Abstract: A sewage treatment device includes a fluidized bed body, a reflux device and a chemical feeding device. The fluidized bed body is sequentially provided with a sedimentation zone, a transition zone and a fluidization zone from top to bottom. The reflux device is connected to the fluidized bed body through a reflux pipe. The reflux pipe extends into the fluidized bed body from the sedimentation zone, and the granularity of a crystal product can be controlled by changing the height of a reflux inlet at the bottom end of the reflux pipe in the fluidized bed body. By controlling the position of the reflux inlet of the reflux pipe in the fluidized bed body, combining product granularity requirements, and adjusting an insertion depth of the reflux pipe, the granularity of a final product can be flexibly regulated and controlled, and meanwhile, a product recovery rate is improved.

Abstract: A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

Abstract: A method of removing polyvinyl alcohol (PVA)-based scaffold from a 3D printed part formed by a 3D printing process that renders a finished product for immediate use. The method principally involves preparing an acidic-aqueous cleansing solution comprising a mixture of carboxylic acid and water; immersing the 3D printed part conventionally bonded with PVA-based scaffold into the acidic-aqueous cleansing solution for a select amount of time to break down and remove the PVA-based scaffold from the 3D printed part; and adding to the acidic-aqueous cleansing solution a select quantity of polymeric carbohydrate to crosslink and bond with the PVA-based scaffold to effect dissolution thereof into the acidic-aqueous cleansing solution.

Abstract: A method of treating a waste liquid: an aluminum dissolution step of dissolving aluminum in an acidic waste liquid and performing separation into a first treated water and a reduced heavy metal precipitate; a gypsum recovery step of adding a calcium compound to the first treated water at a pH of 4 or less, and performing separation into a second treated water and gypsum; a heavy metal coprecipitation step of adding a ferric compound to the second treated water and performing separation into a third treated water and a heavy metal coprecipitate; an aluminum and fluorine removal step of adding an alkali to the third treated water and performing separation into a fourth treated water and a precipitate containing aluminum and fluorine; and a neutralization step of adding an alkali to the fourth treated water and performing separation into an alkali neutralization treated water and a neutralized heavy metal hydroxide.

Abstract: An apparatus for reducing the water content of waste water sludge includes a column for receiving waste water sludge, an outlet at a lower end of the column, a first closure for closing the outlet of the column, a controller for controlling the opening and closing of the closure. The controller is adapted to open and close the first closure to periodically discharge amounts of settled fines from the lower end of the column. A water outlet is adapted to receive water overflowing from an upper end of the column.

Abstract: An arrangement and a method for controlling a dewatering process including measuring values representing operating parameters of the gravitational sedimentation device and using the values as input values for a predictive multivariable model for predicting an operating state of the gravitational sedimentation device. The disclosure further relates to obtaining reference values for the operating parameters, determining at least one predicted output for an operating parameter of the gravitational sedimentation device, and comparing the predicted output to at the reference values to determine control values that will affect changes in operation of the gravitational sedimentation device.

Abstract: A device for treating an effluent composed of liquid and of solid particles to obtain a treated effluent includes a filtration device using gravity separation on a rotating cloth having an inlet intended to receive the effluent to be treated and a first and a second outlet, the filtration device being designed to separate the effluent into a first flow and a second flow, the second flow comprising sludges comprising solid particles, the first flow leaving the filtration device through the first outlet, the second flow leaving the filtration device through the second outlet, and at least one recirculation device designed to recirculate at least a part of the sludges of the second flow to the inlet of the filtration device, the second outlet being linked to the at least one recirculation device. A method for treating an effluent is also provided.

Abstract: A pilot filter system for monitoring water quality in a water treatment system is disclosed. The pilot filter system includes: a filter vessel containing a downward-moving bed of filtration media, the filter vessel being fluidly connected to the water treatment system such that sample influent water from the water treatment system flows into the filter vessel and over the bed, wherein the filter vessel has a filtrate outlet port through which some filtrate is discharged; a media recycle conduit fluidly connected to the filter vessel; and a media recycler for circulating a mixture of water and used filtration media through the media recycle conduit to a point upstream of the bed in the filter vessel.

