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UDC 628.162:62-278
Andrianov A. P., Pervov A. G., Efremov R. V., Spitsov D. V.
Selection of efficient inhibitors for process flow schemes of the Black Sea water desalination
Summary
Sea water desalination by reverse osmosis has been widely used in drinking and domestic water supply. However, one of the major problems that complicate the operation of desalination facilities is the deposition of low solubility salts in membrane apparatus. In order to control the formation of crystal sediments on membranes different methods are used. Inhibitor dosing to raw water is the most efficient method. A variety of efficient inhibiting agents has been developed. Lately one of the main directions of studies in this field has been new types of phosphorus free and easily biodegradable inhibitors. Tests of six new phosphorus free inhibitors were carried out; the comparison with traditionally used Aminat-K inhibitor is given. The experimental dependencies that allow determining the rate of calcium carbonate scale formation in membrane apparatus are presented. Basing on the obtained results the optimal operational expenditures for sea water desalination were calculated. The study was aiming mainly at comparing the efficiency of newly developed and traditional inhibitors in the process of their use in sea water desalination schemes (by the example of the Black Sea water simulant). The conclusion of the efficiency of the inhibitors used is made on the basis of the minimum operational expenditures for desalination.
Key words
water treatment , reverse osmosis , inhibitor , desalination , membrane unit , sea water , low solubility salt deposit
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DOI 10.35776/MNP.2019.09.02
UDC 628.16:62-278
Pervov A. G., Andrianov A. P.
The mechanisms of action of inhibitors in the process of calcium carbonate precipitate formation in reverse osmosis apparatus
Summary
Knowledge of the mechanism of precipitation of slightly-soluble salts on reverse osmosis membranes is extremely important while choosing measures to prevent it and reduce the consumption of concentrate. The conducted studies provided for enunciating a fresh approach to the mechanism of crystalline deposit formation and the role of inhibitors in preventing this process. The development of the experimental technique is based on the idea that the first crystallization phase — crystal nucleation is homogeneous, that is, occurs in stagnant zones in the concentrate volume at high oversaturation with calcium carbonate. Upon the formation the crystals are removed from the stagnant zones and settled on the membrane surface like other suspended particles present in the treated water. The results of studying the adsorption of polymer inhibitor molecules on the crystal surface during nucleation and crystalline growth on the membrane are presented. The experimentally obtained dependences of the rate of adsorption of inhibitors on the dose of inhibitors, the rate of formation of calcium carbonate, the rate of nucleation, and on the total surface of the germinal crystals are given. The study of micrographs of crystals showed the dependence of the size and number of crystals on the oversaturation value in the stagnant zone during nucleation as well as on the effectiveness of the inhibitor. A method is presented that allows determining the concentration of dissolved salts in the stagnant zones of the membrane apparatus and the oversaturation values corresponding to the onset of the crystallization process eliminating the addition and use of various inhibitors.
Key words
calcium carbonate , reverse osmosis , inhibitor , mechanism of precipitation on membranes , stagnant zones , nucleation rate , crystal growth rate , adsorption of inhibitor
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UDC 628.162:62-278
Pervov A. G., Efremov R. V.
The Use of Nanofiltration Membrane OPMN-K for Production of Potable Water and Calculation of Operation Characteristics
Summary
Recommendation on the use of nanofiltration membranes OPMN-K manufactured by the Vladipor OJSC for natural water treatment and production of potable water of high quality are presented. It is shown that at the high efficiency of removal of iron, hardness, fluorine and ammonium ions from water the OPMN membranes are exposed considerably less to the danger of generation of calcium carbonate cake on them than the low pressure reverse osmosis membranes. Depending on quality of influent water and types of membranes these recommendations make it possible to determine the reagent consumptions for operation of plants. Calculations presented show that the use of OPMN-K membranes instead of reverse osmosis membranes ESPA makes it possible to reduce significantly expenditures for operation of the ground water treatment unit.
Key words
nanofiltration membrane , inhibitor , selectivity , operation expenditures , reverse osmosis unit
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UDC 628.165
Pervov A. G., Andrianov A. P., Efremov R. V., Spitsov D. V.
Utilization of reverse osmosis concentrate with removing from it calcium and magnesium ions
Summary
The possible use of pre-developed technology of removing calcium carbonate with seeding agent to reduce the consumption of concentrate from large-scale units operating at the heat power facilities was studied. Concentrate of the operating reverse osmosis units contains inhibitors that inhibit the rate of seed crystal growth and impede the process of its utilization. The correlations between the calcium carbonate growth rate in the concentrate containing inhibiting substances and the dosage of the introduced seed, pH value and permeate yield were studied. For the implementation of the technology membrane apparatus with open channels are used that are resistant to the impact of membrane transfer of low-soluble salt deposits and suspended substances on the process. The developed by the authors technology of the concentrate utilization from reverse osmosis units installed at the heat power facilities for boiler feed water preparation is described. With the help of the developed technology softened water with lowered alkalinity and salt content can be produced. Herewith no chemicals are needed, and the unit does not consume water for its own needs. The technology provides for the complete utilization of reverse osmosis concentrate by improving its quality (in terms of hardness, alkalinity and total dissolved solids) to the requirements that allow using it for engineering purposes (for adding into a heat supply system or a circulation water supply system). Herewith any saline discharges into the environment are eliminated.
Key words
concentrate , inhibitor , reverse osmosis unit , concentrate utilization , calcium carbonate crystallization , seed crystals
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