 4200-465 Porto, Portugal Department of Chemical Engineering, School of Engineering (ISEP), Polytechnic Institute of Porto (IPP), R. Dr. Antonio Bernardino de Almeida S/N, 4200-072 Porto, Portugal * tmata@fe.up.pt

MTBE synthesis catalysed by acid ion exchange resins: Kinetic studies and modeling of multiphase batch reactors

Abstract The kinetics for the liquid phase synthesis of methyl tert -butyl ether (MTBE) from isobutene and methanol using Amberlyst 18 (A18) ion exchange resin as catalyst was experimentally determined in a batch reactor in the temperature range 323–338 K and pressure range 0.8–1.0 MPa. Only methanol and MTBE are sorbed on the active acid sites. The reversible surface reaction on the pore walls and within the gel phase of the microparticles is the rate controlling step; the forward reaction is first order in isobutene and sorbed methanol and the reverse reaction is first order in sorbed MTBE. The experimental results can be described by a two parameter model based on a Rideal-Eley rate expression in liquid phase concentrations; the parameters are the forward reaction rate constant, kar, and the ratio between adsorption/desorption equilibrium constants of MTBE and methanol, D . The reactor model involved mass balances in both the gas and bulk liquid as well as in the macropores and microparticles and also energy balances in the catalyst particle and liquid phase. The activation energy was determined to be 130.2 kJ/mol.

Properties and Sustainability of Biodiesel from Animal Fats and Fish Oil

aLEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto (FEUP), R. Dr. Roberto Frias S/N, 4200-465 Porto, Portugal bDepartment of Chemical Engineering, School of Engineering (ISEP), Polytechnic Institute of Porto (IPP), R. Dr. Antonio Bernardino de Almeida S/N, 4200-072 Porto, Portugal cDepartment of Environmental Engineering, Faculty of Natural Sciences, Engineering and Technology (FCNET), Oporto Lusophone University, R. Dr. Augusto Rosa, 24, 4000-098 Porto, PortugalPortugal *tmata@fe.up.pt

Sustainability Evaluation of Biodiesel Produced from Microalgae Chlamydomonas sp Grown in Brewery Wastewater

This study performs a sustainability evaluation of biodiesel from microalga Chlamydomonas sp. grown in 20 % (v/v) of brewery’s wastewater, blended with pentose sugars (xylose, arabinose or ribose resulting from the hydrolysis of brewer’s spent grains (BSG). The life cycle steps considered for the study are: microalgae cultivation, biomass processing and lipids extraction at the brewery site, and its conversion to biodiesel at a dedicated external biofuel’s plant. Three sustainability indicators (LCEE, FER and GW) were considered and calculated using experimental data. Literature data was used, whenever necessary, to complement life cycle data, thus allowing a more accurate sustainability evaluation. A comparative analysis of the biodiesel life cycle steps was also conducted, with the main goal of identifying which steps need to be improved. Results show that biomass processing, especially cell harvesting, microalgae cultivation, and lipids extraction are the main process bottlenecks. It is also analysed the influence on the microalgae biodiesel sustainability of adding each pentose sugar to the cultivation media, concluding that it strongly influences the biomass and lipid productivity. In particular, the addition of xylose is preferable in terms of lipid productivity, but from a sustainability point of view, ribose is the best, though the difference from xylose is not significant. Nevertheless, culture without pentose addition presents the best sustainability results.

Valorization of Waste Frying Oils and Animal Fats for Biodiesel Production

The increased demand for biodiesel and the difficulties in obtaining enough quantities of raw materials for its production are stimulating the search for alternative feedstocks. Among the various possibilities, the utilization of residual fatty materials, in particular waste frying oils and animal fat residues from the meat and fish processing industries, are increasingly seen as viable options for biodiesel production. This work reviews the state of the art regarding the utilization of waste oils and animal fats as feedstocks for biodiesel production, which are characterized by the presence of high levels of impurities such as high acidity and moisture content. The relative advantages and disadvantages of the different routes for biodiesel production are presented and discussed in this chapter, focusing on their chemical and technological aspects. Also discussed are the questions related to the viability and potential economic advantages of using this type of feedstocks in biodiesel production for road transportation.

Bioethanol from Brewer’s Spent Grains: Acid Pretreatment Optimization

This study performs a parametric study aiming at the optimization of the acid pretreatment step of brewers spent grains (BSG) simultaneously with the enzymatic hydrolysis for conversion into simple sugars fermentable to bioethanol. For this purpose three acids and five enzymes were tested, by adding each two acids (HCl with H2SO4 or HCl with HNO3) either in mixture (in one step) or sequentially (in two steps), to 25 g of dry BSG, together with varying quantities of the enzymes. Results show that when using Viscozyme L or the mixture of Cellulase and Hemicellulase by action of two acids in mixture, the total sugars conversion ranges between 20-27 wt%, in which the mixture of HCl and H2SO4 promotes a greater release of glucose plus maltose, while the mixture of HCl and HNO3 promotes the release of higher amount of xylose and arabinose. Results also show that when Glucanex 100g and Ultraflo L are used simultaneously with the sequential addition of HCl and H2SO4, the highest total sugars conversion (54.5 wt%) is obtained using 2.30 mL of Ultraflo L and 1.67 g of Glucanex 100g. Furthermore, by increasing the amount of Glucanex 100g (from 1.67 to 2.48 g) to the same amount of Ultraflo L (2.30 mL) the total sugars conversion decreased from 54.5 wt% to 40.5 wt%. Moreover, a greater release of glucose was verified by increasing the amount of Ultraflo L (from 1.75 mL to 2.30 mL), while by increasing the amount of Glucanex 100g (from 1.67 to 2.48 g) the release of arabinose and maltose was enhanced. Also, when using Glucanex 100g and Ultraflo L simultaneously with the acids HCl and HNO3, the best method to obtain high conversions of sugars is by the sequential addition of the acids, instead of in mixture. In this work, it resulted in the best conversion of BSG to simple sugars (72.1 wt%), corresponding to about 720 g of sugars per kg of dry BSG.

Bio-refinery approach for spent coffee grounds valorization

Although normally seen as a problem, current policies and strategic plans concur that if adequately managed, waste can be a source of the most interesting and valuable products, among which metals, oils and fats, lignin, cellulose and hemicelluloses, tannins, antioxidants, caffeine, polyphenols, pigments, flavonoids, through recycling, compound recovery or energy valorization, following the waste hierarchy. Besides contributing to more sustainable and circular economies, those products also have high commercial value when compared to the ones obtained by currently used waste treatment methods. In this paper, it is shown how the bio-refinery framework can be used to obtain high value products from organic waste. With spent coffee grounds as a case study, a sequential process is used to obtain first the most valuable, and then other products, allowing proper valorization of residues and increased sustainability of the whole process. Challenges facing full development and implementation of waste based bio-refineries are highlighted.

Sustainability Considerations about Microalgae for Biodiesel Production

This chapter describes how to perform a sustainability evaluation of microalgae biodiesel through its supply chain. A framework for selecting sustainability indicators that take into account all three dimensions of sustainability: economic, societal and environmental, is presented. Special attention is given to a useful definition of the boundary for the system and to the identification of the relevant impacts associated with the biodiesel supply chain stages. A set of sustainability indicators is proposed for quantitative sustainability assessment, based on the impacts deemed relevant for each supply chain stage. Some qualitative arguments are also presented to support the evaluation. Although microalgae appear to be superior in some respects to other currently used feedstocks, the development of large-scale microalgae production systems still needs further research.