Abstract: A method for producing a high-purity carboxylic acid ester, the method including bringing a crude carboxylic acid ester that contains anionic impurities and Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurities into contact with a cation-exchange resin, followed by bringing the crude carboxylic acid ester into contact with an anion-exchange resin to obtain to provide a high-purity carboxylic acid ester in which the Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurity content are each less than 1 ppb and the anionic impurity content is less than 1 ppm.

Abstract: The present invention concerns a process for removing metal ions from waste water, which process comprises providing plant-derived anionic nanofibrillar cellulose, carrying out a purification treatment comprising sorption of positively charged metal ions contained in the waste water to said nanofibrillar cellulose, separating used plant-derived anionic nanofibrillar cellulose from the waste water, and recovering treated waste water. The invention also concerns use of plant-derived anionic nanofibrillar cellulose for removing metal ions from waste water.

Abstract: A water processing device is provided for removing micro-pollutants, in particular medicaments, from water, the device comprising at least one filter unit which is provided for at least one filtering of water in at least one operating state and which comprises at least one tubular filter element with at least two end portions, and comprising at least one adsorption unit which at least partially adsorbs the micro-pollutants in at least one operating state, wherein the at least two end portions enclose an inner angle of from 0° to 90° when in the assembled state.

Abstract: Embodiments of the present invention provide a method, system and computer program product for biometric enclosed space control. A method for biometric enclosed space control includes establishing a set point for an enclosed space and electronically transmitting a directive to a temperature control system to temperature regulate an atmosphere in the enclosed space to maintain a temperature of the atmosphere at the set point. The method also includes detecting a presence of an end user in the enclosed space and remotely sensing biometric measurements of the end user while the end user remains in the enclosed space. Finally, the method includes electronically transmitting a directive to the temperature control system to change the set point in response to a most recently received one of the remotely sensed biometric measurements.

Abstract: Disclosed are novel aqueous aluminum complex compositions and methods of making and using them. The novel compositions comprise very low halide content, even when made from aluminum chlorohydrate. The compositions find use in the production of zeolites, coatings, abrasives, binders, and refractories; and in the treatment of wastewater for example. The methods of making the novel compositions include passing a first aqueous aluminum complex composition through an anion exchange column or otherwise contacting the first composition with the anion exchange resin to provide a second aqueous aluminum complex composition that is different from the first aqueous aluminum complex composition. Also disclosed are methods of making zeolites and aqueous silica-alumina compositions from the novel aqueous aluminum complex compositions.

Abstract: In the case of a method for filling a transportation container (12) with a fluid, the fluid in a purification circuit (1) is conveyed multiple times through the purification installation (7), and by way of a contamination-measurement installation (15) a key contamination indicator of a fluid-specimen quantity in the purification circuit (1) is determined, wherein a filling procedure of the transportation container (12) with the fluid is terminated only once the key contamination indicator undershoots a first threshold value. The fluid-specimen quantity that is provided for determining the key contamination indicator may be diverted from the purification circuit (1), be infed to the contamination-measurement installation (15), and upon determining the key contamination indicator be returned to the purification circuit (1).

Abstract: The present invention relates to a fresh water generation method using a water treatment apparatus, the method including feeding water to be treated into a membrane element including a reverse osmosis membrane or a nanofiltration membrane to separate into concentrate and permeate, in which the method includes, under operation of the apparatus, adjusting a concentrate flow rate and/or a permeate flow rate based on a water quality index of the water to be treated and a water quality index of combined water prepared by combining the concentrate and the permeate at a ratio based on a predetermined permeate recovery rate, so that the water quality index of the water to be treated falls within a tolerance on the water quality index of the combined water.

Abstract: The present invention is for extremely pure solutions of chlorine dioxide, methods for making such solutions and to compositions and methods for storing, shipping and using such solutions. Generally, the chlorine dioxide solutions of the invention are aqueous solutions containing about 2500 ppm or less of total impurities. The chlorine dioxide solution can be prepared by passing dilute highly pure chlorine gas through a bed of substantially solid sodium chlorite and contacting the resulting chlorine dioxide gas with a liquid.

