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 process for reducing boron and/or fluoride ion content of water. Feed water is contacted, in the presence of magnesium, with an alkaline hydroxide to produce treated water and a magnesium precipitate containing boron and fluorine. The precipitate is separated from the treated water. The boron content of water is reducible from above about 0.8 mg/L to below about 0.7 mg/L, and the fluoride ion content is reducible from above about 1 mg/L to below about 0.9 mg/L. The magnesium precipitate is optionally used to neutralize pressure oxidized ore slurry or roaster calcine in the context of gold recovery operations.

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: The invention is directed to a method and pressurized apparatus for removing anions and cations of transition and post-transition metals from aqueous solutions comprising a continuous flow electrolytic cell. Also a method for determining the amount of arsenic in each of its states present in a solution and a method of creating iron III hydroxide, aluminum hydroxide, and manganese dioxide for use as filter or adsorption media.

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: 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 method for removing selenocyanate from aqueous waste water containing a reducing agent by adding a water soluble cupric salt, said waste water containing a reducing agent having a potential to reduce the cupric ion to the cuprous ion, and removing the resulting selenocyanate precipitate from said waste water.

Abstract: Systems and methods for removing oxyanionic contaminants, such as arsenate (As(V)) and selenite (Se(IV)), from polluted water. The system utilizes calcium alginate which has been doped with ferric iron. The system is operated as either a batch-type or continuous feed purifier. A dehydrator is included for drying spent absorbent beads to form a dry disposable solid waste product.

Abstract: A chelate-forming fiber which has, in a fiber molecule, a group having an amino group and at least two hydroxyl groups bonded to carbon (preferably a group represented by the formula (1) described below), and has a capability of forming a chelate with metalloid elements including boron and germanium and compounds thereof, and which can be easily incinerated and can be prepared in a simple and safe manner at low cost; and a process for preparing the same; and a method for capturing metalloids or compounds thereof using the chelate-forming fiber are disclosed. (wherein G represents a sugar alcohol residue or a polyhydric alcohol residue, and R represents a hydrogen atom, a (lower) alkyl group, or G (G is as defined above and may be a group identical with or different from the above G).

Abstract: Arsenic filtering media consisting essentially of calcined diatomite particles, and between 5% and 30% by weight of ferric ions bonded to the calcined diatomite particles. One method for producing the filtering media consists of: generating a mixture of calcined diatomite particles and ferric chloride; allowing the mixture to sit for an extended period, thereby allowing ferric chloride to thoroughly impregnate the diatomite particles; and slowly adding sodium hydroxide to the mixture until the pH of the mixture reaches a value of at least 9.0, for ensuring unhasty and full conversion of ferric chloride into ferric hydroxide. The filtering media thus obtained have strong and durable bonds between ferric ions and the diatomite particles. The filtering media are renewable several times with minimum reduction to their arsenic adsorption capacity. A method for renewing the filtering media comprises in-situ desorption of arsenic using sodium hydroxide and rinsing with water.

Abstract: A process for removing or stabilizing arsenic and/or selenium from aqueous streams or slurries is provided that includes contacting the streams or slurry with a composition containing lanthanum chloride. The lanthanum chloride composition can optionally contain various lanthanides. The composition can optionally contain ferric or ferrous sulfate. The process is preferably conducted by adjusting the pH of solution to between about 8 or 10, adding 2 moles of lanthanum chloride for every mole of arsenic or selenium ions present in solution, adding 5 to 6 moles ferric or ferrous ions for every mole of arsenic or selenium ions present in solution and adjusting the oxidation potential of the solution to between 200-400 mV for removal of selenium ions and between 100-200 mV for removal of arsenic ions.

Abstract: The concentration of dissolved arsenic in water is reduced by contacting the water containing the arsenic with zinc oxide.

Abstract: Dissolved selenium is removed from contaminated water by treating the water in a reactor containing selected endemic and other selenium reducing organisms. Microbes may be isolated from the specific water or imported from other selenium contaminated water, The microbes are then screened for ability to reduce selenium under the site specific environmental conditions. The selected microbes are optimized for selenium reduction, then established in a high density biofilm within a reactor. The selenium contaminated water is passed through the reactor with optimized nutrient mix added as needed. The elemental selenium is precipitated and removed from the water.

