Daniel Varona Gómez

Bio: Daniel Varona Gómez is an academic researcher from University of Los Andes. The author has contributed to research in topics: Figure of merit & Nanofiltration. The author has an hindex of 7, co-authored 14 publications receiving 187 citations. Previous affiliations of Daniel Varona Gómez include Universidad de La Sabana & University of Oviedo.

Industrial Applications of Porous Ceramic Membranes (Pressure‐Driven Processes)

Abstract: Publisher Summary This chapter discusses the industrial applications of porous ceramics membranes. Pressure-driven membrane processes are among the most mature membrane technologies. They are used for liquid separations and are generally classified into four categories: reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), andmicrofiltration (MF). Pressure-driven membrane processes at present have high industrial impact, with a market constantly growing. They are used in a wide range of separation processes and are considered among the best available technologies (BAT), in the European Union environmental recommendations because they present several advantages with respect to other separation processes. The main applications of RO are found in the desalination of brackish and seawater; the production of ultrapure water (electronic industry); concentration of food juice, sugars, and milk; and in the treatment of wastewater. The performance of the ceramic membrane-based systems depends on the separation and permeation properties of the membrane as well as its mechanical integrity. These properties depend on the selective top layer and on the support system on which the active separation layer is coated. Therefore, pore size, porosity, surface roughness, and mechanical properties—all are important parameters.

The Efficiency of Informality: Quantifying Greenhouse Gas Reductions from Informal Recycling in Bogotá, Colombia

Abstract: The dual challenges of increasing urbanization and consumption are centered in cities in the Global South, where growing waste production threatens public and environmental health. Reuse and recycling are widely recognized to provide broad environmental benefits. Although most industrialized cities replaced their informal recycling sectors with municipally run recycling schemes and have had to build their recycling rates anew, most industrializing cities in the Global South remain centers of recycling and reuse through the work of informal workers. Bogota, Colombia, is emblematic of many cities in the Global South seeking to modernize their city, in part by formalizing their recycling system. This article asks: What are the greenhouse gas (GHG) emission implications of this modernization? Using interviews and observation in combination with life cycle assessment, we compare GHG emissions resulting from the baseline case (1,200 tonnes per day [t/d] recycled through informal channels; 5,700 t/d landfilled) to three alternative scenarios that formalize the recycling sector: the prohibition of informal recycling; a reduction in informal recycling coupled with a scale-up of formalized recycling; and the replacement of informal recycling with formal recycling. We find that the baseline recycling scenario, dependent on the informal sector only, emits far fewer GHGs than do all formalization scenarios. Three processes drive the results, in order of magnitude: informal textile reuse (largest GHG savings); landfilling (largest emitter of GHGs); and metal recycling (GHG savings). A hybrid model could combine the incentives and efficiency of the informal system with the better working conditions of the municipal one.

Ictiofauna y desarrollo del sector hidroeléctrico en la cuenca del río Magdalena-Cauca, Colombia

Abstract: The Magdalena-Cauca River basin has 213 species of freshwater fish, of which slightly more than 50% are endemic. This basin accounts for 80% of the Colombian population, holds 80% of the national GDP and within its channels are located the 84% of the hydroelectric plants that supply energy to Colombia. The Andean mountains generate altitudinal gradients in aquatic systems as well as its associated biota along the Magdalena-Cauca basin. To analyze the interaction between the altitudinal gradient in the distribution of species of freshwater fish and the location of existing reservoirs, it was performed an analysis of the altitudinal distribution of endemic and migratory fish species and their implications for their conservation based on the current and future state in the formation of reservoirs, using a review of case studies at global and national levels. It was found that the number of species is inversely proportional to altitude, while the endemics are directly proportional and reservoirs below 700 m altitude affect the conservation status of migratory species. A reservoir creates new species richness gradients and modifies the channels that are used by migratory species as spawning areas. We conclude that the development of the hydropower based on the use of water in the Andean rivers and another activities associated with economic development of Colombian society, has led to changes in freshwater aquatic systems in the Magdalena-Cauca basin, influences in the structure of the assemblages of species of fish and in the dynamic of migration and spawning of freshwater fish species important for artisanal fisheries.

Medios de comunicación y punitivismo

Abstract: Es ya un lugar comun entre la doctrina penal y criminologica espanola considerar a los medios de comunicacion como uno de los actores principales dentro del proceso de deriva punitiva que define a la actual politica criminal. Sin embargo, mas alla de una generica alusion al incremento de la sensacion de inseguridad entre la poblacion por el tratamiento sensacionalista y desproporcionado de la delincuencia, no suele explicitarse el mecanismo o mecanismos a traves de los cuales los medios de comunicacion estarian contribuyendo a dicha deriva punitiva. En el presente trabajo se aborda esta cuestion, analizando las tecnicas concretas a traves de las cuales los medios de comunicacion consiguen tener una incidencia directa en la evolucion de la politica criminal espanola. Estos mecanismos son basicamente dos: el fenomeno de la �agenda setting� (tematizacion de la agenda) y la tecnica del �framing� (encuadre noticioso).

Waste Mismanagement in Developing Countries: A Review of Global Issues.

Abstract: Environmental contamination due to solid waste mismanagement is a global issue. Open dumping and open burning are the main implemented waste treatment and final disposal systems, mainly visible in low-income countries. This paper reviews the main impacts due to waste mismanagement in developing countries, focusing on environmental contamination and social issues. The activity of the informal sector in developing cities was also reviewed, focusing on the main health risks due to waste scavenging. Results reported that the environmental impacts are pervasive worldwide: marine litter, air, soil and water contamination, and the direct interaction of waste pickers with hazardous waste are the most important issues. Many reviews were published in the scientific literature about specific waste streams, in order to quantify its effect on the environment. This narrative literature review assessed global issues due to different waste fractions showing how several sources of pollution are affecting the environment, population health, and sustainable development. The results and case studies presented can be of reference for scholars and stakeholders for quantifying the comprehensive impacts and for planning integrated solid waste collection and treatment systems, for improving sustainability at a global level.

Evaluating scenarios toward zero plastic pollution

Abstract: Plastic pollution is a pervasive and growing problem. To estimate the effectiveness of interventions to reduce plastic pollution, we modeled stocks and flows of municipal solid waste and four sources of microplastics through the global plastic system for five scenarios between 2016 and 2040. Implementing all feasible interventions reduced plastic pollution by 40% from 2016 rates and 78% relative to “business as usual” in 2040. Even with immediate and concerted action, 710 million metric tons of plastic waste cumulatively entered aquatic and terrestrial ecosystems. To avoid a massive build-up of plastic in the environment, coordinated global action is urgently needed to reduce plastic consumption; increase rates of reuse, waste collection, and recycling; expand safe disposal systems; and accelerate innovation in the plastic value chain.

Synthetic membranes for water purification : status and future

Abstract: Membrane technology offers the best options to "drought proof" mankind on an increasingly thirsty planet by purifying seawater or used (waste) water. Although desalination by reverse osmosis (RO) and wastewater treatment by membrane bioreactors are well established the various membrane technologies still need to be significantly improved in terms of separation properties, energy demand and costs. We can now define the ideal characteristics of membranes and advances in material science and novel chemistries are leading to increasingly effective membranes. However developments in membranes must be matched by improved device design and membrane engineering. It is likely that limitations in fluid mechanics and mass transfer will define the upper bounds of membrane performance. Nevertheless major advances and growth over the next 20 years can be anticipated with RO remaining as the key to desalination and reclamation, with other membrane processes growing in support and in niche areas.