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Filter That Makes Viruses Adhere

March 25, 2005

Siberian researchers have developed a biologically active sorbent of a new generation. The sorbent provides for the 100-percent efficient water purification from microorganisms and bacteriophages. Microbiological researches were performed with partial support of the U.S. Civilian Research and Development Foundation (CRDF) grant.

Specialists of the Tomsk Polytechnical University and Scientific Research Institute "Microorganism Culture Collection" (VECTOR State Research Center for Virology and Biotechnology) have developed a biologically active sorbent of a new generation based on cotton pulp, modified 1-percent silica slip containing activated alumina. The sorbent provides for the 100-percent efficient water purification from microorganisms and bacteriophages, it can be applied in a wide range of conditions and possesses sufficient durability and longevity.

Water and aqueous solutions are overfilled with pathogens, viruses and toxins, which so far threaten life and health of people, regardless of undertaken actions. Water purification via filtering is ineffective and underproductive, as fine filters with low throughput capacity have to be utilized. Contemporary purification methods are based on the fact that the majority of bacteria and viruses are negatively charged, therefore they can be captured by a macroporous material possessing positive electrokinetic potential. As a result of the process called electrokinetic capturing, small particles would simply stick to filter material.

Since the 70s of the last centur, researchers of different countries have developed several kinds of cation sorbents. Cuno company set up flow-production of a filter material based on diatomite soil under the "Zeta Plus" trade mark. Other foreign sorbents consist of inorganic and organic fiber, the surface of which is covered with needle-shaped boehmite (aluminium hydroxide) nanoparticles.

Filter materials developed by the Russian researchers also contain aluminium oxide and they were created with application of nanotechnology. Unfortunately, all these sorbents are rather expensive and fragile, they can be used only in neutral and acid medium. Therefore, Siberian microbiologists took up to develop more durable, inexpensive and undemanding filters.

To get the sorbent, the researchers made use of low-cost ecologically safe components. The sorbent is based on cotton pulp, which is covered by big nonspherical particles of aluminium oxide (boehmite). To this end, wetted cellulose was mixed with aluminum powder. However, large particles of aluminium do not get water-oxidized in ordinary conditions. To turn entire aluminium powder into oxide, the sorbent developers had to perform activation with alternating sinusoidal power current (50 Hz).

Tests have proved that the sorbent does not lose durability even after a two-day soaking in distilled water and it is capable of functioning in a wide range of ?? values, including alkaline medium. The sorbent's throughput capacity reaches 15000 litre per square meter per hour. The material fully keeps back the test biological object - bacteriophage MS-2, i.e., it exceeds efficiency of Cuno's Zeta Plus 50S filter, which catches only 99 percent of objects.

Thus, Siberian researchers have created an excellent sorbent of low-cost ecologically safe components by applying simple technologies. In their opinion, the sorbent may be widely applied in medicine, veterinary science, food industry and for purification of water, solutions and outbursts of plants related to utilization of microbiological processes.

Informnauka (Informscience) Agency