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La digestión anaeróbica (DA) ha sido una alternativa ampliamente probada para la gestión y valorización de las aguas residuales del proceso de sacrificio de animales. Sin embargo, la integración de la EA en los mataderos depende de aspectos técnicos y económicos. En los mataderos colombianos, la integración de la EA está limitada por la disponibilidad de tierra. En el presente estudio, se llevó a cabo una evaluación tecnoeconómica de la AD de la corriente de aguas residuales de despojos (OWW) en un digestor tubular mesófilo a escala de laboratorio. El digestor fue operado a tasas de carga orgánica (OLR) de 0.28, 0.50, 1.0, 1.5 y 2.0 kg VS/m d. Se consideraron calderas y un sistema CHP (calor y electricidad combinados) para la integración energética del biogás. Para el estudio económico se consideró la estructura de costos de un matadero colombiano. La EA de OWW a 2,0 kg VS/m d OLR fue inestable con riesgo de inhibición. El aumento del OLR de 0,28 a 1,5 kg VS/m d causó una reducción en la producción específica de biogás (PAS) de 0,474 a 0,069 m/kg VS Sin embargo, la tasa de producción de biogás (BPR) se mantuvo constante en alrededor de 0,105 m/mdig d para OLRs > 0,28 kg VSm d. Por lo tanto, la digestión anaeróbica OWW en plantas de biogás mesófilo de bajo costo es técnicamente factible con OLR entre 0,28 y 1,5 kg VS/m d. La implementación de calderas es económicamente favorable para OLR ≥ 1.0 kg VS/m d. Sin embargo, la viabilidad es muy sensible a las variaciones en la estructura de costos. La implementación de la cogeneración fue factible en el rango de OLR evaluados y su viabilidad no se ve afectada por los cambios en los costos asumidos.333333333

The familiar low cost biodigestores are an important tool for urban and rural development. These natural systems fulfill the criteria of appropriate technology, producing biogás and improved natural fertilizer, through the anaerobic digestion of organic remainders. Also the health and hygiene of the families, as well as of the cattle, affect positively, being a sustainable handling environmentally of remainders that otherwise are polluting. The potential of this technology in Bolivia is very high, and once it has already been developed to cover the three different regions (Altiplane, valley and jungle), validated like development tool and accepted by the families, it is precise `to popularize the technology', so to make it accessible to the greater number of people. In this article a review to the development of the biodigestores in Bolivia, its adaptation to high altitudes, as well as the learned lessons is made, to in the end comment the first steps that already are occurring to popularize this technology.

The issue of this paper is to present theoretical results for a solar chimney with thermal mass, where the glass surface is replaced by photo-voltaic (PV) modules. A portion of the heat ab-sorbed by the PV modules is dissipated to the air channel in convective form, and it exchanges radiation heat with the concrete wall. These cooling phenomena for the PV modules im-prove their efficiency with a lower working temperature. Both phenomena are heating proc-ess to the air and the concrete wall, that produce natural ventilation. The solar chimney is sup-posed to be isolated from any building. The re-sults obtained are an average air mass flow rate around 0.02 kg/s along the day and night, and a maximum PV temperature of 321 K.

Trigeneration or combined cooling, heat and power (CCHP) systems fueled by raw biogas can be an interesting alternative for supplying electricity and thermal services in remote rural areas where biogas can be produced without requiring sophisticated equipment. In this sense, this study considers a performance analysis of a novel small-scale CCHP system where a biogas-fired, 5 kW el externally fired microturbine (EFMT), an absorption refrigeration system (ARS) and heat exchangers are integrated for supplying electricity, refrigeration and hot water demanded by Bolivian small dairy farms. The CCHP solution presents two cases, current and nominal states, in which experimental and design data of the EFMT performance were considered, respectively. The primary energy / exergy rate was used as a performance indicator. The proposed cases show better energy performances than those of reference fossil fuel-based energy solutions (where energy services are produced separately) allowing savings in primary energy utilization of up to 31%. Furthermore, improvements in electric efficiency of the EFMT and coefficient of performance (COP) of the ARS, identified as key variables of the system, allow primary energy savings of up to 37%. However, to achieve these values in real conditions, more research and development of the technologies involved is required, especially for the EFMT. (15) (PDF) Performance Analysis of a Small-Scale Biogas-Based Trigeneration Plant: An Absorption Refrigeration System Integrated to an Externally Fired Microturbine. Available from: https://www.researchgate.net/publication/336398032_Performance_Analysis_of_a_Small-Scale_Biogas-Based_Trigeneration_Plant_An_Absorption_Refrigeration_System_Integrated_to_an_Externally_Fired_Microturbine [accessed Nov 27 2019].

