Abstract: Described herein are methods of separating a first soluble salt from water that contains the first soluble salt and a second soluble salt, by (a) adding a composition to a water product containing a first soluble salt and a second soluble salt, the composition comprising seed crystals composed substantially of a target insoluble salt to be formed from the first soluble salt; and (b) collecting the target insoluble salt. These methods may be used, for example, to separate strontium from water that includes at least one soluble strontium salt and a second soluble salt (such as one soluble calcium salt).

Abstract: Systems and methods for removing organic contaminants from water may be used, for example, to treat produced water from a steam assisted heavy oil recovery operation. The treated produced water may be re-used to create steam. Alternatively, the produced water may be a blowdown stream treated to facilitate further treatment in a thermal crystallizer. The treatments may include pH adjustment or separating de-solubilized organics or both. Other treatments may include one or more of oxidation, sorption and biological treatments. The treatments may be used alone or in various combinations. One exemplary combination includes reducing the pH of produced water, separating de-solubilized organics from the produced water, and oxidizing the produced water or contacting the produced water with activated carbon.

Abstract: A process is provided for dewatering fluid fine tailings, comprising combining fluid fine tailings with fresh oil sands tailings to create a tailings mixture having a sand to fines ratio of about 1.0 to about 2.0; optionally diluting the tailings mixture with water to an optimal density; adding an aqueous polymeric flocculant to the tailings mixture and mixing the polymeric flocculant and tailings mixture to form a flocculated material; and transferring the flocculated material to a deposition cell for dewatering.

Abstract: A process for the disposal of oil sands tailings is provided, comprising: optionally diluting the tailings with sufficient water to yield a tailings feed having a solids content in the range of about 18 wt % to about 36 wt %; adding one or both of a coagulant and a flocculant to the tailings feed to form a centrifuge feed; centrifuging the centrifuge feed to produce a centrifuge cake having a solids content of at least about 50% and a centrate having a solids content of less than about 3 wt %; and introducing the centrifuge cake into an overburden containment structure comprised of oil sand overburden, said overburden containment structure comprising a least one trench for holding the centrifuge cake, or into a deep disposal site for additional dewatering of the centrifuge cake through self-weight consolidation and creep.

Abstract: A system for dewatering a stream of slurry has a first and a second separator. The first separator removes objects above a first size, to produce a stream of primary treated slurry. The second separator removes objects above a second size from the primary treated stream, the second size being smaller than the first size. Optionally, a third separator removes objects above a yet smaller third size from the stream of secondary treated slurry. The first separator has a plurality of sieve mat supports alternately connected to a main support frame section and a movable support frame section so that the flexible sieve mat can be agitated by the movable support frame section, a collector being provided for collecting the primary treated slurry passing through the flexible sieve mat. In an optional step, water contained in the separated solids is removed.

Abstract: Systems and methods for remediating an initially liquid-like slurry pond include distributing one or more floating wicks into the slurry pond, wherein the slurry pond includes a slurry with a supernatant level above the slurry. A method also includes placing a load on the slurry, wherein the load causes an effective stress on the slurry and aids in dewatering the slurry.

Abstract: A dewatering process comprises dispersing an anionic polymer flocculant in a slurry comprising water and oil sands fine tailings to form flocs comprising fines bridged by the anionic polymer flocculant. A cationic polymer flocculant is subsequently dispersed in the flocculated slurry to further flocculate the flocs and form floc aggregates. The floc aggregates comprise flocs bridged by the cationic polymer flocculant. The floc aggregates are then compressed to remove water and form a dewatered compact. A system is also provided for the dewatering processes using inline mixtures and a filter press.

Abstract: A process for dewatering oil sands tailings is provided, comprising providing a tailings feed having a solids content in the range of about 10 wt % to about 45 wt %; adding a flocculant to the tailings feed and mixing the tailings feed and flocculant to form flocs; and centrifuging the flocculated tailings feed to produce a centrate having a solids content of less than about 3 wt % and a cake having a solids content of at least about 50 wt %.

