EP1117619A1 - Procede de destruction de contaminants dans des courants aqueux renfermant des contaminants et catalyseurs utilises a cet effet - Google Patents

Procede de destruction de contaminants dans des courants aqueux renfermant des contaminants et catalyseurs utilises a cet effet

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Publication number
EP1117619A1
EP1117619A1 EP99940830A EP99940830A EP1117619A1 EP 1117619 A1 EP1117619 A1 EP 1117619A1 EP 99940830 A EP99940830 A EP 99940830A EP 99940830 A EP99940830 A EP 99940830A EP 1117619 A1 EP1117619 A1 EP 1117619A1
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EP
European Patent Office
Prior art keywords
contaminant
containing aqueous
reducing agent
oxidation
perchlorate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99940830A
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German (de)
English (en)
Other versions
EP1117619A4 (fr
Inventor
James R. Akse
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Umpqua Research Co
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Umpqua Research Co
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Publication date
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Publication of EP1117619A1 publication Critical patent/EP1117619A1/fr
Publication of EP1117619A4 publication Critical patent/EP1117619A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/02—Temperature
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/03—Pressure
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/15—N03-N
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/40—Liquid flow rate

Definitions

  • nitrate/nitrite and perchlorate levels in drinking water have been linked to serious health problems and sometimes death.
  • the concern over nitrate/nitrite has been driven by increasing levels of these contaminants being detected in drinking water supplies originating from both inorganic and biological sources.
  • Inorganic sources include intense agricultural practices which contribute both ammonium and potassium nitrate fertilizers, explosives and blasting agents, heat transfer salts, glass and ceramics manufacture, matches, and fireworks.
  • Biologically derived organonitrogen compounds are converted to nitrate in natural waters relatively rapidly.
  • Ammonium perchlorate has been widely used by the aerospace, munitions, and fireworks industries, resulting in widespread soil and water contamination.
  • the end of the Cold War has left the Department of Defense (DOD) with approximately 140 million pounds of ammonium perchlorate to be disposed of between 1993 and 2005.
  • DOD Department of Defense
  • Perchlorate contamination in drinking water wells was first detected in early 1997 in northern California. These findings prompted further investigation, and perchlorate was detected in southern California wells, the Colorado River, Las Vegas wells, and Lake Mead.
  • Perchlorate contamination has been detected in eastern Sacramento County at Aerojet General Corporation's facility, a site previously owned by McDonnnell- Douglas, and a site previously owned by Purity Oil Company. Due to the presence of volatile organic chemicals (VOCs), contaminated groundwater at the Aerojet General site was treated and then reinjected into aquifers in the area. Monitoring of the reinjected water indicated that it contained up to 8000 ⁇ g/L of perchlorate. In February 1997, perchlorate was detected in drinking water wells in the Collinso Cordova area at levels as high as 280 ⁇ g/L. In July of 1997, DHS tested 62 wells in northern California, and detected perchlorate in 13. Of the 13, eight exceeded the 18 ⁇ g/L action level. Also, groundwater monitoring wells associated with the United Technologies Corporation in Santa Clara County yielded perchlorate concentrations as high as 180,000 ⁇ g/L, although no contamination of the drinking water systems was evident.
  • VOCs volatile organic chemicals
  • perchlorate contamination has been detected in wells at Loma Linda and Redlands (5-216 ⁇ g/L) associated with past operations of the Lockheed Propulsion Company. Perchlorate was also detected at low levels in wells at Riverside, Chino, Colton, Cucamonga, and Rialto. In Los Angeles County, perchlorate has been detected in concentrations ranging from 4 to 159 ⁇ g/L in the areas of Azusa, Baldwin Park, Irwindale, La Canada, Flintridge, La Puente, Newhall, Pasadena, Santa Clarita, and West Covina.
  • the perchlorate contamination was thought to originate from Aerojet (Azusa), the Azusa landfill, the Whittaker-Bermite site (Santa Clarita), and two Superfund sites, the Jet Propulsion Laboratory (Pasadena) and the Baldwin Park Operable Unit.
  • perchlorate has been found at levels of 5 to 9 ⁇ g/L in the Colorado River. These findings prompted testing in Nevada. In August, Nevada sites were found to contain perchlorate levels of up to 13 ⁇ g/L in drinking water wells, 1700 ⁇ g/L in the Las Vegas Wash, and 165 ⁇ g/L in Lake Mead. Monitoring wells in areas of ammonium perchlorate manufacturing were then found to have levels of 630,000 to 3,700,000 ⁇ g/L. In Utah perchlorate was found at levels of 200 ⁇ g/L at a rocket motor manufacturing facility.
