Reduction of ammonia emissions from laying hen manure in a closed composting process using gas-permeable membrane technology

Nitrogen losses during composting processes lead to emissions problems and reduce the compost fertilizer value. Gas-permeable membranes (GPM) are a promising approach to address the challenge of reducing nitrogen losses in composting processes. This study investigated the applicability of two GPM membrane systems to recover N released during the closed composting process of laying hen manure. The ammonia (NH3) capture process was performed using two different systems over a period of 44 days: the first system (S1) consisted of 120 m of an expanded polytetrafluoroethylene (ePTFE) membrane installed inside a 3.7 m3 portable, closed aerobic composter with forced ventilation; the second system (S2) consisted of 474 m of an ePTFE membrane placed inside as an external module designed for NH3 capture, connected to a closed aerobic composter through a pipe. In both cases, a 1 N H2SO4 acidic NH3 capture solution was circulated inside the membranes at a flow rate of 2.1 L·h−1. The amount of total ammonia nitrogen (TAN) recovered was similar in the two systems (0.61 kg in S1 and 0.65 kg in S2) due to the chosen membrane surface areas, but the TAN recovery rate was six times higher in system S1 (6.9 g TAN·m−2·day−1) than in system S2 (1.9 g TAN·m−2·day−1) due to the presence of a higher NH3 concentration in the air in contact with the membrane. Given that the NH3 concentration in the atmosphere of the membrane compartment directly influences the NH3 capture, better performance of the GPM recovery system may be attained by installing it directly inside the closed aerobic composters. Regardless of the chosen configuration, this technology allows N recovery as a stable and concentrated 1.4% N ammonium salt solution, which can be used for fertigation. The presented GPM systems may be used in community composting systems with low volumes of waste to be treated or in livestock facilities that have implemented best available techniques such as solid–liquid separation or anaerobic digestion, provided that the use of GPM technology in combination with these techniques also contributes to odor mitigation and improves biogas yield

Comparison of the ammonia trapping performance of different gas-permeable tubular membrane system configurations

The technology of gas-permeable tubular membranes (GPMs) is promising in reducing ammonia emissions from livestock manure, capturing NH3 in an acidic solution, and obtaining final products suitable for valorization as fertilizers, in line with the principles of the circular economy. This study aimed to evaluate the performance of several e-PTFE membrane systems with different configurations for the recovery of NH3 released from pig slurry. Ten different configurations were tested: only a submerged membrane, only a suspended membrane in the same chamber, only a suspended membrane in an annex chamber, a submerged membrane + a suspended membrane in the same chamber, and a submerged membrane + a suspended membrane in an annex chamber, considering in each case the scenarios without and with agitation and aeration of the slurry. In all tests, sulfuric acid (1N H2SO4) was used as the NH3 capture solution, which circulated at a flow rate of 2.1 L·h−1. The results showed that NH3-N removal rates ranged from 36–39% (for systems with a single submerged or suspended membrane without agitation or aeration of the slurry) to 70–72% for submerged + suspended GPM systems with agitation and aeration. In turn, NH3-N recovery rates were found to be between 44–54% (for systems with a single membrane suspended in an annex compartment) and 88–91% (for systems based on a single submerged membrane). However, when choosing a system for farm deployment, it is essential to consider not only the capture and recovery performance of the system, but also the investment and operating costs (ranging from 9.8 to 21.2 €/kg N recovered depending on the selected configuration). The overall assessment suggests that the simplest systems, based on a single membrane, may be the most recommendable

Effect of Dried Pig Manure Fertilization on Barley Macronutrients and Sodium in a Nitrate Vulnerable Zone

Dried pig manure (DPM) may be valorized as a fertilizer suitable for barley crop in nitrate vulnerable zones (NVZs). The aim of this study was determine the macronutrients and sodium contents in barley (Hordeum vulgare L.) resulting from its application in a NVZ in Fompedraza (Valladolid, Spain). DPM was applied at three rates (85, 133, and 170 kg N ha-1 year-1); the mineral fertilizer with a nitrification inhibitor was applied at two rates (90 and 108 kg N ha-1 year-1), and these were compared with the control treatment (without fertilization) in a randomized complete block design. Nutrients were monitored in four different plant growth stages and in grain over a 3-year period. DMP-based fertilization increased P and Na contents in plant and decreased those of Ca and Mg. These changes were only translated into a P increase in grain. The Na content in plant should not affect the final crop yield, making this waste management strategy viable even in NVZs. However, N content in plant in tillering and stem elongation stages was lower for DPM-based fertilization than for mineral fertilization, and so was the C content, both in plant and in grain. Since N content is a limiting factor for crop development, supplementary mineral fertilization would be advised to compensate for N immobilization if this organic waste material is to be valorized as a fertilizer

