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WATER DISINFECTION

Worldwide, 780 million people do not have access to sanitized water sources per the Center for Disease Control and Prevention. The outcome of this is approximately 800,000 children deaths under the age of 5 due to diarrheal disease and water infection. 41 million people suffer from active Trachoma, the leading preventable cause of blindness, 10 Million of those are irreversibly blinded per year from this easily preventable disease. The regions most affected by this issue, according to the World Health Organization and UNICEF, are Sub-Saharan Africa, Southern Asia, and Eastern Asia. There are worldwide efforts to improve these current conditions, and proves the need for continued advancement in the field. Water disinfection is a vital part of everyday life and continued advancement on effective, safe, easy to perform, and less labor intensive methodology is vital.

Nowadays electrochemical disinfection has gained increasing attention as an alternative for conventional drinking water treatment, because it is regarded as environmentally friendly, amenable to automation, inexpensive, easily operated and is known to inactivate a wide variety of microorganisms from bacteria to viruses and algae.

As compared with other chemical disinfection methods, the advantages of electrochemical water disinfection are obvious:

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  • No transport, storage, and dosage of disinfectants are required. The disinfecting effect can be adjusted according to the on-site demand.

  • Electrochemical water disinfection shows a reservoir effect and is often more cost-effective and requires less maintenance than other disinfection methods.

  • Photovoltaic power supply makes it possible to use electrochemical water disinfection far from the electrical supply grid. This may be important for its application to drinking water in developing countries.

  • Electrochemical water disinfection can also be used in conjunction with other disinfection methods.

 

Various electrodes have been used in the EAOP process and the common feature is that high over-potential is necessary to facilitate electrochemical production. The need for a cost effective, long life anode has been one of the issues in this industry preventing large scale implementation. The Magneli Reactive Membrane can process large volumes of water effectively, has a long life, is energy efficient and allows for cost and performance advantages to allow wider use of electrochemical disinfection.

In addition to Magneli's technology being used for disinfection, a number of clients have moved the technology forward in the treatments and removal of Nitrates and other contaminants, such as PFAS and 1,4 Dioxane.

REMOVAL OF NITRATES

& PFAS & 1,4 DIOXANE

Nitrates

Physicochemical treatments such as electrodialysis, ion exchange and reverse osmosis are the most common technologies for NO3 – removal from water, but the post-treatments are still needed to address the concentrated solutions produced in these methods. Although biological denitrification can gradually convert NO3 − to N2 [6], it is a time-consuming process and its performance is strongly impacted by the variable conditions, such as dissolved oxygen and temperature.

Recently, Magneli Materials has developed new technology using Ti4O7 material on both  anodes and cathodes of water treatment reactors.  What this has allowed is a water treatment system that can oxidize and reduce at the same time.   

Initial testing has shown 100% removal of Nitrate using this technology, in both industrial waste and in drinking water with very low conductivity.

Lab Scale Reactor.png

In initial testing using lab scale reactors and well water with Nitrate levels from 7 to 21 ppm, complete reduction of Nitrate occurred in one pass through the lab scale reactor, less than 2 minutes at low current densities. Actual results available on request.

Lab Scale reactors are in production and available, and industrial systems are shipping for the Ti407 on the anode and cathode. 

PFAs and 1,4 Dioxide

Clients have been using Magneli’s technology to treat PFAS and 1,4 Dioxane, both difficult to treat and emerging problems in drinking water.   Magneli’s technology completely mineralizes these waste products.

1,4 Dioxane, a widely used solvent, is a persistent organic pollutant frequently found in groundwater.  1,4 dioxane is highly recalcitrant, and commonly applied remediation technologies have been ineffective for its removal. 

 

Advanced Oxidation processes involving UV light have been effective, but their high cost typically limits their use. 

Electro chemical degradation has been shown to effectively mineralize these solvents by reductive dichlorination and OH mediated oxidation.

Poly- and perfluoroalkyl substances (PFAS) pose a serious human health risk due to their toxic effects.They have been globally detected in groundwater, landfill leachates, wastewater treatment plants, and drinking water.

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Among them, perfluorooctanoic acid (PFOA) and perfluoro octane sulfonic acid (PFOS) have received the greatest attention because of their abundance, bioaccumulation, and persistence. The existence of multiple, highly stable carbon−fluorine bonds in the structure of PFASs makes them difficult to eliminate from aqueous media. These compounds were not removed by sand filtration, ozonation, and microbiological degradation. Because PFASs are also resistant to traditional advanced oxidation processes (AOPs), the development of effective treatment technologies for their destructive removal has been a focus of many recent studies.

 

Advanced treatment approaches have been applied for PFOA/PFOS decomposition, such as sonolysis,

microwave−hydrothermal, ultrasonication, photolysis, photocatalysis, and electrochemical oxidation. Among these, electrochemical oxidation has shown promise due to its high energy efficiency, its ability to achieve complete mineralization, and its operational simplicity.

Magneli Materials' Ti4O7 anodes have shown, in research and in pilot scale, to be an effective anode for use in electro chemical systems for the removal of PFAs from water. 

Articles For Water Disinfection

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