MXPA99011717A - Water treatment process - Google Patents

Abstract

Se proporciona un proceso de ablandamiento de agua mejorado, que también reduce el contenido de aniones. Una primer corriente de agua (30) se pasa a través de un a unidad de intercambio de aniones (40,41,42) para retirar aniones indeseables y elevar el Ph. La primer corriente de agua se proporciona a un equipo de ablandamiento de agua reactor/clarificador (20,21,23) en donde actúa como un a fuente de iones hidroxilo.De preferencia una segunda corriente de agua (32) que no pasa a través de una unidad de intercambio de anions, tambén se proporciona al equipo de ablandamiento de aguas. Las corrientes de agua se combinan y procesan a través del equipo de ablandamiento, en donde se separan por precipitación los iones de dureza, produciendo agua ablandada con contenido de aniones reducido. El sistema de intercambio- de aniones utilizando de preferencia tiene un tren de resina continuo a contra corriente (38) y una unidad de regeneración de resina continuoa a contra corriente (39).

Description

WATER TREATMENT PROCESS FIELD OF THE INVENTION The invention relates in general to water treatment and more particularly to an improved process for softening water while reducing the content of anions. DESCRIPTION OF THE RELATED TECHNIQUE Hardness in water is a common problem. The hardness in the water is due primarily to the presence of Ca2 + and Mg2 +, and also in the presence of Ba2 + and Sr2 +, all these are hardness ions. Water is said to "soften" when these cations are removed, such as by water softening equipment. For water softening in large volume or large scale, the traditional process is called cold lime or soda-lime softening. In this process, the lime can be either hydrated lime (Ca (OH2)) or quicklime (CaO). In large systems, the lime source is stored in a storage container. If quicklime is used, hydrated lime (Ca (0H) 2) should first be converted to the quenching, that is, combined with water. In any case, Ca (0H) 2 is supplied and diluted in a lime sludge, where (Ca (OH) ¿) dissociates into Ca2 + and 20H. "This lime sludge is then fed into the reaction section of the equipment. of lime softening, where OHT is combined with g2'1 to form Mg (OH), and this precipitates.

The hardness of the original Ca + in the water, and the Ca2 + introduced by the dissolved lime, are removed by a different reaction. If there is enough natural bicarbonate (HC03 ~) in the water, some of the OH "will react to give carbonate (C032 ~) that will combine with Ca2 + to form CaC03, which precipitates If there is insufficient natural bicarbonate, soda ash (Na2C03) ) is added (which becomes 2Na + and C03 ~) and again CaC3 is formed and precipitates. (The use of soda ash unfortunately contributes substantial Na + to the finished water.) As an alternative to using Ca (OH) As the source of OH ", sodium hydroxide (caustic soda) (NaOH) has been and is employed. Sodium hydroxide also contributes significant amounts of sodium ion to the final water and does not remove essentially different anions to bicarbonate. The traditional lime process generates considerable sludge which is CaC03 and Mg (0H) ¿, and recently, of power, in reducing chloride content and has limited capacity to resist any other anion content (sulfate, phosphate, nitrate) of the water initial. When it is necessary to use soda ash (due to low content of carbonate influent) the traditional process increases the sodium content of the final effluent. As can be seen, the key to removing hardness is the introduction of 0H ~, OH "converts Mg2 + to Mg (0H) and converts HC03" to C032", which then reacts with Ca2 + to form CaC03 (if there is insufficient HC03" natural, Na2C03 is added). In the traditional hydrated lime treatment process, OH "is supplied by Ca (OH) 2- It is also traditional to use NaOH as the source of OH" with the lime treatment equipment. There is a need for an improved water softening process that eliminates or reduces the disadvantages of the traditional lime softening process. COMPENDIUM OF THE INVENTION A process for softening water, comprising the steps of: a) Passing a first stream of water through an anion exchange unit, to raise the pH of the first stream and provide a second stream of water that have a pH of at least 9.5, - b) Provide a second stream of water to water softening equipment comprising reactor and clarifier sections, the second stream of water is used as a source of hydroxyl ions in the softening equipment of water; c) Process a fourth stream of water through the water softening equipment, the fourth stream comprises the second stream; and d) Operating the water softening equipment in the fourth stream of water, to remove by precipitation reactions, hardness ions from the fourth stream and thereby provide a fifth stream of water. An anion exchange system comprising a continuous upstream regeneration resin unit is also provided. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of a water treatment process according to the invention; Figure 2 is a schematic diagram of an alternative water treatment process according to the invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION As used herein, parts are part by weight unless otherwise indicated and parts per million (ppm) and parts per billion (ppb) are parts by weight. When a preferred range such as 5-25 is given, this preferably means at least 5 and especially not more than 25. With reference to Figure 1, the diagram includes a conventional soda / lime water softening equipment or unit water treatment - contact solids or portion or system (reactor / clarifier) that is basically operated as a water softening equipment in the conventional manner except as noted. This water softening equipment consists essentially of a first stage mixing tank or reaction section or zone 20, a reaction section or reaction zone or second stage mixing tank 21 of a clarifier or clarifier section 33 having an area of flocculation 35 and a settling zone 36. Other softening equipment of soda / lime water or conventional hot or cold process lime or reactor / contact solids clarifier may be used. Influent water (typically pH 6 to 8 or about 7) to be treated enters through line 23 at a flow rate of preference of 1.2 to 315.4 more preferably 3.1 to 63.0, especially 6.3 to 50.4 optionally 12.6 to 37.8 liters per second ( 20 to 5,000, more preferably 50 to 1,000, especially 100 to 800 optionally 200 to 600 gallons per minute); something or everything (preferably 10 to 100%, more preferably 25 to 50%, especially 30 to 40% and in particular about 33%) of the influent water passes through line 30 to the anion exchange unit 38 for anion exchange and the rest of the influent water passes through line 32 directly to mixing tank 20, lines 30 and 32 each are portions of line 23. This is preferably controlled by the pH controller 25 or similar device that detects the tank 20 and the control valves 43 and / or 44. Preferably, the pH controller 25 detects the pH of the tank 20 and controls the valves 43 and / or 44, to maintain the pH of the tank 20 at a pH of minus 9.5, more preferably at least 9.8, in particular at least 10, especially at least 10.13, in particular at least 10.6 more particularly at least 10.9 and optionally at least 11.3. The pH of tank 20 preferably starts at 12.5, still more preferably 10.3 to 12, in particular 10.3 to 11.6 and especially 10.6 to 11.2. The preferred method is to control the flow through line 32, the least preferred is to control the flow of water through line 30. If all the influent water is diverted through the anion exchange unit, this usually results in which the water in tank 20 is too caustic; however, in some situations, all the influent water may pass through the anion exchange unit, so that the pH of the effluent from the anion exchange unit is the pH of the water in tank 20. The maximum The preferred pH of the effluent of the anion exchange unit 20 is 10.13 or more preferably 13. The influent water is preferably at room temperature and is preferably neither heated nor cooled during the process. Occasionally, the influent water may be above or below the environment, such as hot influent water received from a cooling tower. The traditional ion exchange unit has two parts, the cation unit and the anion unit. In most installations, the water first passes to the cation unit, where the cations include Ca2 + and Mg2 + sorbed in the resin, releasing H +. The water then passes to the anion unit, where the anions (sulfate S042 ~, nitrate NO1", phosphate PO ^", chloride Cl ", silicate SiO ~ ~, etc.) are sorbed on the resin, releasing OH". Then the H + and OH "combine to give deionized or ion-free water In the present invention, only the second of these two units, the anion unit is used.The anion unit basically takes anions of natural origin (sulfate, nitrate, chloride, etc.) of the water and produces a caustic, alkaline solution high in OHT. This high alkaline pH solution is then used in the treatment equipment as a source of OH "and thus eliminating the need for either Ca (OH) 2 or NaOH.The anion exchange system 22 is illustrated as it has an anion exchange unit 38, which in this embodiment is a continuous upstream anion exchange resin train 38 (comprising a first stage tank 40, a second stage tank 41 and a third stage tank 42 ) and a continuous counterflow resin regeneration unit 39 having a first stage tank 50, second stage tank 51, third stage tank 52, fourth stage tank 53 and a fifth stage tank 5. Anion exchange 38 and regeneration unit 39 are operated as fluidized beds The anion exchange unit or resin train 38 is illustrated as having three tanks with conical bottom 41 and 42; optionally it may have 2 to 6 or more preferably 3 to 5 tanks. Each of these tanks is preferably filled with 20 to 40% capacity with anion exchange resin, preferably in globular form, as is known in the art. There are a sufficient number of tanks in the train 38 and each tank is of sufficient size such that the total contact time of the water with the resin beads preferably is 10 to 30, more preferably 15 to 25 minutes, to allow exchange of effective anions in the resin, in this way, if the flow rate through the resin train 38 is 6.3 1 / sec (100 gallons per minute) and there are three tanks each with 40% filled with resin globules, each Preferred tank can be 6,309.6 1 (1667 gallons). The influent water travels through tanks 40 and 42 through line 30, then line 30a, then line 30b, then exits through line 24.