Abstract: A continuous flow granular/flocculent sludge wastewater process selects for granule biomass capable of nitrogen and phosphorus removal and controls granule size and concentration of granular and flocculent sludge for optimal nutrient, organic, and solids removal in a smaller footprint. It includes anaerobic, anoxic, and aerobic process zones, a high soluble biodegradable COD loaded first reactor in anaerobic or anoxic zones, a granular sludge classifier with recycle of underflow granular sludge to the first reactor, a secondary clarifier to settle flocculent sludge and particulates and recycle of flocculent sludge from the secondary clarifier underflow to an aerobic process zone. Wasting of sludge from the two separate recycle lines controls the bioprocess flocculent and granular sludge concentrations and SRTs. Bypass around and recycle flow to the classifier to maintain desired flow under various influent flow conditions aid control of granule size.

Abstract: The present invention relates to a process for treating primary sludge in a wastewater treatment plant, comprising the steps of admixing an organic coagulant and/or polymer to wastewater; allowing a primary treatment of the wastewater in the presence of the organic coagulant or polymer; separating solids as a primary sludge from said primary treatment; and dewatering the primary sludge. The present invention further relates to a method of improving primary sludge dewaterability and improving energy balance of a wastewater treatment plant.

Abstract: Radionuclides and other unwanted material in a liquid may be treated, removed or reduced through the use of electromagnetic fields applied to the liquid by electrodes that also function as co-precipitators by leaching polyvalent metal ions into the liquid.

Abstract: In a rapid stirrer that stirs sludge and a flocculant in a tank with a stirring blade, the rotation speed of the stirring blade is increased at a set rate with an increase in the amount of charged sludge, the rotation speed of the stirring blade is reduced at the set rate with a decrease in the amount of charged sludge, and flocculated flocs having a fixed floc diameter are stably generated even when operating conditions change so as to fluctuate the amount of charged sludge.

Abstract: A method for combined treatment of electroless copper plating wastewater includes oxidizing hydroxyl-containing organic amine complexants with hydrogen peroxide or sodium hypochlorite to organic acid complexants containing amine group (or amino group) and carboxyl group, precipitating the carboxyl-containing complexants using synergistic effect of ferrous ions and calcium ions and precipitating the copper ions released from the complexes to copper hydroxide precipitate to effectively removing copper. Using this precipitation method to remove complexants in the electroless copper plating wastewater, the problem in the prior art that it is difficult to destroy the hydroxyl-containing organic amine complexant is solved and the COD in the wastewater is effectively reduced.

Abstract: A surface sensing assembly is in communication with an open channel having a material moveable relative to the open channel. The surface sensing assembly includes a light source directing a light beam toward the material, a photo-detector capturing an image of the light beam interacting with the material, and a controller coupled to the light source, the photo-detector, and at least one actuator. The controller is configured to determine an indication of surface topography of the material based on the image. The controller is also configured to control the at least one actuator to adjust a characteristic of the material based on the indication of surface topography.

Abstract: Provided is a water treatment system that prevents overlook and misdetection of abnormal flocculation. The water treatment system includes a mix tank, a flocculation tank, a plurality of floc-particle-diameter measurement devices, a fault detection device that detects abnormal flocculation, and a notification device that notifies occurrence of the abnormal flocculation. The fault detection device includes: a calculator that calculates at least one of a difference and a ratio between particle diameters of floc; a storage that stores therein a tolerable range of at least one of the difference and the ratio between the particle diameters of floc; a determiner that, when the calculated value is within the tolerable range, determines that it is normal, and when the calculated value is outside the tolerable range, determines that it is abnormal; and an outputter that transmits an abnormal flocculation detection signal to the notification device.

Abstract: An embodiment of a screw press separator for separating a slurry containing solid and liquid components has a housing and a cylindrical screen, which is arranged in the housing and on which a longitudinal direction and a circumferential direction are defined. The screen is rotatable about the longitudinal direction. The separator also includes a screw arranged inside the screen for pressing out the slurry, the screw being rotatable about the longitudinal direction, at least one retaining element arranged in the housing, at least one actuator adapted to move the at least one retaining element between a locking position and a freewheeling position, and at least one stop connected to the screen. The separator is configured so that the screen is rotationally fixed in at least a circumferential direction in the locking position and the screen co-rotates with the screw in the freewheeling position.