  • Potassium perchlorate's health effects were originally discovered due to its use in the 1950's to treat Graves' disease, an autoimmune disorder in which patients develop antibodies to the thyroid stimulating hormone (TSH) receptors in the thyroid resulting in hyperthyroidism.
  • TSH thyroid stimulating hormone
  • Perchlorate was found to displace iodine in the thyroid, causing a decrease in production of triiodothyronine (T3) and tetraiodothyronine (T4), two regulating hormones which control TSH production. This effect has been shown to be reversible, with the perchlorate eventually being expelled from the thyroid.
  • TSH thyroid stimulating hormone
  • the observable effects of perchlorate include blocking of iodine uptake and discharge by the thyroid, ⁇ gastrointestinal irritation and skin rash,6>7 and hematological effects including agranulocytosis and lymphadenopathy. '8 Seven cases of fatal aplastic anemia were reported at the same dose level, 6-14 mg/kg/day, at which other side effects occurred.9-14 Following these early studies, the effects of perchlorate exposure on healthy volunteers were studied by Burgi et al.l" in five subjects for eight days at 9.7 mg/kg/day dosage levels. Brabant et al studied five subjects dosed with 12 mg/kg/day of perchlorate for four weeks. Both of these studies observed effects on the thyroid at these levels.
  • the initial effort to establish a RfD for perchlorate was undertaken by the Perchlorate Study Group (PSG), a consortium of companies that use and/or manufacture perchlorates.
  • PSG Perchlorate Study Group
  • NCEAO National Center for Environmental Assessment Office
  • the critical health effect cited in the PSG report was the interference with the thyroid functioning including the release of iodine from the thyroid, inhibition of iodine uptake by the thyroid, increased thyroid weight and volume, increased TSH levels, and decreased T3 and T4 thyroid regulating hormone levels.
  • the PSG's approach to a perchlorate RfD was to select a dose level that represented the highest level tested at which no adverse effects were observed.
  • the critical study used by the PSG in their assessment was by Brabant.1
  • the PSG report recommended a RfD of 12 mg/kg/day.
  • the NCEAO derived the provisional RfD of 1 x 10"4 mg/kg/day later used by the DHS in their recommendations.
  • This RfD was based upon the NOAEL for potassium perchlorate in the functioning of the thyroid combined with uncertainty factors designed to account for sensitive populations, the less than chronic nature of the studies, and database deficiencies.
  • 5 j ⁇ g critical study used in this assessment was that of Stansbury and Wyngaarden which was the only study to report a NOAEL for humans.
  • the NOAEL dosage was established at 0.14 mg/kg/day based on the release of iodine from the thyroid.
  • the U.S. EPA used uncertainty factors (UF) to evaluate the NOAEL.
  • Nitrate and nitrite levels in drinking water have also received intense regulatory scrutiny in the past due to their potential to cause serious health problems especially in infants and the elderly.
  • High nitrate/nitrite levels in drinking water have been linked to serious illness and sometimes death.
  • infants the conversion of nitrate to nitrite by the body can interfere with the ability of blood to carry oxygen.
  • an acute condition can occur leading to shortness of breath and blueness of the skin (i.e., "blue baby syndrome" or methemoglobinemia). In its acute form, this may lead to rapid health deterioration over a period of days.
  • MCL Maximum Contaminant Limit
  • HAL Health Advisory Limit
  • nitrate/nitrite Part of the concern over nitrate/nitrite has arisen from the increasing levels of these contaminants detected in drinking water supplies. Since most nitrogenous chemicals in natural waters are converted to nitrate, all sources of combined nitrogen especially organic nitrogen and ammonia should be considered as nitrate sources. Due to its high solubility and weak retention by soils, nitrates are very mobile and move into groundwater reservoirs (i.e., aquifers) at a rate comparable to that of surface water. Biological degradation of nitrate by anaerobic denitrification reactions to form elemental nitrogen and ammonia is slow so that nitrate persists in the environment. In particular, organic nitrates originating from human sewage and livestock manure are potential sources for this type of ground water contamination.
  • feedlots represent a large point source of this type of organic nitrogen pollution.
  • Intense agricultural practices also contribute through the use of ammonium and potassium nitrate as fertilizers.
  • Other inorganic sources of nitrate contamination include explosives and blasting agents, heat transfer salts, glass and ceramics manufacture, matches, and fireworks.
  • the quantity of nitrate/nitrite released into the environment between 1987 and 1993 in the top fifteen states totaled 2.68 x 10? kg for water releases and 2.42 x 10? kg for land releases. Of these, nitrogeneous fertilizer contributed ⁇ 44 % of the total while industrial sources accounted for ⁇ 30 %.