The objective of this study is to analyze the CO2emissions and economic impacts of the implementation of the National Efficient Cooking Program (NECP) in Ecuador, which aims to migrate the population fromLiquefied Petroleum Gas(LPG)-based stoves to electric induction stoves. This program is rooted in the current effort to change Ecuador'senergybalance, withhydroelectric powerexpected to generate 83.61% of national electricity by 2022, ending the need for subsidized LPG. For this analysis, the 2014 baseline situation has been compared with two future scenarios for 2022: a business-as-usual scenario and an NECP-success scenario. This study demonstrates the viability of migration from imported fossil fuels to locally-producedrenewable energyas the basis for an efficient cooking facility. Thenew policies scenariowould save US$ 1.162 billion in annualgovernment expenditureon cooking subsidies, and reducing CO2emissions associated to energy for cooking in 1.8 tCO2/y.

Slaughterhouses generate an average 6.5 kg of manure/animal. Day. The animals has a weight between 350 and 400 kg. Manure causes economic, environmental and legal problems for the slaughter companies. The aim of this work, was to stabilize the 5,5 % of cattle manure of FOGASA Slaughterhouse by means of low cost digester. The results show organic matter reduce of 60% volatile solid and an average biogas production of 0,9 Nm/d. During anaerobic digestion process efficiencies were reach in terms of biogas production rate, specific biogas production and reduction of the pathogen content of 0,21 m3biogás/m3digestor d y 0,20 m3biogás/KgSV y 90% respectively. The digestate contained nitrogen, phosphorous and potassium, which is an important feature of fertilizers

This paper presents a techno-economic feasibility study of a polygeneration plant proposed for an association of dairy farmers in Bolivia. The systems have been designed in an integrated approach and are based on the resource recovery utilizing available cow dung. The production of biogas is proposed using “low cost” tubular digesters. The biogas is used for the production of electricity and heat in a 40kWelinternal combustion engine. Heat from the exhaust gas is recovered to drive an absorption cooling system for milk refrigeration and for a bio-slurry drying system. The final services are biogas, electricity, cooling and fertilizers. The techno-economic analysis focuses on determining the levelized cost of the services and compare them with the subsidized and non-subsidized prices of other competitive services in the market. Sensitivity analyses for the services prices are carried out to see the influence of the feedstock handling cost and the subsidies on investment capital. Once the selling prices of the services are defined, the payback period of investment capital is determined. The results show that the biogas and electricity costs were found lower than the subsidized prices of similar services in the market while the cost of cooling was found slightly higher. From the sensitivity analysis we have that the feedstock handling cost can be increased from 10 to 18USD/ton while maintaining the biogas price below the subsidized LPG price, and applying subsidies to the investment capital allows reducing the rest of the services costs. The payback period is around 3.5years when a subsidy of 15% is applied in the investment capital and the services are sold at the subsidized prices of the conventional services. Our study has shown that under the conditions of the Bolivian market it is feasible the installation of a polygeneration plant. On the other hand, a market without or with reduced subsidies for the conventional services makes the proposed system more feasible and competitive.

