Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs

The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO2, CH4 and N2O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO2 emissions may decrease, the effect is counterbalanced by increased N2O emissions, especially since N2O has a 300-fold stronger greenhouse effect than CO2. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making

El inventario de historia de pérdidas (IHP): Presentación y utilidad clínica

Las teorías contemporáneas sobre el duelo enfatizan en el papel de la adaptación activa a la pérdida como un factor que afecta a un amplio rango de aspectos psicosociales. A pesar del considerable número de investigaciones empíricas que refuerzan este punto de vista, los investigadores comúnmente han limitado su atención a las respuestas a las pérdidas más recientes sufridas por las personas en duelo antes que estudiar su posible adaptación a las diversas pérdidas sufridas a lo largo de su historia vital. Para ello, los autores presentan el Inventario de Historia de Pérdidas (IHP), el cual evalúa sistemáticamente la forma en que las pérdidas han sido experimentadas por los sujetos y su percepción de haberse adaptado satisfactoria o insatisfactoriamente a cada una de ellas. El IHP puede ayudar en la evaluación psicológica y en la planificación del tratamiento, así como permitir la recolección de datos históricos relevantes para la investigación futura en temas de duelo y pérdida.

Gas collisions and pressure quenching of the photoluminescence of silicon nanopowder grown by plasma-enhanced chemical vapor deposition

The quenching of the photoluminescence of Si nanopowder grown by plasma-enhanced chemical vapor deposition due to pressure was measured for various gases ( H2, O2, N2, He, Ne, Ar, and Kr) and at different temperatures. The characteristic pressure, P0, of the general dependence I(P)=I0exp(-P/P0) is gas and temperature dependent. However, when the number of gas collisions is taken as the variable instead of pressure, then the quenching is the same within a gas family (mono- or diatomic) and it is temperature independent. So it is concluded that the effect depends on the number of gas collisions irrespective of the nature of the gas or its temperature