Abstract: The system and method for remediation of oil-contaminated sand provides for washing and separation of sand from oil and oil-based contamination. The system for remediation of oil-contaminated sand includes a soil washing system for receiving a volume of oil-contaminated sand. The soil washing system mixes the volume of oil-contaminated sand with water to produce a mixture. This mixture is then delivered to a sand separator for separation into a volume of treated sand and a volume of oily wastewater. A flocculation tank receives the volume of oily wastewater. In the flocculation tank, the oily wastewater is mixed with at least one coagulant to separate the oily wastewater into treated water and oily sludge. A sludge hopper receives the oily sludge for collection. A treated water tank receives the treated water for collection and storage.

Abstract: Processes for the removal of arsenic from aqueous solutions such as contaminated waters and process solutions are disclosed. Arsenic is removed from process solutions/effluents either by precipitation with a soluble iron compound, or solvent extraction and subsequent treatment with engineered materials, such as granular iron oxide. Arsenic may also be directly removed from arsenic contaminated ground and/or surface waters using engineered materials, especially by contacting ground and/or surface waters with silica, granular iron oxide and optionally natural zeolite in sequence. The treated solutions/effluents and waters may be released into the environment.

Abstract: A method and a system for selecting and retaining solids with superior settling characteristics, the method comprising feeding wastewater to an input of a processor that carries out a treatment process on the wastewater, outputting processed wastewater at an output of the processor, feeding the processed wastewater to an input of a gravimetric selector that selects solids with superior settling characteristics, and outputting a recycle stream at a first output of the gravimetric selector back to the processor.

Abstract: A method of surface sealing a porous fibrous substrate is provided. According to the method, a porous fibrous substrate possessing a moisture content and a surface with pores is provided. A sealant composition is applied to a surface of the porous fibrous substrate and permitted to penetrate the surface pores of the porous fibrous substrate and undergo cure while participating in a foaming reaction with the moisture content to establish a water-resistant polymeric foam sealant impregnated into the porous fibrous substrate. The water-resistant polymeric foam sealant contains a polyurethane and/or polyurea.

Abstract: An electronic device includes a central control unit and a waveguide device. The waveguide device includes a communication module having a communication function, and an attachment/detachment unit capable of attaching/detaching a high-frequency signal waveguide so that coupling between the module and the high-frequency signal is possible. The communication module includes a communication device, and a transfer structure configured to cause a high-frequency signal emitted from the communication device to be coupled to the high-frequency signal waveguide.

Abstract: The present invention concerns a method and device for oxidative erosion or for decontamination of a metallic surface, comprising a step consisting of intermittently polarizing the metallic surface to be eroded or decontaminated, placed in contact with a solution containing manganese VII, at a more anodic electric potential than the corrosion potential of said surface.

Abstract: A method of controlling a froth flotation cell in a froth flotation circuit for separating substances comprises periodically carrying out a control routine to maximize froth stability during the operation of the cell. The control routine comprises changing the gas flow rate to the cell in a series of steps and assessing the froth stability at each gas flow rate and continuing the step changes in the gas flow rate until the froth stability is a peak froth stability or is within a predetermined range of the peak froth stability of the cell.

Abstract: Portable wet drilling waste treatment. In one example embodiment, a method for portable wet drilling waste treatment may include transporting a transportable frame, maneuvering an open end of a waste conduit, vacuuming air and the wet drilling waste, using a motor-driven vacuum, into the open end of the waste conduit, through the waste conduit, and into a cyclonic separator, separating the wet drilling waste from the air using the cyclonic separator, using a waste auger to transport the wet drilling waste, using a treatment material auger to transport a treatment material, operating the waste auger and the treatment material auger at coordinated rates to transport an effective ratio of the wet drilling waste to the treatment material, using a mixing auger to simultaneously transport the wet drilling waste and the treatment material, and operating the mixing auger at an effective rate resulting in a solidified treated material.

Abstract: Some waters have high sulfate contents, such as acid mine drainage (AMD), which makes them unsuitable for use in fracturing fluids and difficult to dispose. Such waters may be treated with a solution of barium chloride to react with the sulfate ion of the sulfates and precipitate the sulfates as barium sulfate. Not all of the sulfates needs to be removed for the reclaimed water to be useful in formulating a fracturing fluid. The by-product of the reaction is almost pure barium sulfate, which is an inert, commercially valuable material that may be used in drilling fluids, paint and other industries.