Abstract: A method and system for processing fluoride-containing wastewater includes treating the wastewater with brine (waste) created by the regeneration process implemented by in ion exchanging water softener. The brine, which is typically disposed of, contains both calcium and magnesium salts, in varying concentrations and ratios. The regeneration process brine is added to the fluoride-containing wastewater within a reaction tank, and the fluoride ion concentration is monitored. When the fluoride ion concentration falls below a predetermined level (e.g., 15 ppm), the flow of regeneration process brine is stopped. A pH controller monitors the pH within the reaction tank, and adds a basic agent to ensure that the pH remains above a predetermined level (e.g., pH>9). The pH control results in a clear effluent, and a sludge having a high settling rate and a high dewater ability.

Abstract: Methods to separate or recover brine that is present in an invert emulsion are described. The brine is present as an internal phase in the invert emulsion. The brine can be a valuable component, such as an alkali metal formate, and separation and recovering of the brine from the invert emulsion permits the brine to be reused.

Abstract: A process for treating water used in a coal tar process is described. The process involves treating the water with extraction with an extraction agent or adsorption with an adsorbent. The extraction agent includes at least one of amphiphilic block copolymers, cyclodextrins, functionalized cyclodextrins, and soluble cyclodextrin-functionalized polymers, and the adsorbent includes insoluble cyclodextrin-functionalized polymers, exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.

Abstract: Process for the treatment of the aqueous stream coming from the Fischer-Tropsch reaction comprising: feeding the aqueous stream containing the organic by products of the reaction to a distillation or stripping column; separation from the column of an aqueous stream enriched in alcohols having from 1 to 8 carbon atoms and other possible volatile compounds; feeding the aqueous stream containing the organic acids leaving the bottom of the distillation column to an ion exchange step wherein said aqueous stream is put in contact with an anionic exchange resin bed and the production of two outgoing aqueous streams: an aqueous stream (i) enriched in organic acids having from 1 to 8 carbon atoms; a purified aqueous stream (ii) with a low content of organic acids.

Abstract: Methods and apparatus relate to treating fluid to at least reduce selenium content within the fluid. The treating includes conditioning stages to alter a composition of the fluid prior to removal of the selenium content from the fluid. The composition of the fluid after the conditioning stages facilitates the removal of the selenium content or at least limits detrimental impact to selenium removal efficiency.

Abstract: We provide an evaporation based zero-liquid discharge method for generation of steam for enhanced oil recovery (EOR) processes utilizing once-through steam generators (OTSGs). The method includes feeding the OTSG(s) with produced water, vaporizing a fraction of this water for steam injection and blowing down the balance of the water. This water, referred to as OTSG blowdown, can be flashed to produce a vapor stream and a liquid that is fed to a mechanical vapor compression (MVC) evaporative process. The latent energy contained in the vapor stream generated by the upstream flash is beneficially recycled to substantially reduce or eliminate the energy consumption of the MVC process. The evaporative process can be used to reduce the liquid waste for disposal or eliminate the need for liquid disposal by achieving zero liquid discharge.

Abstract: A process for treating feed water for desalination, the process comprising: (a) removing one or more polyvalent anions from the feed water by feeding the feed water into a bed comprising one or more anion exchange resins under conditions sufficient to exchange the polyvalent ions in the feed water with one or more monovalent anions in the resin; and (b) regenerating the bed by feeding a brine stream into the bed under conditions sufficient to exchange one or more polyvalent anions in the resins with one or more monovalent anions in the brine stream.

Abstract: The invention provides waste water treatment processes utilizing an ion exchange resin to remove sulphate anions, while adjusting the pH of the ion exchange loading solution with carbon dioxide gas. The effect of the resin loading reactions is that dissolved sulphate is replaced with sequestered carbon dioxide gas, in the form of dissolved bicarbonate, in the treated water and the cations are not removed from the solution.

Abstract: Cations that can precipitate from an aqueous composition to produce scaling are sequestered by adding a multi-dentate ligand to the aqueous composition. The multi-dentate ligand bonds with the cation to form a non-scaling ionic complex; and the aqueous solution with the ionic complex is used in a process that produces substantially pure water from the aqueous composition, where the cation, absent formation of the ionic complex, is subject to scaling. The pH of the aqueous composition (or a brine including components of the aqueous composition) is then reduced to release the cation from the multi-dentate ligand; and the multi-dentate ligand, after the cation is released, is then reused in a predominantly closed loop.

