Estimation of biogas generated in two landfills in South-Central Ecuador

Producción CientíficaThe landfill is a final disposal technique to confine municipal solid waste (MSW), where organic matter is degraded generating leachate and biogas composed of methane gases (CH4), carbon dioxide (CO2) and other gases that contribute to global warming. The objective of the current research was to estimate the amount of biogas generated through the LandGEM 3.03 mathematical model to determine the amount of electrical energy generated and the number of homes that would be supplied with electrical energy from 2021 to 2144. As a result of the application, it was estimated that in the Pichacay landfill, the highest point of biogas generation in 2053 would be 76,982,177 (m3/year) that would generate 81,226,339.36 (kWh/year), and would supply 5083 homes with electricity. Similarly, in the Las Iguanas landfill, the highest point would be 693,975,228 (m3/year) of biogas that produces 73,223,5296.7 (kWh/year) and would supply electricity to 45,825 homes. Of the performed gas analyses in the Pichacay landfill in 2020, an average of 51.49% CH4, 40.35% CO2, 1.75% O2 and 17.8% H2S was presented, while in the Las Iguanas landfill, for 2020 and 2021, we obtained an average of 51.88/CH4, 36.62% CO2, 1.01% O2 and 187.58 ppm H2S. Finally, the biogas generated by being harnessed minimizes the impacts related to global warming and climate change and would contribute electricity to the nearby communities.Instituto Tecnológico Superior Universitario Oriente (Grant No. 34323674

Economic analysis of microaerobic removal of H2S from biogas in full-scale sludge digesters

Producción CientíficaThe application of microaerobic conditions during sludge digestion has been proven to be an efficient method for H2S removal from biogas. In this study, three microaerobic treatments were considered as an alternative to the technique of biogas desulfurization applied (FeCl3 dosing to the digesters) in a WWTP comprising three full-scale anaerobic reactors treating sewage sludge, depending on the reactant: pure O2 from cryogenic tanks, concentrated O2 from PSA generators, and air. These alternatives were compared in terms of net present value (NPV) with a fourth scenario consisting in the utilization of iron-sponge-bed filter inoculated with thiobacteria. The analysis revealed that the most profitable alternative to FeCl3 addition was the injection of concentrated O2 (0.0019 €/m3 biogas), and this scenario presented the highest robustness towards variations in the price of FeCl3, electricity, and in the H2S concentration

Hydrothermal multivariable approach: Full-scale feasibility study

Producción CientíficaA process configuration combining thermal hydrolysis (TH) and anaerobic digestion (AD) of sludge has been studied with the objective of analysing the feasibility of the technology for full scale installations. The study has been performed through pilot scale experiments and energy integration considerations, and a scheme of the most profitable option is presented: thermal hydrolysis unit fed with 7% total solids (TS) secondary sludge, anaerobic digestion of the hydrolysed sludge together with fresh primary sludge, and a cogeneration unit to produce green electricity and provide hot steam for the thermal hydrolysis process. From a technical and practical point of view, the process scheme proposed is considered to be feasible. Based on the results of the pilot plant performance and the laboratory studies, the process has proven to operate successfully at a concentration of 7-8% TS. After the thermal hydrolysis, sludge viscosity becomes radically smaller, and this favours the digesters mixing and performance (40% more biogas can be obtained in nearly half the residence time compared to the conventional digestion). From an economic point of view, the key factors in the energy balance are: the recovery of heat from hot streams, and the concentration of sludge. The article presents the main energy integration schemes and defines the most profitable one: an energetically self-sufficient process, with a cogeneration unit. The scheme proposed has proven to need no additional energy input for the sludge hydrolysis, generates more that 1 MW green electricity (246 kW surplus with respect to the conventional process), and produces 58% less volume of Class A biowaste. The study and balances here presented set the basis for the scale-up to a demonstration plant (hydrolysis + anaerobic digestion + cogeneration unit

Multiresidue analytical method for pharmaceuticals and personal care products in sewage and sewage sludge by online direct immersion SPME on-fiber derivatization – GCMS

Producción CientíficaThe work here presented aimed at developing an analytical method for the simultaneous determination of 22 pharmaceuticals and personal care products, including 3 transformation products, in sewage and sludge. A meticulous method optimization, involving an experimental design, was carried out. The developed method was fully automated and consisted of the online extraction of 17 mL of water sample by Direct Immersion Solid Phase MicroExtraction followed by On-fiber Derivatization coupled to Gas Chromatography – Mass Spectrometry (DI-SPME – On-fiber Derivatization – GC – MS). This methodology was validated for 12 of the initial compounds as a reliable (relative recoveries above 90% for sewage and 70% for sludge; repeatability as %RSD below 10% in all cases), sensitive (LODs below 20 ng L−1 in sewage and 10 ng g−1 in sludge), versatile (sewage and sewage-sludge samples up to 15,000 ng L−1 and 900 ng g−1, respectively) and green analytical alternative for many medium-tech routine laboratories around the world to keep up with both current and forecast environmental regulations requirements. The remaining 10 analytes initially considered showed insufficient suitability to be included in the final method. The methodology was successfully applied to real samples generated in a pilot scale sewage treatment reactor.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref.VA067U16 and UIC71)Ministerio de Economía, Industria y Competitividad (Projects CTM2015-70722-R and Red NOVEDAR

