Research of Water Preparation Process for Hot Water Supply Systems Using CL-Anionization Method

Abstract

The research results on a new technology for preparing water for hot water supply by chloro-anionization are presented. According to this technology, water for treatment is passed through a high-base anionite in chlorine form and regenerated by a NaCl solution. In the treated water, the concentrations of Cl⁻ and OH⁻ ions are reduced while maintaining the amount of water hardness cations necessary for the healthy development of the human body. The mathematical experimental design was used to obtain expressions which determine the working exchange capacity of A200EMBCl anionites. The results include the successful implementation of this technology at a system of 6 m³/h performance in Baku. The World Health Organization (WHO) does not set strict requirements for total water hardness levels. However, based on research conducted in various countries over the past 50 years, WHO recommends keeping both the maximum (≤7 g-eq/m³) and minimum hardness levels within the range of 2–4 g-eq/m³. This is because consuming softened or desalinated water can lead to serious health issues. WHO also states that even in developed countries, the intake of hardness cations, including those found in food, is not sufficient to support normal human development. For the first time, the technology developed in this study was implemented at the Azerbaijan Diplomatic Academy (Baku, Azerbaijan Republic) in a drinking water treatment system with a capacity of 6 m³/h. In this system, water is passed through a 400 mm diameter filter loaded with A200EMBCl anionite, with a layer height of 1 m, and equipped with an automatic control valve of Clack WS1 type. The average alkalinity of the treated fresh water, with its initial value of 4.4 g-eq/m³, was decreased to be within the range of 1.8–2.2 g-eq/m³. The working exchange capacity of anionite absorption for \({\text{HCO}}_{3}^{ - }\) ions, with a specific consumption of NaCl for regeneration between 45–55 kg/m³, falls within the range of 300–370 g-eq/m³, which conforms well with the data from laboratory research. According to operational data, the formation of scale in hot water heaters has been prevented. There were even observations of pipe cleaning from the existing scale.