Abstract: A method of recovering polyhydroxyalkanoates (PHAs) from municipal waste sludge includes: (a) measuring a solid content in the municipal waste sludge in terms of a volatile suspended solid in the municipal waste sludge; (b) removing supernatant from the municipal waste sludge; (c) freezing the municipal waste sludge; (d) conducting a pretreatment of the municipal waste sludge that has been frozen; (e) adding a surfactant into the pretreated sludge to obtain a slurry; (f) adding a controlled amount of sodium hypochlorite solution to the municipal waste sludge obtained in step (e), a ratio of a volume of the sodium hypochlorite solution to the solid content of the municipal waste sludge ranging from 0.67 mg/ml to 1.25 mg/ml and being defined as a liquid-solid ratio; and (g) separating PHAs from non-PHAs substances in the municipal waste sludge obtained in the step (f).

Abstract: A method of recovering polyhydroxyalkanoates (PHAs) from municipal waste sludge includes: (a) removing coarse particles in the municipal waste sludge and measuring a solid content in the municipal waste sludge in terms of a volatile suspended solid in the municipal waste sludge; (b) removing a supernatant from the municipal waste sludge; (c) freezing the municipal waste sludge; (d) adding a controlled amount of sodium hypochlorite solution to the municipal waste sludge that has been frozen, a ratio of the solid content of the municipal waste sludge to a volume of the sodium hypochlorite solution added in step (d) ranging from 0.67 mg/ml to 4 mg/ml and being defined as a liquid-solid ratio; and (e) separating PHAs from non-PHAs substances in the municipal waste sludge obtained in the step (d).

Abstract: The present disclosure provides apparatus and method for phosphorous removal using dolomite by mixing an inorganic coagulant and dolomite together to improve the phosphorous removal efficiency and controlling pH, which has been lowered due to the use of the inorganic coagulant, close to the neutral by means of dolomite to improve the economic feasibility and minimize an additional neutralizing process.

Abstract: CO2-sequestering formed building materials are provided. The building materials of the invention include a composition comprising a carbonate/bicarbonate component. Additional aspects of the invention include methods of making and using the CO2-sequestering formed building material.

Abstract: A method of flocculating coal fines from produced water that includes the steps of: (A) mixing at least: (i) produced water, wherein the produced water comprises suspended coal fines; (ii) one or more oil-soluble phosphate esters; and (iii) water-immiscible solvent; wherein the mixing is in proportions to obtain an oil-in-water emulsion; (B) allowing or mechanically causing the oil-in-water emulsion to substantially break into: (i) a first fluid having a continuous phase comprising at least some of the water from the produced water; and (ii) a second fluid having a continuous phase comprising at least some of the water-immiscible solvent; and (C) mechanically separating the first fluid and the second fluid. Optionally, the step of mixing further includes mixing with a crosslinker for the one or more phosphate esters to form a gel for suspending the separated coal fines.

Abstract: The invention is directed towards methods and compositions for treating slurry to better dewater alumina trihydrate precipitated from the Bayer process. The method comprises using a product comprising the combination of at least two surfactants together with an optional coupling agent to treat the alkaline slurry with certain amount of alumina trihydrate present. Synergistic effects between binary combinations of nonionic and anionic surfactants result in more efficient dewatering aids for alumina trihydrate slurry when combinations of such surfactants are applied. A coupling agent may be used in formulations to reduce viscosity of such surfactant combinations, allowing the practical application of such products.

Abstract: Systems and methods relate to treating wastewater, such as blowdown from steam generators used in oil sands production. The systems rely on precipitation by acidification of the wastewater along with passing the wastewater at a pressure of at least 138 kilopascals through a multiphase centrifuge to remove at least partially organic and/or silica solids. A resulting treated aqueous stream may meet thresholds desired for injection into a disposal well.

Abstract: Disclosed herein are systems for removing particulate matter from a fluid, comprising a particle functionalized by attachment of at least one activating group or amine functional group, wherein the modified particle complexes with the particulate matter within the fluid to form a removable complex therein. The particulate matter has preferably been contacted, complexed or reacted with a tethering agent. The system is particularly advantageous to removing particulate matter from a tailing solution.

Abstract: The invention is directed to processes for treating biosolids that result in high-value, nitrogen-containing, slow-release, organically-augmented inorganic fertilizer that are competitive with less valuable or more costly conventional commercially manufactured fertilizers. The process involves conditioning traditional waste-water biosolids and processing the conditioned biosolids continuously in a high throughput manufacturing facility. The exothermic design and closed loop control of the primary reaction vessel decreases significantly the amount of power necessary to run a manufacturing facility. The process utilizes green technologies to facilitate decreased waste and enhanced air quality standards over traditional processing plants. The fertilizer produced from recovered biosolid waste is safe and meets or exceeds the United States Environment Protection Agency (USEPA) Class A and Exceptional Quality standards and is not subject to restrictions or regulations.

