ABSTRACT Proper waste management is a major worldwide concern; waste is disposed of directly into the environment, affecting water, soil and air quality. The development and production of green energy sources is strongly encouraged in modern society. The aim of this study, in accordance with Sustainable Development Goals (SDGs) 1, 2 and 7 of the 2030 Agenda of the UN, is to combine the correct disposal of animal waste with the generation of energy to mitigate the energy insecurity of families in an extremely vulnerable semi-arid region in the north-east of the country using biodigesters. To this end, a conceptual proposal was drawn up for a low-cost, easy-to-maintain and easy-to-use biodigester. A small-scale prototype was used to assess its operation by evaluating the main factors that affect biogas production (pH, temperature and the biomass properties: total solids, fixed solids, volatile solids, concentration of volatile fatty acids and C/N ratio). Evaluation of the test prototype gave satisfactory results that corroborate other studies and make it possible to propose an economically viable and efficient full-scale biodigester for biogas production. concern environment water quality society study SDGs (SDGs 1 203 UN semiarid semi arid northeast north east biodigesters end lowcost, lowcost low cost, cost low-cost easytomaintain easy maintain easytouse use smallscale small scale pH, pH (pH properties solids CN C N ratio. ratio . ratio) fullscale full 20

RESUMO Santa Catarina é um importante produtor de banana, responsável por 722 toneladas anuais. Para cada 1.000 kg de banana colhida, são gerados aproximadamente 3.000 kg de pseudocaule, 650 kg de cascas e 350 kg de frutos rejeitados. Estudos avaliaram a utilização de resíduos de banana para produção de bioetanol. Resíduos sólidos como bagaço de pseudocaule de banana, cascas de banana e vinhaça (resíduo de caldo fermentado) são produzidos nesse processo. Este estudo teve como objetivo quantificar e caracterizar esses resíduos para produção de biogás e metano. Cascas de banana e vinhaça foram melhores por conterem menor teor de sólidos totais e relações C:N (carbono:nitrogênio) favoráveis (10 - 30:1), proporcionando maior potencial bioquímico de metano (260 mLCH4 gvs -1) em comparação ao pseudocaule de bananeira bagaço (201 mLCH4 gvs -1). No entanto, a vinhaça apresentou alto teor de sulfeto de hidrogênio (0,0783%), necessitando de dessulfurização do biogás gerado para seu uso seguro. No geral, os resultados indicam que o bagaço do pseudocaule da banana, as cascas de banana e a vinhaça têm potencial substancial para a produção de biogás e metano devido às suas altas taxas de degradação. A composição do biogás atende aos critérios de utilização, com concentrações adequadas de metano e dióxido de carbono, destacando a viabilidade desses resíduos para geração de energia e contribuindo para a sustentabilidade no cultivo da banana. 72 anuais 1000 1 000 1.00 colhida 3000 3 3.00 65 35 rejeitados bioetanol resíduo fermentado processo CN C N carbononitrogênio carbono nitrogênio (carbono:nitrogênio 10 (1 301, 301 30 , 30:1) 260 (26 mLCH -1 201 (20 1. . entanto 0,0783%, 00783 0,0783% 0 0783 (0,0783%) seguro geral degradação 7 100 00 1.0 300 3.0 6 ( 30:1 26 (2 20 0078 0,0783 078 (0,0783% 3. 30: 2 007 0,078 07 (0,0783 0,07 (0,078 0,0 (0,07 0, (0,0 (0, (0

ABSTRACT Santa Catarina is a significant banana producer, responsible for 722 tons annually. For every 1,000 kg of bananas harvested, approximately 3,000 kg of pseudostem, 650 kg of peels, and 350 kg of rejected fruit are generated. Studies have evaluated the use of banana residues for bioethanol production. Solid residues like banana pseudostem bagasse, banana peels, and vinasse (fermented broth residue) are produced during this process. This study aimed to quantify and characterize these residues for biogas and methane production. Banana peels and vinasse were more suitable for containing lower total solids content and favorable C:N (carbon:nitrogen) ratios (10-30:1), yielding higher biochemical potential of methane (260 mLCH4 gvs -1) compared to banana pseudostem bagasse (201 mLCH4 gvs -1). However, vinasse had a high hydrogen sulfide content (0.0783%), necessitating desulphurization for safe biogas use. The results indicate that banana pseudostem bagasse, banana peels, and vinasse have substantial potential for biogas and methane production due to their high degradation rates. The biogas composition meets the criteria for use, with adequate methane and carbon dioxide concentrations, highlighting the viability of these residues for energy generation and contributing to sustainability in banana cultivation. producer 72 annually 1000 1 000 1,00 harvested 3000 3 3,00 65 35 generated fermented residue process CN C N carbonnitrogen nitrogen (carbon:nitrogen 10301, 10301 10 30 , (10-30:1) 260 (26 mLCH -1 201 (20 1. . However 0.0783%, 00783 0.0783% 0 0783 (0.0783%) rates concentrations cultivation 7 100 00 1,0 300 3,0 6 1030 (10-30:1 26 (2 - 20 0078 0.0783 078 (0.0783% 1, 3, 103 (10-30: 2 ( 007 0.078 07 (0.0783 (10-30 0.07 (0.078 (10-3 0.0 (0.07 (10- 0. (0.0 (10 (0. (1 (0

