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Effect of mixed liquor volatile suspended solids on membrane fouling during short and long-term operation of membrane bioreactor

EDSON BALTAZAR ESTRADA ARRIAGA PETIA MIJAYLOVA NACHEVA LILIANA GARCIA SANCHEZ (2015, [Artículo])

The aim of this study was to examine the impact of different Mixed Liquor Volatile Suspended Solids (MLVSS) concentrations on membrane fouling, in a submerged Membrane Bioreactor (MBR) at short and long-term MBR operation for wastewater treatment. Three laboratory-scale in a submerged MBR system were operated under critical flux, sub-critical flux, and an intermittent suction time and backwashing conditions. At short-term MBR operation with mixed liquors of 4,200 and 6,150 mg MLVSS L-1, the hydraulic resistance of membranes followed a same trajectory with averages of 5.0E+12 m-1, whereas for 7,940 mg MLVSS L-1, a high resistance of up to 1.7E+13 m-1 was obtained. The result showed that high biomass concentrations decreased to permeability due to a bio-layer formed in the membrane surface and high Extracellular Polymeric Substance.

Biorreactor de membrana Saturación de la membrana Sólidos suspendidos volátiles Sustancias poliméricas extracelulares BIOLOGÍA Y QUÍMICA

Determinantes del comportamiento de queja del consumidor en México

Determinants of consumer complaint behavior in Mexico

IGNACIO JAVIER CRUZ RODRIGUEZ JAVIER GALAN FIGUEROA (2019, [Artículo])

El objetivo del trabajo es explicar los determinantes del comportamiento de queja del consumidor en los niveles socioeconómico y empresa. Para ello se acude a la metodología de datos de panel estático a fin de estimar el impacto de los determinantes de las quejas de los consumidores. Los resultados a nivel socioeconómico indican que las quejas se encuentran determinadas por el ingreso, las conciliaciones a favor de los consumidores y por la población residente en zonas urbanas. Mientras a nivel empresa los resultados muestran que tanto la cuota de mercado como el tamaño de la firma afectan positivamente las quejas. Se concluye que los resultados coinciden con la literatura revisada y que se puede esperar un aumento en el número de quejas presentadas por los consumidores.

This work aims to quantify the determinants of consumer complaint behavior in socioeconomic and business levels. For this purpose, the static panel data methodology is used in order to estimate the impact of consumer complaints both at the federal level of the Mexican Republic and at the level of the main companies that are considered leaders in their field. The results by the state indicate that the complaints are determined by income, reconciliations in favor of consumers and population residing in urban areas.While at the company level, the results show that both market share and company size positively affect consumer complaints. In conclusion, the results agree with the literature reviewed, and a rise in the number of complaints is possible.

HUMANIDADES Y CIENCIAS DE LA CONDUCTA Datos de panel Efectos fijos y efectos aleatorios Satisfacción de los consumidores Quejas del consumidor Panel data models Fixed effects and random effects Consumer complaint

Estimating lime requirements for tropical soils: Model comparison and development

Fernando Aramburu Merlos João Vasco Silva Frédéric Baudron Robert Hijmans (2023, [Artículo])

Acid tropical soils may become more productive when treated with agricultural lime, but optimal lime rates have yet to be determined in many tropical regions. In these regions, lime rates can be estimated with lime requirement models based on widely available soil data. We reviewed seven of these models and introduced a new model (LiTAS). We evaluated the models’ ability to predict the amount of lime needed to reach a target change in soil chemical properties with data from four soil incubation studies covering 31 soil types. Two foundational models, one targeting acidity saturation and the other targeting base saturation, were more accurate than the five models that were derived from them, while the LiTAS model was the most accurate. The models were used to estimate lime requirements for 303 African soil samples. We found large differences in the estimated lime rates depending on the target soil chemical property of the model. Therefore, an important first step in formulating liming recommendations is to clearly identify the soil property of interest and the target value that needs to be reached. While the LiTAS model can be useful for strategic research, more information on acidity-related problems other than aluminum toxicity is needed to comprehensively assess the benefits of liming.

Exchangeable Acidity Aluminum Saturation Calcium Carbonate Equivalent CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CHEMICOPHYSICAL PROPERTIES LIMES TROPICAL ZONES ACID SOILS ALUMINIUM BASE SATURATION CALCIUM CARBONATE