The aim of this research is to identify the operational conditions and performance of low cost tubulardigestersproducingbiogasfrom theslaughterhousewastewater treatment. Three full scale sequenced tubular digesters (of more than 8 m3each), operating in a slaughterhouse in Cochabamba (Bolivia), have been monitored during one year. The Organic Load Rate (OLR) varied from 0.04 to 1.13 kgSV/m3d (0.04–1.07 kgCOD/m3d), and theHydraulic Retention Time(HRT) from 3.2 to 87.4 days. The passive solar heating design considered drove the slurry temperature to 27 °C, 8 °C more than mean ambient temperature. The first digester has been filled with soda bottle plastic rings in order to increase the internal effective surface and evaluate, obtaining that an increment in 67% of the internal effective surface, more than doubles the biogas production and enables higher OLRs. A Biogas Production Rate (BPR) peak of 0.2 m3/m3d was observed for OLR = 0.37 kgSV/m3d, HRT = 9.7d and Specific Biogas Production (SBP) = 0.55 m3/kgSV. COD removal achieves values above 70% from HRT>19 d. A comparison with otheranaerobic digestiontechnologies demonstrates that low cost tubular digesters with biofilm carriers, are competitive for OLR

Most biogas plants in the world run under psychrophilic conditions and are operatedby small and medium farmers. There is a gap of knowledge on the performance of these systemsafter several years of operation. The aim of this research is to provide a complete evaluation of apsychrophilic, low-cost, tubular digester operated for eight years. The thermal performance wasmonitored for 50 days, and parameters such as pH, total volatile fatty acid (tVFA), chemical oxygendemand (COD) and volatile solids (VS) were measured every week for the influent and effluent.The digester operated at a stabilized slurry temperature of around 17.7◦C, with a mean organic loadrate (OLR) equal to 0.52 kg VS/m3digester*d and an estimated hydraulic retention time (HRT) of25 days. The VS reduction in the digester was around 77.58% and the COD reduction was 67±3%,with a mean value for the effluent of 3.31±1.20 g COD/Lt, while the tVFA decreased by 83.6±15.5%and the presence of coliforms decreased 10.5%. A BioMethane potential test (BMP) for the influentand effluent showed that the digester reached a specific methane production of 0.40 Nm3CH4/kgVS and a 0.21 Nm3CH4/m3digesterd with 63.1% CH4in the biogas. These results, together witha microbiological analysis, show stabilized anaerobic digestion and a biogas production that washigher than expected for the psychrophilic range and the short HRT; this may have been due to thepresence of an anaerobic digestion microorganism consortium which was extremely well-adapted topsychrophilic conditions over the eight-year study period.

El tratamiento de los residuos sólidos urbanos (RSU) o la falta de este es un problema muy extendido en el mundo, y especialmente en los países de medios y bajos recursos. Existen varios métodos para aprovechar estos residuos, además de los vertederos se emplea la incineración con producción de energía, el compostaje de la fracción orgánica, la recuperación de materiales a través del reciclaje, etc. Otro modo de gestionar el problema de los RSU es el empleo de la digestión anaerobia. Esta tecnología que es ampliamente conocida y utilizada para el tratamiento de estiércol de diversos animales, ha sido implementada en los últimos años también para tratar la fracción orgánica de los residuos sólidos orgánicos (FORSU), con diseños complejos y costosos en países industrializados y en los países en vías de desarrollo, como Bolivia, con tecnología menos costosa. En este trabajo se describe el diseño, la construcción y puesta en marcha de un biodigestor novedoso para tratar FORSU. Para ello, previamente se ha realizado una extensa revisión de la literatura existente en el ámbito de la digestión anaerobia de los residuos sólidos orgánicos. El biodigestor Natural S4 Loop, desarrollado y construido en Bolivia, es un reactor de bajo coste que trabaja en flujo pistón y que cuenta con un sistema de recirculación. La alimentación diaria del reactor se realiza con 100 kg de residuos del mercado de Tiquipaya (Cochabamba, Bolivia). Los resultados muestran un tiempo de retención hidráulico (TRH) y una velocidad de carga orgánica (VCO) teóricos de 75 días y 1,7 kg SV/m3·día respectivamente. Este último valor es relativamente bajo en comparación con lo reportado en la literatura, mientras que el TRH es mayor a lo recomendado por otros autores para sistemas que tratan este tipo residuos