ABSTRACT The proper disposal of fruit and vegetable waste is essential to promote environmental sustainability, reduce the carbon footprint, improve soil quality, and contribute to the transition to a circular economy. This study examined the impact of incorporating dairy cattle wastewater (DCWW) into anaerobic co-digestion with fruit and vegetable residues and utilization of the resulting biofertilizer as a diluent in the anaerobic mono-digestion of fruit and vegetable residues (recycle). The specific biogas and methane production and the agronomic quality of the biofertilizer were evaluated in a semi-continuous trial. Two startup strategies were employed: initially, the reactors were entirely fed with inoculum (biofertilizer derived from DCWW), and fruit and vegetable residue feedstock was gradually introduced. Anaerobic co-digestion of fruit and vegetable residues with DCWW yielded the highest specific production of biogas and methane at 720 and 436 L kg-1 of volatile solids (VS), respectively. The addition of DCWW increases fruit and vegetable residue alkalinity by 249% and reduces the volatile acidity by 83.4%. Anaerobic mono-digestion of fruit and vegetable residues enhances macronutrient recovery in the biofertilizer through recycle. Logistically, directing fruit and vegetable residues to rural areas for anaerobic co-digestion with DCWW promotes agricultural biofertilizer use. sustainability footprint economy (DCWW codigestion co digestion monodigestion mono recycle . (recycle) semicontinuous semi continuous trial employed initially DCWW, , DCWW) introduced 72 43 kg1 kg 1 kg- VS, VS (VS) respectively 249 834 83 4 83.4% Logistically use (recycle 7 (VS 24 8 83.4 2 83.

RESUMO A destinação adequada dos resíduos de frutas e vegetais é fundamental para promover a sustentabilidade ambiental, reduzir a pegada de carbono, melhorar a qualidade do solo e contribuir para a transição para uma economia circular. Neste estudo, foram avaliados os efeitos da adição de água residuária da bovinocultura de leite em codigestão anaeróbia com resíduos de frutas e vegetais e o uso do biofertilizante como diluente na monodigestão anaeróbia dos resíduos de frutas e vegetais (reciclo). A produção específica de biogás e metano, bem como a qualidade agronômica do biofertilizante em um estudo semicontínuo, foram avaliados. Foram utilizadas duas estratégias para partida dos reatores: o abastecimento inicial dos reatores totalmente com inóculo (biofertilizante proveniente da digestão anaeróbia da água residuária da bovinocultura de leite) e a progressão de carga para os resíduos de frutas e vegetais. A maior produção específica de biogás e metano foi atingida pela codigestão anaeróbia de resíduos de frutas e vegetais com água residuária da bovinocultura de leite, 720 e 436 L kg-1 de sólidos voláteis (SV), respectivamente. A adição da água residuária da bovinocultura de leite aumentou em 249% a alcalinidade dos resíduos de frutas e vegetais e diminuiu em 83,4% sua acidez volátil. A recuperação de macronutrientes no biofertilizante é favorecida pela monodigestão anaeróbia dos resíduos de frutas e vegetais em função do uso do reciclo. Entretanto, visando a destinação destes ao meio rural, a codigestão anaeróbia com água residuária da bovinocultura de leite favorece o uso agrícola do biofertilizante. ambiental carbono circular reciclo . (reciclo) semicontínuo 72 43 kg1 kg 1 kg- SV, SV , (SV) respectivamente 249 834 83 4 83,4 volátil Entretanto rural (reciclo 7 (SV 24 8 83, 2

ABSTRACT The work refers to the use of a plant of non-typical biogas in Germany. The first one leaves it refers to the exploitation of biogas plants that it doesn’t use liquid substrates (pig or caw manure) in co-fermentation with agricultural materials in Germany to produce biogas. In this case, the principles and methods are described that are used in this country to exploit these facilities and their tendency toward the future. The second part of the part is about these same topics in the environment of Cuba. The third leave they discuss: if these systems are viable and would be possible to introduce in Cuba or in countries of the call “Third World”? This way, is the objective of the present work to disclose this type of technology of biogas production, which is carried out in this country and its feasibility of being introduced in the countries of the call “third world”.

