Water purification is the process of removing contaminants from surface water or groundwater to make it fit for specific purposes. The contaminants may be particulate matter, dissolved minerals or microorganisms. Technologies commonly employed to purify water are distillation, ion exchange, adsorption, filtration, membrane filtration, ultraviolet (UV) radiation or a combination of more than one of these. The technologies most applied currently are membrane filtration and UV radiation. Nanotechnology is significantly advancing water purification technologies, especially in membrane processes.

The following technical classification has been arrived at, based on its commercial usage and popularity.

Note: Please note that the classification is only an indicative of the water purification market. It is not an exhaustive classification of water purification techniques.

Nanotechnology in Water Purification

• The global market for nanotechnology products used in water treatment was worth an estimated $1.4 billion in 2010
• The market will grow at a compound annual growth rate (CAGR) of 9.7% during the next 5 years to reach a value of $2.2 billion in 2015.

Source: BCC Research

Nanotechnology in Water Purification

• The global market for nanotechnology products used in water treatment was worth an estimated $1.4 billion in 2010
• The market will grow at a compound annual growth rate (CAGR) of 9.7% during the next 5 years to reach a value of $2.2 billion in 2015.

Source: BCC Research

Company Profiles

NanoH2O

NanoH2O, Inc. designs, develops, manufactures and markets reverse osmosis (RO) mem­branes that lower the cost of desalination. Based on breakthrough nanostructured materials and industry-proven polymer technology, licensed original TFN technology from University of California, Los Angeles, NanoH2O’s QuantumFlux membranes dramatically improve desalination energy efficiency and productivity. QuantumFlux seawater reverse osmosis (SWRO) membranes, Standard 61 certified by NSF International for the production of drinking water, deliver the highest flux and the highest salt rejection of any SWRO membrane on the market. QuantumFlux membranes are available in standard 8-inch (20 cm) diameter elements that fit easily into new and existing desalination plants, purifying water from a broad range of sources with improved productivity and water quality. NanoH2O is the 2011 Aquatech Innovation Award Winner in the Water Supply category. Quantum Flux membranes are installed in over 50 commercial sites across six continents, representing over 80,000 m3 per day (21 million gallons per day) in cumulative capacity.

The startup has developed its technology based on research from the University of California at Los Angeles. Its formula adds a nanomaterial to a conventional polymer membrane for desalination in order to alter its structure and make it easier for the water to pass through while it blocks out salt and other minerals. The water is potable afterward, but utilities sometimes add back some of the minerals that are filtered out before delivering the water to homes and businesses.

Company Snapshot

Corporate History

Investment Landscape

Source: CrunchBase, PrivCo

Puralytics

Founded in 2007, Puralytics has developed a cost efficient water purification system for distributed use. The company’s products, enabled by advances in semiconductors, optics, and nanotechnology, use natural or LED light to induce photochemical reactions to purify a given volume of water.

Puralytics’ purification technology uses only light energy to activate a photocatalyst nano coating. Water is purified by five simultaneous photochemical reactions, breaking down organic compounds, reducing and removing heavy metals and sterilizing microorganisms. There are no chemical additives and 100% of the water is purified.

Puralytics currently markets two product lines; the Shield and the SolarBag, both based upon Puralytics patent-pending technology. Electrically powered, the Shield is a LED based purification stand-alone system or system component. This unit has an extremely small footprint at 28"x19"x8" and provides 500 gallons per day of purified water. The SolarBag is a direct sunlight activated photochemical water purification bag, manufactured and distributed by channel partners, which can purify 3 liters of water when placed in sunlight for 2 - 4 hours. The SolarBag has promising applications in remote military, emergency response, and emerging markets.

Hydration Technologies’ humanitarian water division is helping Puralytics sell the SolarBag to nonprofits that will distribute it.

Company Snapshot

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IIT Madras

Graphene from Sugar and its Application in Water Purification In Collaboration with: VIT Madras

This paper describes a green method for the synthesis of graphenic material from cane sugar, a common disaccharide. A suitable methodology was introduced to immobilize this material on sand without the need of any binder, resulting in a composite, referred to as graphene sand composite (GSC). Raman spectroscopy confirmed that the material is indeed graphenic in nature, having G and D bands at 1597 and 1338 cm–1, respectively. It effectively removes contaminants from water. Here, we use rhodamine 6G (R6G) as a model dye and chloropyrifos (CP) as a model pesticide to demonstrate this application. The spectroscopic and microscopic analyses coupled with adsorption experiments revealed that physical adsorption plays a dominant role in the adsorption process. Isotherm data in batch experiments show an adsorption capacity of 55 mg/g for R6G and 48 mg/g for CP, which are superior to that of activated carbon. The adsorbent can be easily regenerated using a suitable eluent. This quick and cost-effective technique for the into a commercial water filter with appropriate engineering.

