Georgian Scientists/ . 7 N 4, 2025 468 Georgian Scientists Vol. 7 Issue 4, 2025 https://doi.org/10.52340/gs.2025.07.04.30 Theoretical and experimental studies of the nanofiltration separation process under laminar flow conditions Liana Kuparadze1, Giorgi Bibileishvili2, Nana Gogesashvili3, Tinatin Butkhuzi4, Nona Butkhuzi5, Ia Gogiberidze6 Engineering Institute of Membrane Technologies of Georgian Technical University 1Academic Doctor, Chief Scientist email LianaKuparadze@gmail.com ORCID ID: https://orcid.org/0009- 0002-6786-5669; 2Doctor, Chief Scientist- Doctor, Chief Scientist- e-mail:75bibileishvili@gmail.com ORSID ID:http:/orsid/0009-0003-7712-2436 Abstract The paper presents the nanofiltration process of mineral water from Borjomi, in particular, specifically from borehole No. 37, which is preceded by theoretical studies, as a result of which the speed range for implementing the laminar regime was determined for different heights of the working pressure cell. Experimental studies of mineral water defluoridation-debarring have established that the liquid treated under laminar conditions of the nanofiltration process complies with the normative values of the “ZDK” for mineral waters. Keywords: nanofiltration, laminar flow, Specific productivity. Introduction (problem, relevance) To ensure human health and food safety, it is necessary to comply with the standards of mineral waters, which is directly related to the development, creation and use of modern membrane systems of membrane equipment and technologies [1,2}. As is known, nanofiltration occupies an intermediate position in baromembrane processes between reverse osmosis and ultrafiltration. The reverse osmosis process provides almost complete demineralization of water, while nanofiltration serves for more selective purification. At the same time, it is equally effective in removing organic substances, bacteria and viruses. We should also mention the advantages of nanofiltration technology: on the one hand, the possibility of partial desalination, and on the other hand, nanofiltration membranes can operate at lower pressures than conventional reverse osmosis membranes. {4,5,6,} Georgian Scientists/ . 7 N 4, 2025 469 As is known, under laminar flow conditions, an ordered movement of fluid is observed in layers, with particles moving along specific trajectories without chaotic motion and eddies. The creation of membrane nanosystem technology is preceded by a separate and complex discussion of scientific research, experimental, and design work to demonstrate the effectiveness of baromembrane processes. For this purpose, the paper presents the results of both theoretical and experimental studies of the baromembrane nanofiltration process for laminar regime conditions. One of the most important issues in solving these issues is the creation of conditions that ensure the effective conduct of baromembrane processes through studies of the hydrodynamic and mass transfer processes of the flow in the filtration device. To determine the hydraulic regime parameters, a theoretical calculation of the water flow parameters for the working node of the laboratory device was carried out using the Reynolds number Re = , where v is the velocity, d is the hydraulic diameter, and is the kinematic viscosity of the fluid. The geometric dimensions of the pressure cell of the laboratory working unit are: width B=50mm=50×10-3m; length l=540mm=540×10-3m; heights: h= 0.2mm=0.2 ×10-3m ; h=0.35mm=0.35×10-3m and h= 0.6mm=0.6 ×10-3m. The kinematic viscosity coefficient of water at 200C is =1.004 mm2/s = 1.004×10-6 m2/s. Table 1. presents the hydraulic characteristics for different heights of the working node under laminar regime conditions, Re number values for fluid velocities: 0.5 m/s; 1 m/s; 1.5 m/s; 1.97 m/s; 3.36 m/s; 5 m/s; 5.85 m/s. Table 1. Results of the theoretical calculation (m/s) 0,5 1 1,5 1,97 3,36 5 5,85 h=0,2 mm F=B× = ×0,2=10mm2= × ; =2B+2h=100+0,4=100,4mm=100,4 10-3 R= , 0,09782mm=09782 ×10-3 m; d=4 × =0,398406mm=0,398406×10-3m; cn=5,85 m/s × (m2/ ) 0,1992 ×10-3 0.3984 ×10-3 0,5976 ×10-3 0,7848 ×10-3 1,3386 ×10-3 1,992 ×10-3 , ×10-3 198 396 595 781 1333 1984 2321 Q (m3/s) 5 × 10-6 10 × 10-6 15 × 10-6 19,7 × 10-6 33,6× 10-6 50× 10-6 , × 10-6 h=0,35mm F=B× = ×0,35=17,5m2 , × ; =2B+2h=100+0,7=100,7mm=100,7 10-3m; Georgian Scientists/ . 7 N 4, 2025 470 R= = , , 0,17378 mm=0,17378310-3 m; d=4 × =0,695134 =0,695134 10-3 m; cn=3,36 m/s × (m/ ) 0,3475 ×10-3 0,6951 ×10-3 1,0426 ×10-3 1,3694 ×10-3 , × 10-3 - - 381 762 1144 1583 2326 - - Q (m3/s) 8,7 × 10-6 17,5 × 10-6 26,2 × 10-6 34,47 × 10-6 , × 10-6 - - h=0,6mm F=B× = ×0,6=30mm2= × ; =2B+2h=100+1,2=101,2mm= 101,2 10-3 m; R= = , 0,296242mm=0,29442 ×10-3 d=4 × =1,18577mm=1,18577 10-3 m; cn=1,97 m/s × (m2/ ) 0,5627 ×10-3 1,125 ×10-3 1,68752 ×10-3 , ×10-3 - - - 569 1120 1680 2325 - - - Q (m3/s) 2,7 × 10-6 5,4 × 10-6 8,1 × 10-6 , × 10-6 - - - According to Table 1, based on the theoretical calculation data, the critical values of the Reynolds number were determined for all three different heights in the pressure cell, which led to the appropriate velocity range for laminar flow: for the pressure cell h=0.2 mm, 0