Abstract: A process for treating impure water includes adding magnesium hydroxide and/or ammonium hydroxide to the water. This neutralizes the impure water and reacts with dissolved metals in the water. The metals are precipitated as metal hydroxides/oxides, which are removed from the water. Thereafter barium hydroxide is added to the water. The barium hydroxide reacts with dissolved sulphates to produce barium sulphate and, when magnesium hydroxide is used, with dissolved magnesium, to produce magnesium hydroxide. Barium sulphate and, when present, magnesium hydroxide are removed from the water. When ammonium hydroxide is used, ammonia is stripped from the water. Carbon dioxide is then added to the water. The carbon dioxide reacts with dissolved calcium in the water. The calcium is precipitated as calcium carbonate, which is removed from the water.

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: A flocculating agent that comprises a complex of a metal salt and multiple strands of a temperature sensitive polymer. A process for separating coal fines from an aqueous liquid using a flocculent having a critical flocculation temperature, said critical flocculation temperature being the temperature below which flocculent is hydrophilic and forms floccules with fines and above which the flocculent is hydrophobic, which comprises adding to the aqueous liquid an effective amount of the flocculent at a temperature below the critical flocculent flocculation temperature of the flocculent to cause generation of floccules, said comprising at least a metal complex including a metal salt and a water soluble polymer, separating (for example filtering) floccules from the aqueous liquid, then heating the floccules to a temperature above the critical flocculation temperature of the flocculent to expel water from the floccules to create a solids and expelled water, and separating the expelled water from the solids.

Abstract: A system adapted to condition an initial water feed stream into a treated water stream and to discharge the treated water stream. The initial water feed stream includes at least one of: a plurality of particles; an oil; a volatile organic compound; a hydrogen sulfide; a non-volatile compound; a heavy metal; and, a dissolved ion. The system includes a particle and oil removal subsystem adapted to treat the initial water feed stream to remove the plurality of particles and the oil to form a first partial treated water stream, a chemical oxygen demand reduction subsystem adapted to treat the first partial treated water stream to remove the volatile organic compound, the hydrogen sulfide and/or the non-volatile organic compound to form a second partial treated water stream, and a heavy metal and dissolved ion removal subsystem adapted to treat the second partial treated water stream to remove the heavy metal and the dissolved ion to form a treated water stream.

Abstract: A system for processing drilling mud, the system including a primary separation tank having an inlet for receiving drilling waste and an outlet in fluid communication with a feed line, and an injection pump in fluid communication with a polymer tank and the feed line. The system also includes a clarifying tank in fluid communication with the feed line and a first collection tank, wherein effluent from the clarifying tank is discharged into the first collection tank, and a centrifuge in fluid communication with the clarifying tank and a second collection tank, wherein effluent from the centrifuge is discharged into the second collection tank.

Abstract: System and methods for remediating a slurry pond are disclosed herein. A method includes distributing a material over a surface of the slurry pond, wherein the slurry pond includes residues from a plant operation. A method also includes placing a load on the material, wherein the load causes the material to sink below a level of a supernatant but to remain above a layer of sludge in the slurry pond.

Abstract: Provided is a catalyst material comprising aggregates of nanoneedles of mainly R-type manganese dioxide and having a mesoporous structure. With this, water can be oxidatively decomposed under visible light at room temperature to produce oxygen gas, proton and electron. Also provided is a catalyst material comprising aggregates of nanoparticles of mainly hydrogenated manganese dioxide. With this, acetic acid or an inorganic substance can be synthesized from carbon dioxide gas.

Abstract: The present invention provides a low energy alternative to conventional thermal/evaporation processes for “zero liquid discharge” treatment of strong saline brines. The products of the process include a salt-free liquid and solid salt. In particular, an antisolvent can be mixed with liquids containing high total dissolved solids. The mixture can be chilled, whereby solid salt is precipitated and separated from the mixture at near ambient temperature leaving a mixed liquor. The antisolvent can be selected from a class of organic compounds that form solutions with salt brines that exhibit a critical solution temperature lower than a critical solution temperature of the salt brines alone. The mixed liquor can be heated to a temperature above its lower critical solution temperature to produce an antisolvent liquid phase for recycle to the process. Finally, a reduced salinity aqueous phase can be polished by reverse osmosis or other conventional technology to produce clean water for discharge or beneficial use.