Typically there are 5 to 7 tanks in the regeneration unit 39, each typically with about half the size of the tanks in the train 38. The regeneration unit 39 is run in such a way that the resin pellets are regenerated approximately at the same speed that is spent on the train 38. The resin globules pass through the resin train 38 along the path of line 45, then line 45a, then line 45b. To regenerate, the resin globules follow the path of line 56, then lines 57, 58, 59, 60 and 61 to storage tank 62. Rinsing water (preferably tank 42) passes through lines 63. , 64 and 65 to tank 52. The regenerant solution (preferably 50% NaOH), passes through line 66 to tank 52 where it meets with the rinse water to form a brine typically of 4% NaOH, then through lines 67, 68 and 69 to the spent regenerant tank 70. The depleted regenerant is preferably collected in a separate clarifier where calcium sulfate, calcium carbonate, magnesium hydroxide and other precipitants and suspended solids are added. wash by dragging the regeneration resin, they are collected. The preferred countercurrent design does not require the installation of a pre-filter, since the main countercurrent is continuously washed by dragging in the resin and suspended solids are washed. In addition, the countercurrent design does not require a countercurrent wash step prior to the regeneration of the anionic resin. This method also uses considerably less resin and has lower resin capital costs. Compared to the batch system, the resin is also less stressed with less cracking and breakage and regeneration speed are of much higher yield, better use of regenerant and lower regenerant costs. The continuous countercurrent design also uses process water (such as tank 42) as resin rinse water and regenerant dilution water. The spent regenerant of the countercurrent process will be a high solids salt solution such as NaCl, Na2SO4, NaN03, Na3P04, Na2HP04, etc., which is suitable for other uses. The concentration of this exhausted current can be in the range of 4 to 7%, depending on the design of the process. Less preferable is the continuous resin stream to counter current 38 and / or continuous resin regeneration unit to counter current 39, can be a batch or single tank process or system or configuration using tanks of comparable or appropriate size as is known in technique. Batch regeneration has the resin collected in a batch tank and then regenerated with the regenerating solutions. The regenerated resin is fed to a storage tank to supply regenerated resin to the head of the process train. The spent regenerant is allowed to settle in a storage tank where the solids separate. The anion exchange resin is preferably an interlaced polystyrene matrix, a strongly basic anion exchange resin, gel type (type II) in the form of globules, preferably DIAION SA 20A from Mitsubishi Chemical, which are globules with diameter from 0.4 to 0.6 mm, which have a total capacity (Meq / ml) (min) of 1.3. Other DIAION anion exchange resin globules from Mitsubishi Chemical can be employed, including DIAION PA 408 and PA 418, which are of the porous type (type II) having a total capacity (Meq / ml) (min) of 0.9 to 1.3. Less preferred anion exchange resin globules include Anberlite IRA-410 from Rohm & Haas, a strongly basic type II quaternary ammonium anion exchange resin, and weakly basic anion exchange resins made of interlaced polymethacrylate and crosslinked polyacrylate, and type I anion exchange resins. Anion exchange resin globules Useful can also be obtained from Dow Chemical, Purolite, Mobay and other sources as is known in the art.

In the anion exchange unit 38, anions such as C1"S042 ~, NO" and other anions (phosphate, silicate, etc.) are removed and replaced by OH "ions, thereby raising the pH and becoming a caustic solution The treated water leaving the anion exchange unit 38 on the line 24 has a pH of preferably 9.5 to 13.3 as described above, more preferably 12 to 12.8, and in particular about 12.3 to 12.5. of line 24 is combined with untreated water of line 32 and passed to mixing tank 20. Mixing tank 20 is sized as a function of flow rate to preferably provide 10 to 30, more preferably approximately 15 minutes of In this way, a flow expense of .63 1 / sec (10 gallons per minute) with 15 minutes of contact time would require a tank of 567.5 1 (150 gallons). combine with Mg2 + to give Mg (8) as precipitate. (The silicate is co-precipitated in this process.The OH "is also combined with HC03" of natural origin to give C03 ~ of natural origin to give C032", which combine with Ca2 + to form the CaC03 precipitate. , there is primordially precipitated Mg (0H) y and both CaCO3 and the alkalinity of natural HC03 allows it.If there is enough alkalinity of natural carbonate HC03, then the mixing tank 21 is not required.