  • the contaminant-containing aqueous feed stream preferably comprises a contaminant-containing aqueous feed stream or aqueous brine feed stream.
  • the process of the present invention comprises providing the contaminant- containing aqueous feed stream including an initial amount of at least one of a group of contaminants including perchlorates, nitrates, and nitrites.
  • a preferred process of this invention for the destruction of perchlorate contaminants an oxidation-reduction process is employed in which it is believed that the oxidation state of chlorine in the perchlorate (+7) contaminant is lowered, forming predominantly chloride (-1).
  • a preferred process for the destruction of nitrate and nitrite contaminants it is believed that the oxidation state of nitrogen in the nitrate (+5) and nitrite (+3) contaminants is lowered, forming elemental nitrogen
  • a reducing agent is provided in the contaminant-containing aqueous feed stream.
  • the reducing agent can be present therein in sufficient amount to facilitate the catalytic oxidation-reduction of the present invention.
  • the subject process typically includes adding a non-toxic reducing agent to the contaminant-containing aqueous feed stream.
  • the preferred reducing agents are organic reducing agents, more preferably low molecular weight polar organic species which are highly soluble and have a terminal carbon - oxygen bond.
  • the reducing agent can comprises any one of a carbohydrate, an alcohol or an organic acid, more preferably ethanol or acetic acid.
  • inorganic reductants including dissolved hydrogen and ammoniacal nitrogen species (i.e., NH3 and NH4 ).
  • inorganic species such as hydrogen peroxide, urea, chloramines, or hydrazine hydrachloride which form oxidized by-products that are soluble may also be utilized as reducing agents.
  • organic reducing agents When organic reducing agents are utilized, carbon dioxide and water are the predominant by-products from oxidation of the reductant. If inorganic reducing agents are utilized, then the chief by-products formed depend on the reducing conditions and the specific reducing agent. For example, the oxidation of hydrogen forms hydronium ions, while the oxidation of ammonia forms water, hydronium ions , and nitrogen.
  • the temperature to which the reducing agent-containing, contaminant-containing aqueous stream is typically raised is to a temperature of not more than about 250 degrees C, preferably to a temperature of not more than about 200 degrees C, more preferably to a temperature of not more than about 150 degrees C, and most preferably to a temperature of not more than about 50 degrees C.
  • the heated contaminant-containing aqueous stream is then contacted with an oxidation-reduction catalyst for a period of time sufficient for reducing the initial amount of any of the perchlorates, nitrates, and nitrites contaminants.
  • the step of contacting the reducing agent-containing, contaminant- containing aqueous stream with the oxidation-reduction catalyst is typically conducted for a period of time of not more than about 500 seconds, preferably not more than about 300 seconds, more preferably not more than about 150 seconds, and most preferably not more than about 50 seconds.
  • the oxidation-reduction catalyst is preferably a metallic oxidation- reduction heterogeneous catalyst.
  • Oxidation-reduction catalysts can comprise chemically robust, high surface area supports impregnated with a metal, metal oxide, or with mixtures of metal salts which are subsequently reduced to metallic form.
  • the supports are stable in aqueous solutions at the above-described reduction temperatures.
  • the preferred supports are zirconium dioxide extrudates.
  • the heated contaminant-containing aqueous stream can be subject to pressure, as well as temperature, when it is contacted with an oxidation-reduction catalyst.
  • the preferred pressures employed during the oxidation-reduction sequence is typically up to about 40 atmospheres, preferably up to about 10 atmospheres, more preferably up to about 3 atmospheres, and most preferably up to about 1 atmospheres.
  • the supports generally have a surface area of at least 20 m ⁇ /g, preferably at least 25 m ⁇ /g, more preferably at least 30 m ⁇ /g, and most preferably at least 35 m ⁇ /g.
  • the particle size of the support material is preferably up to about 2 mm, more preferably up to about 3 mm, and most preferably up to about 4 mm.
  • These oxidation-reduction catalysts of the present invention exhibit high activity towards the oxidation of dissolved organic species and towards the reduction of molecular oxygen and other suitable oxidants such as perchlorate, nitrate, and nitrite materials.
  • the preferred metallic materials employed in the oxidation-reduction catalyst of this invention are platinum, palladium, and ruthenium.
  • the subject oxidation-reduction catalysts suitable for the process of this invention are high activity catalysts provided that the support material remains stable at the reaction conditions.
  • Typical oxidation-reduction catalyst of this invention can comprise platinum and/or palladium and/or ruthenium catalytic metals supported on other materials.