Abstract: The present invention relates to a method for treating blood plasma including the steps of ethanol precipitation of the plasma or a fraction of plasma, recovering the precipitate, washing said precipitate, recovering a washed plasma paste, and making said washed plasma paste soluble.

Abstract: CO2-sequestering formed building materials are provided. The building materials of the invention include a composition comprising a carbonate/bicarbonate component. Additional aspects of the invention include methods of making and using the CO2-sequestering formed building material.

Abstract: A process for flocculating and dewatering oil sands fine tailings is provided, comprising: adding the oil sands fine tailings as an aqueous slurry to a stirred tank reactor; adding an effective amount of a polymeric flocculant to the stirred tank reactor containing the oil sands fine tailings and operating the reactor at an impeller tip speed for a period of time that is sufficient to form a gel-like structure; subjecting the gel-like structure to shear conditions in the stirred tank reactor for a period of time sufficient to break down the gel-like structure to form flocs and release water; and removing the flocculated oil sands fine tailings from the stirred tank reactor when the maximum yield stress of the flocculated oil sands fine tailings begins to decline but before the capillary suction time of the flocculated oil sands fine tailings begins to substantially increase from its lowest point.

Abstract: A method of treating a wastewater is provided and can be used, for example, to treat a gas well production wastewater to form a wastewater brine. The method can involve crystallizing sodium chloride by evaporation of the wastewater brine with concurrent production of a liquor comprising calcium chloride solution. Bromine and lithium can also be recovered from the liquor in accordance with the teachings of the present invention. Various metal sulfates, such as barium sulfate, can be removed from the wastewater in the production of the wastewater brine. Sources of wastewater can include gas well production wastewater and hydrofracture flowback wastewater.

Abstract: A method may include providing a returned fluid comprising a fluid; and a solid contaminant; introducing the returned fluid into a solid-liquid sorter thereby separating the returned fluid into an overflow and underflow; flocculating the underflow in a flocculating chamber thereby forming a flocculated fluid; and dewatering the flocculated fluid using a dewatering rack.

Abstract: A new method for removing ammonia nitrogen in coking wastewater is disclosed in this invention. It comprises steps as follow: introducing coking wastewater into a reaction pool into which magnesium and phosphate are added; adding sodium hydroxide to regulate the PH of the mixture around 9.0-10.5; separating the supernatant and the precipitate after proper agitation and natural precipitation; dehydrating the precipitate and then adding alkaline fly ash, water to the dehydrated precipitate and stirring the mixture; decomposing the mixture with heating and absorbing the ammonia gas thereof produced with acidic solution. In consideration of high concentration of ammonia nitrogen in coking wastewater, this invention aims at quick and efficient treatment. The concentration of ammonia nitrogen in treated water meets the highest discharge standard stipulated in [China National] Integrated Wastewater Discharge Standard (GB8978-96).

Abstract: A system and method for removing water from sludge including mixing a blending material into the sludge and compressing the mixture. Additional pre and post compression steps are disclosed. Examples of specific blending materials and methods for their use are disclosed.

Abstract: A system and method for managing fluid mature fine tailings (MFT) containment volume in a tailings pond to a minimum, fixed steady-state volume by balancing the accumulation of the MFT in the pond with consumption of the MFT from the pond by one or both of spiking the MFT into coarse sand tailings forming a coarse sand beach with trapped fines which is segregating for forming a trafficable deposit or centrifuging MFT from the tailings pond and depositing the resulting centrifuge cake on the coarse sand beach. During the life of the oil sand operation, when the volume of MFT approaches the fixed volume of the tailings pond, MFT is consumed from the pond using both sand-spiking and centrifugation as required. Production of MFT in the pond is also reduced by diverting an underflow from a secondary flotation cell in an extraction plant from the tailings pond to a thickener where the fines-rich thickened tailings from the thickener are beached for subsequent dewatering and reclamation.