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: In a method for the remediation of inorganic arsenic species, a solution of inorganic arsenic is passed over zero valent iron under abiotic and anaerobic conditions, thereby removing the inorganic arsenic species and forming arsenic-metal co-precipitates. The metal is preferably in the form of iron filings, and is provided together with sand.

Abstract: A process is disclosed which involves removing hydrocarbons, arsenic and mercury from wastewater produced in oil and gas fields. An oxidant, ferric ions, and flocculent are sequentially added to the wastewater to form a removable sludge containing the arsenic, hydrocarbon, and mercury contaminants. The Oxidation-Reduction Potential of the wastewater is controlled by oxidant addition to allow the required arsenic oxidation to occur while maintaining the mercury in elemental form. The process requires relatively short residence times between chemical additions and provides for large wastewater throughputs. The cleaned wastewater is suitable for discharge to the environment.

Abstract: A method of treatment of an arsenic sludge obtained from a solid-liquid separation step on arsenic waste water by adjusting the value of pH to 12 or higher by adding a calcium compound is disclosed. The method is characterized by addition of hydrated lime and calcining the sludge.

Abstract: Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powdered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials.

Abstract: A method for removing arsenic species from an aqueous medium with modified zeolite minerals comprising providing an aqueous medium containing arsenic species in the form of both arsenate and arsenite, contacting the aqueous medium with an iron (II) laden zeolite mineral so that arsenic in the form of at least one of arsenate and arsenite contained in the aqueous medium can be adsorbed onto the iron (II) laden zeolite mineral forming an arsenic adsorbed iron (II) laden zeolite mineral, and separating the arsenic adsorbed iron (II) laden zeolite mineral from the aqueous medium.

Abstract: The present invention provides an efficient and highly effective method of removing dissolved selenium from a variety of refinery process water and wastewater streams. The present invention also provides a new and effective method of oxidizing selenium and organo-selenium compounds to the selenite [+IV] oxidation state in order to be adsorbed by a metal oxide or metal hydroxide precipitate. The invention includes two continuous stirred-tank reactors (CSTR) operated in series. The stream to be treated and one of several iron salts (ferric sulfate, ferric chloride, etc.) are introduced into the first CSTR, forming ferric hydroxide and ferric oxyhydroxide precipitates. The pH of the first CSTR is automatically controlled by adjusting the injection rate of the ferric salt. The effluent stream from the first CSTR is directed into a second CSTR into which potassium permanganate is introduced.

Abstract: A process for the separation of pentavalent arsenic from an aqueous solution using an N-alkyl pyridinium-containing adsorption medium is disclosed. An oxidizing medium and process for the oxidation of trivalent arsenic to pentavalent arsenic with removal of the pentavalent arsenic so formed is also disclosed.

Abstract: Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powdered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials.

Abstract: A continuous electrochemical processing method and apparatus for electrochemically removing arsenic contaminants from contaminated aqueous solutions comprising: a) identifying the ion(s) to be removed and their oxidation state, b) identifying the pH of the solution, c) constructing an electrolytic cell with a corroding iron anode and an inert cathode surrounding a reaction zone therebetween into which the contaminated solutions are passed, d) applying the required electromotive force to precipitate the desired ionic species, and e) physically removing the precipitates from the aqueous solution.

Abstract: A process for removing contaminating levels of selenium from a contaminated aqueous solution is disclosed. That process includes providing a vessel or flow-permissive container containing a water-insoluble polymeric adsorption medium having a plurality of polymerized C.sub.1 -C.sub.4 N-alkylated pyridinium-containing adsorption sites. An influent of an aqueous solution having a total selenium concentration of about 10 to about 1000 parts per billion is introduced to the vessel or flow-permissive container to contact the insoluble polymeric adsorption medium. The solution is maintained in contact with that insoluble adsorption medium for a time period sufficient for the medium to bind the selenium in the contacting solution. The resulting aqueous solution is discharged from the vessel as an effluent having a total selenium concentration whose ratio to the total selenium concentration of the influent is about zero to about 10.sup.-3.

