Abstract: A process for removing metals from wastewater, which comprises the following: measuring the flow rate and oxidation reduction potential of wastewater as it is fed into a first treatment tank, adjusting the pH of the wastewater, adding a first liquid elixir to the wastewater to react with at least one metal in the wastewater to cause it to either precipitate out of solution, or convert into a form that will allow it to be precipitated out of solution by a second liquid elixir, and to bond with the metal to prevent it from re-dissolving back into solution, adding a second liquid elixir to the wastewater to react with at least one metal in the wastewater to cause it to precipitate out of solution, and to bond with the metal to prevent it from re-dissolving back into solution, feeding the wastewater into a second treatment tank, mixing a third liquid elixir and a fourth liquid elixir into the wastewater to flocculate and/or coagulate the precipitated metals, and separating the flocculated and/or coagulated precip

Abstract: The invention is a process for treating waste slurry generated in the electric furnace production of phosphorus in which a superatmospheric reactor is operated at an elevated temperature to destroy cyanides, phosphorus, and phosphides present in the waste. The process transforms wastes from the phosphorus electric furnace process into non-hazardous solid, liquid, and gaseous wastes that meet environmental regulatory requirements regarding solids for phosphorous, cyanide, phosphine and cyanide flux, and TCLP metals, and regarding the filtrate for UTS metals.

Abstract: The present invention relates to a composite material in which an active organic compound is dispersed, as well as to an effluent treatment process, especially a photographic effluent treatment process. The composite material comprises an aluminosilicate organic-inorganic polymer matrix in fiber form comprising at least on the surface an organic radical having a —SH or —S(—CH2)n—S— function with n between 0 and 4 and in which an active organic compound is dispersed.

Abstract: A swimming pool water treatment system for removing iron from feed water, with the system including a large storage/reaction vessel to which a branch injection/filtration circuit is coupled. An alkali metal hypochlorite is injected into water flowing through the injection/filtration circuit and delivered to the storage/reaction vessel to permit precipitation of the iron oxide. A bank of parallelly coupled filters are provided in the branch filtration circuit upstream from the hypochlorite injection site for removal of insoluble iron precipitated from the treated water within the storage/reaction vessel. The branch injection/filtration circuit further incorporates an ozone injector valve where a flow of ozone is continuously introduced to water flowing through the branch injection/filtration circuit. The storage/reaction vessel is sized sufficiently large so as to permit an adequate contact dwell time for formation of the insoluble iron precipitate.

Abstract: A permeable barrier for decontaminating groundwater having two distinct components for increasing contaminant removal. Preferably, the barrier material is a mixture or distinct layers of bone-char phosphate material and iron oxide pellets. The barrier material can be incorporated as part of a shallow trenching decontamination system, or incorporated in a non-pumping well, or array of non-pumping wells, as part of a deep underground decontamination system. The system can be used for removing, among other things, a radionuclide, such as uranium, from water.

Abstract: This invention provides a method for treating waste water containing organic bases such as tetramethyl ammonium hydroxide and dissolved metals such as Mo, W, Cu and Ni which are generated from mask cleaning and Mo etching processes. The organic base along with Cu and Ni is first removed preferably by passing the effluent through a cation exchange resin followed by passing the cation exchanged effluent through an anion exchange resin to remove the Mo and W metals. The treated waste water meets federal guidelines for dissolved metal contaminant limits for water discharge to water ways. Alternatively, filtered effluent is directly passed through an anion exchange resin to remove Mo and W and the dissolved TMAH and copper and nickel are removed by cation exchange.

Abstract: Embodiments of the present invention relate to methods and systems for removal of contaminants from aqueous solutions. The methods and systems of these embodiments are particularly suited to removal of arsenic species as well as transition-metals, post-transition-metals, phosphates and other contaminants in aqueous solutions. The methods and systems of embodiments of the present invention provide for the addition of a reagent to a contaminated solution in combination with a pressurization process and a depressurization process. Contaminant particulates and solids produced in these processes may be removed by conventional separation techniques.

Abstract: An extruded, thin-walled activated carbon filter tube having a wall thickness of about 0.5 inch (12.7 mm) or less and an average dry density sufficient to remove at least about 99.5% of sub-micron particles from a liquid filtered through said tube.

Abstract: A wastewater treatment system and process for removal of radioactive particulates includes continuous monitoring of charged particles and the addition of chemicals to coagulate and cause removal of the particulates from the wastewater.

Abstract: A method for removing accumulated metals from a cleaning solution is provided. After removal of the metals, the cleaning solution can be discharged or recycled. The process manipulates the pH levels of the solution as a means of precipitating solids. Preferably a dual phase separation at two different pH levels is utilized.

