In the Middle East and North Africa, food security and water security are tightly entwined. In particular, choices about the extent to which food security policies rely on trade rather than domestically produced staples have stark consequences for the region's limited water resources. This paper builds on previous modeling results comparing the cost and benefits of policies to protect consumers against surging international wheat prices, and expands the analysis to consider the consequences of the policies for water resources. A self-sufficiency policy is analyzed as well. Results suggest that trade-based food security policies have no significant effect on the sustainability of water resources, while the costs of policies based on self-sufficiency for water resources are high. The analysis also shows that while information about the water footprint of alternative production systems is helpful, a corresponding economic footprint that fully measures the resource cost of water is needed to concisely rank alternative policies in economic terms that are consistent with sustainable outcomes.

Security of the Water-Energy-Food Nexus has become a global concern, threatened by the rapid urbanization, unsustainable consumption of resources, population growth and climate change that exert pressure on resources to meet the socioeconomic demands. Water-Energy-Food Nexus is central for sustainable development and promoting efficient management of resources. Nevertheless, an efficient and sustainable Water-Energy-Food Nexus design requires the participation of multiple stakeholders in the decision-making process. This work presents a multi-objective optimization model for the design of a Water-Energy-Food system that involves the sustainable production of water, energy and food in areas that share economic activities through the industrial, agriculture and livestock sectors. Additionally, a multi-stakeholder assessment is presented to generate a set of solutions, where different priorities are given to the stakeholders. This approach allows quantifying the level of satisfaction of each of the stakeholders. Integration of resources is addressed according to economic and environmental objectives, such as the minimization of the cost of the system, water abstraction and greenhouse gas emissions. As case study, a region located in Mexico was selected based on its industrial activity and the challenges it currently faces in meeting resource demands due to low water availability. Results show that water reuse is crucial to improve the Water-Energy-Food Nexus sustainability. Also, it was found that the most affected sector for water scarcity is the agricultural sector. This model can be the basis for planning the Water-Energy-Food Nexus at regional level involving different stakeholders and for determining sustainable interactions between resources.

A bibliographic search yielded a set of empirical equations that constitute an easy method for the calculation of some thermophysical properties of both liquid water and ice I, properties that are involved in the modeling of thermal processes in the high-pressure domain, as required in the design of new high-pressure food processes. These properties, closely interrelated in their physical derivation and experimental measurement, are specific volume, specific isobaric heat capacity, thermal expansion coefficient, and isothermal compressibility coefficient. Where no single equation was found, an alternative method for calculation is proposed. Keeping in mind the intended applications and considering the availability of both experimental data and empirical equations, the limits for the set of equations where set in -40 to 120 degrees C and 0 to 500 MPa for liquid water and -30 to 0 degrees C and 0 to 210 MPa for ice I. The equations and methods selected for each property are described and their results analyzed. Their good agreement with many existing experimental data is discussed. In addition, the routines implemented for the calculation of these properties after the described equations are made available in the public domain.

