Science and technology for water purification in the coming decades
TL;DR: Some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re-use of wastewater and efficient desalination of sea and brackish water are highlighted.
Abstract: One of the most pervasive problems afflicting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water-rich. Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy, while at the same time minimizing the use of chemicals and impact on the environment. Here we highlight some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re-use of wastewater and efficient desalination of sea and brackish water.
Citations
More filters
TL;DR: The possible reductions in energy demand by state-of-the-art seawater Desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages are reviewed.
Abstract: In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.
4,840 citations
TL;DR: In this article, the authors reviewed the use of sunlight to produce the OH radicals by TiO2 photocatalysis and photo-Fenton process and summarized most of the research carried out related to solar photocatalytic degradation of water contaminants and how it could significantly contribute to the treatment of persistent toxic compounds.
2,541 citations
TL;DR: The antimicrobial mechanisms of several nanoparticles are reviewed, their merits, limitations and applicability for water disinfection and biofouling control are discussed, and research needs to utilize novel nanomaterials for water treatment applications are highlighted.
2,108 citations
Cites background from "Science and technology for water pu..."
...In particular, its potential to revolutionize century-old conventional water treatment processes has been enunciated recently (USEPA, 2007; Shannon et al., 2008)....
[...]
...In particular, its potential to revolutionize century-old conventional water treatment processes has been enunciated recently (USEPA, 2007; Shannon et al., 2008)....
[...]
TL;DR: The main conclusions arrived at from the overall assessment of the literature are that more work needs to be done on degradation kinetics and reactor modeling of the combined process, and also dynamics of the initial attack on primary contaminants and intermediate species generation.
2,046 citations
Cites background from "Science and technology for water pu..."
..., 2006a), which are highly reactive and non-selective as stated in some key revisionworks (Gogate and Pandit, 2004a,b; Pera-Titus et al., 2004; Devipriyas and Yesodharan, 2005; Pignatello et al., 2006; Comninellis et al., 2008; Shannon et al., 2008)....
[...]
...…2003; Sarria et al., 2004; García-Montaño et al., 2006a), which are highly reactive and non-selective as stated in some key revisionworks (Gogate and Pandit, 2004a,b; Pera-Titus et al., 2004; Devipriyas and Yesodharan, 2005; Pignatello et al., 2006; Comninellis et al., 2008; Shannon et al., 2008)....
[...]
TL;DR: In this article, molecular-level design approaches for membrane materials, focusing on how these materials address the urgent requirements of water treatment applications, are reviewed for water scarcity and the pollution of aquatic environments.
Abstract: Membranes have an increasingly important role in alleviating water scarcity and the pollution of aquatic environments. Promising molecular-level design approaches are reviewed for membrane materials, focusing on how these materials address the urgent requirements of water treatment applications.
1,900 citations
References
More filters
TL;DR: In a warmer world, less winter precipitation falls as snow and the melting of winter snow occurs earlier in spring, which leads to a shift in peak river runoff to winter and early spring, away from summer and autumn when demand is highest.
Abstract: All currently available climate models predict a near-surface warming trend under the influence of rising levels of greenhouse gases in the atmosphere. In addition to the direct effects on climate--for example, on the frequency of heatwaves--this increase in surface temperatures has important consequences for the hydrological cycle, particularly in regions where water supply is currently dominated by melting snow or ice. In a warmer world, less winter precipitation falls as snow and the melting of winter snow occurs earlier in spring. Even without any changes in precipitation intensity, both of these effects lead to a shift in peak river runoff to winter and early spring, away from summer and autumn when demand is highest. Where storage capacities are not sufficient, much of the winter runoff will immediately be lost to the oceans. With more than one-sixth of the Earth's population relying on glaciers and seasonal snow packs for their water supply, the consequences of these hydrological changes for future water availability--predicted with high confidence and already diagnosed in some regions--are likely to be severe.
3,831 citations
TL;DR: Observations suggest that carbon nanotubes, with their rigid nonpolar structures, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
Abstract: Confinement of matter on the nanometre scale can induce phase transitions not seen in bulk systems1. In the case of water, so-called drying transitions occur on this scale2,3,4,5 as a result of strong hydrogen-bonding between water molecules, which can cause the liquid to recede from nonpolar surfaces to form a vapour layer separating the bulk phase from the surface6. Here we report molecular dynamics simulations showing spontaneous and continuous filling of a nonpolar carbon nanotube with a one-dimensionally ordered chain of water molecules. Although the molecules forming the chain are in chemical and thermal equilibrium with the surrounding bath, we observe pulse-like transmission of water through the nanotube. These transmission bursts result from the tight hydrogen-bonding network inside the tube, which ensures that density fluctuations in the surrounding bath lead to concerted and rapid motion along the tube axis7,8,9. We also find that a minute reduction in the attraction between the tube wall and water dramatically affects pore hydration, leading to sharp, two-state transitions between empty and filled states on a nanosecond timescale. These observations suggest that carbon nanotubes, with their rigid nonpolar structures10,11, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
3,115 citations
TL;DR: There are three scientific challenges in addressing water-quality problems caused by micropollutants, and usage and disposal strategies should aim to minimize introduction of critical pollutants into the aquatic environment.
Abstract: The increasing worldwide contamination of freshwater systems with thousands of industrial and natural chemical compounds is one of the key environmental problems facing humanity. Although most of these compounds are present at low concentrations, many of them raise considerable toxicological concerns, particularly when present as components of complex mixtures. Here we review three scientific challenges in addressing water-quality problems caused by such micropollutants. First, tools to assess the impact of these pollutants on aquatic life and human health must be further developed and refined. Second, cost-effective and appropriate remediation and water-treatment technologies must be explored and implemented. Third, usage and disposal strategies, coupled with the search for environmentally more benign products and processes, should aim to minimize introduction of critical pollutants into the aquatic environment.
2,951 citations
TL;DR: Gas and water flow measurements through microfabricated membranes in which aligned carbon nanotubes with diameters of less than 2 nanometers serve as pores enable fundamental studies of mass transport in confined environments, as well as more energy-efficient nanoscale filtration.
Abstract: We report gas and water flow measurements through microfabricated membranes in which aligned carbon nanotubes with diameters of less than 2 nanometers serve as pores. The measured gas flow exceeds predictions of the Knudsen diffusion model by more than an order of magnitude. The measured water flow exceeds values calculated from continuum hydrodynamics models by more than three orders of magnitude and is comparable to flow rates extrapolated from molecular dynamics simulations. The gas and water permeabilities of these nanotube-based membranes are several orders of magnitude higher than those of commercial polycarbonate membranes, despite having pore sizes an order of magnitude smaller. These membranes enable fundamental studies of mass transport in confined environments, as well as more energy-efficient nanoscale filtration.
2,637 citations
TL;DR: A comprehensive overview on the development of polymeric membranes having advanced or novel functions in the various membrane sepn processes for liq. and gaseous mixts can be found in this paper.
1,841 citations