  • Such support materials can include titanium dioxide, cerium oxide, aluminum oxide, silicon dioxide, silicon carbide, and activated carbon.
  • the platinum loading on typical supports employed in the process of this invention may be as high as 20 % by weight, based on the weight of the support material, although a cost-benefit analysis generally can reduce this value by a factor often for commercial application.
  • the ruthenium loading on these supports is preferably up to about 5.0 % by weight.
  • Oxidation-reduction catalysts suitable for this process can also include other metals, metal oxides, or mixed metal oxides supported on a variety of materials.
  • Typical metals in this group include copper, iron, cobalt, and nickel.
  • Typical metal oxides include copper oxide with manganese oxide, chromium oxide with iron oxide, and chromium oxide with cobalt oxide.
  • Metal and metal oxide loadings are up to about 4.0 % by weight , based on the weight, based on the weight of the support material.
  • a preferred oxidation-reduction catalyst for the destruction of perchlorate, nitrate, and nitrite using organic reductants comprises platinum and ruthenium on zirconium dioxide.
  • the optimal platinum loading based on performance-cost evaluation is between about 0.5 and 2.5% by weight.
  • the optimal ruthenium loading based on performance-cost evaluation is between about 0.1 and 0.5 % by weight, based on the weight of the support.
  • a preferred oxidation-reduction catalyst for the reduction of perchlorate, nitrate, and nitrite using dissolved hydrogen as the reductant comprises platinum, palladium, and ruthenium on zirconium dioxide.
  • palladium containing catalysts exhibit higher reaction rates than non- palladium containing catalysts due to the high hydrogen solubility in palladium, combined with the consequent availability of hydrogen at the palladium surface.
  • the optimal loading based on performance - cost evaluation for platinum is between 0.5 and 2.5% by weight, for palladium is between 0.5 and 2.0% by weight, and for ruthenium is between 0.1 and 0.5 % by weight of the support.
  • the preferred catalytic reactor comprises a plug flow reactor containing the catalyst bed.
  • Reducing agents are added at the inlet at ambient temperature and pressure.
  • the aqueous stream is then pressurized, heated, pumped through the reactor, and cooled at the outlet.
  • Reactor temperature control and overall energy efficiency is improved by coupling inlet and outlet flows through a regenerative heat exchanger.
  • perchlorate, nitrate, and nitrite will be reduced in the presence of a stoichiometric excess of the reducing agent at a kinetically determined residence time within the catalyst bed.
  • hydrogen is the reducing agent of choice
  • a stoichiometric excess of gaseous hydrogen is injected into the pressurized stream at a concentration sufficient to reduce the contaminant species at the contact time provided.
  • a preferred oxidation-reduction catalyst for the reduction of perchlorate, nitrate, and nitrite using ammonium cations as the reductant comprises platinum and ruthenium on zirconium dioxide.
  • the optimal loading based on performance - cost evaluation for platinum is between 0.5 and 2.5% by weight, and for ruthenium is between 0.1 and 0.5 % by weight of the support.
  • An aqueous phase catalytic reduction (APCAR) process will catalytically reduce perchlorate, nitrate, and nitrite using a variety of organic and inorganic reductants at low temperatures between 25 and 125°C in water.
  • An APCAR process will catalytically reduce perchlorate, nitrate, and nitrite using a variety of organic and inorganic reductants at temperatures above 150°C in brines which contain between 1 and 12% by weight sodium chloride.
  • the initial amount of any of said perchlorates, nitrates, and nitrites contaminants is substantially reduced. More specifically, the extent of the above-described substantial reduction is preferably by at least about 90%, more preferably by at least about 92%, and most preferably by at least about 95%.
  • Figure 1 is a schematic view of a system 10 of the present invention for destroying contaminants in a contaminant-containing aqueous stream using an organic reducing agent.
  • Figure 2 is a graphical representation of the reduction of 50 mg/L NaClO 4 , using the system described in Figure 1 and PRZr51 oxidation-reduction catalyst, at 60 degrees C. using 50 mM ethanol as the reducing agent.
  • Figure 3 is a graphical representation of the reduction of 50 mg/L NaClO 4 , using the system described in Figure 1 and PRZr51 oxidation-reduction catalyst, at 70 degrees C. using 50 mM ethanol as the reducing agent.
  • Figure 4 is a graphical representation of the reduction of 50 mg/L NaClO 4 , using the system described in Figure 1 and PRZr51 oxidation-reduction catalyst, at 80 degrees C. using 50 mM ethanol as the reducing agent.