An optional mixing tank 21 is the same size as tank 20. If the alkalinity of natural bicarbonate is low or insufficient, carbon dioxide can be fed or injected via line 26 into mixing tank 21, to force the precipitation of calcium , as calcium carbonate. (C02 + 20H "- H0 + C032"; C032"+ Ca2 + -CaC03) This can be controlled by a calcium hardness analyzer or a pH controller (not shown) that detects tank 21, where the pH of preference is 9.5 to 11.5, more preferably 10 to 11, in particular 10.3 to 10.7 As described and as illustrated in Figure 1 and 2, the water softening equipment is operated in the water stream to remove by precipitation reactions, water hardness ions to result in or provide a stream of water having a reduced hardness and reduced anion content The effluent from tank 20 (or tank 21 if employed) passes to clarifier 33 for flocculation, sedimentation and clarification, as is known in the art, clarifier 33 is dimensioned as a function of flow rate and rate of increase as is known in the art.The sludge is pumped via line 28 to a filter press or some other device. similar dehydration, water effluent the treated goes through line 29 to a process use or other final use or reuse as water effectively softened; optionally they can be made at a lower controlled pH by addition of carbonate dioxide by the pH controller 34. Mineral acid less preferably can be used to reduce the pH. If it is sent to a sewer or process water, the pH is preferably 6 to 9; if it is sent for cooling water, the pH is typically 6 or 7 to 8.5. Optionally, a second clarifier can be provided between the first stage mixing tank 20 and the second stage mixing tank 21. In this configuration, high proportions of silica and magnesium removal are achieved. The mud of this intermediate clarifier will have a commercial value for its content of magnesium hydroxide (if the influent is not highly contaminated). The effluent from this intermediate clarifier is then passed to the second stage mixing tank where the optional carbon dioxide is added and calcium carbonate is precipitated. This two-stage process has very high removal rates of magnesium and calcium. The magnesium can be removed to less than one ppm with reduced calcium to less than 10 ppm while the sulfate can be reduced to less than 50 ppm. The reduction of chloride becomes a function of the countercurrent stages used in the design or recycling speed through the unit.

Similar to Figure 1, the invention is less preferably practiced, in a situation, where the mixing and clarifying tanks are replaced by a lined or circumscribed pond (such as a wastewater pond or environmental pond) or of similar capacity storage. In these situations, ponds or capacity storage will have reactor and clarifier sections. Alternatively, tank 20 can receive: a) effluent water from two or more independent or separate anion exchange units and b) untreated water (ie water that has not passed through an anion exchange unit) of 1, 2 or more sources separate or independent of or in substitution by the influent line 23 and / or line 32, such as a series of wells or a series of process lines that are softened for reuse. For example, line 30 may be from a first well and line 32 may come from a second separate well. Figure 2 illustrates a less preferred water treatment system according to the invention. In most forms it is the same as in Figure 1. In Figure 2, the thick line shows the main flow of water. Line 1 transports alkaline solution (high in OH ") as an anion unit effluent (pH preferably 11 to 13.1, more preferably 12.3 to 12.7) of the anion exchange unit 10 to the first stage mixing tank or the second reaction 2. Mixing tank 2 also receives untreated influent water through line 13. The water then flows through the second stage mixing tank or optional reaction zone 3, clarifier 5 and to line 7 through the pump 6. A portion (typically less than half) of the water in line 7 (which has a pH of preference 9.5 to 13.1, more preferably 10.3 to 10.7) is transported and fed or directed by lateral flow through line 8 through the deep medium filter 9 to the anion exchange unit 10, wherein the process is repeated as described above.The portion to be diverted is controlled by the pH controller 14, detection tank 2 and control valve 15, using the same principles used in Figure 1. The other portion of water on line 7 is transported on line 11 to exit the system as end-use, reuse or service water. Carbon dioxide can be added via line 12 as described above for Figure 1 using the pH controller 16 to control the valve 17 to reduce the pH as desired or required. The filter 9 removes particles or fines (particles up to about 1 miera) that are lost or dragged from the clarifier. Any filter can be used; a style of backwashing is preferred. A unit of strong anion resin 10 (of the conventional bottle type) is installed, consisting of its associated equipment including a caustic storage tank (either sodium, potassium or ammonium hydroxide). The