Abstract: The present invention relates to a process for workup of nitrite-comprising alkaline process wastewaters from the nitration of aromatic compounds, wherein the alkaline process wastewater is acidified by addition of acids and the offgas which comprises nitrogen oxides and escapes from the acidified process wastewater is worked up, comprising the steps of a) acidifying the process wastewater by adding acid to a pH below 5, which forms an organic phase which separates out, an acidic aqueous phase and a gaseous NOx-containing phase, and b) removing the gaseous NOx-containing phase.

Abstract: A system and method for removing water from sludge including mixing a blending material into the sludge and compressing the mixture. Additional pre and post compression steps are disclosed. Examples of specific blending materials and methods for their use are disclosed.

Abstract: The invention is a process for treatment of brown grease, where the brown grease comprises water, food solids and free-oil. This process starts with the collection of the brown grease into a container. The brown grease's pH is adjusted with a chemical treatment to produce an adjusted brown grease phase. To the adjusted brown grease phase an anionic copolymer treatment mixture is added along with a cationic copolymer to form a reaction mixture. The reaction mixture reacts for a period of time, and during this time wastewater is discharged from the reaction mixture to produce resulting solids. The resulting solids are then transferred from the container for disposal or are processed further into a fuel or soil additive.

Abstract: A method of removing phosphonates from water includes directing the water into a first settling zone. The water is then directed to a membrane filtration zone and is filtered therein to produce a concentrate containing phosphonates. The concentrate containing phosphonates is then contacted with sludge such that at least some of the phosphonates in the concentrate are adsorbed onto the sludge. Flocculant is added to the sludge and the concentrate to form a floc-mixture which is directed to a second settling zone to form treated concentrate.

Abstract: The present invention relates to a process of concentrating an aqueous suspension of solid particles comprising the steps of adding at least one organic polymeric flocculant to the suspension thereby forming flocculated solids in which the flocculated solids are allowed form a layer of solids and thereby forming a more concentrated suspension in which the process comprises the addition of an effective amount of an agent that is selected from the group consisting of free radical agents, oxidising agents, enzymes and radiation, in which the agent is applied to the suspension prior to or substantially simultaneously with adding the organic polymeric flocculant and/or the organic polymeric flocculant is added to the suspension in a vessel and the agent is applied to the suspension in the same vessel. The process is particularly suitable for solids liquid separation in which the flocculated solids are allowed to settle by sedimentation in a gravity thickener.

Abstract: Methods are disclosed for the precipitation of magnesium hydroxide in a standalone basis or in conjunction with the precipitation of calcium in different forms from saline streams. Methods are also disclosed for flue gas scrubbing in conjunction with the precipitation methods or in a standalone basis. Among the benefits of the disclosed methods is that their resulted spent saline stream and/or gas can be used, for instance, to feed seawater desalination plants and/or to enhance hydrocarbons recovery.

Abstract: Methods to reduce hexavalent chromium (Cr(VI)) in chromite processing wastes include one or more of the following steps: contacting the chromite processing wastes with an oxygen scavenger or chemical reducer; permitting the chromite processing wastes to react with the oxygen scavenger or chemical reducer; contacting the chromite processing wastes with ferrous ion; contacting the chromite processing wastes with sulfide ion; and, contacting the chromite processing wastes with ferrous sulfide.

Abstract: A method of solubilising in an aqueous medium a hydrocarbon or a hydrophobic compound having a hydrocarbon skeleton that carries one or more heteroatom-containing functional groups, e.g. hydroxyl, carboxylic acid or aldehyde (CHO) groups. The method comprises contacting the hydrocarbon or the hydrophobic compound with the aqueous medium that includes at least one non-ionic surfactant containing a hydrophilic part and a hydrophobic part, the hydrophilic part comprising a polyhydroxylated moiety and the hydrophobic part comprising a hydrocarbon chain containing at least 12 carbon atoms, e.g. ethoxylated sorbitol. The amount of surfactant used is sufficient to form micelles including a core formed of the hydrocarbon or the hydrophobic compound.

Abstract: Technologies are generally described for processes, compositions and systems for waste sludge dewatering. In an example, the process may include receiving a waste sludge including a water component and an initial content of suspended particulates. The process may include treating the waste sludge with a combination of flocculant produced by Proteus mirabilis and a flocculant including chloride. The combination may be sufficient to flocculate at least some of the suspended particulates in the water component of the waste sludge and sufficient to produce treated waste sludge. The treated waste sludge may have a water component with a reduced content of suspended particulates. The process may include separating at least some of the water component with a reduced content of suspended particulates from the treated waste sludge to produce dewatered waste sludge.