Abstract: A system of treating high nitrogen content waste water is disclosed, where the system includes a precipitation and conditioning subsystem, an ammonia stripper subsystem, and a denitrification subsystem. The system is adapted to reduce nitrogen contamination to level below about 10 ppm and in certain embodiments below 3 ppm.

Abstract: A system and process for removing hydrocarbons from a gas process feed stream is presented. The treatment process may be, but is not limited to, glycol dehydration, amine sweetening, and MEG reclamation. As an example, a hydrocarbon removal bed containing a solid adsorbent material adsorbs the hydrocarbons in a rich MEG feed stream as it passes through the hydrocarbon removal bed. After the hydrocarbons have been removed, the feed stream flows through a flash separator and a distillation column to reclaim MEG. Alternatively, the hydrocarbon removal bed may be used after the MEG reclamation process to remove hydrocarbons in the distilled water from the distillation column. Spent solid adsorbent material may be regenerated in place.

Abstract: A method for treatment of raw brines from desalination plants (6) having a total salt content greater than 60 g/l, wherein, inter alia, a magnesium ion-containing solution having a magnesium ion content greater than 1 g/1 at a temperature between 75° C. and 100° C. is passed through a first vertical column (42) containing a bed packing of zeolite A (84) with a flow direction from top to bottom and the raw brine that is to be treated is passed at a temperature of 30° C. to 45° C. through this packed first column (42) in the direction of flow from top to bottom until the calcium ion concentration of the eluate leaving the first column (42) indicates a breakthrough of calcium ions through the bed of zeolite A (44).

Abstract: A system and method for hardwood pulp liquid hydrolysate conditioning includes a first evaporator receives a hardwood mix extract and outputting a quantity of vapor and extract. A hydrolysis unit receives the extract, hydrolyzes and outputs to a lignin separation device, which separates and recovers a quantity of lignin. A neutralization device receives extract from the lignin separation device and a neutralizing agent, producing a mixture of solid precipitate and a fifth extract. The solid precipitate is removed from the fifth extract. A second evaporator removes a quantity of acid from the fifth extract in a vapor form. This vapor may be recycled to improve total acid recovery or discarded. A desalination device receives the diluted extract, separates out some of the acid and salt and outputs a desalinated solution.

Abstract: The present invention provides processes for removing nitrogen species from fresh water or high salinity water recirculated aquaculture systems. The processes are based on physico-chemical treatments which are performed at ambient temperatures and at low p H values thus keeping the total ammonia nitrogen concentrations below a value which is considered detrimental for the growth or survival rate of cultured fish/shrimp.

Abstract: The invention provides waste water treatment processes utilizing an ion exchange resin to remove sulphate anions, while adjusting the pH of the ion exchange loading solution with carbon dioxide gas. The effect of the resin loading reactions is that dissolved sulphate is replaced with sequestered carbon dioxide gas, in the form of dissolved bicarbonate, in the treated water and the cations are not removed from the solution.

Abstract: Provided is a method for recovering high-concentration and high-purity amine from amine-containing waste water generated from nuclear power plants and thermal power plants. The method includes: capturing amine and concentrating waste water using a cation exchange resin; separating amine from the concentrated amine-containing waste water; and carrying out further separation of amine via distillation. The method may be applied to treat amine, which causes an increase in biochemical oxygen demand (BOD) and total nitrogen concentration, drastically at the time of its generation from waste water of nuclear power plants and thermal power plants. In this manner, the method may prevent an increase in load of existing waste water treating plants and avoid a need for modifying the equipment in the existing plants.

Abstract: We provide a process for treatment of produced water, including but not limited to water produced by a “steam flood” process for extraction of oil from oil sands, including the removal of color from the water. This removal may be accomplished through addition of color-removal polymers and flocculents. This process may also be useful for other water treatment processes including reverse osmosis and filtration.

Abstract: Embodiments provided herein include methods and apparatuses for purification and recycling of hydrofracture water used in natural gas drilling and production. Embodiments include removal of dissolved solids by precipitation with sodium sulfate and by evaporation using, for example, a multiple effect evaporator.