Abstract: The present invention provides a process for treating arsenic-containing waste water, comprising adding an oxidizing agent, if necessary, to arsenic-containing waste water to oxidize trivalent arsenic in the waste water into pentavalent arsenic; adding a calcium compound to adjust the pH to 12 or higher; separating it into solid and liquid (first solid/liquid separation); calcining the resulting sludge, while adding a ferric salt to the treated solution to adjust the pH to 6-9 after the solid/liquid separation; and separating it into solid and liquid (second solid/liquid separation). According to the present invention, it is possible to remove arsenic from waste water efficiently to yield treated water satisfying various tolerance limits under various regulations, while the arsenic-containing sludge separated from the waste water can become harmless in subsequent continuous steps.

Abstract: Hydrocarbon-soluble aminomethylenephosphonic acid derivatives comprising the structural element of the formula I ##STR1## where R.sup.1 and R.sup.2 are hydrogen, C.sub.1 -C.sub.30 -alkyl which can additionally bear up to 15 hydroxyl groups and/or be interrupted by up to 14 non-adjacent oxygen atoms, C.sub.2 -C.sub.30 -alkenyl, C.sub.7 -C.sub.18 -aralkyl or C.sub.6 -C.sub.14 -aryl which may be substituted by up to three C.sub.1 -C.sub.12 -alkyl groups, C.sub.1 -C.sub.12 -alkoxy groups, halogen atoms, cyano groups, hydroxyl groups or C.sub.1 -C.sub.4 -alkoxycarbonyl groups, for the solvent extraction of iron ions from aqueous solutions.

Abstract: Selenate ion is removed from a selenate ion-containing aqueous waste liquid by treating the aqueous liquid with an organic reducing agent in the presence of a photocatalyst while irradiating the aqueous waste liquid with an actinic radiation to convert the selenate ion into elemental selenium which is in the form of solid precipitates and/or hydrogen selenide which is in the form of a gas.

Abstract: Methods and systems for alleviating the environmental and health hazards associated with environmental contamination by metals are provided. Contained living or non-viable biomasses of metal-accumulating plant seedlings deplete the metal elements and compounds in metal-containing aqueous solutions. Concomitantly, the contained biomasses of plant seedlings accumulate the metal elements and compounds. The energy and nutrient stores of the seeds from which the seedlings develop are exploited to minimize the costs of remediating the metal-containing aqueous solutions.

Abstract: Mine waste water is treated to remove both dissolved and particulate metal values by an improved process, the process comprising:A. Mixing with the mine waste water a sufficient amount of anionic polymer to combine with the dissolved and particulate metal values to form a polymer/metal particle complex,B. Mixing the polymer/metal particle complex of Step A with a source of ferric ions, e.g. ferric chloride, to form a ferric/polymer/metal particle complex,C. Mixing the ferric/polymer/metal particle complex of Step B with a source of hydroxyl ions, e.g. a solution of calcium oxide, to form a hydroxylated ferric/polymer/metal particle complex,D. Mixing sufficient flocculent, e.g. a polyacrylamide, with the complex of Step C to precipitate the complex, andE. Separating the slurry of Step D into a clean water effluent and a high density (e.g. >50% solids), low toxic sludge.

Abstract: Disclosed is a process for disinfecting water which provides a visual indication after the disinfection is complete. First, the water to be disinfected is generally simultaneously intermixed with at least three items. The items are: (1) a disinfectant which is adapted to render harmless substantially all pathogens present in the water upon the disinfectant being intermixed with the water for a time period T.sub.k ; (2) a colorant; and (3) a material which can remove substantially all of the disinfectant and colorant from the water over a time period T.sub.r, where T.sub.r is greater than T.sub.k. Secondly, the water, disinfectant, colorant and the removing material are allowed to remain intermixed for a time period of T.sub.r or greater. At the end of the time period T.sub.r, substantially all pathogens in the water will be rendered harmless, substantially all of the disinfectant will be removed from the water and substantially all of the colorant will be removed from the water.

