Medium-chain carboxylates production from plant waste: kinetic study and effect of an enriched microbiome.

BACKGROUND: The need for addition of external electron donors such as ethanol or lactate impairs the economic viability of chain elongation (CE) processes for the production of medium-chain carboxylates (MCC). However, using feedstocks with inherent electron donors such as silages of waste biomass can improve the economics. Moreover, the use of an appropriate inoculum is critical to the overall efficiency of the CE process, as the production of a desired MCC can significantly be influenced by the presence or absence of specific microorganisms and their metabolic interactions. Beyond, it is necessary to generate data that can be used for reactor design, simulation and optimization of a given CE process. Such data can be obtained using appropriate mathematical models to predict the dynamics of the CE process. RESULTS: In batch experiments using silages of sugar beet leaves, cassava leaves, and Elodea/wheat straw as substrates, caproate was the only MCC produced with maximum yields of 1.97, 3.48, and 0.88 g/kgVS, respectively. The MCC concentrations were accurately predicted with the modified Gompertz model. In a semi-continuous fermentation with ensiled sugar beet leaves as substrate and digestate from a biogas reactor as the sole inoculum, a prolonged lag phase of 7 days was observed for the production of MCC (C6-C8). The lag phase was significantly shortened by at least 4 days when an enriched inoculum was added to the system. With the enriched inoculum, an MCC yield of 93.67 g/kgVS and a productivity of 2.05 gMCC/L/d were achieved. Without the enriched inoculum, MCC yield and productivity were 43.30 g/kgVS and 0.95 gMCC/L/d, respectively. The higher MCC production was accompanied by higher relative abundances of Lachnospiraceae and Eubacteriaceae. CONCLUSIONS: Ensiled waste biomass is a suitable substrate for MCC production using CE. For an enhanced production of MCC from ensiled sugar beet leaves, the use of an enriched inoculum is recommended for a fast process start and high production performance.

Viviendo la experiencia de cuidar a un familiar mayor y ser empleado: roles en conflicto / Living the experience of caring for an elderly relative and being employed: roles in conflict

Objetivo: Develar la experiencia vivida de personas que realizan el doble rol de cuidar a un familiar mayor dependiente y trabajar remuneradamente. Metodología: investigación cualitativa fenomenológica. Participaron 14 personas que asistieron a un programa de apoyo al trabajador-cuidador familiar, y que eran cuidadores de una persona mayor dependiente, de quienes se recogió la experiencia a través de una entrevista semiestructurada. Se entrevistó hasta alcanzar la saturación de significados. El análisis se realizó a través del método propuesto por Streubert. Resultados: el fenómeno se develó en la categoría comprensiva multiplicidad de roles compuesta por las subcategorías angustia/agobio y culpa. Conclusiones: resulta urgente visibilizar las consecuencias de la multiplicidad de roles y desarrollar políticas públicas para la conciliación de ellos (AU)

Objective: To reveal the lived experience of people who perform the double role of caring for a dependent elderly relative and working remuneratively. Methodology: qualitative phenomenological research of 14 people who participated in a family worker-caregiver support program, and were caregivers of a dependent elderly person, from whom the experience was collected through a semi-structured interview. It was interviewed until a saturation of meanings was reached. The analysis was performed through the method proposed by Streubert. Results: the phenomenon was revealed in the comprehensive multiplicity of roles category composed of the subcategories distress/burden and guilt. Conclusions: it is urgent to make visible the consequences of the multiplicity of roles and develop public policies for their reconciliation (AU)

Exploring the combined effect of total ammonia nitrogen, pH and temperature on anaerobic digestion of chicken manure using response surface methodology and two kinetic models.

Ammonia inhibition is the most challenging issue in the anaerobic digestion (AD) of nitrogen-rich substrates. Total ammonia nitrogen (TAN) concentration, temperature and pH are the main operational parameters affecting the chemical equilibrium between free ammonium nitrogen (NH3; FAN) and ammonium ions (NH4+). However, it is still unclear how these parameters together affect digestion performance by influencing this equilibrium. To determine the effect and linkages of these parameters, a Box-Behnken design-response surface methodology (RSM), correlation analysis and two kinetic models were carried out. The results revealed that the linear effect of TAN, the interaction effect between TAN and temperature, and temperature and pH were significant, however, the quadratic effect of TAN, temperature and pH were also significant. Furthermore, TAN and temperature were positively correlated with Mmax, k and Rmax. Findings from this study could provide a theoretical basis to develop the way of relieving ammonia inhibition.