  • Figure 5 is a graphical representation of an Arrhenius plot of the reduction of NaClO 4 , using results of Figures 2-4.
  • Figure 6 is a graphical representation of the reduction of 20 mg/L NaNO 3 , using the system described in Figure 1 and PRZr51 oxidation-reduction catalyst, at 80 degrees C. using 20 mg/L ethanol as the reducing agent.
  • Figure 7 is a graphical representation of the reduction of 30.6 mg/L NaNO 3 , using the system described in Figure 1 and PRZr51 oxidation-reduction catalyst, at 100 degrees C. using 20 mg/L ethanol as the reducing agent.
  • Figure 8 is a graphical representation of the reduction of 50 mg/L NaClO 4 , using the system described in Figure 1 and PRZr51 plus 2% palladium oxidation- reduction catalyst, at 80 degrees C. using hydrogen as the reducing agent. Hydrogen Reduction of 50 mg/L NaClO 4 at 80°C over the PRZr51 + 2%Pd Catalyst.
  • Figure 9 is a graphical representation of the reduction of NaClO 4 , using the system described in Figure 1 and PRZr51 plus 2% palladium oxidation-reduction catalyst, at 90 degrees C using hydrogen as the reducing agent.
  • Figure 10 is a graphical representation of the reduction of NaClO 4 , using the system described in Figure 1 and PRZr51 plus 2% palladium oxidation- reduction catalyst, at 100 degrees C. using hydrogen as the reducing agent.
  • Figure 11 is a graphical representation of an Arrhenius plot of the reduction of NaClO 4 , using the system described in Figures 8-10.
  • Figure 12 is a graphical representation of the reduction of 50 mg/L NaClO 4 , using the system described in Figure 14 below, catalyzed by a PRZr51 oxidation-reduction catalyst, at 120 degrees C, using ammonium ions in the form of NH 4 C1 as the reducing agent.
  • Figure 13 is a graphical representation of the reduction of NaClO 4 , using the system described in Figure 14 below, at 130 degrees C, using ammonium ions in the form of NH 4 C1 as the reducing agent.
  • Figure 14 is a schematic view of a system 40 of the present invention for destroying contaminants in a contaminant-containing aqueous stream using a non-organic reducing agent.
  • the process of the present invention utilizes a highly active oxidation- reduction catalyst to destroy particularly perchlorates and nitrates/nitrites contaminating aqueous streams.
  • APCAR aqueous phase catalytic reduction
  • FIG. 1 A schematic representation of a preferred APCAR system 10 is shown in Figure 1.
  • the system is configured as a plug flow reactor 20 containing an oxidation-reduction catalyst designed to promote perchlorate and/or nitrate/nitrite reduction, forms innocuous inorganic by-products.
  • the choice of reductants and the APCAR process configuration will depend on the perchlorate or nitrate/nitrite concentration. For example, at low perchlorate concentrations the intrinsic organic carbon levels in drinking water will suffice for destruction and only a single reactor pump 24 is needed.
  • non-toxic organic reductants such as carbohydrates, alcohols, or organic acids are metered from the reduction reservoir 28 by the metering pump 26 into the inlet stream 30 prior to the reactor pump 24.
  • Inorganic reductants may also be used including hydrogen gas.
  • ammoniacal nitrogen species i.e., NH 3 and NH 4 +
  • Metering pumps are used to introduce water soluble reductants, while a pressurized tank coupled to a mass flow controller is utilized to introduce gaseous reductants.
  • heat is transferred from the reactor's treated water to the influent water by passage through a regenerative heat exchanger 22.
  • the APCAR reactor temperature is controlled through a combination of heat exchanger 22, preheater 25, and resistive heating within the reactor 20.
  • the temperature from the preheater 25 is read by the inlet thermocouple 21, and the temperature at the outlet of the reactor 20 is read by the outlet thermocouple 23.
  • the water perchlorate and nitrate/nitrite levels are typically reduced below 5 ⁇ g/L and 10 mg/L, respectively.
  • the amount of reductant as quantified by the Total Organic Carbon (TOC) level which decreases as the reducing agent is oxidized.
  • the effluent water temperature is then reduced to ambient conditions following flow through the regenerative heat exchanger.
  • a catalytic reduction test system 10 similar to that shown in Figure 1, was constructed.
  • a 19.63 cn_3 plug flow reactor was filled with PRZr51 catalyst (i.e., 2% platinum and 0.5% ruthenium on zirconium oxide extrudates between 1 mm and 3 mm in diameter) and challenged with 50 ppm (mg/L) of NaCl ⁇ 4- As a reductant, the NaCl ⁇ 4 solution contained 50 mM of ethanol.