RESUMEN El trabajo se refiere a la utilización de una planta de biogás no tipicas en Alemania. La primera parte se refiere a la explotación de plantas de biogás que no utilizan sustratos líquidos (excretas porcinas o vacunas) en co-fermentación con materiales agrícolas en Alemania para producir biogás. En este caso, se describen los principios y métodos que se utilizan en este país para explotar estas instalaciones y su tendencia hacia el futuro. La segunda parte trata de estos mismo tópicos en el ambito de Cuba. La tercera parte se discuten: si estos sistemas son viables y serian posibles introducir en Cuba o en paises del llamado Tercer Mundo?. De esta forma, el objetivo del presente trabajo es divulgar este tipo de tecnología de producción de biogás, la cual se realiza en este país y su factibilidad de ser introducida en los paises del llamado tercer mundo.

Abstract Biorefineries are strategic actors in economic, social, and environmental aspects, which must consider energy transition policies and the objectives of a circular and sustainable economy. Despite its potential to reduce greenhouse gases, the impact of bioenergy technology in biorefineries linked to sugarcane must be evaluated and addressed to ensure its sustainable growth on the environment, biodiversity, water resources, and use from the earth. From the point of view of CO2 capture, Colombia has been advancing in policies for the implementation of carbon capture, use, and storage technology. The use of biogas from residual biomass opens a range of opportunities and challenges for the country. This review contributes to the implementation of bioenergy technologies with CO2 capture in biorefineries associated with sugarcane and could be useful to guide professionals in decision-making and future research on sustainable biorefineries.

Resumen Las biorrefinerías son actores estratégicos en aspectos económicos, sociales y ambientales, que deben considerar las políticas de transición energética y los objetivos de una economía circular y sostenible. A pesar de su potencial para reducir gases de efecto invernadero, el impacto de la tecnología bioenergética en biorrefinerías vinculadas a la caña de azúcar debe evaluarse y abordarse para asegurar su crecimiento sostenible en el medio ambiente, la biodiversidad, los recursos hídricos y el uso de la tierra. Desde el punto de vista de captura de CO2, Colombia ha venido avanzando en las políticas para la implementación de la tecnología de captura, uso, y almacenamiento de carbono. El aprovechamiento de biogás a partir de la biomasa residual abre un abanico de oportunidades y desafíos para el país. Esta revisión contribuye a la implementación de tecnologías de bioenergía con captura de CO2 en biorrefinerías asociadas a la caña de azúcar y que podría ser útil para guiar a los profesionales en la toma de decisiones y las investigaciones futuras sobre biorrefinerías sostenibles.

Abstract This study carried out Bg anaerobic Cd. RSM was employed to investigate the optimum experimental conditions for Bg yield. The input parameters were PD substrates combination, either with WH or GS. Using six different identical 25 L cylindrical digesters, 6 experimental setups of the substrate combinations were carried out, for an incubation time of 22 days, under ambient T of 33 °C, and pH of 6.7. The setups digesters were: 25% PD:75% WH (1); 50% PD:50% WH (2); 75% PD:25% WH (3); 25% PD:75% GS (4); 50% PD:50% GS (5); and 75% PD:25% GS (6). From experimental observations, Bg yield started on day 5, for setups 1, 2, 4 and 5, followed by setup 3 on day 6. Setup 6 was the last digester to produce Bg, on day 7. Setup 2 recorded the highest Bg yield (75 cm3/day), while setup 6 had the lowest value yield (48 cm3/day). Furthermore, additional setups (7 and 8) were carried out for determining Bg characteristics and evaluating the effect of a pre-activated active slurry in its yields. Optimum Bg yield (75 cm3/day) was attained by 50% PD:50% WH. This result validates Bg production through substrates Cd, and the employment of optimization tools, in order to obtain ideal process parameters. Furthermore, quadratic model developed by RSM was highly reliable and reproducible, while the predicted values were close to the experimental ones.

