Herramientas para la evaluación de riesgos sobre el ambiente y salud, por la disposición final de residus sólidos urbanos

En el campo de la protección ambiental y de la salud pública y ocupacional, es necesario controlar, en la medida de lo posible, las fuentes de emisión de contaminantes ambientales y su impacto. Para tal fin, es indispensable realizar investigaciones multidisciplinarias que apoyen el desarrollo de políticas públicas basadas en evidencia, encaminadas al beneficio social y cuyo costo económico asociado pueda ser medido. La evaluación de riesgos (ER) es una herramienta que, aplicada al sector del manejo de residuos sólidos urbanos (RSU) y la operación de sitios de disposición final (SDF), puede ayudar a estimar cuantitativamente y a jerarquizar los riesgos ocasionados por esos sitios. La información que una ER proporciona, servirá para apoyar la elaboración de medidas normativas de prevención de riesgos, así como en la toma de decisiones de control ambiental, a través del suministro de la mejor información científica disponible a las agencias normativas y entidades de gobierno. Los estudios de ER por la operación de un SDF de RSU con fines de investigación epidemiológica deben incluir a la población ocupacionalmente expuesta como la primera en estar en contacto con los contaminantes, para la identificación de rutas de exposición completas, la estimación y la medición de la exposición real a contaminantes, o bien, la elaboración de modelos de la exposición sobre la base de los datos existentes, avaladas por un equipo multidisciplinario de expertos en dichos sectores. Este trabajo expone las condiciones para la realización de cualquier estudio de ER al ambiente y a la salud humana por SDF de RSU, así como algunos instrumentos computacionales existentes que podrían ayudar a completar el procedimiento.In the field of environmental protection and public health, it is necessary to control, to the extent possible, emission sources of environmental pollutants and their impact. To this purpose it is essential to carry out multidisciplinary research to support the development of public policies evidence-based, aimed at social benefit and whose associated economic cost can be measured. Risk assessment (RA) is a tool that, applied to the handling of municipal solid waste (MSW) and the operation of waste disposal sites (WDS) sector, can help to quantitatively estimate and prioritize the risk caused by such sites. The information that a RA provides will support the development of risk prevention normative measures, as well as in decision on environmental control through the delivery of the best scientific information available to regulatory agencies and government agencies. The RA studies by the operation of WDS valuables for epidemiological research should include: the people occupationally exposed as the first to be in contact with the contaminants for the identification of complete exposure pathways, the estimation and measurement of actual exposure to contaminants or, the exposure modeling on basis of existing data, supported by a multidisciplinary team of experts in these sectors. This paper exposes the key points for conducting any RA study of WDS on the environment and human health, as well as some existing computational tools that could help to complete the task.Los autores agradecen al IPN-SIP (Proyecto 20161464) por el apoyo financiero que permitió el desarrollo de este proyecto

Influence of different airflows and the presence of bulking agent on biodrying of gardening wastes in reactors.

El biosecado consiste en evaporar el agua de un sustrato biodegradable mediante el calor generado en la fermentación aerobia. Para conseguir una biomasa con baja humedad a partir de los residuos de jardinería de un campus universitario, se ha aplicado este proceso de secado biológico a dichos residuos. Por otra parte, se quiere analizar la influencia que tiene la adición de un agente texturizante en el proceso. El biosecado de este sustrato se realiza en 10 reactores con caudal de aire conocido entre 0.88 y 6.42 L/min• kg (d/w). Al sustrato de cinco reactores se añadió un 15 % de material texturizante (MT), y los otros cinco solo con césped. Los parámetros que influyeron en el proceso fueron: aireación, temperatura y humedad inicial del biorresiduo. Los resultados obtenidos indicaron que los ensayos con MT presentaron una mayor reducción de humedad; después de 20 días el contenido en agua se redujo entre un 50 y un 69 %, permitiendo la producción de un combustible biomásico con un poder calorífico inferior (PCI) de entre 11063-13709 kJ kg–1. Después de la experiencia se concluyó también con que el MT mejora la reducción de humedad, la reducción de amoniaco y permite un buen desarrollo de la fase termofílica. Sin embargo, el aumento del caudal de aire proporcionado al reactor no es linealmente proporcional a la pérdida de peso del sustrato.Biodrying consists on evaporating the water from a biodegradable substrate by the heat generated in the aerobic fermentation. To achieve a biomass with low humidity from garden waste of a university campus, this biological drying process has been applied. On the other hand, the influence of bulking agent (BA) for improving the process must be analyzed. In this work the effect of biodrying process on properties of lawn mowing and garden waste used as substrate was studied. Biodrying was performed in 10 reactors with known aeration rate from 0.88 to 6.42 L/min• kg d/w. Five reactors had 15 % of bulking agent (BA) and five reactors had only grass. The parameters influencing the process were: aeration, temperature and initial moisture of biowaste. The results obtained indicate that the essays with BA presented the best reduction of moisture; after 20 days the water content of waste was reduced between 50 and 69 %, allowing the production of biodried waste with a low heat value (LHV) between 11063-13709 kJ kg–1. After the experiences it is also found that the BA improves moisture reduction, drops NH3 production and permits good performance of thermophilic phase. However, the increase in aeration rate was not linearly proportional to the weight loss.The authors are grateful to the Spanish Ministry of Science and Innovation for funding for this study (Project ACI2009-0993) in the program “Convocatoria de Ayudas del Programa Nacional de Internacionalización de la I+D. Subprograma de Fomento de la Cooperación Científica Internacional (ACIPROMOCIONA)”