  • PRZr51 catalyst i.e., 2% platinum and 0.5% ruthenium on zirconium oxide extrudates between 1 mm and 3 mm in diameter
  • 50 ppm (mg/L) of NaCl ⁇ 4- As a reductant the NaCl ⁇ 4 solution contained 50 mM of ethanol.
  • the effluent NaClO4 concentration was monitored using a perchlorate ion selective electrode (i.e. nitrate ion selective electrode) which has previously been shown to respond to CIO4 " more strongly than to NO3 * 22 Using this electrode, CIO4 " concentrations between 0.2 and 20 ppm were accurately determined. Reaction kinetics for the reduction of NaCl ⁇ 4 were studied as a function of flow rate and temperature. At each temperature, the effluent NaCl ⁇ 4 concentration (C) was determined for different flow rates (Q). The residence time within the reactor (reactor space-time, ⁇ ) was determined according to the following (1),
  • Equation 2 was derived from the resulting (C, ⁇ ) ordered pairs using the Levenberg-Marquardt method.23. Correlation coefficients (r ⁇ ) for the derived rate constants were calculated using a linear regression of experimentally observed concentrations versus those calculated from Equation 2. At least four data points were gathered for each temperature of operation.
  • Rate constants which are shown as functions of temperature were then fitted to the Arrhenius expression as (1/T, In k) ordered pairs using a least squares approximation to a linear equation, are given by the (3),
  • T is the temperature in degrees Kelvin
  • E a is the Arrhenius activation energy
  • R is the gas constant
  • A is the pre-exponential factor determined from the slope and intercept, respectively.
  • the Arrhenius activation energy was determined to be 49.12 kJ/mole (11.74 kcal/mole) with a pre-exponential factor of 5.74 x 10 ⁇ sec - 1 . Based on these data, the extent of perchlorate reduction can be controlled by a combination of temperature and reactor residence time. Using a properly designed APCAR process, the elimination of perchlorates from ground and surface waters or a variety of waste waters is achievable by adjustment of temperature and catalyst contact time.
  • a 200 ⁇ g/L perchlorate level in water can be lowered to below the provisional RfD (i.e., 6 ⁇ g/L) at 60°C after contact with the catalyst for 3 minutes.
  • the reaction temperature and catalyst contact time can be adjusted to destroy perchlorate, reducing the concentration to acceptable values. At very low perchlorate levels significant destruction can be achieved at very low temperature.
  • the reduction of nitrate was evaluated in the same reactor system using ethanol as the reductant.
  • This system was challenged with 20 mg/L solution of NO3 " (as NaNO3) containing 20 mg/L of ethanol at 80°C.
  • the flow rate was varied between 0.5 and 10 mL/min corresponding to reactor space times between 42 and 942 seconds. Good pseudo first order kinetics were obtained over these reaction conditions. The results are shown in Figure 6.
  • the pseudo first order reduction rate was 0.0114 sec" 1 . Under these conditions, a 95% reduction of the nitrate concentration can be achieved in ⁇ 260 seconds.
  • the reduction of 30.6 mg/L of NaNO3 with 20 mg/L of ethanol as reductant was investigated at 100°C.
  • Figure 7 shows the destruction of nitrate as a function of reactor space time.
  • the reaction rate determined from this curve was 0.0214 sec" 1 .
  • a 95% reduction of the nitrate concentration at 100°C requires 140 seconds.
  • the Arrhenius activation energy for this reaction is 34.5 kJ/mole (8.25 kcal/mole) with a pre-exponential factor of 1,445 sec -1 .
  • Adjustment of either reaction temperature or the catalyst bed size can be used to ensure that the destruction of nitrate in a wide variety of water samples will meet regulatory limits as required.
  • ⁇ is the mole fraction of hydrogen in water
  • pH2 is the hydrogen pressure in atmospheres
  • H k is the Henry's Law Constant. Since the ⁇ is independent of temperature, the hydrogen pressure needed to maintain a fixed ⁇ is dependent only on the Henry's Law Constant. At room temperature, the Henry's Law Constant for hydrogen is 77,600. Since Henry's Law Constant increases with temperature reaching a maximum at ⁇ 90°C, the reactor pressure must exceed the equilibration pressure to maintain a single phase. The stoichiometry for the reaction between hydrogen and perchlorate is given by (5).
  • the pseudo first order reaction rate constants were 0.0051, 0.0102, and 0.0207 sec" 1 at 80°, 90°, and 100° C, respectively. These values are lower than those obtained using ethanol as the reductant (i.e., 0.0116, 0.0185, and 0.0317 sec" 1 at 60°, 70°, and 80° C, respectively).