Resumen La piña, Ananas comosus, es uno de los cultivos de mayor importancia en Costa Rica, produciendo un prominente 1,7 % del Producto Interno Bruto (PIB) nacional; sin embargo, metodologías actuales para tratar los residuos de las hojas de las plantas pueden causar potenciales problemas en la salud pública debido a proliferación de moscas, además de contaminación ambiental y aporte a los gases de efecto invernadero. El objetivo del presente estudio fue la utilización del jugo de las hojas de la planta de piña para evaluar la producción de biogás en combinación con gallinaza como sustratos. Se realizaron pruebas de potencial de biometano con distintas concentraciones de jugo y gallinaza (70/30, 80/20 y 90/10), así como pruebas con cada sustrato de manera independiente. Los resultados muestran que mayores cantidades de biogás se produjeron en los sistemas con proporciones de 80/20 y 70/30. Adicionalmente, se realizó una estimación de la inversión requerida, con el fin de realizar un estudio tecno-económico mediante la metodología de Peters y Timmerhaus. Del análisis tecno-económico, se concluye que el proceso es altamente rentable, con un período de retorno de inversión de 2,3 años.

ABSTRACT Introduction: An opportunity for the local development of Placetas, a municipality in the central region of Cuba, is the use of biogas generated from the swine waste from its Genetic Center as an energy alternative for the drying of different materials available in the area. Objective: To present a technological proposal for a multipurpose dryer for grains, tubers, protein plants and organic fertilizer, using biogas generated from swine waste as an energy source. Materials and Methods: The physicochemical parameters of the streams involved were identified, appropriate technologies were selected, process demands were estimated, and a rotary dryer was designed using the high-temperature method. Results and Discussion: A direct drying scheme was selected in a rotary equipment, ensuring ease in the handling of non-adherent granular solids and using mixtures of air and gases from biogas combustion as an energetic alternative. The technological proposal allows the treatment of 300 kg/h of wet material. It satisfies the drying service provided to productive forms of the area and their own productive needs. For tubers and protein plants, according to their initial humidity, a semi-continuous drying scheme was proposed with two passes and a hopper for storage and recycling of the material. The rotary dryer requires 0.7 m in diameter and 3.0 m in length. Conclusions: The developed proposal satisfies the productive demands with safety, energy efficiency, productivity and sustainability, contributing to the reduction of environmental impact and to the increase of the technical-economic effectiveness.

RESUMEN Introducción: Una oportunidad para el desarrollo local de Placetas, un municipio en la región central de Cuba, es el aprovechamiento del biogás generado con los residuales porcinos de su Centro Genético como alternativa energética para el secado de diferentes materiales disponibles en la zona. Objetivo: Presentar una propuesta tecnológica de secadero multipropósito para granos, tubérculos, plantas proteicas y fertilizante orgánico, que utiliza biogás generado con residuales porcinos como fuente energética. Materiales y Métodos: Se identificaron los parámetros físico-químicos de las corrientes involucradas, se seleccionaron las tecnologías adecuadas, se estimaron las demandas del proceso y se diseñó un secador rotatorio por el método de alta temperatura. Resultados y Discusión: Se seleccionó un esquema de secado directo en un equipo rotatorio, garantizando facilidad en el manejo de los sólidos granulares no adherentes y utilizando mezclas de aire y gases de la combustión del biogás como alternativa energética. La propuesta tecnológica permite tratar 300 kg/h de material húmedo. Se satisface la prestación del servicio de secado a formas productivas de la zona y las necesidades productivas propias. Para tubérculos y plantas proteicas, atendiendo a su humedad inicial, se propuso un esquema de secado semicontinuo con dos pases y una tolva para el almacenamiento y reciclo del material. El secador rotatorio requiere 0,7 m de diámetro y de 3,0 m de longitud. Conclusiones: La propuesta desarrollada satisface las demandas productivas con seguridad, eficiencia energética, productividad y sostenibilidad, contribuyendo a la reducción del impacto ambiental y al incremento de la efectividad técnico económica.

