Influencia de la incorporación de lixiviados sobre la biodegradabilidad anaerobia de aguas residuales domésticas

El tratamiento de los lixiviados constituye uno de los retos más importantes en el diseño y operación de rellenos sanitarios; la combinación de éstos con aguas residuales domésticas para su tratamiento mediante sistemas anaerobios constituye una opción con alto potencial de aplicación, principalmente en países en vía de desarrollo. Este trabajo presenta un estudio de la influencia de la incorporación de lixiviados generados en un relleno sanitario en el que se disponen residuos sólidos residenciales sobre la biodegradabilidad anaerobia de aguas residuales típicamente domésticas. Fueron estudiados cinco sustratos que correspondie- ron a agua residual doméstica y lixiviado, y tres mezclas de agua residual y lixiviado en proporciones de 10, 20 y 30% de lixiviado. El seguimiento de la biodegradabilidad se realizó durante 30 días mediante la medición de la producción acumulada de metano y la variación en la concentración y composición de los ácidos grasos volátiles (AGV); al final del ensayo se hizo el análisis de los componentes de la demanda química de oxígeno (DQO). Los resultados obtenidos indicaron que en las condiciones en que fue realizado el ensayo y para el tipo de lixiviado evaluado, la proporción máxima en volumen que puede ser degradada conjuntamente con agua residual doméstica por vía anaerobia sin que cause efectos inhibitorios significativos fue del 10%. Proporciones de lixiviados superiores presentaron comportamiento similar al del lixiviado, indicando potenciales efectos inhibitorios en el proceso anaerobio.Treating leachate is one of the most important challenges in designing and operating a sanitary landfill. Anaerobic treatment u- sing a mixture of leachate and domestic sewage represents a suitable treatment option having good potential applicability in developing countries. The influence of adding leachate from a domestic sanitary landfill on the anaerobic biodegradability of domestic sewage has been evaluated in this paper. Five samples were evaluated for the study: 100% domestic sewage (DS), 100% leachate (L) and three leachate mixtures (L) with domestic sewage (DS) as follows: 10%(L):90%(DS), 20%(L):80%(DS) and 30%(L):70%(DS). The samples’ anaerobic biodegradability was monitored for 30 days using methane production accumulation and variation in volatile fatty acid (VFA) concentration and composition. A detailed analysis of chemical oxygen demand (COD) composition was performed at the end of the monitoring period. The results of the study showed that a 10%(L):90%(DS) mixture provided the maximum leachate (L) domestic sewage (DS) combination mixture which could be anaerobically biodegradable with no significantly inhibitory effects. Mixtures using a higher percentage of leachate showed significantly potential inhibition effects on the anaerobic biodegradation of domestic sewage

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Aerobic/anoxic biological filter for nitrogen removal of UASB effluents

