MOSCOW, September 28Scientists at the North Caucasus Federal University (NCFU) have found a way to combat biofouling of water intakes in water supply systems using electricity; their development is expected to contribute to better water supply, as well as saving energy, reported the Ministry of Science and Higher Education of the Russian Federation.
Pipelines at water intakes, especially in warm climates, are often overgrown with aquatic organisms — small animals that live in water. Sometimes this process is so intense that it leads to critical pressure losses in the suction water intake system and the threat of stopping pumping stations, excessive energy consumption, equipment wear and possible accidents.
The most common bivalve mollusks are zebra mussels. Their layer on the inner walls of pipelines reaches a thickness of 7-10 cm, and the mass of fouling is up to 7 kg per square meter. m. The resistance of pipelines increases sharply, which entails additional energy costs for water supply. Additional electricity costs, according to experts, amount to 10-12% of total electricity consumption.
There are traditional ways to combat zebra mussels. To do this, reagents are used — water is chlorinated, ozonated, or silver preparations are added. But NCFU researchers took a different route. They noticed that without the biofilm that forms on the pipeline from bacteria, mollusk larvae cannot attach to the surface. And if you electrically “charge” bacteria, then the water molecules line up polarly around them, forming several ordered layers of pure water at the molecular level around the microbes. This creates osmotic pressure, which leads to the rupture of bacterial cells and, as a result, to the absence of biofilm.
“We proposed giving a weak positive charge to the internal surfaces of pipelines. In this way, the growth of bacteria on the walls of pipelines is suppressed and a biofilm does not form,” said one of the authors of the study, Professor of the Department of Heat and Gas Supply and Real Estate Expertise of NKFU Nikolay Stoyanov.
For protection against shellfish scientists proposed using a special DC power station. The “positive” electrode is connected to a metal pipe, which should be protected from biofouling, and the “negative” electrode is connected to the cathode.
According to the authors of the development, this approach is much cheaper than traditional methods. For example, a city water utility in an average Russian city can spend up to 50 million rubles per year on combating biofouling. The idea of NCFU scientists is estimated to cost tens and even hundreds of times less. Moreover, this approach can also be used in other industries — for example, to protect parts of ships submerged in water from fouling with shells, which significantly affect speed.