This paper aims to develop a multi-criteria decision analysis (MCDA) tool for rainwater harvesting (RWH) on a university campus in Bogota, Colombia. The specific type of MCDA our research proposes is known as CRIDE (multi-CRIteria DEcision support tool), which allows us to study various methods of RWH. In order to account for uncertainties such as the variability of expert opinions and imprecision stemming from the different criteria required, we have designed this tool to incorporate ELECTRE II and the Monte Carlo method. For this case study we apply a methodology that evaluates the performance of six RWH scenarios. These six input scenarios emerged from an ideal one, wherein all rainwater throughout the campus is successfully harvested and treated until potable. From there, reality sets in: the other five scenarios are varying degrees of deviance from the ideal one, both in terms of water quantity and quality. In regard to collection and treatment we used sustainable urban drainage systems (SUDS). As for the evaluation of each of the scenarios, we outline eight criteria, which include hydraulic performance, compatibility with the University's Master Plan and financial aspects. Our research concludes that CRIDE as a means of support during the decision-making process generates a complete view of possible solutions, in addition to ranking these solutions. The CRIDE-based approach allows for the proposal of a methodology that evaluates the relevance of an established criteria set, using robustness, redundancy and sensitivity.

Ingeniería y Ciencia, ing. cienc. ISSN 1794-9165 Volumen 8, número 15, enero-junio de 2012 Macrófitas flotantes en el tratamiento de aguas residuales; una revisión del estado del arte ResumenLos tratamientos de aguas residuales que involucran macrófitas flotantes han demostrado ser eficientes en la remediación de aguas con contenidos de nutrientes, materia orgánica y sustancias toxicas como arsénico, zinc, cadmio, cobre, plomo, cromo, y mercurio. Su importancia radica en su aptitud para ser empleados en núcleos rurales debido a su bajo consumo de energía convencional y la practicidad en el montaje y operación de los sistemas de tratamiento. Aun así, todavía no se han esclarecido rigurosamente los procesos que tienen lugar en la depuración de aguas residuales con macrófitas flotantes.El presente artículo pretende hacer un recorrido por la literatura existente sobre macrófitas flotantes, identificando los aspectos generales, ventajas y des- 221|Macrófitas flotantes en el tratamiento de aguas residuales; una revisión del estado del arte ventajas del uso de estas plantas para depurar aguas residuales. De igual manera se identifican los antecedentes de mayor relevancia desde los inicios de esta aplicación. Serán descritos los modelos de diseño con macrófitas y los criterios generalmente aceptados, revisando rigurosamente las eficiencias de remoción de distintas especies de macrófitas flotantes. Por ultimo serán abordadas según lo analizado las perspectivas actuales y retos futuros para el desarrollo de esta técnica.Palabras claves: Macrófitas flotantes, plantas flotantes, tratamientos naturales de aguas residuales, sistemas blandos, fitoremediación, humedales, jacinto de agua. AbstractThe wastewater treatments with floating macrophytes have proven effective in the remediation of waters with nutrient content, organic matter and toxic substances such as arsenic, zinc, cadmium, copper, lead, chromium, and mercury. Its importance lies in its ability to be used in rural communities due to their low consumption of conventional energy and practicality in the assembly and operation of treatment systems. Still, it has not been clarified thoroughly the processes taking place in the purification of wastewater with floating macrophytes.This article attempts to review the existing literature on floating macrophytes, thus identifying the general aspects, advantages and disadvantages of using these plants for treating wastewater. Similarly, identify the most important background since the beginning of this application. There will be described models and design criteria mostly employed, rigorously reviewing removal efficiencies of different species of floating macrophytes. Finally it will be addressed as discussed current perspectives and future challenges for the development of this technique. Key words:Floating macrophytes, floating plants, natural wastewater treatment, soft systems, phytoremediation, wetlands, water hyacint. ResumoOs tratamentos deáguas de residuais que envolvem macrófitas flutuantes tem demonstado ser eficien...

In this review, the factors affecting the transfer of oxygen in activated sludge processes using fine-pore diffusers for water resource recovery are critically discussed. In water resource recovery facilities, the energy required for aeration constitutes 50% to 80% of the total energy consumed by the plant. This critical review highlights the use of fine-pore diffuser aeration and emphasizes the significance of accounting for the following factors: diffuser aging and fouling, diffuser layout, diffuser type, selector benefits, local environmental conditions (temperature and atmospheric pressure), influent wastewater variability, dissolved oxygen control systems, and airflow rates. In our review, we were unable to find mathematical models that could be used to develop dynamic α-factor predictions and diffuser fouling predictions. Although the development of a model that considers all the factors that affect oxygen transfer efficiency (OTE) in activated sludge systems would be extremely valuable, the creation of such a model is outside the scope of this review.

Endocrine disruptors have been studied for their high occurrence in different environments including aquatic; however, in the context of developing countries, their occurrence, magnitude and potential threat have little information. This study involved the analysis of various components of the urban water cycle in the city of Bogotá, Colombia. As a result, it was found that the compounds with the highest occurrence are plasticizers such as phthalates and bisphenol A, whereas among the drugs, carbamazepine presented the highest concentrations (0.68-31.45 µg L); the analysis of the threat coefficient (HQ) showed the importance of bis(2-ethylhexyl) phthalate (BEHP) and estrone (E1) that can reach surface waters from domestic and industrial discharges.

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