Biogas from anaerobic digestion as an energy vector: Current upgrading development

Producción CientíficaThe present work reviews the role of biogas as advanced biofuel in the renewable energy system, summarizing the main raw materials used for biogas production and the most common technologies for biogas upgrading and delving into emerging biological methanation processes. In addition, it provides a description of current European legislative framework and the potential biomethane business models as well as the main biogas production issues to be addressed to fully deploy these upgrading technologies. Biomethane could be competitive due to negative or zero waste feedstock prices, and competitive to fossil fuels in the transport sector and power generation if upgrading technologies become cheaper and environmentally sustainable.Unión Europea - (URBIOFIN project 745785, H2020-BBI-JTI-2016)Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CLU 2017-09

Anaerobic digestion of food waste coupled with biogas upgrading in an outdoors algal-bacterial photobioreactor at pilot scale

[EN] This work aimed at integrating the anaerobic digestion of food waste (FW) with photosynthetic biogas upgrading at pilot scale in order to obtain a high quality biomethane and a nutrient-laden algal biomass as the main byproducts from FW treatment. The performance of a 100 L anaerobic digester treating food waste integrated via raw biogas and digestate injection with a 1.2 m2 outdoors high-rate algal pond (HRAP) was evaluated. Biogas production in the digester averaged 790 ± 89 mL g VSin-1 (68 ± 8 L d-1) (35 ◦C, 1 bar) at a loading rate of 0.86 g VS L-1 d-1 and a steady state chemical oxygen demand removal efficiency of 83 ± 7%. The biogas produced (60% CH4 / 39% CO2) was upgraded in a 2.5 L absorption column interconnected with the HRAP via culture broth recirculation at a liquid to biogas ratio of 2, resulting in a maximum CO2 removal efficiency of 90% and a maximum CH4 content of 93.9%. The HRAP, supplied with the centrifuged liquid digestate supplemented with synthetic wastewater (5.0 ± 1.1 L d-1, Total nitrogen (TN) = 793 ± 110 mg N L-1, P-PO43- = 39 ± 19 mg P L-1), supported TN and total phosphorus maximum removal efficiencies of 100% in both cases. Pseudoanabaena sp. and Chlorella vulgaris were identified as the dominant speciesSIEste trabajo contó con el apoyo de la Junta de Castilla y León y EU-FEDER (CLU 2017-09, CL-EI-2021-07, UIC 315). También se reconoce al Ministerio de Ciencia, Innovación y Universidades de España (FJC 2018-038402-I) por la financiación del contrato de investigación Juan de la Cierva-Formación de Lara Ménde

H2 addition through a submerged membrane for in-situ biogas upgrading in anaerobic digestion of sewage sludge

In-situ upgrading of biogas in a mesophilic anaerobic digester of sewage sludge by sparging H2 through a membrane was studied. Large gas recirculation rates were required to facilitate H2 transfer to the bulk liquid phase; at  ∼200 L Lreactor−1 d−1, H2 utilization efficiency averaged 94% and the specific CH4 production increased from 0.38 L Lreactor−1 d−1, during conventional digestion, to 0.54 L Lreactor−1 d−1. Sludge digestion was not compromised by elevated H2 partial pressure nor by the associated rise in the pH (8.1) because of CO2 removal. In this regard, VFA accumulation was not detected and the performance of VS removal was similar to the observed without H2 supply. Microbial analysis revealed that homoacetogens were outcompeted by hydrogenotrophic methanogens. Methanoculleus sp., Methanospirillum sp., Methanolinea sp. and Methanobacterium sp. were the hydrogenotrophic archaea present over the experiment

Effect of operating pressure on direct biomethane production from carbon dioxide and exogenous hydrogen in the anaerobic digestion of sewage sludge

