Browsing by Author "Borysov, Ivan A."

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    Reduction of Water Calcium Hardness in the Denitrifying Biofilter
    (Taylor and Francis Ltd., United Kingdom, 2025) Borysov, Ivan A.; Kovalenko, Ihor L.; Gevod, Viktor S.; Frolova, Liliya A.
    ENG: Sustainable development goals emphasize the need for cost-effective removal of nitrates from water of sources where there is no centralized tap water supply. This paper describes the properties of the carbonate system in the filtrate of the point of use handy submersible denitrifying biofilter. Device has a U-shaped design with open tops of both elbows and operates in displacement (piston) mode. These allows getting up to 5 liters of denitrified water daily in one gulp, reducing the concentration of nitrate ions in the water by 96-98% from its initial value of 3⋅10−3⁢𝑀−1.2⋅10−2⁢𝑀 and the water hardness to reduce depending of initial nitrate concentration. The denitrification process occurs with the consumption of ethyl alcohol as a bacterial food substrate injected to water and accompanies by the accumulation of alkaline bacterial exometabolites in the filtrate. During the microbiological transformation of 3⋅10−3⁢𝑀 nitrate ions into nitrogen gas, the filtrate enriches with 2.6⋅10−3⁢𝑀 bicarbonate ions and 3.9⋅10−4⁢𝑀 of hydroxyl ions. This results in a reduction of filtrate hardness from 3.75 mg-eq/L to 1.87 mg-eq/L when in contact with atmospheric air. Physical experiments and mathematical modeling verified the concentrations of carbonate components and calcium ions in both the initial and denitrified water.
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    Reliable and Accessible Point-of-use Water Denitrification System
    (Ukrainian State University of Science and Technologies, Dnipro, 2025) Gevod, Viktor S.; Borysov, Ivan A.; Kovalenko, Ihor L.
    ENG: This paper describes the design and operation of a reliable and accessible point-of-use water denitrification system. The system includes a U-shaped submersible denitrifying biofilter and a bubble-film extractor. The biofilter utilizes the combined actions of denitrifying, sulfate-reducing, and sulfur bacteria. Denitrifying bacteria convert nitrates into nitrogen gas and reduce the calcium hardness of water in proportion to the nitrate concentration. When the water is contaminated with both nitrates and sulfates and the bacterial community receives excess nutrients (ethanol), some sulfates are converted into hydrogen sulfide. This process facilitates the removal of heavy metal ions from the water in the form of hydrosulfides. When the sulfate-reducing bacteria produce excess hydrogen sulfide, the sulfur bacteria convert it into colloidal sulfur at the biofilter outlet. The bubble-film extractor removes colloidal sulfur, heavy metal hydrosulfides, calcium carbonate dispersions, and hydrogen sulfide from the filtrate. The system is user-friendly, requiring no special skills or knowledge for installation and maintenance. The proposed system demonstrates cost-effective denitrification and water polishing over long-term use.