Abstract: A method for treatment of coke wastewater, including (1) introducing wastewater into a regulating reservoir into which an acid liquor is added until the pH value of the wastewater ranges between about 5.5 and about 6.5; (2) introducing the wastewater into a three-dimensional electrode treatment device for electrolysis treatment; and (3) introducing the wastewater into a coagulation reaction tank into which an alkali liquor is added until the pH value of the wastewater ranges between 8 and 10, and as a coagulant polysilicate ferric magnesium is added into the wastewater for a hybrid reaction of between 5 and 15 mins; allowing the wastewater to flow into a sedimentation basin for plain sedimentation of between 4 and 6 hrs; and extracting a supernatant liquor to yield a processed effluent.

Abstract: The present invention relates to a method and apparatus for removing and recovering copper by treating an acidic waste liquid containing copper ions such as an etching waste liquid resulting from etching a copper printed board in an etching solution of cupric chloride and a waste liquid after renewing a plating bath liquid in producing electrolytic copper foil. In particular, a copper recovering method of recovering copper from a copper-containing acidic waste liquid includes adding a liquid mixture of a copper-containing acidic waste liquid and an oxidizing agent to an alkaline agent solution while a pH of the alkaline agent solution to which the liquid mixture has been added is being controlled so as never to decrease to seven or lower, and by obtaining a solid material whose main component is copper oxide.

Abstract: A sewage treatment apparatus comprises a first stage equipment for treating sewage feed to obtain a first effluent and a second stage equipment for treating the first effluent to obtain a second effluent. The second stage equipment comprises a mixer (VI) for mixing the first effluent and a flocculation agent to obtain the first effluent containing the flocculation agent and a flocculation-clarification equipment (VII) comprises a first flocculation reaction chamber (A), into which the first effluent containing the flocculation agent is entered and subjected to flocculation reaction to form a mixture of water and dreg; a first separation chamber (C), into which the mixture of water and dreg from the first flocculation reaction chamber (A) is entered and separated to obtain a first part of the second effluent and a first dreg; and a second separation chamber (D), into which part of the first dreg is entered and separated to obtain a second part of the second effluent and a second dreg.

Abstract: Provided is an apparatus for efficiently removing a pollutant source in a snout of a steel plating line such as a steel galvanizing line. The pollutant removing apparatus includes at least one pollutant collecting member connecting to a snout between a heating furnace and a plating tank, and a contact-free inducer varying magnetic field within the snout to forcibly guide, without contact, a pollutant source of a steel plate or a processing unit to the pollutant collecting member.

Abstract: The present invention provides a method of treating an aqueous system for biocide control, by adding an acidified solution that includes monoalkyldithiocarbamate salt and alkyl isothiocyanate to an aqueous system. A biocide feed system is also provided that is configured to generate a reproducible level of alkyl isothiocyanate. The method and system provide effective levels of alkyl isothiocyanate for rapid biocidal activity, along with levels of monoalkyldithiocarbamate salt which can decompose to form additional alkyl isothiocyanate and provide longer-term biocidal activity.

Abstract: Techniques are described that relate to enhancing flocculation and dewatering of thick fine tailings, for example by reducing process oscillations. One example method includes dispersing a flocculant into thick fine tailings having a turbulent flow regime to produce turbulent flocculating tailings; subjecting the turbulent flocculating tailings to shear to build up flocs and increase yield stress, to produce a flocculated material having a non-turbulent flow regime; and shear conditioning the flocculated material to decrease the yield stress and produce conditioned flocculated tailings within a water release zone; and dewatering the conditioned flocculated tailings, for example by employing sub-aerial deposition. The thick fine tailings may have a Bingham Reynolds Number of at least 40,000 upon flocculant addition.

Abstract: An upflow continuous backwash deep bed sand filter (UCBF) having a recycle line for returning carbonaceous denitrifying bacteria attached to biomass to the influent of the UCBF. The recycle line returns the biomass to the treatment process at a location upstream of the upflow continuous backwash filter. Further, a liquid level control unit is provided that reduces fluctuations and significant drop in the liquid level upstream of the upflow continuous backwash filter, thereby avoiding or minimizing flow turbulences, air induction, and undesirable wastewater aeration resulting in the need to dose excessive carbon source to remove dissolved oxygen in the aerated wastewater.