ABSTRACT Introduction: The fish processing industry generates large volumes of wastewater, which are generally treated in lagoons, generating bad odors and emitting polluting gases into the atmosphere. According to their organic matter content, these can be treated in anaerobic reactors with a microalgae coupling for the bioremediation of the effluent, due to their high N, P and CO2 removal capacity. Objective: To determine the potential of fish processing wastewater from the fishing industry in Sancti Spíritus for biogas and microalgae production. Materials and Methods: The physicochemical characteristics of the wastewater are taken as a starting point and mass balances are performed using indexes from the literature to determine the volumes of biogas and the amount of biomass harvested from the microalgae Chlorella vulgaris. Results and Discussion: The analyzed waters represent a potential for obtaining biogas and for the development of microalgae cultures as a promising alternative to improve process performance, which allows obtaining energy and high value-added products. Conclusions: The wastewater from the Pescaspir fishing company produces 21.8 m3 of biogas per day and 0.58 kg/d of dry microalgal biomass, so the proposed treatment system allows the generation of renewable energy, the production of biomass, obtaining a purified effluent and reducing the environmental impact on natural aquatic systems, in addition to other possible technological applications.

RESUMEN Introducción: La industria de procesamiento del pescado genera grandes volúmenes de aguas residuales, que generalmente son tratadas en lagunas, generando malos olores y emitiendo gases contaminantes a la atmósfera. De acuerdo a su contenido de materia orgánica estas pueden ser tratadas en reactores anaerobios con un acople de microalgas para la biorremediación del efluente, debido a su alta capacidad de remoción de N, P y CO2. Objetivo: Determinar el potencial de las aguas residuales del procesamiento de pescado de la industria pesquera en Sancti Spíritus para la producción de biogás y microalgas. Materiales y Métodos: Se toma como punto de partida las características fisicoquímicas de las aguas residuales y se realizan balances de masa empleando índices de la literatura, para determinar los volúmenes de biogás y la cantidad de biomasa cosechada de la microalga Chlorella vulgaris. Resultados y Discusión: Las aguas analizadas, representan un potencial para la obtención de biogás y para el desarrollo de cultivos de microalgas como alternativa prometedora para mejorar el rendimiento de los procesos, lo que permite obtener energía y productos de alto valor añadido. Conclusiones: Las aguas residuales de la empresa pesquera Pescaspir, permiten obtener 21,8 m3 de biogás al día y 0,58 kg/d de biomasa microalgal seca, por lo que el sistema de tratamiento propuesto permite la generación de energía renovable, la producción de biomasa, la obtención de un efluente depurado y la reducción del impacto ambiental que causan en los sistemas acuáticos naturales, además de otras posibles aplicaciones tecnológicas.

ABSTRACT Introduction: In Cuba, there is a tendency to decentralize productions with the creation of livestock modules where different livestock species coexist, such as swine, cattle and poultry. In this context, anaerobic digestion (AD) is an alternative for the decarbonization of the agricultural sector, since it generates energy during waste treatment. Objective: To evaluate the AD of swine manure (SM) and poultry manure (PM) with cattle manure (CM) in terms of biochemical methane potential (BMP), and kinetic parameters in mono and co-digestion. Materials and Methods: The trial was conducted in 2 L reactors at 27 °C (average). The BMP of SM, PM and CM was determined in mono-digestion, and then with addition of 15, 30 and 45 % of CM, to the PM40:SM60 mixture. To describe the kinetic behavior of the process, experimental data were fitted to three first and second order models. Results and Discussion: The experimental BMP with CM addition was higher than expected, with increase between 26-31 %, demonstrating the synergy of the mixtures; since the C/N ratio and the methanogenic archaeal community were improved. The models were adjusted to the experimental data with adjusted coefficients of determination higher than 90 %. Conclusions: The addition of CM increased the experimental methane yield over the expected one. The Hill model shows a maximum yield of 369 LCH4/kgVS for mixtures with 15 and 30 % CM. The best variant was with 15 %, and it is necessary to transport manure from 20 cows to the biodigester.