Abstract: Methods for the purification of steam, systems for purifying steam, methods for measuring and/or controlling steam flow rates, and uses for purified steam are provide. Also provided are substantially gas-impermeable membranes, such as perfluorinated ionomers (e.g., perfluoroethylene-sulfonic-acid/tetrafluoroethylene membranes), having a high ratio of water vapor permeation relative to gas permeation through the membrane. Also provided are methods of operation of such membranes at relatively high operating temperatures for the purification of steam and for operation of such membranes at relatively low temperature and sub-atmospheric pressures for the purification of steam. In a preferred embodiment, the system 400 for purifying steam comprises heater 404 for creating a source of a steam feed, and a purification device 416 for housing a substantially gas-impermeable membrane 424. In the operation of system 400, water, such as deionized water, is added to vessel 402 to provide a source of the steam feed.

Abstract: Process and apparatus for completely recovering the reusable components of an abrasive slurry used in slicing crystalline materials of silicon, quartz or ceramics when it becomes exhausted and enriched with undesired waste matter. The process consists of an initial centrifuge separation of the exhausted slurry as such and of a wet size-sorting treatment of the fraction containing the abrasive grains obtained from the centrifuge, carried out in a battery of hydrocyclones or centrifuges connected in series. The section for the recovery and purification of the abrasive grains comprises a multifunctional apparatus that performs all the required operations within a single pressure vessel.

Abstract: A water treatment process for substantially removing one or more ionic species from a feed water includes an ion containing aqueous solution to produce a treated water product, the process including: (a) a sorption step, including contacting a solid sorbent with said feed water to produce a solution depleted in said one or more ionic species and a loaded sorbent; (b) a concentrating step, includes concentrating an inlet stream including the ionic species depleted solution to produce a concentrate rich in said one or more ionic species and said treated water product; and (c) a desorbing step, including contacting said loaded sorbent with an aqueous desorbant including said concentrate to thereby desorb at least some of said one or more ionic species from said loaded sorbent.

Abstract: A fuel purification system includes a fuel cell stack and a fuel purification unit, such as a distillation unit. The fuel cell stack is adapted to provide heat to the fuel purification unit, and the fuel purification unit is adapted to provide a purified fuel to the fuel cell stack.

Abstract: The present invention generally relates to the small-scale separation of a mixture of two or more components with different boiling points into enriched fractions. In some embodiments, a first and second fluid (e.g., a liquid and a gas, a liquid and a liquid, etc.) are passed through a channel. The first fluid may include at least two components, each with a unique boiling point. Upon contacting the first and second fluids within the channel, at least a portion of the most volatile of the components in the first fluid (i.e., the component with the lowest boiling point) may be transferred from the first fluid to the second fluid. In some instances, the transfer of the volatile component(s) from the first fluid to the second fluid may be expedited by heating, in some cases above the boiling point(s) of the component(s) to be transferred from the first fluid to the second fluid. Contact between the first and second fluids may be maintained, for example, via segmented flow, bubbling flow, etc.

Abstract: A method and solution for eluting one of antimony(V) and a mixture of antimony(III) and antimony(V) from an ion exchange resin, comprises contacting the resin with an eluting solution comprising thiourea having a concentration of at least 0.002 M and hydrochloric acid having a concentration of at least 3 M. The method can be used for electrolytes in an industrial electrorefining process, by the further steps of contacting the electrolyte with an ion exchange resin to adsorb the antimony from the electrolyte and separating the resin from the electrolyte, before contacting the resin with the eluting solution comprising thiourea and hydrochloric acid. The method and solution address the difficulties of removing antimony(V), and allow for increased reuse of the resins.

Abstract: The invention comprises water desalination methods and a system for such, which includes treatment of water in cation and anion ion exchange columns, and regenerating the columns after treatment of the water to set them up again for a further treatment cycle, and also providing recoverable by-products during the regeneration of the ion exchange columns instead of waste.

Abstract: Methods are provided for vapor deposition coating of hydrophobic materials and applications thereof. The method for making a hydrophobic material includes providing a natural mineral, providing a silicone-based material, heating the silicone-based material to release vaporous molecules of the silicone-based material, and depositing the vaporous molecules of the silicone-based material to form a layer of the silicone-based material on surfaces of the natural mineral.

Abstract: Methods for the purification of steam, systems for purifying steam, methods for measuring and/or controlling steam flow rates, and uses for purified steam are provide. Also provided are substantially gas-impermeable membranes, such as perfluorinated ionomers (e.g., perfluoroethylene-sulfonic-acid/tetrafluoroethylene membranes), having a high ratio of water vapor permeation relative to gas permeation through the membrane. Also provided are methods of operation of such membranes at relatively high operating temperatures for the purification of steam and for operation of such membranes at relatively low temperature and sub-atmospheric pressures for the purification of steam. In a preferred embodiment, the system 400 for purifying steam comprises heater 404 for creating a source of a steam feed, and a purification device 416 for housing a substantially gas-impermeable membrane 424. In the operation of system 400, water, such as deionized water, is added to vessel 402 to provide a source of the steam feed.

