Hybrid Technologies
Water demineralization membrane methods – reverse osmosis and electrodialysis are widely used nowadays in different sectors of the national economy. Each of these methods has its advantages and disadvantages. Join application of these demineralization methods allows to achieve finally high treatment results.Water requirements in power industry depend on the type of used equipment and operating mode and vary from a simple removal of suspended matters and hardness salts for heat networks to deep demineralization and removal of organic pollutants and dissolved gases for CHP and APS. To ensure a proper operation of modern water-heating equipment it is necessary to maintain a proper water regime. Boiler house water regime is characterized by a set of controllable parameters of loop water quality and ranges of rated values thereof. To meet the applicable norms and maintain a proper boiler house water regime it is required to achieve a proper water treatment.
Application of sodium cycle units for reduction of total hardness before water feeding to fill or make-up a boiler house loop or heat network is associated with certain capital and operating expenses, and increase of environmental load in the region due to an abundant quantity of acid-alkali wastes.
We offer a reagent-free technology for production of extra pure water including reverse osmosis water treatment followed by electro-deionisation. At stage one of the reverse osmosis unit demineralized water – permeate – corresponds to distilled water (0.2 MOhm) in term of its quality. Then the permeate is fed to stage two - electro-deionizator (electrodialysis unit with ion-exchange resins in demineralization chambers) where the initially demineralized water go through the final treatment process. Electro-deionisation process includes a constant ion exchange in ion exchangers and regeneration under action of electric current without the use of any reagents. Specific electrical resistivity of treated water at output from the electro-deionizator is 10-18 MOhms.
The combined technology for production of extra pure water may be used in beiotechnology, microelectronics, production of pure substances, however a wide application of this process is heat-power engineering where production of major quantities of deeply demineralized water without the use of any reagents has, in addition to high parameters, a significant socioeconomic effect due to a significant reduction of liquid chemically active wastes.
Application of combined waste water treatment schemes allows to increase dramatically the degree of recycled use of water, and in certain cases – to make a waste-free production with circulating water supply.
We have developed and introduced a scheme for treatment of flush water from hot galvanizing production. After reagent treatment waste water was fed to a reverse osmosis unit where the produced permeate was returned back to the workflow cycle, and brine – to electrodialysis unit – concentrator with standing brine chambers where solution could be concentrated from 20 to 180 g/l with a possibility of further additional evaporation to produce dry salt. The electrodialysis unit dialysate was returned to stage one (reverse osmosis unit). The extent of recycled use of water made 95%.
A metallurgical production waste water treatment technology has been developed including reverse osmosis and electrodialysis. Initial water with mineralization some 30 g/l, after reagent precipitation, is concentrated in electrodialysis unit to 120 g/l, brine is fed for evaporation by exhaust gas heat from the main production, and dialysate with a residual concentration of 3-5 g/l is fed to reverse osmosis unit where it is treated to meet fish standards and subsequently discharged to water reservoir. Reverse osmosis stage two brine (15-18 g/l) is fed to stage one.
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