size of the anion unit 10 depends on the water quality, flow rate, desired contact time and how it is filled with the anion exchange resin pellets (preferably 20 to 40%). The carbon dioxide can be provided by line 4 to the optional mixing tank 3, in case there is insufficient alkalinity of bicarbonate in the water. As can be seen, the unit of Figure 2 is constructed and separated in most aspects equal to or comparable to the unit of Figure 1. The mixing tanks 2, 3 and the clarifier 5 are the same as in the Figure 1; The operating pHs and the conditions and controls are the same or comparable. When the filter 9 and the anion exchange unit are filled with particles, they are washed countercurrently as illustrated by the countercurrent washing supply lines 16, 19 with the backwash which is added to the tank 2. As a option, there can be a second filter 9 and / or a second anion unit 10; the system can be switched to the backs while the first units are backwashed and regenerated. After the anion unit 10 is washed countercurrently, it is regenerated by typically carrying 4% NaOH, then rinsing slowly, then rinsing all as is known in the art. The slow and fast rinse waters can be directed by duct to a storage tank, where they can be pumped slowly to tank 2; This is an optional step to reduce the reject fluid load. Optionally, the ion unit 10 and the filter 9 can be replaced by a countercurrent anion exchange unit and regeneration unit, countercurrent as in Figure 1. In both Figures 1 and 2, the regenerant exhausted from the resin of anions is collected in a storage tank 70 or 46, for recovery on or off site; The reactor sludge / clarifier is also collected for recovery on or off site. With respect to regenerant recovery processes, ammonium hydroxide can be used for anion regeneration and the spent regenerant can be mixed with the sludge produced to create a nitrogen-rich fertilizer. This fertilizer can be further increased with phosphorus compounds. Optionally, potassium hydroxide can be used as the anion regenerant. The spent potassium hydroxide regenerator can be a valuable product for use in wastewater plants (activated waste plants). Potassium can provide a valuable nutrient to the process. When sodium dioxide is used as a regenerant, the spent regenerant can be used as a reagent for aluminum processing or a caustic feed material, soda ash, or sodium bicarbonate manufacturing. If the water to be treated contains a high content of chlorides, the spent regenerant can be used to make sodium hypochlorite. The sludge (sometimes referred to as slurry of lime) produced, can (depending on the metals contained in the influent water) be dried, pelletized and used in steel production. Alternatively, the sludge (if derived from heavy metal-free water) can be used in a flue gas desulfurization unit for power plant station. If lime is used as a regenerant, gypsum or calcium chloride can be obtained as useful by-products. The use of lime as a regenerant is convenient in waters with high sulphate content or where there is use for gypsum sludge. If sodium or potassium hydroxide is used as the regenerant to treat waters of high chloride content, the spent regenerant can be used as a feed material to a caustic membrane or diaphragm plant to produce the alkali and chlorine. For waters that have a high sulfate content where potassium sodium hydroxide is used as a regenerant, the spent regenerant is suitable as a limiting material to a LeBlanc (or comparable) process of caustic soda, sodium bicarbonate or caustic plant . Additional benefits of the invented system are as follows: organic materials such as oily materials that can normally embed an anionic resin unit, can be removed from the flocculation process or by continuous counterflow flow.

Some portion of dissolved organic materials (primarily acids or anions) that can pass from a conventional lime softener, are captured in the inventive process. The amount of reduction is a function of the percentage of flow through the anion circuit. Unlike reverse osmosis or evaporation technology, capital and operating costs are rather low. Maintenance is minimal and operational control is substantially simple. The unit can handle a wide variety of influent waters and can automatically adjust to changes in influent quality. As can be seen, the anion exchange units in Figures 1 and 2 are used independently of any cation exchange unit; there is no cation exchange unit (removing cations and adding H +) before the water passes through the clarifier. It is noted that a small cation exchange unit can be added at the effluent end to polish the effluent water, such as to improve the removal of sodium and / or reduce the pH (Na + is replaced by H +; H + is combined with OH " to give H20) before the effluent is sent for use or service, but this is completely optional.This procedure is particularly useful in waters with low magnesium and calcium content, but high chloride content. waste of high sodium content