Abstract: The invention proposes a method of destruction of volatile organic and inorganic compounds in wastewater, this method includes following stages: stripping the aforementioned volatile compounds in a stripping-chemisorption column; preliminary heating the gaseous medium containing these volatile compounds in a first heat regenerator; thermal, flare or thermo-catalytic oxidation of the volatile compounds in circulating gaseous medium; cooling the gaseous medium in a second heat regenerator; chemisorption of acidic gases from the gaseous medium in the stripping-chemisorption column with stripping at the same time additional amount of the volatile compounds from the wastewater. After specific period, direction of the gaseous medium flow is alternated. The proposed method can be executed at elevated temperature. The invention includes as well systems realizing the proposed method.

Abstract: It is intended to effectively suppress corrosion of a feed-water supply pipe in a preheater, by means of recirculation of boiler water to feed-water to be supplied to a steam boiler, even if a concentration of an alkaline component of the feed-water is relatively high. An alkali metal hydroxide is added from an agent-adding unit (14) to feed-water after removing therefrom a water hardness component in a water-softener unit (15) using a cation exchange resin and then removing therefrom dissolved gas in a degasifier unit (16). Then, the feed-water is supplied to a steam boiler 20 via a feed-water supply line 13 while being heated by a preheater (41). A part of boiler water having a pH value increased along with an increase in concentration of the alkali metal hydroxide resulting from enrichment thereof in the steam boiler (20) is mixed with the feed-water via a recirculation line (38).

Abstract: A fuel purification system includes a fuel cell stack and a fuel purification unit, such as a distillation unit. The fuel cell stack is adapted to provide heat to the fuel purification unit, and the fuel purification unit is adapted to provide a purified fuel to the fuel cell stack.

Abstract: There is provided an efficient treatment method for boron-containing water capable of reducing an amount of use of medical agent and an amount of generation of sludge. A treatment method for boron-containing water of an embodiment includes a first process of concentrating boron-containing water to obtain boron-concentrated liquid. Further, the method includes a second process of making the boron-concentrated liquid to be brought into contact with a layered inorganic hydroxide, and making the layered inorganic hydroxide adsorb boron in the boron-concentrated liquid to remove boron.

Abstract: In accordance with particular embodiments, a desalination system includes a plurality of evaporators. The plurality of evaporators includes at least a first evaporator and a last evaporator. The plurality of evaporators are arranged in cascading fashion such that a concentration of salt in a brine solution increases as the brine solution passes through the plurality of evaporators from the first evaporator towards the last evaporator. The desalination system also includes a plurality of heat exchangers. An input of each evaporator is coupled to at least one of the plurality of heat exchangers. The system also includes a vapor source coupled to at least one of the plurality of evaporators.

Abstract: A highly efficient method for treating contaminated water streams from any source where alkanlinity, hardness, or dissolved solids need to be removed before the water is discharged to the surrounding environment or sent to a secondary treatment facility.

Abstract: The present invention relates to a process for separating at least one propylene glycol from a mixture (M) comprising water and said propylene glycol, said process comprising (I) evaporating the mixture in at least two evaporation and/or distillation stages at decreasing operating pressures of the evaporators and/or distillation columns obtaining mixture (M?) and mixture (M?); (II) separating the mixture (M?) obtained in (I) in at least one further distillation step, obtaining a mixture (M-I) comprising at least 70 wt.-% of water and a mixture (M-II) comprising less than 30 wt.-% of water.

Abstract: A process for treatment of an aqueous stream to produce a low solute containing distillate stream and a high solute/solids containing blowdown stream utilizing a method to increase the efficiency of an evaporator while providing an essentially scale free environment for the heat transfer surface. Multi-valent ions and non-hydroxide alkalinity are removed from aqueous feed streams to very low levels and then the pH is increased preferably to about 9 or higher to increase the ionization of low ionizable constituents in the aqueous solution. In this manner, species such as silica and boron become highly ionized, and their solubility in the concentrated solution that is present in the evaporation equipment is significantly increased. The result of this is high allowable concentration factors and a corresponding increase in the recovery of high quality reusable water with essentially no scaling.