RESUMEN Introducción: En Cuba, existe tendencia a descentralizar producciones con la creación de módulos pecuarios donde coexisten diferentes especies de ganado, como porcino, vacuno y avícola. En este contexto, la digestión anaerobia (DA) resulta una alternativa para la descarbonización del sector agropecuario, ya que genera energía durante el tratamiento de residuales. Objetivo: Evaluar la DA de estiércol porcino (EP) y gallinaza (EG) con estiércol vacuno (EV) en términos del potencial bioquímico de metano (PBM), y parámetros cinéticos en mono y codigestión. Materiales y Métodos: El ensayo se realizó en reactores de 2 L a 27 ºC (promedio). Se determinó el PBM del EP, EG y EV en monodigestión, y luego con adición de 15, 30 y 45 % de EV, a la mezcla EG40:EP60. Para describir el comportamiento cinético del proceso, se ajustaron los datos experimentales a tres modelos de primero y segundo orden. Resultados y Discusión: El PBM experimental con adición de EV fue superior al esperado, con incremento entre 26-31 %, demostrando la sinergia de las mezclas; ya que se mejoró la relación C/N y la comunidad de arqueas metanogénicas. Los modelos se ajustaron a los datos experimentales con coeficientes de determinación ajustado superiores al 90 %. Conclusiones: La adición de EV aumentó el rendimiento de metano experimental respecto al esperado. El modelo de Hill muestra un rendimiento máximo de 369 LCH4/kgSV para las mezclas con 15 y 30 % de EV. La mejor variante fue con 15 %, y se necesita transportar estiércol de 20 vacas al biodigestor.

Controlling the chemical parameters of the anaerobic digestion (AD) process is essential for the bioconversion of organic matter to methane; among these parameters include the presence and concentration of volatile fatty acids (VFAs). It is thus necessary to use efficient analytical methods that are capable of identifying and quantifying VFAs in reactor effluents in order to obtain an immediate response to their conditions. In this study, the liquid-liquid extraction (LLE) method was optimized and validated - through an adaptation of the official method, using acetone and KHSO4, and gas chromatography with flame ionization detector (GC-FID) was used for the determination of acetic, propionic, isobutyric, butyric, isovaleric and valeric acids present in the effluents. The limit of detection (LOD) and limit of quantification (LOQ) obtained were 1.2-2.5 mg L-1 and 1.9-3.7 mg L-1, respectively, for all analytes. These low LODs and LOQs are essentially important because the presence of isobutyric and isovaleric acids above 5.0 mg can be considered indicative of imbalances in AD. The proposed method, which presented satisfactory results with good repeatability (4.2-20.7%) and recovery (90.9-104.0%) rates, was applied for the analysis of effluent samples from three continuous stirred-tank reactors (CSTR). AD (AD methane VFAs. . (VFAs) conditions study liquidliquid liquid LLE (LLE KHSO4 KHSO GCFID GC FID (GC-FID acetic propionic butyric LOD (LOD LOQ (LOQ 1.22.5 1225 1.2 2.5 1 2 5 1.2-2. L1 L L- 1.93.7 1937 1.9 3.7 9 3 7 1.9-3. L1, 1, respectively analytes 50 0 5. 4.220.7% 42207 4.2 20.7% 4 20 (4.2-20.7% 90.9104.0% 9091040 90.9 104.0% 90 104 (90.9-104.0% rates stirredtank stirred tank CSTR. CSTR (CSTR) (VFAs 22 1.22. 122 12 1. 25 2. 1.2-2 93 1.93. 193 19 37 3. 1.9-3 220 4.220.7 4220 42 4. 207 20.7 (4.2-20.7 9104 90.9104.0 909104 909 90. 1040 104.0 10 (90.9-104.0 (CSTR 1.22 1.2- 1.93 1.9- 4.220. 422 20. (4.2-20. 910 90.9104. 90910 104. (90.9-104. 4.220 (4.2-20 91 90.9104 9091 (90.9-104 4.22 (4.2-2 90.910 (90.9-10 (4.2- 90.91 (90.9-1 (4.2 (90.9- (4. (90.9 (4 (90. ( (90 (9

ABSTRACT Among the impurities that are harmful to the energy conversion of biogas generated in landfills is hydrogen sulfide (H2S). The present study compared the efficiency of H2S removal with the use of granular activated carbon (GAC) of two commercial brands, Norit GAC and Pelegrini GAC, and with the use of granular iron oxide from mineral residues. The tests were conducted on a laboratory scale, in a glass column, filled with filtering material, applying an inlet flow of gas and monitoring the outlet concentration. The best removal efficiencies occurred with the use of Norit GAC, which presented longer rupture times. Wet gas tests were also carried out, in which rupture and equilibrium times increased with the use of Norit GAC, while with the use of Pelegrini GAC the same adsorptive behavior was not observed. Tests with iron oxide showed low potential for H2S removal due to reduced specific surface values, although it provided removal of the contaminant. Knowledge of the saturation time and adsorption equilibrium data is essential for a better understanding and planning of adsorption systems, in addition to the conduction of studies on the influence of external factors and variations in initial concentration. H2S. HS . H S (H2S) (GAC brands residues scale column material concentration out observed values contaminant systems (H2S

