Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
  • C02F1/4618—Devices therefor; Their operating or servicing for producing "ionised" acidic or basic water
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
  • C02F5/02—Softening water by precipitation of the hardness
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
  • C02F2103/023—Water in cooling circuits
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/06—Controlling or monitoring parameters in water treatment pH

Definitions

• This invention is related to the use of an electrolysis device for water treatment.
• One embodiment of the present invention concerns a method of water treatment comprising: providing an electrolysis device comprising an electrolysis vessel; providing feed streams to the first salt water chamber of the vessel, second salt water chamber of the vessel, acidic chamber of the vessel, and alkalic chamber of the vessel, the acidic chamber producing an acidic solution and the alkalic chamber producing an alkalic solution; directing at least a portion of the contents of the first and second salt water chambers into a precipitation tank; directing at least a portion of the alkalic solution into the precipitation tank, thereby increasing the pH in the precipitation tank to produce precipitate; and removing the precipitate from the precipitation tank.
• Another embodiment of the present invention concerns an electrolysis device comprising a pair of electrodes arranged in the electrolysis vessel, serving as a positive electrode and a negative electrode, respectively; and a cell unit arranged between the positive and negative electrodes, the cell unit comprising a bipolar membrane element and at least one cation exchangeable membrane, the bipolar membrane element having a cation exchangeable side and an anion exchangeable side, the cation exchangeable side being closer to the negative electrode than the anion exchangeable side, the at least one cation exchangeable membrane being arranged between the anion exchangeable side of the bipolar membrane element and the positive electrode, so as to define an alkalic chamber between the bipolar membrane element and the cation exchangeable membrane; wherein the cation exchangeable membrane is selective.
• Fig. 1 schematically illustrates one embodiment of the bipolar membrane
• FIG. 2 schematically illustrates a method of operating bipolar membrane of Fig. i;
• FIG. 3 schematically illustrates a method of operating bipolar membrane of Fig. i;
• FIG. 4 schematically illustrates a method of operating bipolar membrane of Fig. i;
• FIG. 5 schematically illustrates a method of operating bipolar membrane of Fig. i;
• FIG. 6 schematically illustrates a method of operating bipolar membrane of Fig. i;
• Fig. 7 schematically illustrates a method of operating bipolar membrane of Fig. 1; and [0014] Fig. 8 schematically illustrates a method of operating bipolar membrane of Fig. 1.
• Approximating language may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about”, is not limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be combined and/or interchanged, and such ranges are identified and include all the sub-ranges stated herein unless context or language indicates otherwise. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions and the like, used in the specification and the claims, are to be understood as modified in all instances by the term "about”.
• Cooling towers are widely used in industries to remove heat in processes, such as oil refinery, chemical processes, and power generation plants. Cooling towers are also used in the HVAC systems common in commercial, institutional, and hospital buildings. Water consumption in cooling tower operation constitutes the largest water withdrawal from natural water sources in many countries. Water scarcity has become an increasing concern worldwide. According to the data published by Global environment outlook, 5% of population was facing water scarcity problems in 2000, mainly in the middles east area. However, by year 2030, nearly half of world population will be water stressed.
• the present invention is directed toward a method of treating water from cooling towers operating at a high cycle of concentration using an electrolysis device, such as a bipolar membrane or its combination with a nanofiltration unit.
• Cooling tower water is provided to the electrolysis device.
• An acidic solution generated from the electrolysis device is added to cooling towers to reduce alkalinity and pH.
• An alkalic solution generated from the electrolysis device is added to a portion of cooling tower blowdown stream in a separation apparatus to precipitate calcium, silica and other scale forming species.
• the water after precipitates removal in the separation apparatus is softened and returned to cooling tower.
• This method allows cooling tower to operate at high cycles of concentration and/or achieve zero liquid discharge, thus significantly reducing water consumption and water treatment chemical usage.
• a first embodiment of the electrolysis device 2 for producing an acidic solution and alkalic solution includes a pair of electrodes respectively acting as a positive electrode 21 and a negative electrode 22, at least one cell unit 23 between the positive and negative electrodes 21, 22, and a vessel 24 for housing the electrodes 21, 22 and the cell unit 23 therein.
• the positive and negative electrodes 21, 22 respectively connect with an anode and a cathode of a DC power supply 25.
• the vessel 24 includes at least a first inlet 243, second inlet 244, third inlet, 245, and fourth inlet 246 for inducing a feed stream to flow through the electrolysis device 2.