Abstract: The invention relates to a device and method for preparing liquid from solid materials such as medicinal materials. It includes liquid and materials for preparing the liquid at the beginning and the end of the process. The device uses a steam generator, an intermediate switch valve and a material chamber, which are connected sequentially with pipes, and further includes an outlet pipe, which is at the bottom of the material chamber. The method involves the steps of: distillation and absorption; immersion; and repetition. The device and method for preparing liquid alternates the distillation and immersion steps, which reduces harmful substance in the prepared liquid that would otherwise occur by conventional methods. The method not only extracts soluble effective matter, but also reduces loss of volatile effective matter. Ultimately, the method makes the steps for preparing liquid simple and clear, and it can prepare liquid quantitatively, effectively and without pasty and shrinkable characteristics.

Abstract: Methods and apparatus relate to treating fluid to at least reduce selenium content within the fluid. The treating includes conditioning stages to alter a composition of the fluid prior to removal of the selenium content from the fluid. The composition of the fluid after the conditioning stages facilitates the removal of the selenium content or at least limits detrimental impact to selenium removal efficiency.

Abstract: A process for treating produced water to generate high pressure steam. Produced water from heavy oil recovery operations is treated by de-oiling the produced water to provide a de-oiled evaporator feedwater that is fed to an evaporator. The pretreated produced water stream is evaporated to produce (1) a distillate having a trace amount of residual solutes therein, and (2) evaporator blowdown containing substantially all solutes from the de-oiled produced water feed. The distillate may be directly used, or polished to remove the residual solutes therein, before being fed to a steam generator. Steam generation in a once-through steam generator, or in a packaged boiler such as a water tube boiler having a steam drum and a mud drum with water cooled combustion chamber walls, produces high pressure steam for down-hole use.

Abstract: Process for the treatment of the aqueous stream coming from the Fischer-Tropsch reaction comprising: feeding the aqueous stream containing the organic by products of the reaction to a distillation or stripping column; separation from the column of an aqueous stream enriched in alcohols having from 1 to 8 carbon atoms and other possible volatile compounds; feeding the aqueous stream containing the organic acids leaving the bottom of the distillation column to an ion exchange step wherein said aqueous stream is put in contact with an anionic exchange resin bed and the production of two outgoing aqueous streams: an aqueous stream (i) enriched in organic acids having from 1 to 8 carbon atoms; a purified aqueous stream (ii) with a low content of organic acids.

Abstract: Provided is a method for recovering high-concentration and high-purity amine from amine-containing waste water generated from nuclear power plants and thermal power plants. The method includes: capturing amine and concentrating waste water using a cation exchange resin; separating amine from the concentrated amine-containing waste water; and carrying out further separation of amine via distillation. The method may be applied to treat amine, which causes an increase in biochemical oxygen demand (BOD) and total nitrogen concentration, drastically at the time of its generation from waste water of nuclear power plants and thermal power plants. In this manner, the method may prevent an increase in load of existing waste water treating plants and avoid a need for modifying the equipment in the existing plants.

Abstract: Systems, methods and compositions for the separation and recovery of hydrocarbons from particulate matter are herein disclosed. According to one embodiment, a method includes contacting particulate matter with at least one ionic liquid. The particulate matter contains at least one hydrocarbon and at least one solid particulate. When the particulate matter is contacted with the ionic liquid, the hydrocarbon dissociates from the solid particulate to form a multiphase system.

Abstract: It is intended to effectively suppress corrosion of a feed-water supply pipe in a preheater, by means of recirculation of boiler water to feed-water to be supplied to a steam boiler, even if a concentration of an alkaline component of the feed-water is relatively high. An alkali metal hydroxide is added from an agent-adding unit (14) to feed-water after removing therefrom a water hardness component in a water-softener unit (15) using a cation exchange resin and then removing therefrom dissolved gas in a degasifier unit (16). Then, the feed-water is supplied to a steam boiler 20 via a feed-water supply line 13 while being heated by a preheater (41). A part of boiler water having a pH value increased along with an increase in concentration of the alkali metal hydroxide resulting from enrichment thereof in the steam boiler (20) is mixed with the feed-water via a recirculation line (38).