Abstract: Silicon is employed as a reducing agent in an acid bath to adsorb noble metals present as contaminants in the acid. In the manufacture of silicon devices for electronic memory and other devices, polonium-210 is adsorbed by silicon getters to reduce soft error rate attributable to alpha particle emissions from the radioactive polonium. The noble metals in addition to polonium which can be plated onto silicon using the disclosed method are gold, silver, platinum, copper, palladium, mercury, selenium and bismuth.

Abstract: A method of treating an aqueous stream having inorganic material dissolved therein, the method comprising the steps of: (a) adding organic solvent to the aqueous stream in an amount effective to form an inorganic precipitate comprising at least a portion of the inorganic material; (b) removing at least most of the organic solvent from the aqueous stream by vacuum membrane distillation; and (c) after step (b), removing at least most of the inorganic precipitate from the aqueous stream.

Abstract: Multi-arm star polymers are derived from silicon containing dendrimers and have arms containing the moiety where each R′ can be the same or different and is an alkyl group containing 1-6 carbon atoms such as methyl and ethyl or an aryl group such as phenyl; R″ is alkylene radical —(CH2)a— in which a has a value of 2 or 3; and R′″ is the —(CH2)bCH3 group in which b has a value of 1-50. These compositions can be used for dissolving metals and other electrophiles.

Abstract: A material and method for removal of environmental oxyanions (and especially phosphates), the material comprising a substrate such as a clay modified with complexing elements selected from Group IIIB, Group IVB, and lanthanide elements (or a mixture of such elements). The resultant modified substrate can bind oxyanions and make them unavailable for utilisation in the environment; in the case of phosphates, by algae and the like. The method includes forming a capping of material at the sediment/water interface, applying the material in the form of pellets at the sediment/water interface, or injecting the pellets into the sediment.

Abstract: A method for treating in situ large bodies of water contaminated with heavy metals and having varying density stratas to immobilize the contaminant metals is disclosed. The method, or process for in situ immobilization of metals is focused on treating large bodies of water having metals therein that are also adjacent a border of soil or earthen materials in an attempt to immobilize the metals from penetrating through the soil. Initially, the density mean of the body of water is determined, which is densest typical at regions at or approaching 4 degrees C.

Abstract: A novel process and apparatus are disclosed for cleaning wastewater containing metal ions in solution, hydrogen peroxide, and high solids, e.g., greater than about 50 mg/l particulate solids. A carbon adsorption column removes hydrogen peroxide in the wastewater feed containing high solids. A ion exchange unit removes the metal ions from solution. The process and apparatus remove metal ions such as copper from a high solids byproduct polishing slurry from the chemical mechanical polishing (CMP) of integrated circuit microchips to form an environmentally clean wastewater discharge.

Abstract: Process for removing heavy metal ions from aqueous media, characterized in that, to precipitate out the heavy metal ions, a sulphide precipitation is carried out in the presence of iron oxide.

Abstract: Disclosed is a method of removing heavy metals contained in exhaust gas which has been generated by burning a waste liquid containing the heavy metals discharged in a process of producing organic compounds. The method includes the steps in the order of: (a) a combustion step of burning the waste liquid to produce exhaust gas; (b) a gas-liquid contact step of rendering a liquid containing an alkali compound in contact with the exhaust gas to collect the heavy metals in bottoms of the liquid; and (c) a coagulating step of adding a coagulant to the bottoms to coagulate the heavy metals in the bottoms for removal of the heavy metals. According to this method, the heavy metals contained in the exhaust gas can be efficiently separated and removed.

Abstract: An apparatus and method for removing a metal residue from a process waste stream. In one aspect, an apparatus for a waste stream treatment assembly is provided which includes a waste stream metal removal reactor having at least one inlet and at least one outlet, a fluid delivery system connected to the at least one inlet of the waste stream metal removal reactor and a chelating agent supply source, and a filtering member disposed in communication with the at least one outlet of the waste stream metal removal reactor. In another aspect, a method is provided which includes adding a chelating agent to a process waste stream to form a metal complex, and removing the metal complex from the process waste stream prior to disposal.

Abstract: A process is disclosed for obtaining colloid-forming metal particles from an aqueous mine waste solution containing that metal in ionic form. In accordance with this process, an aqueous mine waste solution containing that metal in ionic form is provided having a pH value of about 4.0 to about 6.5. The solution is electrified with direct current a about 1.2 to about 2.0 volts to reduce the desired metal ions to colloidal metal particles. A slurry of cellulose particles is agitatingly added to the colloid composition followed by a flocculant to form a solid phase cellulosic floc containing the colloid. The solid and liquid phases are separated, and the solid phase is dried, fluxed and heated to a temperature sufficient to melt the flux and colloid and form larger metal particles that can then be recovered. The colloid-forming metal is preferably gold.