Este trabajo evalúa la eficiencia de un sistema de tratamiento en un reactor de lodos activados, operado bajo presión, ubicado en el Campus Aguas Claras, Universidad Santo Tomas sede Villavicencio. El cuál tuvo como alimentación, agua residual sintética propuesta, con el fin de controlar las características de la misma, a la entrada del reactor. Se determinó la eficiencia del reactor, inicialmente realizando una caracterización del efluente a través de monitoreo in situ de los siguientes parámetros: Temperatura del agua, pH, Oxígeno disuelto y Caudal; seguido a esto, se midieron las variables independientes de la investigación, tales como la presión entre 3, 5 y 8 psi, en relación con la ley de Henry, para determinar la solubilidad del oxígeno en la mezcla de agua, asimismo, el tiempo de retención hidráulico (3, 4 y 6 horas), posteriormente se midieron variables, ex situ, como la DBO5, DQO y los SSV, determinando de esta manera, la remoción final de la materia orgánica en el reactor (eficiencia). La temporalidad del trabajo abarcó los meses de septiembre a noviembre de 2019; en el cual a finales de septiembre se operó el biorreactor dejando un periodo de estabilización y adaptación de las bacterias de una semana. Posteriormente se iniciaron las corridas operacionales durante la primera semana de octubre, luego el muestreo y toma de datos se realizó durante las diferentes semanas del mismo mes y comienzos del mes de noviembre, periodo en el cual las variaciones para tiempo de retención hidráulico y presión se determinaron de la siguiente manera: TRH variación semanalmente, y la presión cada dos días. En este sentido, sumado a la revisión de información secundaria se evaluó y comparó el diseño actual del sistema de lodos activados operado bajo presión, respecto a referentes teóricos de reactores convencionales, consecuentemente, se identificaron aspectos a mejorar en el tratamiento, proponiendo consideraciones de diseño tendientes a mejorar la eficiencia de remoción de carga contaminante, mediante información técnica del sistema de tratamiento que facilite el proceso de mantenimiento, seguimiento y control de las condiciones operativas. Los resultados en la investigación, fueron la mayor eficiencia de remoción del 91,09% para DQO y 96,66% para DBO con una presión de 8 psi, un tiempo de retención de 4 horas y un oxígeno disuelto de 4,7 mg/L. Contrariamente, la menor eficiencia se evidenció en 53,07% con una presión de 3 psi, un tiempo de retención de 6 horas y una concentración de OD de 3,4 mg/L, así como la corrida operacional en la cual se presentó un porcentaje de remoción de 76% con una presión de 8 psi, un tiempo de retención de 6 horas y un OD 5,8 mg/L respectivamente. El análisis estadístico de varianza indico que existe una relación significativa entre la presión aplicada al biorreactor y la eficiencia que se obtuvo del proceso, indicando así que a una mayor presión se presentan mejores porcentajes de remoción, por otro lado, los tiempos de retención no presenta ninguna relación significativa con la eficiencia del proceso. | This work evaluates the efficiency of a treatment system in an activated sludge reactor, operated under pressure, located in the Santo Tomas University Aguas Claras Campus from Villavicencio -Colombia. Which was fed by synthetic waste-water proposed, in order to control the characteristics of it, at the entrance of the reactor. The efficiency of the reactor was determined, initially making a characterization of the effluent by an on-site monitoring of the following parameters: Water temperature, pH, Dissolved oxygen and Flow; after this, the independent variables of the investigation were measured, the pressure (3, 5 y 8 psi) , in relation to Henry's law, to determine the solubility of oxygen in the water mixture, the hydraulic retention time (3 , 4 y 6 hours), after which independent variables were measured. , ex situ, such as BOD5, COD and SSV, that is determining the final removal of organic matter in the reactor (efficiency). The temporality of the work covered the months of September to November; in which at the end of September the bioreactor was operated leaving a period of a week for the stabilization and adaptation of the bacteria. Later, the operational runs began during the first week of October, then the sampling and data collection was carried out during the different weeks of the same month and beginning of November, period in which the variations for hydraulic retention time and pressure were determined. as follows: TRH variation weekly, and pressure every two days. In this sense, in addition to the review of secondary information, the current design of the activated sludge system operated under pressure was evaluated and compared to theorical referents of conventional reactors, consequently, aspects to be improved in the treatment were identified, proposing design considerations tending to improve the efficiency of removal the charge, by means of technical information of the treatment system that facilitates the process of maintenance, monitoring and control of the operative conditions. The results in the investigation, are presented by the highest removal efficiency, which was 91.09% for COD and 96.66% for BOD with a pressure of 8 psi, a retention time of 4 hours and a dissolved oxygen of 4.7 mg / L, conversely, the lowest efficiency was found in 53.07% with a pressure of 3 psi, a retention time of 6 hours and an OD concentration of 3.4 mg / L, as well as the operational run in which a removal percentage of 76% was presented with a pressure of 8 psi, a retention time of 6 hours and an OD of 5.8 mg / L respectively. The statistical analysis of variance indicated that there is a significant relationship between the pressure applied to the bioreactor and the efficiency obtained from the process, indicating that at a higher pressure there are better percentages of removal, on the other hand, retention times do not present no significant relationship with the efficiency of the process. | Ingeniero Ambiental | http://www.ustavillavicencio.edu.co/home/index.php/unidades/extension-y-proyeccion/investigacion | Pregrado