US, WASHINGTON (ORDO NEWS) — The development of wastewater recycling technologies is associated with epidemiological risks. The content of pathogens, such as noroviruses and adenoviruses, causing gastroenteritis, in such sources can reach ten individuals per liter, while due to the small size (usually 10-300 nanometers), their destruction is difficult.
Existing methods of water purification, as a rule, are based on disinfection with ultraviolet and chlorine, however, their effectiveness has been repeatedly called into question, in addition, such methods are dose-dependent.
In 2011, American scientists introduced membrane bioreactor (MBR), which did a good job of filtering viruses, however, the permeability of the material decreased over time, increasing operating costs.
In a new article, specialists from Ben-Gurion University and other universities described an inexpensive method of water purification using a commercially available polyethersulfone ultrafiltration membrane (PES). To increase permeability, the material was polymerized using a hydrogel coating based on two SPP monomers.
After that, the membrane was tested by Fourier transform spectroscopy of the impaired total internal reflection in the infrared (ART-FTIR) and used to filter the bacteriophage of human adenovirus 2 (HAdV-2) and RNA virus MS2 infecting Escherichia coli and other members of the family enterobacteriaceae, not exceeding 450 nanometers in size.
In addition, the authors tested a new membrane, contaminating it with soluble microbial waste products (SMPs) from wastewater from Traverse City, Michigan. The results of the first tests showed that after polymerization, the viral load in the samples decreased a million times compared to the untreated membrane (the initial level was 100–1000 copies of viral RNA per milliliter) for HAdV-2.
At the same time, the flow of water decreased by only four percentage points. A comparable decrease in viral load was observed in the case of MS2 with a decrease in water flow by 31 percentage points. After contamination of the material with SMPs, permeability did not change significantly: the level of pathogens in water decreased a million times or more.
According to the researchers, after cleaning, the viruses remained detectable in water, despite the fact that the membrane permeability was designed to remove objects with a molecular mass of at least 150 kilodaltons, which may be due to material defects. At the same time, the modified MBR significantly exceeded the conventional membrane in terms of filtration.
ART-FTIR data also showed that the method allows one to obtain a membrane with an increased repulsion range, as a result of which viruses are “discarded” by the hydrogel surface to a greater distance. Moreover, the development does not require the creation of fundamentally new materials or devices and involves the use of commercially available filters, which simplifies its implementation.
The article was published in the journal Water Research .
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