Constata-se, principalmente em países em desenvolvimento, o uso crescente de reatores anaeróbios de manta de lodo (UASB) como primeira unidade de tratamento biológico de esgotos sanitários. Embora eficientes na remoção de fração considerável de matéria orgânica, os reatores anaeróbios produzem efluentes que requerem pós-tratamento, principalmente para a remoção de compostos nitrogenados reduzidos. No presente estudo, foi avaliado o desempenho de uma nova configuração de filtro biológico percolador (FB), constituído por dois compartimentos superpostos, um para a nitrificação e outro para a desnitrificação. Utilizou-se um novo material plástico como leito suporte para crescimento da biomassa e avaliou-se a viabilidade da utilização do biogás produzido no reator UASB como doador de elétrons para desnitrificação. Embora a nova configuração de FB tenha permitido a ocorrência dos processos de nitrificação e desnitrificação, são necessárias mudanças no projeto da interface entre os compartimentos para evitar o acúmulo de biomassa nesse local. O material suporte caracterizou-se pela durabilidade e elevado índice de vazios, além de ter oferecido condições favoráveis para a aderência e colonização de biomassa. A utilização de biogás para a desnitrificação mostrou-se viável e eficiente. Como foi constatada a presença de oxigenio dissolvido no compartimento desnitrificante, o metano foi o principal constituinte do biogás utilizado como doador de elétrons. Para a taxa de carregamento hidráulica média aplicada de 5,6 \'M POT.3\'/\'M POT.2\'.d e taxa de carregamento orgânica média aplicada de 0,26 kgDQO/\'M POT.3\'.d, a nitrificação ocorreu de forma eficiente, obtendo-se entre 60 e 74% de conversão de N-amon, sendo que o efluente final apresentou, em média, concentração abaixo de 10 mg/L. A desnitrificação ocorreu de forma bastante satisfatória mesmo na presença de OD. Obtiveram-se concentrações de nitrato menores que 10 mg/L. Contudo, acredita-se ser possível a obtenção de maiores eficiencias de remoção desde que as condições anóxicas no compartimento desnitrificante sejas mantidas.UASB reactors have been increased used as first unit of biological domestic sewage treatment mainly in developing countries. Although efficient in the removal of considerable fraction of organic matter, effluents from anaerobic reactors, however, require being post-treated, especially for the removal of reduced nitrogen compounds. In the present study, the performance of a new configuration of trickling filter (TF) composed of a nitrification compartment at its upper part followed by a denitrification compartment was evaluated. A new plastic material was used as support media for biomass attached-growth and the biogas produced by the UASB reactor was used as electron donor for denitrification. Although the new TF configuration has allowed obtaining the nitrification and denitrification, the design in the interface among the compartments should be changed to avoid biomass accumulation. The support media was characterized by the durability and high percentage of void spaces, resides offering favorable conditions for the biomass attachment and colonization. The use of the biogas for denitrification was found to be viable and efficient. The presence of disolved oxygen (DO) was verified in the denitrification compartment, leading to the hypothesis that methane might have been the main component of the biogas used as electrons donor. Regarding the performance of TF for nitrogen removal, efficient nitrification was achieved for the applied hydraulic load around 5.6 \'M POT.3\'/\'M POT.2\'.d and applied organic load around 0.26 kgDQO/\'M POT.3\'.d. Under such conditions, about 74% of N-ammonia was removed and the final effluent presented average concentrations of N-ammonia below 10 mg/L. Despite the presence of OD, the denitrification was performed in a satisfactory way. Nitrate concentrations smaller than 10 mg/L were obtained. In addition, it is believed that maintaining anoxic conditions in the lower compartment would make it possible to obtain higher denitrification efficiencies

Metodologías para establecer valores de referencia de metales pesados en suelos agrícolas: perspectivas para colombia

From an environmental perspective, the importance of heavy metals in soils is related to their toxicity either due to their accumulation or to any interaction between them and some of their specific properties.  In each case, heavy metals can move through the soil profile and transfer into the trophic chain through water bodies or crops affecting human health.  In developed countries, the establishment of baseline values has permitted improvements in the soil environmental management plans.  Baseline values have become a control tool for environmental agencies to test the impact of heavy metals in a variety of agricultural activities.  This article analyses different concepts related to heavy metals levels in agricultural soils and the effects of soil characteristics on their concentration, at the same time some methodologies to obtain specific baseline values from identification of the natural concentration are reviewed.  It is included some prospects related to soil protection and remediation in Colombia.  Currently, in Colombia there are no studies related to obtain baseline values of heavy metals in agricultural soils.  For this reason it is necessary to get support from agencies such as the Ministry of Environment, Housing and Territorial Development and Ministry of Agriculture, in order to start and develop research in some primary agricultural sectors to guarantee the production and the environmental sustainability of soils.Los problemas ambientales de los metales pesados en los suelos están relacionados con su carácter tóxico cuando se acumulan o cuando interactüan con algunas propiedades especificas, se movilizan a  través del perfil a la cadena trófica mediante los cuerpos de agua o los cultivos y pueden llegar a afectar la salud humana. En países desarrollados el establecimiento de valores de referencia de estos metales ha permitido el mejoramiento de la planeación y la gestión ambiental del recurso suelo, y se ha convertido en un instrumento de control para las entidades ambientales que ha permitido evaluar el impacto en diferentes actividades agrícolas.En este artículo se analizan diferentes conceptos relacionados con los niveles de metales pesados en suelos agrícolas y la incidencia de las características edafológicas en su concentración. Se revisan, igualmente, algunas metodologias para derivar valores de referencia especificos aplicables a suelos agrícolas colombianos, y se plantean algunas perspectivas orientadas a la protección y recuperación de suelos en el país. En Colombia en la actualidad no se cuenta con criterios y estándares de calidad para metales pesados en suelos agrícolas; por esto se hace necesario gestionar el apoyo de entidades gubernamentales con el fin de iniciar y desarrollar investigaciones en diferentes sectores agricolas primarios, contribuyendo de esta forma a garantizar la producción agrícola y la sostenibilidad ambiental del recurso suelo