Effect of airflow on biodrying of gardening wastes in reactors

Biodrying consists of reducing moisture by using the heat from aerobic bio-degradation. The parameters that control the process are: aeration, temperature during the process, initial moisture of biowaste, and temperature and relative humidity of the input air. Lawn mowing and garden waste from the gardens of the University Jaume I, Castellón (Spain) were used as a substrate. Biodrying was performed in 10 reactors with known air volumes from 0.88 to 6.42 L/(min·kg dry weight). To promote aeration, 5 of the reactors had 15% of a bulking agent added. The experiment lasted 20 days. After the experiments it was found that the bulking agent led to greater weight loss. However, the increased airflow rate was not linearly proportional to the weight loss

Evaluación del cumplimiento de factores normativos de sitios de disposición final utilizando sistemas de información geográficos, caso de estudio: Estado de México

Currently, the State of Mexico (SM), the most densely populated Mexican State generates more than 19 000 t/d of municipal solid waste (MSW), which is disposed in waste disposal sites (WDS). Therefore, landfill siting should consider territorial issues and legal framework to minimize negative impacts. However, the inadequate record and management at WDS makes it difficult to get precise data related to volumes, sources and composition of MSW disposed, as well as to estimate leachate and biogas emissions. The aim of this work was to determine the status of WDS in the SM, by applying a methodological approach based on the analysis of WDS location, waste handling, disposal practices, general operations, as well as the emission of biogas and leachate. Cartography of the area and geographical information systems (GIS) technology were used to generate spatial data for sites assessment, taking into account the factors and risk parameters for the operation of the WDS. Applying the assessment methodology to 83 WDS of the SM, it was determined the current situation of sites location regarding the distances from landfill location to restricted areas and their compliance with federal and state regulations established in Mexico. The findings of this study show that although the few sites properly managed as landfills receive the higher amount of waste, the vast majority of the studied sites in the SM operate improperly, generating biogas and leachate, which impact negatively on water, groundwater, air, soil and probably human health.Actualmente, en el Estado de México (EM), el estado más poblado de México, se generan más de 19000 t/día de residuos sólidos urbanos (RSU) y se depositan en los sitios de disposición final (SDF). Por consiguiente, el emplazamiento de SDF debe considerar el marco legal y cuestiones territoriales para minimizar los impactos negativos. Sin embargo, la gestión y registros inadecuados en los SDF hace que sea difícil obtener datos precisos relativos a los volúmenes, los orígenes y la composición de los RSU dispuestos, así como para estimar las emisiones de lixiviados y biogás. El objetivo del presente trabajo fue determinar el estado de los SDF del EM, mediante la aplicación de un enfoque metodológico basado en el análisis de su ubicación, el manejo de residuos, las prácticas de disposición, las operaciones generales, así como también la emisión de biogás y lixiviados. Se utilizaron sistemas de información geográfica (SIG) y la cartografía de la zona para generar los datos espaciales para la evaluación de los sitios, teniendo en cuenta factores y parámetros de riesgo para su funcionamiento. Se evaluaron 83 SDF dentro del EM, se determinó la situación actual de su ubicación con respecto a las distancias a áreas restringidas y su conformidad con las regulaciones federales y estatales en México. Los resultados muestran que, aunque los sitios que están gestionados adecuadamente reciben la mayor cantidad de RSU, la gran mayoría de los sitios estudiados en el EM operan incorrectamente, generando biogás y lixiviados, que repercuten negativamente en las aguas superficiales y subterráneas, el aire y el suelo y probablemente en la salud humana

Biodrying under Greenhouse Conditions as Pretreatment for Horticultural Waste

The biodrying process was studied as an alternative technology to reduce the mass and volume of horticultural waste. Four static piles were prepared inside a greenhouse: two containing whole waste and two consisting of shredded waste. All the piles were compared with a test pile containing whole waste and placed outside the greenhouse. In two cases, ventilation ducts were installed to improve aeration. Each greenhouse was 2.0 m wide, 3.5 m long and 1.16 m high. The air temperature and relative humidity were monitored both inside and outside the greenhouse. Mass, humidity, organic matter and total nitrogen in the waste were measured. Piles inside the greenhouse showed decreases of 80% and 75% in weight and volume, respectively, during the first 16 days. The data obtained in this work suggest that biodrying could improve the handling and transport of horticultural waste while also minimizing the impact of pollutants

The Relationship of Moisture and Temperature to the Concentration of O2 and CO2 during Biodrying in Semi-Static Piles

Biodrying was studied over 46 days in two piles (P1 and P2) composed of orange peel and two structuring materials (mulch: P1; sugarcane bagasse: P2). The oxygen and carbon dioxide levels were recorded at different depths (0.1 to 0.6 m). From the beginning to days 33–35 the drying was carried out by a combination of microbial heat, convection, and solar irradiance; moisture reached 30%, corresponding to a water activity (aw) of 0.88–0.9, which was insufficient to maintain microbial activity. Additionally, the O2 and CO2 levels (21% and 0%, respectively) evidenced the end of the biological phase of the process. After day 35, the drying occurred only by convection and solar irradiance. At the end, moisture reached 14% (P1) and 12% (P2), showing that the turning frequency, as well as the type and proportion of the structuring materials, were adequate and significantly influenced moisture reduction, allowing the aeration necessary for biodrying. At the end, a material with an average calorific value of 15,500 kJ/kg was obtained, comparable to wood and other fuels obtained from orange peel, making the biodrying process a suitable option for the stabilization and energy recovery of agricultural and agro-industrial waste with high moisture content