Evaluation of different capture solutions for ammonia recovery in suspended gas permeable membrane systems

Gas permeable membranes (GPM) are a promising technology for the capture and recovery of ammonia (NH3). The work presented herein assessed the impact of the capture solution and temperature on NH3 recovery for suspended GPM systems, evaluating at a laboratory scale the performance of eight different trapping solutions (water and sulfuric, phosphoric, nitric, carbonic, carbonic, acetic, citric, and maleic acids) at 25 and 2 °C. At 25 °C, the highest NH3 capture efficiency was achieved using strong acids (87% and 77% for sulfuric and nitric acid, respectively), followed by citric and phosphoric acid (65%) and water (62%). However, a remarkable improvement was observed for phosphoric acid (+15%), citric acid (+16%), maleic acid (+22%), and water (+12%) when the capture solution was at 2 °C. The economic analysis showed that water would be the cheapest option at any working temperature, with costs of 2.13 and 2.52 €/g N (vs. 3.33 and 3.43 €/g N for sulfuric acid) in the winter and summer scenarios, respectively. As for phosphoric and citric acid, they could be promising NH3 trapping solutions in the winter months, with associated costs of 3.20 and 3.96 €/g N, respectively. Based on capture performance and economic and environmental considerations, the reported findings support that water, phosphoric acid, and citric acid can be viable alternatives to the strong acids commonly used as NH3 adsorbents in these systems

Effect of the type of gas-permeable membrane in ammonia recovery from air

Producción CientíficaAnimal production is one of the largest contributors to ammonia emissions. A project, “Ammonia Trapping”, was designed to recover gaseous ammonia from animal barns in Spain. Laboratory experiments were conducted to select a type of membrane most suitable for gaseous ammonia trapping. Three types of gas-permeable membranes (GPM), all made of expanded polytetrafluoroethylene (ePTFE), but with different diameter (3.0 to 8.6 mm), polymer density (0.45 to 1.09), air permeability (2 to 40 L·min−1·cm2), and porosity (5.6 to 21.8%) were evaluated for their effectiveness to recover gas phase ammonia. The ammonia evolved from a synthetic solution (NH4Cl + NaHCO3 + allylthiourea), and an acidic solution (1 N H2SO4) was used as the ammonia trapping solution. Replicated tests were performed simultaneously during a period of 7 days with a constant flow of acidic solution circulating through the lumen of the tubular membrane. The ammonia recovery yields were higher with the use of membranes of greater diameter and corresponding surface area, but they were not affected by the large differences in material density, porosity, air permeability, and wall thickness in the range evaluated. A higher fluid velocity of the acidic solution significantly increased—approximately 3 times—the mass NH3–N recovered per unit of membrane surface area and time (N-flux), from 1.7 to 5.8 mg N·cm−2·d−1. Therefore, to optimize the effectiveness of GPM system to capture gaseous ammonia, the appropriate velocity of the circulating acidic solution should be an important design consideration.Unión Europea (project LIFE15-ENV/ES/000284

Effect of acid flow rate, membrane surface area, and capture solution on the effectiveness of suspended GPM systems to recover ammonia

Ammonia losses from manure pose serious problems for ecosystems and human and animal health. Gas-permeable membranes (GPMs) constitute a promising approach to address the challenge of reducing farm ammonia emissions and to attain the EU’s Clean Air Package goals. In this study, the effect of NH3-N concentration, membrane surface area, acid flux, and type of capture solution on ammonia recovery was investigated for a suspended GPM system through three experiments, in which ammonia was released from a synthetic solution (NH4Cl + NaHCO3 + allylthiourea). The effect of two surface areas (81.7 and 163.4 cm2) was first evaluated using three different synthetic N emitting concentrations (3000, 6000, and 12,000 mg NH3-N∙L−1) and keeping the flow of acidic solution (1N H2SO4) constant (0.8 L·h−1). A direct relationship was found between the amount of NH3 captured and the NH3-N concentration in the N-emitting solution, and between the amount of NH3 captured and the membrane surface area at the two lowest concentrations. Nonetheless, the use of a larger membrane surface barely improved ammonia capture at the highest concentration, pointing to the existence of other limiting factors. Hence, ammonia capture was then studied using different acid flow rates (0.8, 1.3, 1.6, and 2.1 L∙h−1) at a fixed N emitting concentration of 6000 mg NH3-N∙L−1 and a surface area of 122.5 cm2. A higher acid flow rate (0.8–2.1 L∙h−1) resulted in a substantial increase in ammonia absorption, from 165 to 262 mg of NH3∙d−1 over a 14-day period. Taking the parameters that led to the best results in experiments 1 and 2, different types of ammonia capture solutions (H2SO4, water and carbonated water) were finally compared under refrigeration conditions (at 2 °C). A high NH3 recovery (81% in 7 days), comparable to that obtained with the H2SO4 solution (88%), was attained when chilled water was used as the capture solution. The presented results point to the need to carefully optimize the emitter concentration, flow rate, and type of capture solution to maximize the effectiveness of suspended GPM systems, and suggest that chilled water may be used as an alternative to conventional acidic solutions, with associated savings