Source: ACS

Understanding the Degradation Pathway of the Pesticide, Chlorpyrifos by Noble Metal Nanoparticles

Application of nanoparticles (NPs) in environmental remediation such as water purification requires a detailed understanding of the mechanistic aspects of the interaction between the species involved. Here, an attempt was made to understand the chemistry of noble metal nanoparticle–pesticide interaction, as these nanosystems are being used extensively for water purification. Our model pesticide, chlorpyrifos (CP), belonging to the organophosphorothioate group, is shown to decompose to 3,5,6-trichloro-2-pyridinol (TCP) and diethyl thiophosphate at room temperature over Ag and Au NPs, in supported and unsupported forms. The degradation products were characterized by absorption spectroscopy and electrospray ionization mass spectrometry (ESI MS). These were further confirmed by ESI tandem mass spectrometry. The interaction of CP with NP surfaces was investigated using transmission electron microscopy, energy dispersive analysis of X-rays, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS reveals no change in the oxidation state of silver after the degradation of CP. It is proposed that the degradation of CP proceeds through the formation of AgNP–S surface complex, which is confirmed by Raman spectroscopy. In this complex, the P–O bond cleaves to yield a stable aromatic species, TCP. The rate of degradation of CP increases with increase of temperature and pH. Complete degradation of 10 mL of 2 ppm CP solution is achieved in 3 h using 100 mg of supported Ag@citrate NPs on neutral alumina at room temperature at a loading of 0.5 wt %. The effect of alumina and monolayer protection of NPs on the degradation of CP is also investigated. The rate of degradation of CP by Ag NPs is greater than that of Au NPs. The results have implications to the application of noble metal NPs for drinking water purification, as pesticide contamination is prevalent in many parts of the world. Study shows that supported Ag and Au NPs may be employed in sustainable environmental remediation, as they can be used at room temperature in aqueous solutions without the use of additional stimulus such as UV light.

Source: ACS

Department of Environmental Geosciences, University of Vienna

Measuring and Modeling Adsorption of PAHs to Carbon Nanotubes Over a Six Order of Magnitude Wide Concentration Range

Understanding the interactions between organic contaminants and carbon nanomaterials is essential for evaluating the materials’ potential environmental impact and their application as sorbent. Although a great deal of work has been published in the past years, data are still limited in terms of compounds, concentrations, and conditions investigated. We applied a passive sampling method employing polyoxymethylene (POM-SPE) to gain a better understanding of the interactions between polycyclic aromatic hydrocarbons (PAHs) and multiwalled carbon nanotubes (CNTs) over a 6 orders of magnitude wide concentration range. In the low-concentration range (pg-ng L–1), sorption of phenanthrene and pyrene was linear on a nonlogarithmic scale. Here, sorption could thus be described using a single sorption coefficient. Isotherm fits over the entire concentration range showed that (i) monolayer sorption models described the data very well, and (ii) the CNTs sorption capacity was directly related to their surface area. Sorption coefficients for 13 PAHs (11 of which have not been reported to date) were also measured at environmentally relevant low concentrations. No competition seemed to occur in the low-concentration range and sorption affinity was directly related to the solubility of the subcooled liquid of the compounds.

Source: ACS, Medienportal

National Nanotechnology Center, NANOTEC, Thailand

"SOS water" mobile water purifier

Researchers at Thailand’s National Nanotechnology Center (NANOTEC) have build the first locally made prototype solar powered water purification unit "SOS water" which combined the use of antimicrobial nanocoating to ceramic filters. Compared to conventional ceramic filter, an antimicrobial nanocoating ceramic filter will increase an extra security by killing or incapacitating bacteria left in the water and preventing the growth of mold and algae in the body of the filter. The project was implemented as a result of the need to provide drinking water to communities affected by the 2011 mega flooding in Thailand.

The researchers adapted the antimicrobial nanocoating know-how for water filtration and assembled into in the production of mobile solar-operating system (SOS) water purification. The raw water goes through 6 filtration steps one of which is the antimicrobial nanocoating ceramic filtration unit. The quality of drinking water meets the 2010 guide standard of drinking water by Department of Health, Ministry of Public Health, Thailand. The SOS water system is capable of producing 200 liters of drinking water per hour and easily integrated into a pick-up, light truck, a trailer or a flat hull boat. The researchers have collaborated with the Thai Red Cross Society to do field testing of a prototype SOS water the result of which was outstanding. NANOTEC has donated the prototype SOS water to HRH Princess Maha Chakri Sirindhorn, Executive Vice President of the Thai Red Cross Society on June 28, 2012 for community relief effort.