are treated, a magnesium cycle cation exchange unit can be placed in front of the anion train. (A magnesium cycle cation exchange unit removes cations such as Na + from the water and replaces them with Magnesium ions In this configuration, sodium is removed and replaced by magnesium and magnesium then removed in its normal form in the inventive process The following examples further illustrate various aspects of the invention. EXAMPLE 1 A pilot plant is basically configured as illustrated in Figure 1. Tanks 40 and 42 each were cone bottom tanks of 113.55 TL- (30 gallons); tank 20 was 113.55 1 (30 gallons) (approximate pH 11.3 to 11.6) and line 32 was controlled by the pH 25 controller. Tank 21 (113.55 1 (30 gallons)) is used and uses either spray or bubbling of C02 on line 26 by a pH controller that detects tank 21 and maintains the pH of approximately 10.3 to 10.6. Clarifier 33 was a 264.95 1 (70 gallon) cone bottom tank with overflow weir. The total flow expense was .38 1 / sec (6 gallons / minute) with .13 1 / sec (2 gallons / minute) through line 30 to unit 38 and .25 1 / sec (4 gallons / minute) through line 32 directly to tank 20. Each of tanks 40 and 42 is filled with approximately .03 m3 (1 cubic foot) (approximately 40% capacity of Mitsubishi DIAION SA 20 anion exchange resin globules, which have been prepared by impregnation or soaking in 4% NaOH and rinsing in water DI The total globule contact time was thus about 18 minutes.Plant globules move periodically from tank 42 to tank 41, to tank 40, particularly when the pH drops in tank 20. Tanks 50 and 54 were of 56.78 1 (15 gallons) each, the rinse water in tank 54 came from tank 42 (pH 12.3-12.5) Regenerant solution in tank 52 was 50% NaOH. 50 (containing NaCl, Na2S04, etc.) went through a recycling operation Approximately 11335.50 1 (300 gallons) each of 5 different water sources are run through the pilot plant The results shown in Table 1 are the averages of three readings. calcium as CaC03; Magnesium is expressed as CaCO3; chloride is expressed as NaCl; sulfate is expressed as S04; Sodium is expressed as Na. TABLE 1 WATER SOURCE INFLUENT (pp EFFLUENT _% "OF m) (ppm) REDUCTION l.WATER DISPOSAL 1 CALCIUM 1703 33 98.08% MAGNESIUM 671 0.2 99.97% CHLORIDE 6800 2500 63.24% SULFATE 2160 417 80.69% SODIUM 2860 2250 21.33% 2. WATER D? DISPOSAL 2 3. WATER FROM COOLING TOWER CALCIUM 745 51 93.15% MAGNESIUM 1072 0.21 99.98% CHLORIDE 4700 3000 36.17% SULFATE 7710 5220 32.30% SODIUM 3690 3210 13.01% 4. GUZ DE POZO 1 CALCIO 723 17 97.64% MAGNESIUM 290 6 97.99% CHLORIDE 500 390 22.00% SULFATE 582 49 91.55% SODIUM 332 268 19.28% . GUZ DE POZO 2 CALCIO 112 10 91.41% MAGNESIUM 1065 0.21 99.98% CHLORIDE 150 50 66.67% SULFATE 68 0.3 99.56% SODIUM 97 67 30.93% The results, particularly the 100% reduction, were surprising and unexpected. EXAMPLE 2 Table 2 shows for the selected components, test results of the water samples Nos. 6, 7 and 8, which are run through a static laboratory test configured or in a pattern basically according to the design or configuration of Figure 2, and running according to Figure 2 described above. The resin globules were Mitsubishi Chemical DIAION S.A. 20 A. The numbers are parts per million. TABLE 2 CompoAgua Water Water Water Water Water ineflueninefluenin-efluen fluente te No. fluent you No. fluent you No. No. 6 6 No. 7 7 No. 8 8 Calcium 462 28.9 26 25 30 24 (as Ca) Magnesium 240 0.147 6 0.145 5.4 0.14 (as Mg) Chloride 2600 1700 715 600 1450 -730 Sulfate 15000 100 425 25 860 33 Silice 3.4 1.25 5 < 1.0 7.6 < 1.0 Sodium 2900 1740 Potassium 81.8 48.2 Estron7.18 1.15 Cio Lead 0.127 < 0.01 These test results show that, in a proportion that was surprising and unexpected, the invention process is effective in softening the water and reducing the content of selected components. The invention also surprisingly reduces the concentrations of sodium and potassium as illustrated in water sample No. 6. In addition to softening the influent water, the invention also effectively reduces the concentration of undesirable anions particularly chloride, sulfate, phosphate, nitrate and silicate. ) and reduces the concentration of undesirable amphoteric components and non-hardness cations. It is considered and the test so far indicated, that the reductions in percent shown in Table 3 can be achieved by the practice of the present invention; that is, the invention can be used to treat influent water having components (mainly ionic material) in the following concentration ranges (ppm) to achieve the percent reductions in the concentration listed. For calculations of ppm concentration, Ca and Mg are expressed as CaCO3; Cl is expressed as NaCl; sulfate is expressed as S04", phosphate is expressed as P; nitrate is expressed as N03; nitrite is expressed as N02; and silica is expressed as Si02.If there are two streams of water, the aggregate concentration of one component of the two streams is the concentration that would exist if the two streams were combined and mixed.