  • the logarithms of each reaction rate constant were then plotted as a function of the reciprocal of the absolute temperature (°K _1 ) producing an excellent linear fit as shown in Figure 11. Based on the slope , the Arrhenius activation energy was determined to be 80.5 kJ/mole (19.24 kcal/mole) with a pre-exponential factor of 4.09 x 10 ⁇ sec" 1 .
  • System 40 comprises a influent reservoir 41 from which an contaminant-containing aqueous feed stream is transferred by pump 42 into preheater 43, and in turn into reactor 44.
  • Themocouples 45 read the inlet temperature into the preheater 43 and the outlet temperature exiting reactor 44.
  • the inlet and outlet temperatures are regulated by temperature controllers 46 which in turn run the power controllers/resistive heating elements 47.
  • a secondary regulator 48 controls the flow of product effluent from the reactor 44 which collects in effluent reservoir 49.
  • System 40 utilizes ammonium chloride, NH4CI, as the reductant. Balancing the oxidation - reduction reaction between sodium perchlorate, NaCl ⁇ 4, and NH4CI yields (6),
  • the reactor 4 contains 20 cm3 of the PRZr51 catalyst.
  • the influent contained 50 mg/L NaCl ⁇ 4 concentration and 330 mg/L NH4CI concentration. Assuming a complete conversion of perchlorate to chloride, a five fold excess of ammonium was used during these runs. In the presence of excess ammonium, the reaction becomes zero order with respect to the reductant.
  • the reaction kinetic experimental results at 120°C and 130°C are shown in Figures 12 and 13, respectively. The flow rates were varied between 0.71 and 4.62 mL/min, corresponding to reactor space times between 104 and 676 seconds. Good zero order reaction kinetics with respect to perchlorate reduction were obtained for these reaction conditions.
  • the pseudo zero order reaction rate constants are 0.1184 and 0.1808 mg L" 1 sec" 1 at 120° and 130° C, respectively.
  • the oxidation-reduction catalyst used in these experiments is composed of 2 weight % platinum and 0.5 weight % ruthenium on a zirconia support.
  • the preparation of this high activity reduction catalyst involves the homogeneous adsorption of aqueous ions containing ruthenium and platinum onto a zirconium oxide (i.e., Zr ⁇ 2) support.
  • Zr ⁇ 2 zirconium oxide
  • Other catalysts that are effective at oxidizing aqueous organic species using molecular oxygen should exhibit similar reduction behavior, since like PRZr51, they are all effective at reducing molecular oxygen and other oxygen sources using a variety of organic contaminants as a reductant.
  • catalysts which should behave in this manner include platinum and ruthenium on supports such as activated carbon, titanium dioxide, silicon dioxide, and other transition metal oxides. Platinum alone and combinations of palladium have also been shown to function as effective oxidation catalysts. In particular, the addition of 2.0 weight % palladium to PRZr51 provided excellent performance when hydrogen was utilized as the reductant.
  • Perchlorate or nitrate/nitrite contaminants in a variety of waters can be processed at low temperature and pressure.
  • the PRZr51 catalyst has been shown to promote the rapid reaction of both NaClO4, NH4CIO4, and NaNO3 using a variety of reductants at temperatures between 60° and 80°C. These moderate treatment conditions reduce energy consumption and translate directly into the potential for economies in size, weight, and power.
  • the APCAR process can treat water at temperatures below 80°C where the reaction occurs rapidly.
  • the chief byproducts are innocuous inorganic chlorine compounds, carbon dioxide, and water.
  • the APCAR system can operate as a self-contained process within a drinking water plant or at a wastewater treatment facility. The APCAR system eliminates perchlorate from drinking water or other contaminated water, does not produce a secondary more highly concentrated contaminant stream, and as an added benefit, reduces the concentration of organic contaminants.
  • the APCAR process can also treat water at low temperatures.
  • the chief by-product is nitrogen gas, carbon dioxide, and water.
  • the amount of reductant required to treat contaminated water depends on the contamination level which for nitrate/nitrite will be highly variable depending on the water's source. In general, due to the more typical level of nitrate/nitrite contamination (>10 mg/L), a reducing agent such as ethanol, sugar, or acetic acid will be needed albeit at low levels since background orangic levels in water will exhibit insufficient reducing capacity. As with perchlorate, the APCAR system will eliminate nitrate/nitrite without producing a secondary waste stream.
  • the end products for the reduction of perchlorate depends on the reductant, the catalyst, and the reaction conditions.