Abstract: A water treatment apparatus provides treatment of water to remove, for example, hydrogen sulfide and iron, dissolved or dispersed in ground water. The system is provided with water from a conventional well and pump and includes a venturi-type aerating device which may be supplied air by a compressor. The air and water mixture are supplied to a first aerating tank through a spray nozzle which reduces the aerated water flow to a mist of fine droplets. A draw tube adjacent the bottom of the first tank provides the water to a treatment tank which is partially filled with a chemically active filtration media. The treatment tank is also equipped with a draw tube which draws off the treated water at the bottom of the tank and provides it to a third, deaerating tank wherein the air separates from the water and is purged to the atmosphere. Reduction of hydrogen sulfide content from 30 ppm to less than 5 ppm has been achieved.

Abstract: A bioreactor for reacting an aqueous heavy metal and sulfate containing mine drainage solution with sulfate reducing bacteria to produce heavy metal sulfides and reduce the sulfuric acid content of the solution. The reactor is an elongated, horizontal trough defining an inlet section and a reaction section. An inlet manifold adjacent the inlet section distributes aqueous mine drainage solution into the inlet section for flow through the inlet section and reaction section. A sulfate reducing bacteria and bacteria nutrient composition in the inlet section provides sulfate reducing bacteria that with the sulfuric acid and heavy metals in the solution to form solid metal sulfides. The sulfate reducing bacteria and bacteria nutrient composition is retained in the cells of a honeycomb structure formed of cellular honeycomb panels mounted in the reactor inlet section. The honeycomb panels extend upwardly in the inlet section at an acute angle with respect to the horizontal.

Abstract: An in situ method and system for reductive dechlorination, the precipitation of chromium, the precipitation of heavy metals, and microbial denitrification. The invention comprises the formation of in situ anaerobic reactive zones to precipitate and filter out dissolved heavy metals as metallic sulfides, to degrade nitrate to nitrogen gas, to reduce chlorinated hydrocarbons to ethene, and to precipitate and filter out chromium. The invention is comprised of an injection well or wells that extend into a contaminated groundwater. A conduit located within the injection well conveys carbohydrates and sulfates to the contaminated groundwater. Microbes digest the carbohydrates to produce sulfate reducing and methanogenic conditions within the reactive zone that include a dissolved oxygen level less than about 0.5 mg/l, a redox potential less than about −250 mv, and a dissolved organic carbon to contaminant ratio of greater than about 50:1.

Abstract: A novel process and apparatus are disclosed for cleaning wastewater containing metal ions in solution, hydrogen peroxide, and high solids, e.g., greater than about 50 mg/l particulate solids. A carbon adsorption column removes hydrogen peroxide in the wastewater feed containing high solids. A chemical precipitation unit removes the metal ions from solution. The process and apparatus remove metal ions such as copper from a high solids byproduct polishing slurry from the chemical mechanical polishing (CMP) of integrated circuit microchips to form an environmentally clean wastewater discharge.

Abstract: A process for treating sulphate-containing waste water comprises introducing a feedstock comprising sulphate-containing waste water, into a pond. The sulphate-containing waste water is subjected to biological sulphate reduction in the pond, thereby to convert dissolved sulphate anions to dissolved sulphide anions. Treated waste water, containing the dissolved sulphide anions, is withdrawn from the pond.

Abstract: A coagulant which is the reaction product of a trivalent metal salt (eg., FeCl3), excluding chromium salts, an acid phosphorous compound and an aluminum hydroxy chloride, and a process for preparing such coagulant. This coagulant may be effectively used to remove suspended solids and various impurities in most water treatment applications.

Abstract: A process for treating water having anions comprising sulfur and oxygen dissolved therein involves subjecting the anions to an anaerobic biological reduction to sulfide anions dissolved in the water, followed by a biological oxidation of the sulfide anions to elemental sulfur suspended in the water. The sulfur is separated from the water. The reduction and oxidation are effected together in a series of common reaction stages in which there are oxidizing conditions which permit the biological oxidation without preventing the biological reduction.

Abstract: A method treats process water containing metal ions, in connection with bleaching of lignocellulosic pulp. The method is characterized by the steps of a) adjusting the Mg2+ content of the process water to form a flocculating base for metals and an organic substance; b) supplying a carbonate source to the process water to precipiate calcium as calcium carbonate; c) increasing the pH of the process water by adding white liquor to precipipate metals such as metal hydroxides; d) adding a flocculating agent to the process water; and e) separating the precipitated, flocculated metal compounds from the process water by flotation.