• the cell unit 23 includes at least one alkalic chamber 236 and at least one acidic chamber 235 defined between ion exchangeable membranes, which will be discussed in detail below.
• the cell unit 23 of the vessel 24 of electrolysis device 2 comprises a bipolar membrane element 230, a cation exchangeable membrane 231, and an anion exchangeable membrane 232.
• the bipolar membrane element 230 has a cation exchangeable side 233 and an anion exchangeable side 234, and is used as a water splitter.
• the cation exchangeable side 233 of the bipolar membrane element 230 is closer to the positive electrode 21 than the anion exchangeable membrane 232.
• the cation exchangeable membrane 231 is arranged between the anion exchangeable side 234 and the positive electrode 21.
• the anion exchangeable membrane 232 is arranged between the cation exchangeable side 233 and the negative electrode 22.
• a direct current from the power supply 25 flows through the bipolar membrane element 230 causing the water to split with OH ions being produced on the anion exchangeable side 234 and a corresponding number of H + ions being produced on the cation exchangeable side 233 of the bipolar membrane element 230.
• the generated OH and H + ions are prevented from moving further by the cation exchangeable membrane 231 and the anion exchangeable membrane 232, respectively.
• Cation exchangeable membrane 231 is selective and only passes univalent cationic ions.
• Anion exchangeable membrane 232 is selective and only passes univalent anionic ions. Accordingly, Na + ions from the salt water received by second inlet 244 move through cation exchangeable membrane 231 toward the negative electrode 22, while Ca , Mg , Ba , Fe Fe , and ⁇ do not move through cation exchangeable membrane 231. Further, CI " ions from the salt water received by first inlet 243 move through anion exchangeable membrane 232 toward the positive electrode 21, while C0 3 2 ⁇ , S0 4 2" and PO 4 3" do not move through the anion exchangeable membrane 232.
• an alkalic chamber 236 is defined between the bipolar membrane element 230 and the cation exchangeable membrane 231, and an acidic chamber 235 is defined between the bipolar membrane element 230 and the anion exchangeable membrane 232.
• a first salt water chamber 237 is defined between negative electrode 22 and anion exchangeable membrane 232.
• a second salt water chamber 238 is defined between positive electrode 21 and cation exchangeable membrane 231.
• a first inlet 243 provides a feed stream to the first salt water chamber 237
• a second inlet 244 provides a feed stream to the second salt water chamber 2308
• a third inlet 245 provides a feed stream to the acidic chamber 235
• a fourth inlet 244 provides a feed stream to the alkalic chamber 236.
• the feed streams provided to first salt water chamber 237 and second salt water chamber 238 may be comprised of at least one of cooling tower make up water, cooling tower blow down water, or low quality water
• the vessel 24 further includes an acidic outlet 24 l and an alkalic outlet 242 respectively for the alkalic solution of alkalic chamber 236 and the acidic solution of acidic chamber 235 to flow out of.
• the vessel 24 also includes a first salt water outlet 247 and a second salt water outlet 248 respectively for the salt water of first salt water chamber 237 and second salt water chamber 238 to flow out of.
• the feed stream entering the acidic chamber 235 through inlet 245 can be one or both of pure water or the acidic solution exiting acidic outlet 241 of the vessel 24.
• the feed stream entering alkalic chamber 236 through inlet 246 can be one or both of pure water or the alkalic solution exiting alkalic outlet 242 of vessel 24.
• the alkalic solution produced at alkalic outlet 242 can be used to create a high pH environment to precipitate hardness and other species in aqueous systems, such as CaC0 3 , CaMg(C0 3 ) 2 , Ca 3 (P0 4 ) 2 , Ca 5 (P0 4 ) 3 OH, CaS0 4 , Fe(OH) 3 , Al(OH) 3 , MgSi0 3 etc.
• the acidic solution produced in acidic chamber 235 can be used to adjust pH of cooling tower water and clean hardness off membranes or electrodes in the vessel 24.
• the bipolar membrane element 230 has a water splitting feature to split water directly into H + and OH .
• the application of the bipolar membrane element 230 greatly improves the efficiency of the electrolysis device 2 for producing alkalic solution and acidic solution from the water.
• the bipolar membrane element 230 may be a bipolar membrane which includes a cation exchangeable layer and an anion exchangeable layer, or a bipolar module formed by a combination of anion and cation exchangeable membranes which functions as a bipolar membrane.