Biogas digesters are used to produce methane from anaerobic digestion of animal manure in long lot of developing countries to replace wood as the traditional source of fuel to produce energy for domestic purposes. A variety of factors affect the rate of digestion and biogas production. One of the most important is temperature. Simple and small fixed dome digesters are partially or totally buried into the soil are widely used with more than 30 million having been constructed in Asia. For this reason, this study is focused on these. Temperature inside the digester is affected by many heat transfer phenomena which depend on of many parameters from the environmental conditions where the digester is installed: like ambient air temperature and soil temperature profiles. The algorithm developed takes into account these situations for simple and small digesters and in which input data required are easily available. To improve other studies of heat transfer models and temperature of heated lagoon digesters or floating drum digesters the algorithm includes some variations: the effect of the temperature of the slurry feeding, gas volume variations and soil temperature dependence on depth. The model elaborated is an acceptable first approximation of the model desired, as the model has been tested using data from Hanoi, Vietnam, cause the monthly average errors of computed temperatures are below 20%. To better understand how heat transfer phenomena are acting or which is the most influent or how much heat transfer is exchanged, more studies should be carried out using the model develop here because any remarkable conclusion cannot be deduced from obtained results. Outgoing

Premi al millor Projecte de Fi de Carrera presentat durant el curs 2009-2010 en l'àmbit de Medi Ambient que atorga AGBAR El objeto de este proyecto es el trabajo de campo desarrollado en el período comprendido entre febrero y octubre de 2009 en Cusco (Perú) con el apoyo del CCD (UPC). La mayoría de la población de la zona se dedica a la actividad agropecuaria. Los excretos animales se usan, cuando no se desaprovechan, como combustible para la cocción de los alimentos. Esta práctica conlleva consecuencias negativas de un punto económico y social (el tiempo de recolección, preparación y almacenamiento impide el desarrollo de otras actividades) así como sanitario (el almacenamiento de esta materia orgánica cerca del hogar así como la combustión ineficiente de esta materia constituyen fuentes de infección importantes). La conversión anaeróbica de los excretos permite la producción de un combustible más limpio, el biogás, y al mismo tiempo, se produce un fertilizante natural, el biol. Sin embargo algunos parámetros dificultan la transferencia de esta tecnología, las bajas temperaturas medias (8- 10°C) de la zona dificultan la conversión anaeróbica en un digestor no calentado, y la economía de subsistencia de la mayoría de los habitantes limita el coste del biodigestor. Este trabajo es parte de una investigación, iniciada en noviembre de 2005, para la adaptación de la digestión anaeróbica a las condiciones particulares de la zona alta de la sierra peruana. Desde el principio se escogió el modelo de digestor tubular de plástico (PTD) y se demostró que se podía utilizar esta tecnología en las condiciones de la zona. Ahora, en el marco del presente proyecto, la investigación se enfoca a la mejora tanto de las prestaciones del PTD como de la utilización de los productos (biol y biogás). Se han construido, en la Universidad Nacional San Antonio Abad del Cusco tres digestores con el objetivo de entender y mejorar la conversión anaeróbica. Gracias a estas instalaciones, se investigó a continuación, la producción y la composición del gas producido según las cantidades de materia orgánica introducidas, y la posible mejora de los quemadores de cocina para el uso de biogás a baja presión. Y al final, se estudiaron unas variantes de diseño con elementos que permiten almacenar el calor y aumentar así la producción de biogás. Al mismo tiempo, en colaboración con el Instituto para una Alternativa Agraria, se procedió al seguimiento de los biodigestores ya instalados, a la capacitación de la población local y a la diseminación de la tecnología con el objetivo de difundir a gran escala un modelo apropiado a los requisitos sociales, ambientales, tecnológicos, económicos y políticos. Finalmente, se presentan en este documento los resultados de los experimentos llevados a cabo en las instalaciones de la UNSAAC así como propuestas de mejora para las siguientes investigaciones para llegar a un prototipo final eficiente, asequible y apropiable para que su desarrollo en la región sea un éxito. Award-winning