Abstract: A water treatment module and process for treating power plant condensate water utilizing a sulfonated ion exchange resin comprising copolymer beads having an interpenetrating polymer network of at least two polymer components wherein at least one of the polymer components is derived from a monomer mixture having a styrenic content less than about 80 molar percent. In one preferred embodiment the multiple polymer components include: (i) a first polymer component derived from a first monomer mixture comprising a monovinylidene monomer having a styrenic content less than about 50 molar percent and (ii) a second polymer component derived from a second monomer mixture comprising: a second monovinylidene monomer having a styrenic content greater than about 50 molar percent and a crosslinking agent. The ratio of the molar percent crosslinking agent of the first polymer component to the second polymer component is less than about 0.7.

Abstract: Heavy metals including lead, copper, zinc, and cadmium, are effectively extracted from sludge mixtures by treatment of the mixture with carboxyl derivatives of fructans, having a degree of substitution of 0.2-3.0.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: Silver recovery from a silver-bearing spent photographic solution is achieved by reducing the silver ions to silver metal with an organic reducing agent, especially a photographic developer reagent; in particular a spent photographic developer solution provides a convenient source of reducing agent for the silver recovery; in this case the developer reagents which typically are phenol-type compounds are oxidized leading to a less toxic discharge effluent having a lower COD and BOD.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal from waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the like are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal from waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the like are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: A method of removing a dissolved metal constituent from a contaminated liquid is provided. The method comprises the steps of: providing a flow stream containing the contaminated liquid; providing a plurality of shell components formed by comminuting a shell stock including at least one shell having a biomineralized calcium carbonate composition; combining the shell components with the flow stream; and converting at least one shell component to a substantially insoluble biometallic nodule by maintaining contact between the shell components and the dissolved metal constituent over a predetermined time period. The biometallic nodule thus formed contains at least a portion of the metallic constituent in a biogenic metallic carbonate form. After their formation, the biometallic nodules are separated from the treated flow stream.

Abstract: The simultaneous precipitation of soluble heavy metal ions from semiconductor wastewater containing abrasive solids and enhancement of microfilter operation is achieved through the addition of an effective amount of a water-soluble polymer containing dithiocarbamate functionalities to the wastewater.

Abstract: A method and apparatus for removing a group of species of metal ions from an aqueous solution to be purified which involves the steps for each species in succession of adjusting the pH of the aqueous solution to a value where hydroxide precipitates of said species in its highest valency state are insoluble, then passing the aqueous solution through an ion state modification cell to raise the valence of the respective species to its highest valency state thus causing the ion specie to form the insoluble hydroxide, then removing the precipitated hydroxide from the aqueous solution by appropriate steps of settling and press filtering. A magnetic field is imposed between the electrodes which improves the efficiency of the ion state modification step.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal form waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the lie are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: The present invention is directed to a method for removing selenium from a waste stream. The process is a multi-step process that removes selenium from a waste stream in the form of barium selenate and/or barium selenite. In a further step, the barium selenate and/or barium selenite forms a complex precipitate with barium sulfate, which encapsulates the barium selenate and/or barium selenite. The complex precipitate is subsequently removed from the waste stream.

Abstract: A process for the removal of dissolved metals and/or metalloids from an aqueous medium having a high content of salt wherein the aqueous medium in the presence of manganese (II) ions and an oxidation agent is passed through a particulate carrier material having a specified density, initial average grain size and flow rate, so as to fluidize carrier material particles in the aqueous medium, and whereby the coated material particles thereby formed are separated from the aqueous medium.

Abstract: An amorphous potassium aluminosilicate filtration media which may be mixed with activated carbon filters water to remove oxygen, chlorines, hardness, alkalinity, ammonia, hydrogen, hydrogen sulfide, sodium sulfite and other contaminants. The particular sodium aluminosilicate is a porous amorphous material formed under ultraviolet light or sunlight to produce pore sizes of 60 Å to 250 Å at ambient temperatures (20° C.-35° C.) and low relative humidity (5%-20%). The media is initially formed as a microporous primarily amorphous gel containing Na2O, Al2O3, SiO2 and H2O. The sodium therein is displaced by potassium, whereby the filter removes impurities from water without introducing sodium. The potassium aluminosilicate may be a second stage filter to a first stage filter composed of a strong base anion media charged with potassium carbonate and/or bicarbonate.

Abstract: A non-iron sulfide is introduced into an iron-containing zone to form ferrous sulfide. A contaminated aqueous composition is then contacted with the ferrous sulfide to react with said contaminants.

