Application of a sustainable location index approach to landfill site selection in Monterrey, Mexico.

Landfilling is the main method to manage municipal solid waste (MSW) in Latin America due to the economic, technological and political characteristics of the region. The disposal of MSW in landfill sites may affect the quality of the environment and compromise a considerable share of the municipal budgets. The selection of suitable sites reduces the environmental and economic impact of landfills. In the present study the sustainable location index (SLI) is proposed as a methodology to assess environmentally, and economically, sanitary landfill site selection in the Metropolitan Area of Monterrey, a representative large-size city of Latin America. EVIAVE methodology was modified to include administrative and economic dimensions, which are assessed as a sustainable approach using together the SLI integrated with geospatial and multicriteria analysis tools. The assessment showed that the zones with the lowest SLI changes drastically when the importance of the economic or environmental factor varies. This result suggest that the inclusion of sustainability in landfill site selection decision-making is complex and it may requires the inclusion of local particularities such as municipal budgets, policies of MSW management and public perception about environmental deterioration.

Optimization of municipal solid waste collection routes in a Latin-American context.

Latin-American cities need efficient municipal solid waste (MSW) collection systems, specifically in municipalities with fast urbanization. Poor logistics in collection routes is one of the causes of inefficient MSW management. A strategy for designing the MSW collection routes, considering an environmental and economic analysis, was developed and tested in the Metropolitan Area of Monterrey (MMA), one of the cities with the highest urban and economic development in Mexico. Life cycle assessment and costs analysis were performed to evaluate archetypal routes' environmental and economic impact in the current MSW collection system. The assessment of the environmental impact was realized through midpoint indicators of the ReCiPe 2008 method. The mathematical model describing the collection routes was developed using actual data from the MSW collection system in MMA, optimized by the Traveling Salesman Problem (TSP), and solved in RStudio. This study shows a reduction of between 9 and 20% of greenhouse gas emissions and distance covered in current collection stages, respectively. The results also demonstrate the influence of road direction, collection-truck efficiency, and traffic load in different stage on the environmental and economic impacts of the collection routes. A life cycle inventory, with realistic inputs and outputs of the MSW collection system, was developed. These inventories are scarce in Mexico and Latin America; their development helps designing cleaner MSW collection systems.Implications: The optimization of urban solid waste collection systems is a strategy to reduce costs and environmental impacts, considering factors such as distance or fuel consumption. However, mathematical models within the optimization require detailed information of the road network to achieve reliable results. In this context, Latin America shows difficulties in increasing its collection systems' efficiency due to economic constraints and limited access to information from locals governments. The use of geographic information systems has been shown to collect real data on a city's roads. This work aims to propose a strategy for designing urban solid waste collection routes with the least environmental and economic impacts through an optimization strategy that considers the road network's real-time data, added to an environmental analysis developed with a life cycle assessment approach. We believe that our results could help the design of urban solid waste collection systems for cities with Latin American characteristics. Additionally, an inventory of specific inputs and emissions for waste collection in this type of city will be generated, supporting future sustainable management strategies.

Anaerobic co-digestion of fruit and vegetable waste: Synergy and process stability analysis.

Anaerobic mono- and co-digestion of fruits and vegetable waste (FVW), slaughterhouse waste (SHW), and cattle manure (CM) under mesophilic conditions (35°C) were conducted through biochemical methane potential tests to investigate how the FVW in a co-substrate formulation improves the methane yield, the degradative synergy between substrates, and especially the stability of the process. The co-digestion of FVW:SHW and FVW:CM were evaluated with volatile solids (VS) ratios of 1:2, 1:1, and 2:1. The results indicated that the highest synergistic effect was found in the co-digestion FVW:CM at 1:1 VS ratio. However, the co-digestion FWV:SHW at 1:2 VS ratio increased the methane yield by 74.2% compared to the mono-digestion of FVW (776.3 mL CH4 g VSadded-1). As a critical condition in these processes, the stability was evaluated using the early warning indicator VFA/TA (volatile fatty acids/total alkalinity). The co-substrate SHW promotes greater stability in methane production as the soluble carbohydrate content in FVW increases. It was proposed that the high protein (49.04 ± 0.96% VS) and ammonia content (693 ± 3 mg L-1) of SHW leads to the formation of a dampening system known as a carbonate-acetic buffer. It was concluded that balanced distribution between carbohydrates, proteins, and lipids is crucial to increase methane yields, and the low methane productions were associated with low N-NH4+ concentrations (FVW:CM co-digestions). The results obtained in this study can serve as a basis to design full-scale digesters under similar operating conditions and with the same substrate:co-substrate relationships.Implications: The production of methane from the anaerobic digestion process of food, and lose waste presents a viable alternative of valorization and could help to mitigate environmental impacts. However, anaerobic digestion from these substrates carries high instabilities and low methane yields. The need to increase these yields and contribute to process stability must be considered in the selection of a co-substrate. In this context, this work aims to evaluate the best fruits and vegetable waste: co-substrateformulation, that promotes higher methane yield, a synergy between substrates, and to improve the AD process stability in the presence of perturbations in the substrate composition. We believe that our results could be helpful for the design processes for methane production from fruit and vegetable waste, to contribute to competitiveness with conventional energies and promote the sustainability of these processes.