• the positive and negative electrodes 21, 22 are made from highly porous carbon materials selected from any of activated carbon, carbon black, carbon nanotubes, graphite, carbon fiber, carbon cloth, carbon aerogel, or combination thereof.
• Surface area of the carbon material is in a range of from about 500 to 2000 square meters per gramme as measured by nitrogen adsorption BET method, high porous positive and negative electrodes 21, 22 each have a shape, size or configuration that is a plate, a block, a cylinder, or a sheet. It is also anticipated that positive and negative electrodes 21, 22 can be made of any metal or porous material deemed suitable by a person having ordinary skill in the art, such as activated carbon.
• Fig. 2 discloses one embodiment in which electrolysis device 2 is used to generate acid solution for cooling tower water pH adjustment or cleaning of electrolysis device 2 and to generate base for hardness precipitation.
• the output of salt water tank 301 is provided as a feed stream to said first salt water chamber 237 and second salt water chamber 238 of vessel 24.
• Salt water tank 301 can contain one or more of cooling tower make up water, cooling tower blow down water, or low quality water. Low quality water is any water that needs to be treated to soften and/or remove undesirable ion species, such as brackish water. Water is provided as a feed stream to the acidic chamber 235 and alkalic chamber 236. The output of acidic chamber 235 is provided to cooling towers.
• the output of alkalic chamber 236 is provided to precipitation tank 304, and the output of the first and second salt water chambers 237 and 238 is also provided to the precipitation tank 304. Accordingly, the addition of the alkalic solution from alkalic chamber 236 into precipitation tank 304 increases the pH in precipitation tank 304 to a desired value to precipitate metal salts and metal hydroxides, such as CaCC"3, MgCCh, CaS0 4 , Mg(OH) 2 , etc. After the precipitate is removed from precipitation tank 304, the treated water from precipitation tank 304 is provided to a water storage tank or to cooling towers.
• the desired pH value in precipitation tank 304 after the addition of alkalic solution from electrolysis device 2 is between about7 to 14, preferably between about 8 to 13 and more preferably between about 9 to 12.
• all or part of the acidic solution produced in acidic chamber 235 can be returned to acidic chamber 235 as a feed stream.
• all or part of the alkalic solution produced in alkalic chamber 236 can be returned to alkalic chamber 236 as a feed stream. This would allow for the concentration of the acid and base solutions to be increased with time within acidic chamber 235 and alkalic chamber 236. Further, this would allow for the pH within the precipitation tank 304 increases to enhance precipitation.
• Fig. 4 discloses another embodiment in which electrolysis device 2 is used to generate an acidic solution for cooling tower water pH adjustment or cleaning of electrolysis device and to generate a base solution for hardness precipitation.
• cooling tower blowdown is delivered to selective membrane 501, which outputs a divalent ion stream that is provided to precipitation tank 502.
• Selective membrane 501 may be a nano filtration unit.
• the divalent ion stream contains one or more divalent ions, such as Ca 2+ , Mg 2+ , Ba 2+ , Fe 2+ ' Fe 3+ , Al 3+ , C0 3 2 ⁇ , S0 4 2 ⁇ and P0 4 3 ⁇ , etc.
• Selective membrane 501 outputs a univalent ion stream that is provided to the first and second salt water chambers 237 and 238 of vessel 24.
• the univalent ion stream contains one or more univalent ions, such as Na + , CI " , etc.
• a water feed stream is provided to the acidic chamber 235 and alkalic chamber 236 of vessel 24.
• the alkalic solution output of the alkalic chamber 236 is provided to the precipitation tank 502, which increases the pH in precipitation tank 502 to a desired value to precipitate metal salts and metal hydroxides, such as CaC0 3 , MgC0 3 , CaS0 4 , Mg(OH) 2 , etc.
• the desired pH value in precipitation tank 304 after the addition of alkalic solution from vessel 24 is between about 7 to 14, preferably between about 8 to 13 and more preferably between about 9 to 12.
• the precipitates are then removed from precipitation tank 502 and the remaining treated water contained in precipitation tank 502 is used as cooling tower make up water or for other industrial processes.
• the output of the first and second salt water chambers 237 and 238 is combined with the remaining treated water from the precipitation tank 302 as cooling tower make up water or for other industrial processesv
• the acidic solution output of the acidic chamber 235 can be used to adjust pH of cooling tower water and/or adjust the pH of treated water stream exiting from precipitation tank 502, and to clean membranes of vessel 24. Returning the remaining water from precipitation tank 502 to the cooling tower reduces water consumption and reduces or eliminates the waste water discharged to a sewer or river. Further, the use of high quality water in the cooling tower reduces the amount of chemicals required to treat the water in the cooling tower, thus reducing disposal cost and impact on the environment.
