He was the head of the chemical engineering section in a technology driven spin-off for 3 years (2008)(2009)(2010)(2011). His research activities have mainly focused on effluent gases biofiltration, such as air (odor removal), biogas (desulfurization and upgrading), and bioremediation of high value metals. Currently, he is a partner team leader of a LIFE EU project (Biogasnet) and project leader of two projects related to the bioremediation of platinum group metals from three-way catalysts. He

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... s co-author of 28 scientific contributions to ISI journals (H-index of 14, Scopus databases), 2 patents, 7 books chapters, more than 40 conference proceedings in international congresses; he has supervised five M.S. students, four Ph.D. theses, and four Ph.D. theses are in progress. M.R. belongs to the Editorial Board of ChemEngineering and serves as Guest Editor for ChemEnginering in this Special Issue "Advances in Biogas Desulfurization". He is regularly involved in the peer-review in ISI journals (more than 100 since 2009) and he has participated in the peer-reviewing processes of technical and scientific projects (NCSTE of Kazakahstan and UEFISCDI of Romania). vii Issue about biogas desulfurization useful. Finally, I would like to thank the effort contributed by all the authors, the publisher and the reviewers that allowed this book to be published. Martín Ramírez Abstract: This Special Issue contains three articles and two reviews. The biological reactors used in the studies were fed with real biogas from Landfill or STPs. One research article concerns the use of a pilot scale plant with a combined process with a chemical and biological system. The other two studies concern anoxic biotrickling filters, with one study focused on the study of variable operation and its optimization through the response surface methodology, and the other focused on the selection of packing material. The reviews concern the current state of biogas desulfurization technologies, including an economic analysis, and the microbial ecology in biofiltration units. This Issue highlights some of the most relevant aspects about biogas desulfurization. Abstract: Desulfurization processes play an important role in the use of biogas in the emerging market of renewable energy. In this study, an iron-redox biological process was evaluated at bench scale and pilot scale to remove hydrogen sulfide (H 2 S) from biogas. The pilot scale system performance was assessed with real biogas emitted from a closed landfill to determine the desulfurization capacity under outdoor conditions. The system consisted of an Absorption Bubble Column (ABC) and a Biotrickling Filter (BTF) with useful volumes of 3 L and 47 L, respectively. An acidophilic mineral-oxidizing bacterial consortium immobilized in polyurethane foam was utilized to regenerate Fe(III) ion, which in turn accomplished the continuous H 2 S removal from inlet biogas. The H 2 S removal efficiencies were higher than 99.5% when H 2 S inlet concentrations were 120-250 ppmv, yielding a treated biogas with H 2 S < 2 ppmv. The ferrous iron oxidation rate (0.31 g·L −1 ·h −1 ) attained when the system was operating in natural air convection mode showed that the BTF can operate without pumping air. A brief analysis of the system and the economic aspects are briefly analyzed. Abstract: In this study, a pilot biotrickling filter (BTF) was installed in a wastewater treatment plant to treat real biogas. The biogas flow rate was between 1 and 5 m 3 ·h −1 with an H 2 S inlet load (IL) between 35.1 and 172.4 gS·m −3 ·h −1 . The effects of the biogas flow rate, trickling liquid velocity (TLV) and nitrate concentration on the outlet H 2 S concentration and elimination capacity (EC) were studied using a full factorial design (3 3 ). Moreover, the results were adjusted using Ottengraf's model. The most influential factors in the empirical model were the TLV and H 2 S IL, whereas the nitrate concentration had less influence. The statistical results showed high predictability and good correlation between models and the experimental results. The R-squared was 95.77% and 99.63% for the 'C model' and the 'EC model', respectively. The models allowed the maximum H 2 S IL (between 66.72 and 119.75 gS·m −3 ·h −1 ) to be determined for biogas use in a combustion engine (inlet H 2 S concentration between 72 and 359 ppm V ). The 'C model' was more sensitive to TLV (-0.1579 (gS·m −3 )/(m·h −1 )) in the same way the 'EC model' was also more sensitive to TLV (4.3303 (gS·m −3 )/(m·h −1 )). The results were successfully fitted to Ottengraf's model with a first-order kinetic limitation (R-squared above 0.92). Abstract: The packing material selection for a bioreactor is an important factor to consider, since the characteristics of this material can directly affect the performance of the bioprocess, as well as the investment costs. Different types of low cost packing materials were studied in columns to reduce the initial and operational costs of biogas biodesulfurization. The most prominent (PVC pieces from construction pipes) was applied in a bench-scale biotrickling filter to remove the H 2 S of the biogas from a real sewage treatment plant in Brazil, responsible for 90 thousand inhabitants. At the optimal experimental condition, the reactor presented a Removal Efficiency (RE) of up to 95.72% and Elimination Capacity (EC) of 98 gS·m −3 ·h −1 , similar to open pore polyurethane foam, the traditional material widely used for H 2 S removal. These results demonstrated the high potential of application of this packing material in a full scale considering the robustness of the system filled with this support, even when submitted to high sulfide concentration, fluctuations in H 2 S content in biogas, and temperature variations. Abstract: The desulphurisation of biogas for hydrogen sulphide (H 2 S) removal constitutes a significant challenge in the area of biogas research. This is because the retention of H 2 S in biogas presents negative consequences on human health and equipment durability. The negative impacts are reflective of the potentially fatal and corrosive consequences reported when biogas containing H 2 S is inhaled and employed as a boiler biofuel, respectively. Recognising the importance of producing H 2 S-free biogas, this paper explores the current state of research in the area of desulphurisation of biogas. In the present paper, physical-chemical, biological, in-situ, and post-biogas desulphurisation strategies were extensively reviewed as the basis for providing a qualitative comparison of the strategies. Additionally, a review of the costing data combined with an analysis of the inherent data uncertainties due underlying estimation assumptions have also been undertaken to provide a basis for quantitative comparison of the desulphurisation strategies. It is anticipated that the combination of the qualitative and quantitative comparison approaches employed in assessing the desulphurisation strategies reviewed in the present paper will aid in future decisions involving the selection of the preferred biogas desulphurisation strategy to satisfy specific economic and performance-related targets.