RESUMO Dentre as impurezas prejudiciais à conversão energética do biogás gerado em aterros sanitários, encontra-se o sulfeto de hidrogênio (H2S). Este trabalho comparou a eficiência de remoção de H2S com o uso de carvão ativado granular (CAG) de duas marcas comerciais, CAG Norit e CAG Pelegrini, e com o uso de óxido de ferro granular proveniente de resíduos minerais. Os ensaios foram conduzidos em escala laboratorial, em coluna de vidro, preenchida com material filtrante, aplicando-se fluxo de entrada de gás e monitorando-se a concentração de saída. As melhores eficiências de remoção ocorreram com o uso do CAG Norit, que apresentou maiores tempos de ruptura. Também foram realizados ensaios com gás úmido, em que os tempos de ruptura e de equilíbrio aumentaram com o uso do CAG Norit, enquanto com o uso de CAG Pelegrini não se visualizou o mesmo comportamento adsortivo. Os ensaios com óxido de ferro mostraram baixo potencial de remoção de H2S, devido aos valores reduzidos de superfície específica, embora tenham proporcionado a remoção do contaminante. O conhecimento sobre dados de equilíbrio é fundamental para melhor entendimento e planejamento de sistemas de adsorção, além da inclusão de estudos de influência de fatores externos e de variações de concentração inicial. sanitários encontrase encontra H2S. HS . H S (H2S) (CAG comerciais minerais laboratorial vidro filtrante aplicandose aplicando monitorandose monitorando saída úmido adsortivo específica contaminante adsorção inicial (H2S

Electricity usage has risen tremendously over the years, as has its price. This resulted in an increase in the quest for less expensive, viable, and ecologically acceptable means of producing energy for electricity. Currently, the primary source of power in South Africa is sourced from fossil fuels, which have negative environmental consequences. The use of biogas as an alternative can mitigate the impacts of using fossil fuels to generate power. This study has examined the availability and accessibility of waste that may be utilized to generate biogas using common South African livestock excrement. A typical South African home uses 31 kWh of power daily, which equates to 111.6 MJ of energy. According to calculations, about 30 m³ of biogas is needed to produce enough energy to power a household. For the generation of mono-digestion biogas, 12 beef cows, 8 dairy cows, 3898 chickens, 156 pigs, 281 sheep and 300 goats would be needed to meet this need. Moreover, the livestock dung required to meet the daily requirement of 31 kWh is 713 kg for beef and dairy cows, 390 kg for chickens, 468 kg for pigs, 506 kg for sheep and 466 kg for goats. Co-digestion of various wastes is nonetheless a viable and advised method for enhancing the amount and quality of biogas.

ABSTRACT The hydrogen sulfide (H2S) present in biogas needs to be removed due to concerns about corrosion during transportation, storage, health and safety. One of the existing removal processes is biological, using a biotrickling filter (BTF). In this study, the performance of full-scale BTF for H2S removal under different operating conditions was evaluated. The BTF system was operated for 300 days, during which two spraying regimes (constant and intermittent) and two sources of nitrate (NO3-) as nutrient solution were evaluated (residual effluent from pig farming and synthetic solution prepared with commercial NaNO3). The performance was monitored by the following parameters: removal efficiency (RE), elimination capacity (EC), pH, dissolved oxygen (DO), empty bed residence time (EBRT) and nitrate concentration (NO3-). The results showed an REH2S = 36.3% with an EC= 1.95 gH2S m-3 d-1 for constant spraying, RE= 99.59% and EC= 4.2 gH2S m-3 d-1 for intermittent spraying with residual effluent from pig farming and RE=99.26% and EC= 4.13 gH2S m-3 d-1 with synthetic solution prepared with commercial NaNO3 solution. The results indicate that intermittent spraying provides better efficiency in the removal of H2S from biogas regardless of the nitrate source (effluent or synthetic medium). HS H S (H2S transportation storage safety biological BTF. . (BTF) study fullscale full scale 30 days NO3 NO (NO3- NaNO3. NaNO NaNO3) parameters RE, RE , (RE) EC, EC (EC) pH DO, DO (DO) EBRT (EBRT NO3. REHS REH 363 36 3 36.3 195 1 95 1.9 gHS gH m3 m m- d1 d d- 9959 99 59 99.59 42 4 2 4. RE9926 26 RE=99.26 413 13 4.1 medium. medium medium) (BTF (NO3 (RE (EC (DO 36. 19 9 1. 995 5 99.5 RE992 RE=99.2 41 (NO 99. RE99 RE=99. RE9 RE=99 RE=9

