State-of-the-art of reverse osmosis desalination

Nanotechnology is being used to enhance conventional ceramic and polymeric water treatment membrane materials through various avenues. Among the numerous concepts proposed, the most promising to date include zeolitic and catalytic nanoparticle coated ceramic membranes, hybrid inorganic–organic nanocomposite membranes, and bio-inspired membranes such as hybrid protein–polymer biomimetic membranes, aligned nanotube membranes, and isoporous block copolymer membranes. A semi-quantitative ranking system was proposed considering projected performance enhancement (over state-of-the-art analogs) and state of commercial readiness. Performance enhancement was based on water permeability, solute selectivity, and operational robustness, while commercial readiness was based on known or anticipated material costs, scalability (for large scale water treatment applications), and compatibility with existing manufacturing infrastructure. Overall, bio-inspired membranes are farthest from commercial reality, but offer the most promise for performance enhancements; however, nanocomposite membranes offering significant performance enhancements are already commercially available. Zeolitic and catalytic membranes appear reasonably far from commercial reality and offer small to moderate performance enhancements. The ranking of each membrane nanotechnology is discussed along with the key commercialization hurdles for each membrane nanotechnology.

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A review of water treatment membrane nanotechnologies

Factors affecting the rejection of organic solutes during NF/RO treatment—a literature review

Fouling and subsequent chemical cleaning of nanofiltration (NF) membranes used in water quality control applications are often inevitable. To unravel the mechanisms of organic fouling and chemical cleaning, it is critical to understand the foulant-membrane, foulant-foulant, and foulant-cleaning agent interactions at the molecular level. In this study, the adhesion forces between the foulant and the membrane surface and between the bulk foulant and the fouling layer were determined by atomic force microscopy (AFM). A carboxylate modified AFM colloid probe was used as a surrogate for humic acid, the major organic foulant in natural waters. The interfacial force data were combined with the NF membrane water flux measurements to elucidate the mechanisms of organic fouling and chemical cleaning. A remarkable correlation was obtained between the measured adhesion forces and the fouling and cleaning behavior of the membrane under various solution chemistries. The AFM measurements further confirmed that divalent calcium ions greatly enhance natural organic matter fouling by complexation and subsequent formation of intermolecular bridges among organic foulant molecules. Efficient chemical cleaning was achieved only when the calcium ion bridging was eliminated as a result of the interaction between the chemical cleaning agent and the fouling layer. The cleaning efficiency was highly dependent on solution pH and the concentration of the chemical cleaning agent.

Organic Fouling and Chemical Cleaning of Nanofiltration Membranes: Measurements and Mechanisms

Małgorzata Kabsch-Korbutowicz

Papers

Analysis of membrane fouling in the treatment of water solutions containing humic acids and mineral salts

Effect of Al coagulant type on natural organic matter removal efficiency in coagulation/ultrafiltration process

Ultrafiltration of SDS solutions using polymeric membranes

Application of ultrafiltration integrated with coagulation for improved NOM removal

Separation of anionic surfactants on ultrafiltration membranes