• all or part of the acidic solution output of acidic chamber 235 can be returned to acidic chamber 235 as a feed stream.
• all or part of the alkalic solution output of alkalic chamber 236 can be returned to alkalic chamber 236 as a feed stream. This would allow for the concentration of acid and base solutions to be increased with time within acidic chamber 235 and alkalic chamber 236.
• the output of salt chambers 237 and 238 is combined with the remaining treated water from the precipitation tank after precipitate removal as cooling tower make up water or for other industrial processes.
• Fig. 6 discloses another embodiment in which electrolysis device 2 is used to generate acidic solution for cooling tower water pH adjustment, the cleaning of electrolysis device 2, and/or to generate base for hardness precipitation.
• a feed stream of low quality water such as brackish water
• selective membrane 601 which outputs a divalent ion stream that is provided to precipitation tank 602.
• the feed stream can be comprised of at least one of cooling tower make up water, cooling tower blow down, or low quality water.
• the divalent ion stream contains one or more divalent ions, such as Ca 2+ , Mg 2+ , Ba 2+ , Fe 2+ ' Fe 3+ , Al 3+ , C0 3 2 , S0 4 2 ⁇ , P0 4 3 , etc.
• Selective membrane 601 outputs a univalent ion stream that is provided to the first and second salt water chambers 237 and 238 of electrolysis device 2.
• Selective membrane 601 may be a nanofiltration unit.
• the univalent ion stream contains one or more univalent ions, such as Na + , CI " , etc.
• a water feed stream is provided to the acidic chamber 235 and alkalic chamber 236 of vessel 24.
• the output of the alkalic chamber 236 is provided to the precipitation tank 602, which increases the pH in precipitation tank 602 to a desired value to precipitate Ca and Mg salts and metal hydroxides.
• the desired pH value in precipitation tank 602 after the addition of alkalic solution from vessel 24 is between about 7 to 14, preferably between about 8 to 13 and more preferably between about 9 to 12.
• the precipitates are then removed from precipitation tank 602 and the remaining treated water contained in precipitation tank 602 is used as cooling tower make up water or for other industrial processes.
• the output of first and second salt water chambers 237 and 238 is combined with the remaining treated water from the precipitation tank and used as cooling tower make up water or for other industrial processes.
• the acidic solution output of the acidic chamber 235 can be used to adjust the pH of cooling tower water, adjust the pH of the treated water stream exiting from precipitation tank 602, and/or clean membranes of vessel 24. [0046] Further, as is shown in Fig. 7, it is also contemplated that in some embodiments all or part of the output of acidic chamber 235 can be returned to acidic chamber 235 as a feed stream. Further, all or part of the output of alkalic chamber 236 can be returned to alkalic chamber 236 as a feed stream. This would allow for the concentration of acid solution and base solution to be increased with time within acidic chamber 235 and alkalic chamber 236.
• the output of first salt water chambers 237 and 238 is combined with the remaining treated water from the precipitation tank and used as cooling tower make up water or for other industrial processes.
• a first portion of blowdown from a cooling tower operating at a high cycle of concentration, greater than about 7 cycles, and pure water are provided to an electrolysis unit.
• the electrolysis unit uses the first portion of blowdown and pure water to generate an acidic solution in acid chamber 235, an alkalic solution in alkalic chamber 236, and a salt water solution in first and second chambers 237 and 238.
• the acidic solution is provided to the cooling tower to reduce the alkalinity and pH of the water circulating through the cooling tower.
• the alkalic solution is mixed with a second portion of blowdown in precipitation tank 702 to precipitate and remove calcium and other scaling forming species from the second portion of blowdown, thereby softening the second portion of blowdown.
• the softened second portion of blowdown is then returned to the cooling tower as make up water.
• the blowdown is filtered by a nano filtration unit 701 after leaving the cooling tower.
• the first portion of blowdown is comprised of one or more univalent ions and the second portion of blowdown is comprised of one or more divalent ions.
• the salt water solution is added to the softened second portion of blowdown and returned to the cooling tower as makeup water.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Hydrology & Water Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Removal Of Specific Substances (AREA)

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• 2010
  • 2010-12-23 US US12/977,274 patent/US8764957B2/en active Active
• 2011
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  • 2011-12-02 BR BR112013014643A patent/BR112013014643A2/pt active Search and Examination
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