Technical and economic comparison of the efficiency of drinking water preparation from underground water sources using the membrane technology of nanofiltration and traditional technologies

Research subject: research on the improvement of modern membrane methods of well water purification with the purpose of creating a universal effective technology for removing hardness salts, iron, fluorides, ammonium, strontium from water, etc. from water. Experimental studies have been carried out to determine the quality of water purification by water membranes from iron ions, stiffness and fluoride, and also to determine the rates of formation of calcium carbonate precipitations on membranes. For various cases of well water cleaning in the Podolsky District of New Moscow, an economic comparison of the newly developed membrane technology with the “classical” technological solutions offered by the main leading domestic companies was carried out. Objectives: justification of the effectiveness of the application of a newly developed membrane technology for the purification of well water based on a comparison of its economic and environmental indicators with the indicators of technologies currently existing in the market of water treatment equipment. Materials and methods: an overview of the methods for cleaning well water from various contaminants, a description of technological schemes, and their advantages and disadvantages is shown. A new approach to the development of technological schemes for wastewater treatment with a minimum consumption of water for own needs is described, consisting in processing water in two stages. Experiments were carried out to determine the technological characteristics of membrane units (the filtrate output, the rates of precipitation formation on the membranes). The studies were carried out on laboratory stands using nanofiltration membranes with different selectivities indicators. The determination of the costs of service reagents and equipment costs was carried out with the help of calculations according to a program previously developed by the authors to determine the technological characteristics of membrane units. Results: calculations show that membranes effectively retain iron, hardness and fluoride ions even at high values of the filtrate output (0.75...0.9). In the development of units, preference should be given to the use of membranes with low selectivity, low energy consumption, and low reagent costs. This was demonstrated using the experimentally obtained dependences of the rate of growth of the calcium carbonate precipitate on the type of membranes and the multiplicity of the volumetric concentration of the source water. Conclusions: the use of universal membrane systems in container design for the purification of well water at a flow rate of 10 m³/h and above shows that even in the simplest cases (removal of only iron from water) the proposed technology demonstrates high economic and ecological effect in comparison with the technologies traditionally used for this purpose due to its simplicity, small size, the absence of reagents and wastewater. The use of universal units makes it possible to easily cover large areas with a large number of wells and consumers due to their construction, installation and maintenance according to a single scheme.