Experiencia con la prótesis de pericardio bovino Carpentier-Edwards® en posición pulmonar en pacientes con cardiopatías congénitas / Experience with Carpentier Edwards® bovine pericardium implantations in pulmonary position in patients with congenital heart diseases

Introducción. El número de pacientes con cardiopatías complejas corregidas en la infancia que necesitan una sustitución valvular pulmonar para restaurar la competencia o solucionar la estenosis del tracto de salida de ventrículo derecho ha aumentado en los últimos años. El injerto ideal continúa siendo motivo de controversia. En el servicio de cardiocirugía del Hospital Ramón y Cajal de España, se comenzó a utilizar prótesis de pericardio bovina de Carpentier-Edwards siendo el objetivo de este estudio su evaluación a corto y medio plazo. Materiales y Métodos. Entre enero de 2004 y mayo de 2010 fueron intervenidos 42 pacientes para sustitución valvular pulmonar mediante prótesis de pericardio bovino. El estudio fue ambispectivo con prospección durante los dos últimos años. Resultados. La mediana de la edad fue de 20,96 años (amplitud intercuartil 10,5 años). El número medio de cirugías previas fue de 1,9±0,9 siendo el tiempo medio entre la última cirugía y la implantación de la prótesis de 17,2±7 años. Las indicaciones quirúrgicas fueron: disfunción del ventrículo derecho (45%), su dilatación progresiva (38%), arritmias ventriculares (14%) y síncopes (3%). La mortalidad precoz de causa cardiológica fue de dos pacientes. El tiempo medio de seguimiento fue de 2,1±1,4 años (rango entre 0,1 y 6,3 años) estando el 94,3% de ellos en clase funcional I de la New York Heart Association. El gradiente Doppler pico transprotésico por ecocardiografía fue de 18,5±17 mm Hg. No se observaron cambios degenerativos ni ningún tipo de deterioro estructural de la prótesis. Conclusiones. La prótesis de pericardio bovino en posición pulmonar presenta excelentes resultados a corto y medio plazo. Sin embargo, es necesario un seguimiento mayor para confirmar lo resultados iniciales respecto a su durabilidad y hemodinamia a largo plazo...

Introduction. In recent years the number of patients with complex congenital heart disease previously corrected in infancy who need a pulmonary valve replacement has increased dramatically. The ideal substitute remains a source of dispute. Nowadays, in the unit of heart surgery of the Hospital Ramon y Cajal in Spain, its being implanting in this position the bovine pericardium Carpentier-Edwards prosthesis. The aim of the study is its short and mediumtermassessment. Material and methods. Between January 2004 and May of 2010, 42 patients have been operated for pulmonary valve replacement with pericardium prosthesis. The study was ambispective, being prospective in its last two years. Results. The median age of the patients was 20.96 years (interquartile 10.5 years). The mean number of surgeries prior to the pulmonary valve replacement was 1.9±0.9, being the mean time between the “corrective” surgery and the prosthetic implantation 17.2±7 years. The main indications for this surgery were: right ventricle dysfunction (45%), progressive dilation of the same ventricle (38%), ventricular arrhythmias (14%) and syncopes (3%). Two patients died in the immediate postoperative due to cardiological causes. The mean follow-up time has been 2.1±1.4 years (0.1-6.3). The 94.3 % of the surviving patients are in functional class I, according to the New York Health Association. The peak Doppler transprosthetic gradient determined by echocardiography was 18.5±17 mm Hg. In the echocardiograpic follow-up there have been neither degenerative changes nor any type of structural deterioration of the prosthesis. Conclusions. The bovine pericardium prosthesis in pulmonary position presents excellent results in the short and medium-term. However, it is necessary a longer follow-up to confirm our initial results regarding its durability and haemodynamics long-term...

Guías de práctica clínica de la Sociedad Española de Cardiología en el postoperado de cardiopatía congénita / Guidelines of the Spanish Society of Cardiology in the postoperative course of congenital heart diseases

La mejora progresiva en los métodos de protección miocárdica, la aparición de nuevas técnicas quirúrgicas y la mayor sofisticación en los cuidados perioperatorios, han hecho que el pronóstico de la mayoría de las cardiopatías congénitas haya mejorado ostensiblemente en las últimas décadas. Para ello, es necesaria la coordinación de un equipo multidisciplinario de profesionales que traten a estos enfermos con el objetivo principal de mantener un adecuado aporte de oxígeno a todos los órganos y tejidos.Este equipo debe, en primer lugar, conocer la evolución normal de la cardiopatía y de su posible postoperatorio, para así identificar y tratar los problemas que aparezcan en el caso de un período posquirúrgico anormal.Las causas que pueden desencadenar un postoperatorio anómalo pueden agruparse en: a) la propia fisiopatología del defecto cardíaco antes de la intervención y los cambios que la cirugía produce en la misma; b) los efectos que en los diferentes órganos y aparatos producen el bypass cardiopulmonar, la parada circulatoria y la hipotermia profunda, y c) la presencia de defectos residuales. Cualquiera de estas variables puede ocasionar un postoperatorio más prolongado de lo normal y un aumento de la morbimortalidad.Las tres alteraciones hemodinámicas primarias que pueden provocar un postoperatorio anormal son: disfunción del ventrículo izquierdo, disfunción del ventrículo derecho e hipertensión pulmonar.Aunque no siempre relacionados con la cardiopatía ni con la propia cirugía, los problemas específicos de los diferentes órganos pueden alterar de forma significativa el postoperatorio de estos enfermos. Se discuten separadamente los concernientes al sistema nervioso central, pulmón, riñón, tracto gastrointestinal y los problemas infecciosos más frecuentes (AU)