http://www.revistadechimie.ro REV.CHIM.(Bucharest)♦70♦ No. 3 ♦2019 866 Hydrodynamic Surface Evaluation of a Polymeric Reverse Osmosis Membrane Using a Crossflow Cell MIHAELA - ELENA DASCALU 1 , FLORIN NEDEFF 1 *, EMILIAN MOSNEGUTU 1 , IOAN GABRIEL SANDU 2,3 , JUAN ANTONIO LOPEZ - RAMIREZ 4 1 Vasile Alecsandri University of Bacau, Department of Environmental Engineering and Mechanical Engineering, 157, Calea Marasesti, 600115, Bacau, Romania 2 Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science & Engineering 61A D. Mangeron Blvd, Iasi, 700050, Romania 3 Romanian Inventors Forum, 3 Sf Petru Movila, St. Bl L11, Sc A, Et III, Ap 3, Iasi, 700089, Romania 4 Universidad de Cadiz, Departamento de Tecnologías del Medio Ambiente, CASEM - Polig. Río San Pedro, s/n. 11510 Puerto Real, Cadiz, Spain The purpose of this research was to visualize the fouling process of a flat-sheet polymeric membrane into a flow cell, using particles to study their deposition onto the membrane surface. This set of experiments was analyzed from an imagistic point of view, designing for this purpose a measuring installation where hydrodynamic surface evaluation was carried out with an image processing concerning to the reverse osmosis operation. To ensure the measurements accuracy, calculations, logical approximation, and comparisons were made with existing and verified models, revealing that the differences were insignificant. Keywords: filtration, fouling membrane, reverse osmosis, imaging analysis Natural waters, irrespective of their origin, contain many impurities, of a mineral and organic nature, dissolved (salts, gases) or dispersed (suspended matter), in a higher or lower concentration, which they train during natural circulation [1]. Wastewater treatment and purification is a set of measures and processes by which the mineral, organic and bacteriological impurities contained in the waste water are eliminated or reduced to certain limits, such that these waters do not affect the qualitative characteristics of the receptor in which they are evacuated. For treatment and wastewater treatment several processes based on physical, chemical and biological processes are used [1- 7]. Filtration is a method of separating solid impurities from fluids, following flow through permeable porous media, called filter media or filters [8-13]. The quality of the underground water and groundwater is increasingly subject to the harmful influence of anthropogenic substances, agricultural pollution and the increasing presence of chlorinated hydrocarbons. Optimal solutions that combine conventional processes with advanced technologies, such as membrane filtration, guarantee a high level of flexibility and superior water quality [8-17]. The processes that involve the use of membranes, including RO, are widely used in water treatment processes and are of importance growing globally. As a result, membrane filtration potability plants, allow for better, more complete and easier monitoring of water sources [18, 19]. The main factors influencing the performance of a system based on reverse osmosis are [19-21]: pressure, temperature, concentration of dissolved salts in the inlet water. Reverse osmosis is one of the most effective methods of water treatment for dangerous contaminants such as nitrates, nitrates, mercury, arsenic, lead, pesticides, fluorides, etc. [19-25]. Reverse osmosis systems retain dissolved chemicals as well as biological agents in water, resulting water having a high degree of purity [22, 25]. The * email: florin_nedeff@ub.ro; Phone: +40745157751 membranes fouling is the most important problem in the water filtration process, for which continuous studies are being done to reduce this effect, limiting the effectiveness of membranes can affect negatively plant performance [25, 26]. Visualization of the fouling process of the membranes was done by hydrodynamic evaluation of the surface of an RO polymeric membrane with a flat-sheet configuration using various kinds of particles, to view the filtering process in the flow cell through an imaging analysis. The evaluation of hydrodynamics, the surface of the polymeric membrane, using different types of pollutants, can provide useful information in the art and responses in terms of velocities or flow behavior in cells via the membrane. The present study aims to investigate de possibility to establish some correlations between polymeric reverse osmosis membrane operation and a crossflow cell hydrodynamic surface evaluation. Experimental part The flow cell is a cross flow filtration unit (cross-flow of water) for the laboratory, specially designed to evaluate flat membrane models in a variety of applications [27]. The flow cell used to perform flat membrane experiments is a unique model made of Plexiglas’s (approximately 92% transparent), with both smooth and glossy faces, with extreme resistance to impact and natural protection against ultraviolet radiation [27]. The flow cell simulates the flow dynamics on commercially available membrane elements, such as the industrial spiral. By using a combination of Plexiglas, lamellas, feed spacing and membrane, the operating conditions and fluid dynamics can vary for wide ranges [27]. In figure 1, the technological scheme of the plant containing the flow cell is represented. Experimental research implied the use of particles to visualize the flow of water in the flow cell or visualization