Abstract: A method of treating tailings comprising a solids fraction and a hydrocarbon fraction is disclosed. A primary flow is supplied to a jet pump, the primary flow comprising water and less than 20% solids by mass. A secondary flow is supplied to a mixing chamber of the jet pump, the secondary flow comprising a slurry of water and tailings, the slurry comprising more solids by mass than the primary flow. The jet pump is operated using the primary flow such that the tailings are agitated to effect at least a partial phase separation of the hydrocarbon fraction from the tailings. The methods disclosed herein may also be applied to treat tailings ponds.

Abstract: A method of dewatering algae and recycling water therefrom is presented. A method of dewatering a wet algal cell culture includes removing liquid from an algal cell culture to obtain a wet algal biomass having a lower liquid content than the algal cell culture. At least a portion of the liquid removed from the algal cell culture is recycled for use in a different algal cell culture. The method includes adding a water miscible solvent set to the wet algal biomass and waiting an amount of time to permit algal cells of the algal biomass to gather and isolating at least a portion of the gathered algal cells from at least a portion of the solvent set and liquid of the wet algal biomass so that a dewatered algal biomass is generated. The dewatered algal biomass can be used to generated algal products such as biofuels and nutraceuticals.

Abstract: Methods of treating water, methods of removing radium from water, methods for controlling the amount of at least one target element removed from water and the amount of at least one target element in a pellet, a pellet and treated water. The method may generally include providing water including a principal ion and a target element, contacting the water with a fluidized bed, the fluidized bed including seed material, and controlling at least one of a type and a size of the seed material to remove principal ion and target element from the water. The target element may include radium. The principal ion may include calcium, magnesium, etc.

Abstract: The present invention relates to a method for recovering an organic-inorganic element-doped metal oxide from a hydrolysable metal compound, accompanied with contaminated water treatment. The present invention comprises steps of: a) adding a hydrolysable metal compound as a coagulant to a contaminated water to form a separable floc between the hydrolysable metal compound and contaminants present in contaminated water; b) separating the separable floc and the pre-treated water after flocculation treatment; and c) calcinating the separated floc over 500° C. to produce an organic-inorganic element-doped metal oxide. More preferably, the present invention further comprises subjecting the pre-treated water of the step b) to a microwave treatment to cause a photocatalytic degradation of an organic contaminant that remains in the pre-treated water, with the assistance of the remaining hydrolysable metal compound.

Abstract: The invention relates to a method for removing arsenic as scorodite from solutions that contain iron and arsenic. In accordance with the method, arsenic is first precipitated as ferric arsenate and subsequently processed hydrothermally into crystalline scorodite.

Abstract: A method for neutralizing brines that contain high levels of silica accompanied with a high pH. Brine is processed through a reactor in which the pH is lowered and the resultant silica precipitate is adsorbed onto a sacrificial crystal structure. The resultant stream is then processed through a solids removal zone wherein the solids are removed and recovered for reuse. The neutralized solids-free brine is then suitable for down-hole injection in the heavy oil industry or further treatment by common water treatment methods if further adjustment is required for other industries.

Abstract: The present invention provides a method and an apparatus for treating a chlorine-containing waste, which can separate and recover a chlorine component from a chlorine-containing waste, and also can achieve a high chlorine removal thereby obtaining a high purity chlorine compound, and can decrease the amount of water for recovering chlorine.

Abstract: There are provided a method of manufacturing an Fe/Ni-containing material having a low content of sulfur (S) from an Fe/Ni/SO4-containing liquid waste, a ferronickel mass using the Fe/Ni-containing material, and a method of manufacturing the ferronickel mass. The method of manufacturing an Fe/Ni-containing material from an Fe/Ni-containing liquid waste includes: removing SO4 from an Fe/Ni/SO4-containing liquid waste by adding an SO4 neutralizing agent to the liquid waste so that pH of the liquid waste can be maintained to a pH level of 0.5 to 2.5; precipitating Fe and Ni in the form of hydroxide [(Ni,Fe)(OH)] by adding NaOH to the SO4-free solution; washing the precipitate with water; and manufacturing an Ni/Fe-containing material by filtering and drying the washed Ni/Fe-containing sludge.