Resumo Realizou-se este estudo com o objetivo de caracterizar a produção e a digestão anaeróbia de dejetos de suínos em terminação submetidos a restrição alimentar ou suplementados com ractopamina ou cromo. Os dejetos foram provenientes de 50 suínos machos castrados, em fase de terminação, com ± 154 dias de idade, com peso inicial de 99,0 ± 4,4 kg e final de 117,2 ± 5,8 kg. As dietas experimentais foram: controle (dieta convencional); restrição qualitativa (redução de 7,5% de energia líquida em relação à dieta controle); restrição quantitativa (redução de 15% no fornecimento de ração); cromo (0,8 mg); e ractopamina (10 ppm). Os dados foram submetidos à análise de variância por meio do delineamento em blocos ao acaso, no qual as semanas de análises foram consideradas como blocos (cofator). Não foram observadas diferenças entre as dietas nas produções de dejetos na matéria natural (MN), matéria seca (MS), matéria mineral (MM) e matéria orgânica (MO). Animais que receberam a dieta controle apresentaram o maior coeficiente de resíduo e não houve diferença entre as demais dietas. Não foram observadas diferenças entre as dietas para sólidos totais, pH e nitrogênio total dos afluentes e efluentes. O maior rendimento de biogás (574 mL g-1 de SV adicionados) foi obtido com os digestores abastecidos com dejetos de animais alimentados com dieta qualitativamente restrita. Conclui-se que a dieta com restrição qualitativa resulta em maior produção de dejetos, porém com menores excreções de nitrogênio e fósforo e maior rendimento de biogás. Realizouse Realizou se 5 castrados 15 idade 990 99 0 99, 44 4 4, 1172 117 2 117, 58 8 5, convencional convencional) redução 75 7 7,5 controle) ração ração) 0,8 08 (0, mg mg) 10 (1 ppm. ppm . ppm) acaso cofator. cofator (cofator) MN, MN , (MN) MS, MS (MS) MM (MM MO. MO (MO) totais efluentes 574 (57 g1 g 1 g- adicionados restrita Concluise Conclui 9 11 7, 0, (0 ( (cofator (MN (MS (MO 57 (5

Abstract The aim of this study was to characterize the production and anaerobic digestion of manure from finishing pigs subjected to feed restriction or supplemented with ractopamine or chromium (Cr). The waste came from 50 barrows in the finishing phase, aged ± 154 days, with a starting weight of 99.0 ± 4.4 kg and a final weight of 117.2 ± 5.8 kg. The experimental diets were as follows: control (conventional diet), qualitative restriction (7.5% reduction in net energy compared to the control diet), quantitative restriction (15% reduction in feed supply), Cr (0.8 mg), and ractopamine (10 ppm). The data were subjected to an analysis of variance using a randomized block design, in which the weeks of analysis were considered blocks (cofactors). There were no differences in manure production between the diets regarding natural matter (NM), dry matter (DM), mineral matter (MM), or organic matter (OM). Animals fed the control diet had the highest residue coefficient, and there was no difference among the other diets. No differences were observed among the diets regarding total solids, pH, or total nitrogen in the tributaries or effluents. The highest biogas yield (574 mL g-1) of added volatile solids (VS) was obtained in the digesters supplied with manure from animals fed a qualitatively restricted diet. It can be concluded that a qualitatively restricted diet results in higher manure production but with lower nitrogen and phosphorus excretion and higher biogas yields. Cr. . (Cr) 5 phase 15 days 990 99 0 99. 44 4 4. 1172 117 2 117. 58 8 5. follows conventional diet, , diet) 7.5% 75 7 (7.5 15% (15 supply, supply supply) 0.8 08 (0. mg, mg mg) 10 (1 ppm. ppm ppm) design cofactors. cofactors (cofactors) NM, NM (NM) DM, DM (DM) MM, MM (MM) OM. OM (OM) coefficient pH effluents 574 (57 g1 g 1 g-1 VS (VS yields (Cr 9 11 7.5 (7. 0. (0 ( (cofactors (NM (DM (MM (OM 57 (5 g- 7. (7