Treatment of COD analysis liquid wastes generated in environmental laboratories

COD analysis is often carried out in environmental labs. Its wastes are considered hazardous due to the content of metals such as Cr, Ag and Hg; treating these wastes is considered complex and expensive. The experimental results of metal ion precipitation in COD wastes with affordable chemical products are reported in this work. Cr (VI) was chemically reduced by adding 200 mg.L-1 of glucose to Cr (III). Final Cr (VI) concentration was less than 0.5 mg.L-1. Cr (III) was precipitated as a metallic hydroxide by adding NaOH and Ag was reduced to less than 0.2 mg.L-1 by adding 2 g.L-1 of NaCl. Hg was reduced to less than 0.005 mg.L-1 with 10 g.L-1 of FeS. The proposed reduction-precipitation methodology allowed minimising the liquid residue’s hazardous characteristics so that it complied with the maximum allowable values established in Chapter 6, Article 74 of Decree 1594/1984 that regulates the use of water and liquid residues

The influence of incorporating leachate on anaerobic biodegradability of domestic sewage

Treating leachate is one of the most important challenges in designing and operating a sanitary landfill. Anaerobic treatment u- sing a mixture of leachate and domestic sewage represents a suitable treatment option having good potential applicability in developing countries. The influence of adding leachate from a domestic sanitary landfill on the anaerobic biodegradability of domestic sewage has been evaluated in this paper. Five samples were evaluated for the study: 100% domestic sewage (DS), 100% leachate (L) and three leachate mixtures (L) with domestic sewage (DS) as follows: 10%(L):90%(DS), 20%(L):80%(DS) and 30%(L):70%(DS). The samples’ anaerobic biodegradability was monitored for 30 days using methane production accumulation and variation in volatile fatty acid (VFA) concentration and composition. A detailed analysis of chemical oxygen demand (COD) composition was performed at the end of the monitoring period. The results of the study showed that a 10%(L):90%(DS) mixture provided the maximum leachate (L) domestic sewage (DS) combination mixture which could be anaerobically biodegradable with no significantly inhibitory effects. Mixtures using a higher percentage of leachate showed significantly potential inhibition effects on the anaerobic biodegradation of domestic sewage

Optimización de la etapa de arranque de reactores anaerobios mediante el mejoramiento de la calidad de diferentes semillas en condiciones dinámicas de operación

IP 1106-12-031-96Incluye anexos.PONENCIA(S) EN CONGRESO: Evaluacion de potenciales semillas parala inoculacion de reactores anaerobios /;Luis Francisco Ramirez ... [et al.] -- p. 34-44 -- En: Seminario'-Taller Latinoamericano sobre tratamiento;anaerobio de aguas residuales. (4 : 1996 : Bucaramanga) --[s.l: s.n], 1996 -- p. ; 28 cm. -- Influencia de;la variacion de la carga organica en la etapa de arranquede unreactor UASB / Jenny A. Rodriguez V. ... [et;de la Digestion Anaerobia y Caracterizacion de Lodos Anaerobios.(1997 jun. 4-6 : Medellin) / Francisco;Molina, Didier Alazard ; Organiza: Grupo de higiene AmbientaleIndustrialde la Facultad de Ingenieria de la;Universidad de Antioquia. -- Medellin : Universidad de Antioquia, 1997. --p. ; 28 cm.;al.] -- En: Seminario Internacional sobre tratamiento de aguasresidualesy biosolidos. (oct. 12-13 : Tunja); [s.l : s.n], -- p. ; 28 cm. -- El tratamiento de aguasresiduales una labor interdisciplinaria de;ingenieros y microbiologos / Fransisco Jose Molina Perez -'- en:Congreso Internacional El Laboratorio y la;Salud Integral: Una Persectiva (1998 nov. 13-15 : Medellin) --ARTICULO(S) EN REVISTA: Evaluacion de la;presion selectiva y de la adicion de bacterias liofilizadas comoalte alternativas de mejoramiento de una;semilla de lodo activado crudo espesado para el arranque de reactores UASB/ Jorge Humberto Sierra C., Julio;Cesar Saldarriaga M. -- En: Revista Facultad de Ingenieria. --No. 22 (jun. 2001); p. 7-21. -- Evaluacion;microbiologica de un lodo crudo proveniente de la planta de tratamiento deaguas residuales del municipio de;El Retiro y del mismo lodo a condiciones anaerobias / FernandoNaranjo P.,Maria Elena Gonzalez D., Francisco;Molina P. -- En: Revista Facultad de Ingenieria. -- No. 22(jun. 2001); p. 22-28 -- CURSO(S): Microbiologi