Abstract: The present invention relates to an apparatus for removing volatile impurities such as mercury and selenium from a weak acid solution resulting from scrubbing gases created in the production of sulfuric acid by roasting of sulfide concentrates. The apparatus comprises a calcine filtering unit for removing calcine from the weak acid solution, a sodium sulfide mixing unit for precipitating mercury from the weak acid solution, a sodium dithionite mixing unit for precipitating selenium from the weak acid solution, and a mercury-selenium filtering unit for filtering the precipitated mercury and selenium from the weak acid solution. The present invention further relates to a treatment plant utilizing such an apparatus, a process for removing volatile impurities from a weak acid solution, and a selenium cake obtained by utilizing the resent invention.

Abstract: A process for treating sulphate- and metal-containing waste water, includes subjecting, in a reaction stage, the sulphate- and metal-containing waste water to biological sulphate reduction in which sulphates in the waste water are converted to sulphides, with metals present in the waste water precipitating out and treated waste water being obtained. The precipitated metals are withdrawn from the reaction stage, while treated waste water is withdrawn from the reaction stage. The treated waste water is subjected to polishing and/or to nutrient removal.

Abstract: Wastewater streams containing tacky or sticky components and heavy metals, such as photoresist-containing streams from printed-circuit board manufacture and water streams from paint spraying processes, can be detackified and the metals simultaneously removed by addition of a metal salt, such as an iron salt, and a sulfide material. The combination of metal salts and sulfide reacting products produces a detackified metal sulfide sludge that improves the filterability of the wastewater while also removing dissolved metal ions from the wastewater.

Abstract: The present invention uses fish bones and fish hard parts to remediate, clean-up, stabilize, immobilize, or otherwise treat metal-contaminated water, soil or waste of any sort. The fish bones and fish hard parts can be mixed in with soils and wastes, or emplaced as a permeable reactive barrier in a trench or excavation, or emplaced as a liner or barrier surrounding a waste form, disposal site, or contaminated site. All that is needed is intimate contact between the fish bones and fish hard parts and the contaminated waste form, soil particles, or water. In a system of, for example, soil, waste, groundwater, surface water, waste streams, or the digestive tracts of animals, the presence of fish bones and fish hard parts reduces the amount of metal that can mobilize and migrate out of the system. Fish bones and fish hard parts remove metals from waters passing through the system or originating within the system.

Abstract: A method and apparatus for bioprocessing particles wherein particles are entrapped a porous material and have biologically active microorganisms on their surfaces. A liquid (carrying oxygen and/or nutrients for said microorganisms) is passed through the entrapped particles and microorganisms and microorganisms are active to breakdown said particles. After a suitable period of time the particles are removed from the matrix.

Abstract: A waste water stream containing cyanide bearing compounds and heavy metals such as copper, silver, nickel, iron and the like is directed from a source after pH adjustment to a first tank containing adsorption material in the form of granular activated carbon. The waste water is oxygenated by compressed air. The cyanide bearing compounds and heavy metal are adsorbed onto the surface of the adsorption material which is pretreated to an initial pH in the range between about 8.5 to 11. The effluent from the first tank is pH adjusted by a pH controller which adds a caustic solution to the effluent to maintain a control point pH. The pH adjusted effluent is directed toward a second tank containing pretreated adsorption materials. The water stream free of cyanide and metal contaminants is directed to an effluent tank for safe discharge. Thereafter a stripping solution preferably containing sulfuric acid is circulated through the tank to remove the adsorbed metal for the adsorption material.

Abstract: An aqueous solution, for example, effluent from an off-gas scrubber, is treated to remove metal and metalloid ions by in situ precipitation of ferrous ions by the addition thereto of a ferrous ion-containing solution, salt or other such ferrous ion-containing source and a hydroxyl-yielding base in the presence of the metals and metalloids. The reaction conditions include a temperature of at least about 60° C., and a pH of from about 6 to about 10.

Abstract: The present invention relates to a process for the treatment of arsenic-containing sludge obtained by adjusting arsenic-containing waste water to a PH of 12 or greater by the addition of a calcium compound and subjecting the waste water to solid-liquid separation, the process comprising the steps of adding a calcium compound to the arsenic-containing sludge slurry obtained by the solid-liquid separation, dewatering the resulting sludge, drying the dewatered sludge, and calcining the dried sludge. According to the present invention, arsenic-containing sludge obtained by treating waste water to precipitate arsenic present therein can be calcined to yield a calcined product which involves no risk of arsenic redissolution when it is dumped. Moreover, there is no possibility that arsenic compounds may be volatilized during calcination.