Experiencia de participar en un programa de apoyo al trabajador/cuidador familiar de adultos mayores dependientes / Experience of participating in support program for working/family caregivers of a disabled elder

Introducción: El envejecimiento poblacional aumenta el riesgo de tener dependencia y con ello demandar cuidados. Las familias son quienes principalmente cuidan a sus mayores, teniendo también que asumir responsabilidades laborales. El doble rol como trabajador y cuidador se convierte en un factor de riesgo para su propia salud. Objetivo: Generar conocimiento comprensivo acerca de la experiencia vivida de participar en un programa de apoyo al trabajador/cuidador familiar de un adulto mayor dependiente, ofrecido en el espacio laboral. Metodología: estudio cualitativo fenomenológico. Se realizaron 14 entrevistas semiestructuradas a personas que participaron en al menos un 70% de los talleres del "Programa de apoyo al trabajador/ cuidador familiar", y que eran cuidadores primarios o secundarios de un adulto mayor dependiente. Se entrevistó hasta cumplir con el criterio de saturación de resultados. El análisis se realizó a través del método propuesto por Streubert y cols. Resultados: se develaron tres categorías comprensivas: apoyo institucional para el fortalecimiento del trabajador/ cuidador, necesidades de cuidado del cuidador y multiplicidad de roles. Conclusiones: Los participantes reconocen el programa de apoyo a cuidadores familiares como un gesto de preocupación, solidaridad y empatía a través del cual la institución demuestra el valor que tienen sus empleados y una forma de validarlos como seres humanos trascendentes y multidimensionales

Background: The aging population process increases the risk of dependency and thus, it demands special care. Family members have primarily taken care of the elderly, also attending to their working responsibilities. This double-role, as worker and caregiver becomes a risk factor for their own health. Aim: To generate comprehensive knowledge about the lived experience of worker/ caregivers of dependent elderly relatives, who participate of a support program offered by the employer in the workplace. Methodology: Phenomenological qualitative study. semi-structured interviews were carried out with individuals who participated in at least 70% of the support program's workshops. To take part on the study, these individuals had to be the primary or secondary caregiver of a dependent elderly relative. Fourteen interviews were conducted and analyzed until data saturation was reached. Then, data was analyzed through a method suggested by Streubert et al. Results: Three comprehensive categories were found: Institutional support for worker/caregiver strengthening, the Worker/caregiver needs, and the Multiplicity of roles. Conclusions: Participants recognize the support program delivered by their employer as a sign of concern, solidary and empathy towards them. Through it, the institution shows appreciation for its employees, and recognizes them as transcendental and multidimensional human beings

Biomass potential analysis of aquatic biomass and challenges for its use as a nonconventional substrate in anaerobic digestion plants.

Aquatic macrophytes are important components of aquatic habitats. However, the overgrowth of aquatic plants can cause severe problems for the management of bodies of water. As a result, these plants must be removed and disposed of as waste. However, the usage of this biomass as a substrate in biogas plants would appear to be more beneficial. The present study shows the advantages and barriers to the use of harvested aquatic biomass for energy production in Germany. The results cover several aspects of this issue, such as the question of biomass potential, the quality of the harvested aquatic plants, and ensiling for the purpose of conservation for anaerobic digestion. In addition, the social aspects of the de-weeding in bodies of water are discussed.

Effect of particle size reduction and ensiling fermentation on biogas formation and silage quality of wheat straw.

The effect of ensiling fermentation and mechanical pretreatment on the methane yield of lignocellulosic biomass was investigated in order to determine the optimum pretreatment conditions for biogas production. Wheat straw was treated using the following techniques: mechanical disintegration by chopping and extruder-grinding to particle sizes of 2.0 and 0.2cm, respectively, and ensiling by 30% and 45% total solids with addition of enzymatic, chemical and biological silage additives individually and in combination. The total and volatile solid content, biochemical methane potential and products of silage fermentation of 32 variants were tested. The results indicate that the methane potential increased by 26% (from 179 to 244mLCH4g-1VS) by reducing particle size. The maximum methane potential of 275mLCH4g-1VS was obtained from silage with 30% total solids and extruder grinding. However, the effect of the addition of silage additives on the methane potential was limited.