Abstract: The present invention is a method to remove metals from solutions by precipitating the metals and adding cellulosic fiber to the solution. The precipitates attach to the cellulosic fibers to form products. The products may be removed from the solution by gravity separation techniques or by filtration. The removed products may be dewatered and incinerated. The method provides a simple and effective technique for removing low concentrations of metals from high volume solution streams.

Abstract: The present invention in one embodiment, is a process that uses a chemical treatment to remove heavy metals from wastewater; heavy metals from wastewater containing oxygenated hydrocarbons; and arsenic, organic acids, and heavy metals from antifreeze solutions. In one aspect such a method includes adding an iron salt, to an antifreeze solution containing arsenic and heavy metals with adequate mixing for dispersion throughout the solution. Then, a base is added to increase the pH to a level from about 8 to 10. As the base is added, a precipitate with contaminates forms and is then removed by standard filtration techniques. The arsenic, organic acids, and heavy metals co-precipitate with the iron and are removed by filtration. The process may either be a batch process or a continuous process. In one aspect the wastewater is generated by a process according to the present invention for purifying contaminated soil or sediment.

Abstract: The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous.

Abstract: A method for purifying aqueous solutions having varying concentrations of contaminants and/or various contaminants including ions of several metals and elements by conducting precipitation in a first precipitation stage by adding lime in a surplus quantity whereby a pH of about 12 is established and maintained in the solution and a major part of the contaminant content is precipitated so as to form a solution having a substantially constant composition and to form a precipitate that is isolated and removed together with residual lime. Precipitation is then conducted in a second precipitation stage by adding a reagent for precipitation at a pH in the range of 4-11 wherein residual contaminant in the formed solution from the first precipitation stage is precipitated the precipitate is isolated and returned to the first precipitation stage.

Abstract: A filter basket and filtration media for an inverted bottle type water dispenser which is disposed below the inverted bottle, depending from the collar of the water reservoir into the water reservoir and receiving the neck of the bottle, so that all the water discharged from the bottle passes through the filter basket in a downward direction. The filter basket has an inverted conical upper section which funnels all the water which is drained from the bottle to a filtration compartment at its lower section. The filtration compartment remains submerged in water. The filtration compartment contains the filtration media and discharges the filtered water therefrom directly into the water reservoir. Air released in the spigot when it is opened rises upwardly through the filtration media to be received in the bottle. The filtration media comprises an aluminosilicate gel with pore sizes in the range of sixty to two hundred and fifty Angstroms which provides for rapid flow of water and air therethrough.

Abstract: A process for removing selenium and/or arsenic from aqueous streams including industrial process waters and drinking water is provided comprising contacting the stream with a composition comprising lanthanum oxide whereby selenium and/or arsenic are adsorbed. Preferred compositions comprise lanthanum oxide and alumina.

Abstract: A water or wastewater purification process is described for reducing selenium and arsenic concentrations in contaminated water or wastewater streams. Iron loaded cation exchange resins, when contacted with contaminated water or wastewater streams are effective to form immobilized complexes with selenite and arsenate contaminants. The iron loaded resins can be easily regenerated by sequential treatment with acid and a solution of a soluble iron salt.

Abstract: A process for the precipitation and separation of inorganic species form aqueous solutions. The method comprises the step of adding a miscible organic solvent to inorganic-aqueous solution so that a solid precipitate from the aqueous solution is formed. The resultant solid precipitate is separated from the organic-water mixture. After separating the solid precipitate, the miscible organic solvent is removed and recovered from the organic-water mixture by applying vacuum or other means of recovery. The separated miscible organic solvent can then be condensed and returned to the process. The water is stripped of traces of miscible organic solvent and removed from the system as product water.

Abstract: Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powdered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials.

Abstract: The removal of arsenic, from aqueous liquids by adsorption on alumina, is facilitated by selecting the alumina adsorbent to have a particle size below about 200 micrometers, forming a slurry of the alumina and aqueous liquid and agitating the slurry. It has been found that alumina can be selected to have a particle size sufficiently small, or preferably a combination of both particle size sufficiently small and pore size and number sufficiently large, to achieve 50 ppb or less arsenic within about 2 hours treatment. The alumina with adsorbed arsenic is separated from the slurry by steps preferably comprising microfiltration. A precipitation pretreatment can be combined with the slurry treatment e.g. to handle more concentrated solutions.