Abstract: The present application provides a method of detecting an amount of a treatment agent, such as a flocculating agent, in a process stream comprising the step of measuring at least one absorption property of a sample obtained from the process stream at a wavelength of less than about 250 nm. Processes and systems for monitoring and regulating addition of treatment agents to process streams are also provided.

Abstract: The present invention provides a coagulation processing method capable of adding a sufficiently-dissolved coagulant aqueous solution to being processed water and materializing high-efficiency coagulation processing, a coagulation processing unit, and a water processing apparatus. A coagulation processing unit includes a coagulant aqueous solution storage tank 1 to have a stirrer 5 and store a coagulant aqueous solution, a particle size distribution measurement device 50 to measure the particle size distribution of the coagulant aqueous solution in the coagulant aqueous solution storage tank 1, a coagulation tank 11 to mix being processed water with an added coagulant aqueous solution and form a coagulation, a coagulation removing section 9 to remove the coagulation from the being processed water containing the coagulation, and a control section 6 to control the stirrer 5 so that a median size in the particle size distribution of the coagulant aqueous solution may be not more than 1.

Abstract: A method of wastewater reutilization by which reusable water can be stably obtained from a wastewater. Ozone is added to a wastewater, such as water resulting from sewage treatment, in such a small amount as to result in a residual ozone concentration as measured before membrane filtration of 0.01-1.0 mg/L. Ozone is thus brought into contact with fine solids contained in the wastewater to alter the surface properties of the fine solids so that the solids are easily to coagulate. Thereafter, a coagulant, e.g., PACl, is added from a coagulant addition device (3). The fine solids are coagulated in a coagulation tank (5) or a line mixer and the resultant water is subjected to membrane filtration with an ozone-resistant separation membrane (6) such as ceramic membrane. Thus, reusable water is obtained which has a residual ozone concentration, as measured after filtration through the membrane, less than 0.5 mg/L.

Abstract: An oil recovery process that utilizes one or more filtration medium comprises a filter cake and a second filtration medium being nonwovens sheet to remove silica and/or oil and/or dissolved organics and/or dissolved solids from produced water which includes separating oil from the produced water and precipitating silica into particles and wherein the produced water having the precipitated silica is directed to a filtration medium which operates in a direct flow filtration mode and removes the precipitated silica from the produced water to form a filtrate stream.

Abstract: A Method for cleaning degraded oil comprising oil-soluble degradation products and a system for implementing the method are disclosed. The method comprises the steps of receiving an inlet flow (1, 1a, 1b) of degraded oil, precipitating oil-soluble degradation products from the degraded oil by cooling the degraded oil, passing the cooled degraded oil as a filtration flow (3, 3a, 3b) through a filter (104, 204, 304) so as to retain the precipitated degradation products in the filter, and discharging an outlet flow (2, 2a, 2b) of cleaned oil.

Abstract: A process for treating waste water having a low level of metallic contaminants by reducing the toxicity level of metallic contaminants to an acceptable level and subsequently discharging the treated waste water into the environment without removing the treated contaminants.

Abstract: According to one embodiment, a fluorine recovering apparatus includes a precipitating device allowing fluoride ion-containing water to react with calcium source to form precipitate, a mixing tank mixing a filter aid including particles of a magnetic material having a diameter of 0.5 to 5 ?m with a dispersion medium to produce slurry, a filter aid feeder to the mixing tank, a solid-liquid separator with a filter depositing a filter aid layer, and depositing the precipitate on the filter aid layer, a cleaning mechanism removing the filter aid and the precipitate, a separating tank separating the filter aid and the precipitate, and a returning mechanism returning the filter aid to the filter aid feeder.

Abstract: The present invention relates to a method for purification of produced water and to a system for carrying out the inventive method. Further, the invention relates to a purified produced water product obtainable according to the invention. A unique sequence of unit operations including the addition of dissolved calcium hydroxide and the subsequent precipitation thereof enable a particularly efficient removal of contaminating substances from produced water from the petrochemical industry.

