ON THE ISSUE OF WATER PURIFICATION IN A CLOSED CYCLE OF USE

Abstract

The article reveals the principles of water purification in a closed cycle of use. The necessity of introduction of a
closed water cycle is investigated. It is emphasized that the composition and concentration of wastewater circulating in a
closed cycle can have significant differences depending on the origin of the water, which significantly affects the choice of the
technological line used. The main methods of water purification are identified, which include: physical, chemical and
biological processes based on each other. Each method is described separately, highlighting the advantages and
disadvantages. The concept of the approach to water purification by means of mechanical purification is revealed and the
structure of the first stage of water purification (mechanical purification) in the conditions of the closed cycle of use is
offered. The approach to biological treatment with separation of the main processes is described. The implementation of the
biological process of water purification in the conditions of a closed cycle of use is schematically represented. It is emphasized
that biological water purification in comparison with other methods of purification does not transform pollution into other
forms, which provides almost zero production waste. The advantages of the biological method include: the absence of harmful
chemicals in the technological process; low energy consumption; possibility of autonomous work; the possibility of using the
resulting excess activated sludge as fertilizer; absence of impurities and suspensions in effluents. The processes of
ammonification, nitrification and denitrification, which form the basis of the biological process of water purification, are
described. The description of chemical purification is made and it is emphasized that the purpose of its introduction is the
removal of phosphorus, as well as the removal of sulfides, suspended and organic substances. The scheme of phosphorus
conversion and transformation forms in the process of water purification in the conditions of a closed cycle of use is offered.
The necessity of introducing a closed cycle of water use by solving such problems as the shortage of fresh water needed to
meet the needs of consumers, as well as the reduction or complete reduction of water discharged into the city collector is
substantiated. It is emphasized that the introduction of the described technology allows to realize the waste of production,
which eliminates the loss of raw materials and brings additional benefits for the production of secondary products.