Producción CientíficaThe development of biological Power-to-Methane in-situ technologies aimed at producing biomethane directly in a single anaerobic digestion unit by the supply of external hydrogen, find its limiting step in the gas-to-liquid mass transfer of poorly soluble hydrogen. Increasing the operating pressure with an exogenous hydrogen supply could enhance transfer rates of hydrogen and carbon dioxide (enriching gas phase with methane) and simultaneously control the liquid media pH because the methanation of hydrogen and carbon dioxide prevents the acidification caused by carbon dioxide/bicarbonate equilibrium displacement. Thus, the feasibility of operating the anaerobic digestion of sludge at a pressure higher than the atmospheric pressure with an exogenous hydrogen supply to improve the solubilisation of hydrogen and subsequent bioconversion of hydrogen and carbon dioxide into methane by methanogenic archaea was studied. A mesophilic sludge digester (35 L) was operated at variable absolute pressure up to 300 kPa. Hydrogen was continuously supplied through the sludge recirculation stream, coupled to a static mixer. Hydrogen conversion increased with the operating pressure (up to 99%), and the methane concentration in the digester off-gas averaged 92.9 ± 2.3% at 300 kPa (maximum of 95.2%). pH approached 7 under such conditions, and the efficiency of organic matter removal was similar to that observed during conventional anaerobic digestion at atmospheric pressure without a detrimental accumulation of volatile fatty acids. This study confirmed that increasing the system pressure (mass transfer driving force) can be a viable alternative to high energy-consuming mixing methods to enhance the hydrogen gas-liquid mass transfer.Junta de Castilla y León, programa EU-FEDER (CLU 2017-09 y UIC 071

Anaerobic digestion of food waste coupled with biogas upgrading in an outdoors algal-bacterial photobioreactor at pilot scale

Producción CientíficaThis work aimed at integrating the anaerobic digestion of food waste (FW) with photosynthetic biogas upgrading at pilot scale in order to obtain a high quality biomethane and a nutrient-laden algal biomass as the main byproducts from FW treatment. The performance of a 100 L anaerobic digester treating food waste integrated via raw biogas and digestate injection with a 1.2 m2 outdoors high-rate algal pond (HRAP) was evaluated. Biogas production in the digester averaged 790 ± 89 mL g VSin-1 (68 ± 8 L d-1) (35 °C, 1 bar) at a loading rate of 0.86 g VS L-1 d-1 and a steady state chemical oxygen demand removal efficiency of 83 ± 7%. The biogas produced (60% CH4 / 39% CO2) was upgraded in a 2.5 L absorption column interconnected with the HRAP via culture broth recirculation at a liquid to biogas ratio of 2, resulting in a maximum CO2 removal efficiency of 90% and a maximum CH4 content of 93.9%. The HRAP, supplied with the centrifuged liquid digestate supplemented with synthetic wastewater (5.0 ± 1.1 L d-1, Total nitrogen (TN) = 793 ± 110 mg N L-1, P-PO43- = 39 ± 19 mg P L-1), supported TN and total phosphorus maximum removal efficiencies of 100% in both cases. Pseudoanabaena sp. and Chlorella vulgaris were identified as the dominant species.Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (projects CLU 2017-09, CL-EI-2021-07 and UIC 315)Ministerio de Ciencia, Innovación y Universidades (grant FJC 2018-038402-I

XII reunión de la Mesa Española de Tratamiento de Aguas Residuales

Desde 1980 el Grupo de Tecnología Ambiental del Departamento de Ingeniería Química y Tecnología del Medio Ambiente de la Universidad de Valladolid trabaja en el desarrollo de tecnologías eficientes, económicas y sostenibles de tratamiento, gestión y valorización de contaminantes, tanto para aguas residuales como para gases y residuos sólidos. La investigación del grupo se ha dirigido principalmente al desarrollo de procesos biológicos, empleando técnicas de biología molecular para su caracterización y seguimiento. Actualmente, el grupo está formado por 10 investigadores senior, 6 post-docs y 17 doctorandos. En los últimos diez años, ha participado en 40 proyectos con financiación pública y 51 con financiación privada, con una producción científica de 27 Tesis Doctorales defendidas, 207 publicaciones JCR, 222 congresos Internacionales y 6 patentes, trabajando en diversas líneas de investigación (http://envtech.uva.es/): - Procesos anaerobios de tratamiento, incluyendo la aplicación de tecnologías de membranas, el estudio de procesos microaeróbicos para la eliminación de H2S, o el enriquecimiento de biogás por conversión biológica de CO2 y H2. - Tratamiento de aguas residuales, con estudios microbiológicos de los procesos de eliminación de nutrientes, análisis y tratamiento de microcontaminantes y combinando eliminación de nutrientes, minimización de fangos y optimización energética. - Tratamiento, minimización y valorización de fangos, aplicando pretratamientos como la explosión de vapor o la hidrólisis térmica para incrementar la producción de biogás. - Tratamiento biológico de aguas residuales mediante consorcios de algas y bacterias, acoplando procesos de oxidación de materia orgánica, eliminación de nutrientes, enriquecimiento de biogás o captura de CO2. - Tratamiento biológico de gases de efecto invernadero, olores y compuestos orgánicos volátiles mediante biorreactores de alta transferencia de materia - Valorización de residuos lignocelulósicos y de biomasa algal para producir bioenergía en forma de alcoholes o de biogás, aprovechando la fracción proteica como biofertilizantes o alimentación animal