Source: NANOTEC

LEITAT Technological Center, Spain

Ceramic and Polymeric Membranes for Water Purification of Heavy Metals and Hazardous Organic Compounds

To develop a new generation of nanostructured Low-Fouling and Self-Cleaning Membranes for Water Purification possessing several key properties such as:

• catalytic degradation of pharmaceuticals and organics
• removal of heavy metals
• scavenging of precious metals and rare earths

Source: Nano4water

Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany

Fouling resistant ceramic honeycomb nanofilters for efficient water treatment

Improve the efficiency of high performance water purification by ceramic membranes:

• strongly increase membrane area of ceramic NF membranes
• apply and test anti fouling layers to reduce fouling tendency
• develop process schemes for treatment of different waters
• Life cycle assessment, cost analysis, techno-economical evaluation
• Active participation of industrial partners: RKV (membrane manufacturer), VMW (end-user) and CYCLUS (OEM, end-user)

Source: Nano4water

Division of Materials Science, Lulea University of Technology, Sweden

Nanoenabled membranes based on bio-materials for water purification

• Development of bio-based nano-enhanced membranes for water treatment, with special focus on fertilizers, pesticides, heavy metal ions and mictobial contaminants relevant in Europe
• Use biobased nanomaterials like cellulose nanofibers and cellulose or chitin nanocrystals isolated from industrial residues and side-streams
• Tailored interaction with contaminants and low/anti fouling by surface functionalization
• The membranes and filters, possible compostable after use (eg. with recovered fertilizers)
• Prototype of membrane modules and scale up plan

Source: Nano4water

Harvard University, School of Engineering and Applied Sciences

An Electrochemical Carbon Nanotube Filter for Water Treatment Applications

Carbon nanotubes (CNTs) have a number of unique physical chemical properties such as have high aspect ratios, high specific surface areas, mechanical strength, chemical stability, and are conducting or semiconducting. Thus, CNTs can be formed into mechanically-strong and electrically-conducting porous thin films or three-dimensional networks that have potential for many applications including water purification. Chad D. Vecitis of Harvard University designed and modified a filtration device to allow for in situ electrochemistry using a perforated stainless steel cathode and an electrochemically-active multi-walled carbon nanotube (MWNT) microfilter anode; 40 to 100 mm in height and pore diameter of 50 to 130 nm. The electrochemical carbon nanotube filter performance towards the removal and oxidation of aqueous dyes, anions, and microorganisms is evaluated. Electrochemical filtration at 2 V resulted in >98% oxidation of influent dye and >6-log removal and/or inactivation of influent bacteria and virus. Environmental applications of the electrochemical CNT filter are discussed.

Source: Harvard University, Carnegie Mellon

Penn Engineering, University of Pennsylvania

High Speed Water Sterilization System for Developing Countries

HydraVita is a high-speed water sterilization system designed for use in developing countries. To our knowledge, this is the first sterilization system to implement a silver nanowire/carbon nanotube-coated cotton filter (AgNW/CNT filter). The device’s main capabilities are inactivating bacteria and reducing the turbidity levels of water. In order to accomplish these objectives, HydraVita incorporates two main components: a turbidity-mesh cartridge that eliminates organic impurities and a AgNW/CNT filter cartridge that kills bacteria. In order to power the filter, the system is equipped with two 12V rechargeable batteries and a solar panel. This allows HydraVita to be used in remote locations with no connection to the power grid. Furthermore, the system is designed for modularity so that it can be easily disassembled for cleaning and maintenance in the field. The input and output water reservoirs are outfitted with standard NPT valves that give operational flexibility to the user, as it can be directly connected to a hose, water tank, or piping system. HydraVita’s novelty stems from its high-speed functionality, low manufacturing cost, modularity, and ease of maintenance.

Source: FINAL POSTER.pdf Penn Engineering

Wright State University, United States

Metal Nanoparticles on Hierarchical Carbon Structures: New Architecture for Robust Water Purifiers

A new architecture for robustand powerful water purification media has been investigated. It consists of carbon nanotubes (CNT) attached to porous microcellular substrates. This is similar to several elegant and multifunctional designs seen in nature where dendrites and capillaries are attached to larger organs increasing their surface area. For this application, palladium and silver nanoparticles are attached to these surfaces for catalytic and anti-microbial activities. Palladium is a powerful catalyst for several reactions. In this study, the kinetics of carbon tetrachloride removal form water using Pd-activated material has been measured, and found to be very high. Silver nanoparticles are useful as antimicrobial agents and as plasmonic sensors. The effectiveness of these structures to remove E-coli from water has been tested, and the rates compared to currently available nano-silver materials. Both nano-particles were seen to be strongly attached to the nanotubes which were in turn strongly attached to the substrate. Durability tests indicate that failure occurs by delamination of graphite inside the substrate, rather than removal of individual CNT or nanoparticles from CNT. This observation bodes well for future use of this architecture in robust and efficient water purification devices.

Source: TechConnect