Estudio de un proceso de compostaje de estiércol de conejo mediante técnicas espectroscópicas y análisis de ácidos húmicos y fúlvicos

El tratamiento de los residuos ganaderos se considera actualmente un importante paso, determinante para el desarrollo del sector ganadero. Un método de manejo del estiércol y enmienda del suelo de bajo costo lo constituye el uso agrícola del estiércol animal para cultivos forrajeros, pero también, existen otras técnicas como el compostaje y la biometanización.Su uso agrícola debe ser siempre la primera alternativa, ya que permite economizar en la adquisición de abonos y supone una forma eficiente y sostenible de emplearlos y optimizar el uso de la energía y la materia contenidos en ellos.La recuperación de recursos y el subsiguiente compostaje juegan un papel importante en la gestión de residuos, dado que los compost de calidad, ricos en materia orgánica estable, se podrían emplear como abono en sustitución de fertilizantes químicos, siendo fácil de producir en las explotaciones ganaderas. Las características de las deyecciones ganaderas pueden ser muy diferentes en función de la especie, la edad del ganado, el tipo de granja, la alimentación o el manejo. Sin embargo, en cualquier caso, la aplicación del compost como enmienda orgánica a los suelos, no sólo supondría un incremento de la materia orgánica del suelo, sino también conllevaría otro tipo de mejoras como en sus propiedades físicas o biológicas, importantes para el sostenimiento de su calidad.En este trabajo se propone el compostaje de estiércol de una explotación cunícola (3160 kg) con diferentes tipos de materiales estructurantes. Para ello, se conforman tres pilas dinámicas con aireación natural: pila 1 [estiércol + 200 kg cama (viruta + orina + pelo)], pila 2 [estiércol + 52 kg paja cebada], pila 3 [estiércol + 52 kg paja cebada]. Se tomó una muestra semanal durante la fase activa del proceso de compostaje que duró diez semanas y una muestra mensual durante la fase de maduración, que se desarrolló a lo largo cinco meses. Se realizaron análisis por triplicado de todas las muestras, controlando los parámetros básicos de seguimiento del proceso (temperatura, humedad, pH, CE, C/N, etc.). Además, se estudiaron las transformaciones que sufría la materia orgánica durante el proceso mediante un método espectroscópico [infrarrojo de transformada de Fourier (FTIR)], que permitía conocer la composición química de la materia orgánica, permitiendo controlar la calidad del producto final. Los espectros FTIR revelaron una transformación inicial de los compuestos más sencillos, tras la que se sucedió una descomposición y mineralización de compuestos orgánicos más complejos, para finalmente dar lugar a reacciones de polimerización de materiales orgánicos más resistentes, característicos del proceso de formación de humus.Palabras clave: estiércol cunicola, compostaje, FTIR, materia orgánica

Effects of protonation, hydroxylamination, and hydrazination of g-C3N4 on the performance of Matrimid®/g-C3N4 membranes

Producción CientíficaOne of the challenges to continue improving polymeric membranes properties involves the development of novel chemically modified fillers, such as nitrogen-rich 2-D nanomaterials. Graphitic carbon nitride (g-C3N4) has attracted significant interest as a new class of these fillers. Protonation is known to afford it desirable functionalities to form unique architectures for various applications. In the work presented herein, doping of Matrimid® with protonated g-C3N4 to yield Matrimid®/g-C3N4 mixed matrix membranes was found to improve gas separation by enhancing the selectivity for CO2/CH4 by up to 36.9% at 0.5 wt % filler doping. With a view to further enhancing the contribution of g-C3N4 to the performance of the composite membrane, oxygen plasma and hydrazine monohydrate treatments were also assayed as alternatives to protonation. Hydroxylamination by oxygen plasma treatment increased the selectivity for CO2/CH4 by up to 52.2% (at 2 wt % doping) and that for O2/N2 by up to 26.3% (at 0.5 wt % doping). Hydrazination led to lower enhancements in CO2/CH4 separation, by up to 11.4%. This study suggests that chemically-modified g-C3N4 may hold promise as an additive for modifying the surface of Matrimid® and other membranes.European Union (project LIFE15-ENV/ES/000284)Ministerio de Asuntos Económicos y Transformación Digital (projects MAT2016-76413-C2-R1 and MAT2016-76413-C2-R2

