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.

Science and technology for water purification in the coming decades

Arsenic removal from water/wastewater using adsorbents—A critical review

Metal and metal oxide nanoparticles exhibit unique properties in regard to sorption behaviors, magnetic activity, chemical reduction, ligand sequestration among others. To this end, attempts are being continuously made to take advantage of them in multitude of applications including separation, catalysis, environmental remediation, sensing, biomedical applications and others. However, metal and metal oxide nanoparticles lack chemical stability and mechanical strength. They exhibit extremely high pressure drop or head loss in fixed-bed column operation and are not suitable for any flow-through systems. Also, nanoparticles tend to aggregate; this phenomenon reduces their high surface area to volume ratio and subsequently reduces effectiveness. By appropriately dispersing metal and metal oxide nanoparticles into synthetic and naturally occurring polymers, many of the shortcomings can be overcome without compromising the parent properties of the nanoparticles. Furthermore, the appropriate choice of the polymer host with specific functional groups may even lead to the enhancement of the properties of nanoparticles. The synthesis of hybrid materials involves two broad pathways: dispersing the nanoparticles (i) within pre-formed or commercially available polymers; and (ii) during the polymerization process. This review presents a broad coverage of nanoparticles and polymeric/biopolymeric host materials and the resulting properties of the hybrid composites. In addition, the review discusses the role of the Donnan membrane effect exerted by the host functionalized polymer in harnessing the desirable properties of metal and metal oxide nanoparticles for intended applications.

Polymer-supported metals and metal oxide nanoparticles: synthesis, characterization, and applications

Water is the most important and essential component of earth's ecosystem, playing a vital role in the proper functioning of flora and fauna. But water resources are contaminating continuously. The whole world may be in great water scarcity in the coming few decades. Among many water treatment methods, adsorption is considered to be one of the best. Many articles describe adsorption applications for water treatment in batch mode. Only few works report laboratory, pilot and commercial applications of adsorption technology. This review is a critical evaluation of the contribution of adsorption technology at laboratory, pilot and process scales. Water treatment, through column operations, has been divided into two parts: removal of (i) inorganic and (ii) organic pollutants. Attempts have been made to evaluate the application of adsorption columns at the ground level. Besides, efforts have also been made to emphasize the importance of adsorption columns at commercial levels to tackle water treatment problems i...

Arun K. Deb

Papers

Well-head arsenic removal units in remote villages of Indian subcontinent: field results and performance evaluation.