  • the reductant for example, when ethanol is oxidized to carbon dioxide (CO2) in the presence of sodium perchlorate (NaClO4), several reactions are possible. This is shown in (7) through (9), where the formation of the more reduced forms of chlorine (i.e., chlorate, hypochlorite, and chloride) results in the more effective use of ethanol as a reducing agent.
  • the catalyst plays an important role in determining the reduction byproducts.
  • a high chloride residual determined by precipitation with AgNO3 coupled with very low free chlorine residuals determined by method SM4500Q24 indicates that chloride is the chief by-product of NaCl ⁇ 4 reduction.
  • Potassium Perchlorate (CASRN 7778-74-7)( Aerojet General Corp.), Memorandum from Joan S. DoUarhide, Superfund Health Risk Technical Support Center, Environmental Criteria and Assessment Office, Office of
  • Methylthiouracil, and Carbimazole in the Treatment of Thyrotoxicosis are Methylthiouracil, and Carbimazole in the Treatment of Thyrotoxicosis

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)

Abstract

Le procédé de cette invention vise à détruire des contaminants dans un courant aqueux renfermant des contaminants. Ce procédé consiste à générer un courant (30) d'alimentation aqueux contenant des contaminants et comprenant une quantité initiale d'au moins un groupe de contaminants tels que des perchlorates, nitrates et nitrites. Le courant d'alimentation aqueux contenant des contaminants comprend un agent (28) réducteur. Le procédé consiste ensuite à chauffer (22) le courant aqueux contenant les contaminants et l'agent réducteur, et enfin à mettre en contact le courant aqueux chauffé, contenant les contaminants, avec un catalyseur (20) d'oxydo-réduction sur une durée suffisante pour réduire d'au moins 90 % la quantité excédentaire des contaminants tels que les perchlorates, nitrates et nitrites.
EP99940830A 1998-08-06 1999-08-05 Procede de destruction de contaminants dans des courants aqueux renfermant des contaminants et catalyseurs utilises a cet effet Withdrawn EP1117619A4 (fr)

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US9561498P 1998-08-06 1998-08-06
US95614P 1998-08-06
US9735398P 1998-08-21 1998-08-21
US97353P 1998-08-21
PCT/US1999/017219 WO2000007943A1 (fr) 1998-08-06 1999-08-05 Procede de destruction de contaminants dans des courants aqueux renfermant des contaminants et catalyseurs utilises a cet effet

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KR100490865B1 (ko) * 2001-12-11 2005-05-19 국보산업 주식회사 촉매습식산화공정을 이용한 폐수처리방법
US6800203B2 (en) * 2002-05-29 2004-10-05 U.T. Battelle Catalytic destruction of perchlorate in ferric chloride and hydrochloric acid solution with control of temperature, pressure and chemical reagents
RU2597387C1 (ru) * 2015-05-21 2016-09-10 Федеральное государственное бюджетное образовательное учреждение высшего образования "Уфимский государственный нефтяной технический университет" Способ очистки воды и устройство для его осуществления

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EP0359074A1 (fr) * 1988-09-10 1990-03-21 Solvay Umweltchemie GmbH Procédé, catalyseur et dipositif d'élimination de la concentration de nitrite et/ou de nitrate de l'eau
US5554300A (en) * 1995-02-22 1996-09-10 Purifics Environmental Technologies, Inc. Purification system

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CH633497A5 (de) * 1977-03-30 1982-12-15 Kernforschungsanlage Juelich Verfahren zur reduktion von reduzierbaren schadstoffen in waessrigen loesungen.
US5118447A (en) * 1991-04-12 1992-06-02 Battelle Memorial Institute Thermochemical nitrate destruction
EP0630291B1 (fr) * 1992-03-13 1995-11-02 Solvay Umweltchemie GmbH Catalyseur a support resistant a l'abrasion
DE4207962A1 (de) * 1992-03-13 1993-09-16 Solvay Umweltchemie Gmbh Katalytisches wirbelschichtverfahren zur behandlung waessriger fluessigkeiten
US5608112A (en) * 1994-08-15 1997-03-04 The Trustees Of Princeton University Process for reducing organic pollutants

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EP0359074A1 (fr) * 1988-09-10 1990-03-21 Solvay Umweltchemie GmbH Procédé, catalyseur et dipositif d'élimination de la concentration de nitrite et/ou de nitrate de l'eau
US5554300A (en) * 1995-02-22 1996-09-10 Purifics Environmental Technologies, Inc. Purification system

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See also references of WO0007943A1 *

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WO2000007943A1 (fr) 2000-02-17
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