Abstract: Disclosed herein is a controlled method of minimizing radioactive sludge generation in treatment of wastewater from an oil and/or gas well. The method comprises measuring a concentration of a radioactive material in wastewater to be treated and measuring a concentration of barium in the wastewater to be treated. The method further comprises adding a calculated quantity of sulfate to the wastewater to be treated sufficient to precipitate a quantity of barium sufficient to reduce the concentration of the radioactive material to a level such that sludge precipitated in a secondary precipitation has a radiation level below a defined radiation level.

Abstract: A method for monitoring and controlling the chemistry of a Zero Liquid Discharge (ZLD) process in power plants is described. The method identifies the principal phenomena of precipitation of calcium sulphate and calcium carbonate which can occur in such system and the principal critical sections affected by such precipitation phenomena. The interventions aimed at keeping or restoring the sustainable chemical conditions with respect to the precipitation of calcium sulphate and calcium carbonate in all the critical sections of the ZLD system are then indicated, ensuring saturation ratios of calcium sulphate and calcium carbonate lower than or equal to 1 through time.

Abstract: A flocculation-magnetic separation is provided which reduces the usage amount of flocculation agents as well as the usage amount of magnetic powders and realizes an improvement in the quality of treated water.

Abstract: The present invention relates to systems and methods of wastewater treatment that rely primarily on the use of water treatment chemicals to clean wastewater without the need to use filtration mechanisms. The present invention generally provides a system that is less complex and less expensive to operate than wastewater treatment systems in the prior art.

Abstract: The invention provides methods and compositions for detection and removal of sulfate from a liquid. The method provides much faster removal of sulfate than the prior art does and does so while requiring the use of far less aluminum. The method involves sequentially adding an acidic to neutral pH generating aluminum agent to the liquid, an alkaline pH generating aluminum agent to the liquid, after having added the acidic to neutral pH generating aluminum agent, and an alkaline calcium agent to the liquid. The most efficient rate possible can be obtained by also using a fluorophore to precisely determine the amount of sulfate in the liquid.

Abstract: Methods and systems for treatment of wastewater. In some embodiments, the system may comprise one or more modules such as an electrochemical module, an electrocoagulation module, a flotation module, an evaporation module, and an ultrafiltration module. One or more detection modules may also be provided to analyze the concentration of one or more wastewater components in the wastewater. Data from such modules may be used to adjust one or more operational parameters or conditions in the treatment system. The system may also comprise one or more features designed to minimize adverse effects on the environment, such as avoiding adding chemicals to the stream, extracting salt or other chemicals for re-use, and/or use of carbon dioxide gas from on-site combustion processes.

Abstract: A mercury remediation method and apparatus for reducing mercury levels in water to a nanogram per liter level that uses four treatment steps: (1) chelation; (2) oxidation; (3) reduction; and (4) air stripping, vapor/liquid separation. There is a fifth step in the process, which does not involve the wastewater. It is to scrub the stripper air of the volatile mercury in an off-gas adsorption unit or to condense volatile mercury in a cryogenic mercury trap.

Abstract: Described herein are systems, methods, and apparatuses for aggregating microorganism in an aqueous suspension. In particular, are systems, methods, and apparatuses that apply an electrical field to an aqueous suspension comprising microorganisms as the aqueous suspension follows a flow path to cause aggregation of the microorganisms. The electrical field may comprise different types of pulses. In some embodiments, the flow path for the aqueous suspension may vary.

Abstract: Described herein are systems, methods, and apparatuses for aggregating microorganism in an aqueous suspension. In particular, are systems, methods, and apparatuses that apply an electrical field to an aqueous suspension comprising microorganisms as the aqueous suspension follows a flow path to cause aggregation of the microorganisms. The electrical field may be continuous or pulsed. In some embodiments, the flow path for the aqueous suspension may vary.

Abstract: A method for monitoring and controlling the chemistry of a Zero Liquid Discharge (ZLD) process in power plants is described. The method identifies the principal phenomena of precipitation of calcium sulphate and calcium carbonate which can occur in such system and the principal critical sections affected by such precipitation phenomena. The interventions aimed at keeping or restoring the sustainable chemical conditions with respect to the precipitation of calcium sulphate and calcium carbonate in all the critical sections of the ZLD system are then indicated, ensuring saturation ratios of calcium sulphate and calcium carbonate lower than or equal to 1 through time.