It is considered that Na and K are removed by association with Mg (OH) 2 magnesium silicate and precipitates of CaCO3 / such as by being trapped in the molecular structure or by binding or adsorbing on the surface, etc. The silica is removed by precipitation as magnesium silicate and / or anion exchange removal. The anions are removed in the anion exchange unit, being trapped in the structure of other precipitates when adsorbed on the surface of other precipitates or in some cases upon withdrawal as precipitates of insoluble salt, such as calcium phosphate or calcium sulfate or as complexes such as sodium ferrocyanide. With respect to the metal ions, some are amphoteric and are removed in the anion exchange unit, others pass through the anion exchange unit and precipitate as their salt, hydroxide or carbonate in the reactor / clarifier. The invented process and system will remove this ionic material as well as or better than the traditional lime treatment system. The traditional lime treatment system produces considerable mud; the present invention avoids this by minimizing sludge and waste production and eliminates many of the operational headaches of conventional lime treatment. The present invention can be used to produce potable water in areas of poor quality and to convert seawater into drinking water; can clean or polish waste water to create usable-process water; It can polish process water for prolonged use. In an area with brackish or high chloride or sulfate water, the invention can produce rinse water or process that improves the quality of the product, in a process such as caustic soda, or refining sodium bicarbonate. In coastal areas, it makes the production of magnesium hydroxide and magnesium oxide from seawater more economical and environmentally friendly. Gypsum, magnesium hydroxide and calcium carbonate can be individually formed. The effluent water from this process can be sent to a reverse osmosis (RO) process to produce potable water at a fraction of the cost of normal RO process seawater. With this process, the rejection of RO can be re-introduced in the process head to be re-processed or evaporated, to produce a medium quality sodium chloride. The content of anions in the final effluent is greatly reduced. These anions will include chloride, sulfate, nitrate, silicate, phosphate and organic acids. The elimination of the organic component has the added benefit of color reduction and total organic carbon abatement (TOC = Total Organic Carbon). When the invention is employed in a potable water application, the reduction of TOC will result in a lower potential to produce THMs (tri-HaloMetanes). Although preferred embodiments of the invention have been shown and described, it will be understood that various modifications and changes may be considered without departing from the scope of the invention as described and claimed.

Claims (35)

1. CLAIMS 1.- A process for softening water, characterized in that it comprises the steps of: a) passing a first stream of water through an anion exchange unit to raise the pH of the first stream _and providing a second stream of water that has a pH of at least 9.5, the anion exchange unit is a unit adapted to release hydroxyl ions; b) providing the second stream of water to the water softening equipment, comprising reactor and clarifier sections, the second stream of water being used as the main source of hydroxyl ions in the water softening equipment; c) processing a fourth stream of water through the water softening equipment, the fourth stream comprises the second stream; and d) operating the water softening equipment in the fourth water stream to remove, by precipitation reactions, hardness ions from the fourth stream and thereby provide a fifth stream of water.
2. 2. Method according to claim 1, characterized in that it further comprises the step of combining the second stream of water with a third stream of water to give the fourth stream of water, the third stream of water has not been passed through. the anion exchange unit.
3. 3. - Method according to claim 2, characterized in that it also comprises the step of providing an initial water stream, the first water stream is a portion of the initial stream, the third stream of water is a portion of the initial stream.
4. 4. - Method according to claim 2, characterized in that the anion exchange unit is a resin train of continuous anion exchange against current.
5. 5. - Method according to claim 2, characterized in that the anion exchange unit using anion exchange resin, the process further comprises the step of regenerating the anion exchange resin in a continuous resin regeneration unit to against the current
6. 6. - Method according to claim 4, characterized in that the anion exchange unit uses anion exchange resin, the process further comprises the step of regenerating the anion exchange resin in a continuous resin regeneration unit upstream .
7. 7. - Method according to claim 2, characterized in that it also comprises the step of combining the second and third streams of water in a first mixing tank and verify and control the pH of the contents of the first mixing tank to maintain the pH between 10 and 12.5.
8. 8. - Method according to claim 7, characterized in that it also comprises the steps of passing the fourth stream of water from the first mixing tank to a second mixing tank, injecting carbon dioxide into the fourth stream of water, and verifying and controlling the pH of the fourth stream of water in the second mixing tank, to maintain the pH between 10 and 11.
9. 9. - Method according to claim 2, characterized in that the first stream, before passing through the Anion exchange unit and the third stream, together have an aggregate initial concentration of magnesium, the fifth stream of water has a magnesium concentration of at least 90% lower than the initial magnesium concentration.
10. 10. Method according to claim 2, characterized in that the first stream, before passing through the anion exchange unit and the third stream as a whole, have an initial aggregate concentration of calcium, the fifth stream of water has a calcium concentration of at least 90% lower than the initial calcium concentration.
11. 11. - Method according to claim 2, characterized in that the first current, before passing through the anion exchange unit and the third stream together, have an initial aggregate concentration of chloride, the fifth stream of water has a chloride concentration of at least 90% lower than the initial chloride concentration .
12. 12. - Method according to claim 2, characterized in that the first stream, before passing through the anion exchange unit and the third stream together, have an initial aggregate concentration of sulfate, the fifth stream of water has a sulfate concentration of at least 40% lower than the initial sulfate concentration.
13. 13. - Method according to claim 2, characterized in that the first stream, before passing through the anion exchange unit and the third stream as a whole, have an aggregate initial concentration of barium, the fifth stream of water has a barium concentration at least 90% lower than the initial barium concentration.