DESARROLLO DE PROTOTIPO DE MEMBRANA PARA LA CAPTACIÓN DE GAS AMONIACO EN LA ATMÓSFERA DE LAS GRANJAS

ResumenLa UE a través de su Directiva 2001/81/CE (Directiva Techos) ha fijado límites máximos para las emisiones de gases a todos Estados miembros a partir de 2010 con el objetivo de mitigar la contaminación atmosférica. Para ello, se están revisando Protocolo de Gotemburgo de 2012 y la Directiva de Techos, con una propuesta de techos de emisión en 2020 y 2030 que permitan hacer un seguimiento de las emisiones para conseguir el objetivo de 2030, la cual afecta también al NH3, gas para el que se han constatado cantidades de 375,3 Gg según el inventario de 2012, con una previsión de 396,3 en el año 2020 cuando el techo establecido es de 365,0 Gg.El sector agroganadero está muy relacionado con la emisión de NH3 a la atmósfera, especialmente aquel que se genera por la descomposición de la urea y del ácido úrico de las excretas. El NH3 emitido puede formar aerosoles, acidificar suelos y generar otros muchos problemas. Además, en la atmósfera puede formar partículas PM 2.5, que atacan al sistema cardiovascular de las personas. Por ello, es necesaria la adopción de medidas para su reducción, como la gestión del estiércol, cuidar la alimentación del ganado y sistemas de estabulación.Este trabajo propone reducir las emisiones de NH3 de la atmósfera de una instalación de ganadería porcina utilizando una tecnología de membranas permeables al gas. Para ello, se diseña y construye un prototipo a escala piloto que consiste en un contenedor metálico con forma rectangular y cerrado. En su interior se disponen 32 paneles sobre los que se sitúa una membrana tubular de ePTFE microporosa, que permite únicamente la difusión gaseosa. Además, cuenta con un depósito de 200 litros de capacidad que contiene 150 litros de ácido sulfúrico 1N. Este está conectado con las membranas mediante tuberías. De este modo, el ácido circula por el interior de las membranas mediante un bombeo continuo, permitiendo que el NH3 emitido del purín, se combine con los iones H+ del ácido, quedando atrapado en dicha solución en forma de iones NH4+, retirándolo de la atmósfera de la granja al mismo tiempo que se forma sulfato de amonio (NH4)2SO4 (fertilizante). Así, se alcanzaría un doble beneficio, ambiental y económico. A lo largo de 162 días de funcionamiento, se ha alcanzado una tasa de captura media diaria de NH3  de 128.3 mg/l*d-1, siendo el mayor valor de captura diaria de 491.5 mg/l*d-1 y el menor de 96.7 mg/l*d-1. El dispositivo propuesto funciona adecuadamente retirando NH3 del aire de la granja y recuperándolo en forma de sal y, por tanto, cumple con el objetivo planteado

Estándares de calidad en la enseñanza virtual de postgrado

The aim of this study is to provide a panoramic view of the new offer of postgraduate, EHEA-adapted university teaching in Spain, whether of a virtual or mixed-mode nature. It also offers an overview of the degree to which such studies comply with the quality criteria and assessment benchmarks proposed by the degree program verification scheme of the National Quality and Acreditation Agency (Agencia Nacional de Calidad y Acreditación— ANECA).2 The application of quality standards may help to detect strengths and weaknesses in this kind of university studies as well as identify the features of quality virtual educational actions. In connection with this, during the process of assessing quality, weaknesses were detected in the teaching planning in the study programs and in the application of the material and human resources proper to studies of this kind.El objetivo de este artículo es ofrecer en primer lugar una panorámica en cifras de la nueva oferta de enseñanza de posgrado universitario adaptada al EESS en las enseñanzas de carácter virtual o semipresencial así como una visión sobre el cumplimiento de los criterios y referentes de evaluación de calidad propuestos por el programa de verificación de títulos de la Agencia Nacional de Calidad y Acreditación (ANECA)1 en este tipo de enseñanzas. Estos estándares pueden servir para identificar las características de las acciones formativas virtuales de calidad