Teresa M. Mata

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.

Life Cycle Assessment of Different Reuse Percentages for Glass Beer Bottles

Life cycle assessment (LCA) is increasingly becoming an important tool for ecological evaluation of products or processes. In this study the environmental impacts associated with the returnable and the non-returnable glass beer bottles were assessed in order to compare different reuse percentages. The inventory analysis is performed with data obtained from two Portuguese companies (a glass bottles producer and a brewery) and completed with the BUWAL database. It includes all operations associated with the bottles’ manufacture, the brewery and the wastewater treatment plant. The environmental impact assessment considers both the potential ecological and ecotoxicological effects of the emissions. The environmental impact categories included and discussed in this study are the contribution to ecological and human health, global warming, stratospheric ozone depletion, acidification, eutrophication and photochemical ozone creation. The first category is divided into three subcategories that are human toxicity, critical air volume and critical water volume. This study was performed for several reuse percentages and returnable bottle cycles, and is comprised of a sensitivity analysis. The general output is that the relative importance of the impacts associated with the use of returnable and/or non-returnable bottles depends on the number of cycles performed by the returnable bottles. According to the impact index defined in this study, the most significant impacts are the eutrophication and the final solid wastes generated, and the least significant impact is the ozone depletion.

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

Designing environmentally friendly chemical processes with fugitive and open emissions

Fugitive or open emissions can dominate the potential environmental impacts of a chemical process. In this work the design and simulation calculations of a process provide an opportunity to visualize relationships between economic potentials and potential environmental impacts. The analysis of the economic and environmental effects of process alternatives are completed quickly and easily using order-of-magnitude costing techniques and the Waste Reduction algorithm for environmental evaluation. In the example studied, the hydrodealkylation of toluene, both the economic and environmental results point towards the alternative of recycling diphenyl to extinction, which is a form of pollution prevention by source reduction. As open emissions are eliminated, the importance of fugitive emissions is shown to increase. Finally, results show where economic optimum and minimal environmental impact designs occur, and therefore one can see tradeoffs between these designs. Published by Elsevier Ltd.

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

Comparison of allocation approaches in soybean biodiesel life cycle assessment

This work shows the influence of using different allocation approaches when modelling the inventory analysis in a soybean biodiesel life cycle assessment (LCA). Results obtained using mass, energy and economic based allocations are compared, focusing on the following aspects: normalised potential environmental impact (PEI) categories, total PEI and relative contributions to the total PEI from each life cycle stage and environmental impact category. Similar results are obtained either using economic and energy based allocations. However, different results are obtained when mass based allocation is used when compared with the other two. This study also illustrates that using different allocation approaches in biodiesel LCA may influence the final conclusions, especially in comparative assertions, emphasising the need to perform a sensitivity analysis in the LCA interpretation step.

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.

Designing Eco-Efficient Biodiesel Production Processes from Waste Vegetable Oils

Abstract In this work the conventional alkali-catalyzed transesterification process for biodiesel production from waste vegetable oils is studied considering the two process alternatives normally used industrially: with and without free fatty acids (FFA) pre-treatment. Simulation models of these process alternatives are developed using the chemical process simulator ASPEN Plus® and their potential environmental impacts (PEIs) and economic potentials are determined and compared. Results show that the contribution to total PEIs of the process alternative with the FFA pre-treatment is 25% higher than the alternative without pre-treatment. Concerning the economic potential the process alternative with the FFA pre-treatment is greater showing a net present value of about 1.8 times higher than the alternative without the FFA pre-treatment. The comparison using plant data will be performed as future work.

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.