14. 14. - Method according to claim 2, characterized in that the first stream, before passing through the anion exchange unit and the third stream as a whole, have an initial - added concentration of cyanide the fifth stream of water has a cyanide concentration at least 40% lower than the initial cyanide concentration -
15. 15. - Method according to claim 2, characterized in that the first stream, before passing through the anion exchange unit and the third stream as a whole, have an initial aggregate concentration of silica the fifth stream of water has a concentration of silica at least 50% lower than the initial silica concentration.
16. 16. - Method according to claim 9, characterized in that the first stream, before passing through the anion exchange unit, and the third stream together have initial aggregate concentrations of calcium, chloride and sulfate, the fifth stream of water has a calcium concentration at least 90% lower than the initial calcium concentration, a chloride concentration at least 20% lower than the initial chloride concentration and a sulfate concentration at least 40% lower than the initial sulfate concentration .
17. 17. Method according to claim 2, characterized in that it also comprises processing the fourth stream of water through the water softening equipment at a flow rate of at least 3.15 1 / sec (50 gallons per minute).
18. 18. Method according to claim 2, characterized in that the flow rate of the second water stream is not greater than 50% of the flow rate of the fourth water stream.
19. 19. - Method according to claim 2, characterized in that a portion of the fifth stream of water is used to provide the first stream of water.
20. 20. An anion exchange system comprising an anion exchange unit and a continuous resin regeneration unit upstream, the anion exchange unit uses the anion exchange resin and is operable to exchange anions in an aqueous stream, the continuous-stream resin regeneration unit is operable to receive used anion exchange resin from the anion exchange unit, regenerate the resin in a counter-current form and return the regenerated resin to the unit of anion exchange for re-use.
21. 21. A method according to claim 4, characterized in that the continuous anion exchange current resin train comprises at least two separate tanks.
22. 22. - A method according to claim 4, characterized in that the train of anion exchange resin continuous upstream comprises at least three separate tanks.
23. 23. A method according to claim 5, characterized in that the continuous regenerative resin regeneration unit comprises at least one tank and a second tank, the process further comprising the steps of: e) adding exchange resin anions used before the tank, the anion exchange resin used has been employed in the anion exchange unit; f) adding regenerating liquid from the second tank to the third tank; g) subsequently removing the regenerant liquid from the first tank; h) transferring the used anion exchange resin from the first tank to the second tank; i) afterwards add regenerating liquid to the second tank, the regenerant liquid that is removed from the first tank is more exhausted than the regenerant liquid added to the "first tank of the second tank, the regenerant liquid removed from the second tank to be added to the first tank is more exhausted that the regenerant liquid added to the second tank
24. 24. - A method according to claim 6, characterized in that the continuously regenerating resin regeneration unit comprises at least a first tank and a second tank, the process further comprises the steps from: e) adding used anion exchange resin to the first tank, the anion exchange resin used has been used in the anion exchange resin; f) adding regenerating liquid from the second tank to the first tank; g) subsequently removing the regenerant liquid from the first tank; h) transferring the used anion exchange resin from the first tank to the second tank; i) after adding regenerating liquid to the second tank, the regenerating liquid that is removed from the first tank is more exhausted than the regenerating liquid added to the first tank of the second tank, the regenerating liquid removed from the second tank to be added to the first tank is more exhausted than the regenerating liquid added to the second tank.
25. 25. - The method according to claim 1, characterized in that the second stream of water has a pH of at least 10.6.
26. 26. The method according to claim 1, characterized in that the second stream of water has a pH of at least 11.3.
27. 27. The method according to claim 1, characterized in that the process is free from a step of passing a water current through a cation exchange unit.
28. 28. The method according to claim 1, characterized in that the second stream of water has a pH of at least 12.
29. 29.- The method according to claim 2, characterized in that the second stream of water has a pH at least 12.
30. 30.- The method according to claim 1, characterized in that the second stream of water has a pH of at least 12-12.8 The method according to claim 2, characterized in that the fifth Water flow is a current that circulates at an expense of 1.26 to 315.4 liters per second (20 to 5,000 gallons per minute) 32. The method according to claim 1, characterized in that the fifth stream of water is a stream that It circulates at an expense of
31. 31.5 to 63.08 liters per second (50 to 1,000 gallons per minute) 33. - The conformity procedure _ with claim 2, characterized in that 25 to 50% of the fourth water current a has passed through the anion exchange unit. 34.- The method according to claim 23, characterized in that the continuously regenerating resin regeneration unit comprises at least 5 tanks. 35.- The method according to claim 1, characterized in that the second stream of water has a pH of 11 to 13.1.