Abstract: A process for treatment of hazardous liquid waste comprising trace amounts of hazardous elements in solution as oxyanions by oxyanion fixation within ettringite and related minerals. In accordance with the disclosed process, reagents for forming ettringites are mixed with the waste stream resulting in the formation of oxyanion-substituted ettringite and related materials. The resulting ettringite and related minerals are separated by filtration from the liquid. Thereafter, the liquid, having an elevated pH, is neutralized by carbon dioxide sparging resulting in precipitation of excess reagents in the liquid. Thereafter, the precipitates are filtered, producing a clean liquid.

Abstract: Heavy metal ions react with iron particles in acidic aqueous solution to form heavy metallic particles that are suitable for recycling and reuse when recovered from the aqueous solution. Chelating agents that are present are deactivated by bonding to ferrous ions produced from the iron particles. An alkali metal hydroxide is utilized to precipitate remaining heavy metal ions including ferrous and ferric ions which are recycled to the acidic aqueous solution.

Abstract: The present invention is a method to remove metals from solutions by precipitating the metals and adding cellulosic fiber to the solution. The precipitates attach to the cellulosic fibers to form products. The products may be removed from the solution by gravity separation techniques or by filtration. The removed products may be dewatered and incinerated. The method provides a simple and effective technique for removing low concentrations of metals from high volume solution streams.

Abstract: A contaminant precipitating composition and method are disclosed. The composition comprises a water soluble branched polymeric composition effective for the purpose of precipitating contaminants from an aqueous solution. The method comprises adding an amount of the composition, effective for the purpose, to the aqueous solution so as to complex, precipitate and remove contaminants from the aqueous solution.

Abstract: Selenium compounds present in aqueous liquids can be removed using a poly dithiocarbamate materials. The selenium compounds are then removed by precipitation or sedimentation. Optionally, an oxidizing agent may be added to the system prior to the addition of the poly dithiocarbamate. Various filtration methods may be employed to remove the selenium-dithiocarbamate materials from aqueous liquids.

Abstract: A contaminant precipitating composition and method are disclosed. The composition comprises a water soluble, branched, polydithiocarbamic acid salt effective for the purpose of precipitating contaminants from an aqueous solution. The method comprises adding an amount of the composition effective for the purpose to the aqueous solution so as to complex, precipitate and remove contaminants from the aqueous solution.

Abstract: Novel methods for purifying contaminated subsurface groundwater are disclosed. The method is involves contacting the contaminated subsurface groundwater with methanotrophic or heterotrophic microorganisms which produce contaminant-degrading enzymes. The microorganisms are derived from surface cultures and are injected into the ground so as to act as a biofilter. The contaminants which may be treated include organic or metallic materials and radionuclides.

Abstract: The present invention in one embodiment, is a process that uses a chemical treatment to remove arsenic, organic acids, and heavy metals from antifreeze solutions. In one aspect such a method includes adding an iron salt, to an antifreeze solution containing arsenic and heavy metals with adequate mixing for dispersion throughout the solution. Then, a base is added to increase the pH to a level from about 8 to 10. As the base is added, a precipitate forms and is then removed by standard filtration techniques. The arsenic, organic acids, and heavy metals co-precipitate with the iron and are removed by filtration. The process may either be a batch process or a continuous process.

Abstract: A system for removing hazardous contaminants such as radon gas and volatile synthetic organic chemicals from domestic water supplies includes a perforated, horizontally-oriented tray which is baffled to define a curved (e.g., serpentine, spiral) liquid flow path. Contaminated water is distributed upon a portion of the tray and flows as directed by the baffles to a downcomer and into a storage tank. Air is blown into the storage tank, which is located below the perforated tray, and up through the perforations. The forced air causes the water flowing across the tray to froth, and evaporates the contaminants out of the frothing water. The forced air, carrying the volatilized contaminants, is then vented outside the home.