+

WO1992005119A1 - Adiabatic process for the extraction of aqueous wastes - Google Patents

Adiabatic process for the extraction of aqueous wastes Download PDF

Info

Publication number
WO1992005119A1
WO1992005119A1 PCT/US1991/004278 US9104278W WO9205119A1 WO 1992005119 A1 WO1992005119 A1 WO 1992005119A1 US 9104278 W US9104278 W US 9104278W WO 9205119 A1 WO9205119 A1 WO 9205119A1
Authority
WO
WIPO (PCT)
Prior art keywords
stream
waste
reactor
further characterized
oil
Prior art date
Application number
PCT/US1991/004278
Other languages
French (fr)
Inventor
James F. Grutsch
Original Assignee
Chemical Waste Management, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Chemical Waste Management, Inc. filed Critical Chemical Waste Management, Inc.
Publication of WO1992005119A1 publication Critical patent/WO1992005119A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/002—Sludge treatment using liquids immiscible with water

Definitions

  • This invention relates generally to the treatment, dewatering, and detoxifying of contaminated aqueous wastes including wastewaters, slurries, and sludges.
  • the treatment of these contaminated streams has become a national environmental priority, since such streams are being created by so many sources, such as landfills, research, industry, power plants, government and many other chemical, pharmaceutical, biological, plating, and photographic processes.
  • this invention involves a novel process that concentrates solid waste materials and catalytically oxidizes volatile pollutants, both of which are contained in the aqueous wastes that can be treated by this invention. Further, this invention has the capability of providing a useful condensate product.
  • the novel process disclosed herein couples efficient evaporation with gas phase catalytic oxidation.
  • this process can provide for the recapture of distilled quality water that is substantially free of minerals and organics and that may, therefore, be safely returned to rivers and streams or reused in industrial processes.
  • aqueous waste streams such as sewage and animal and human wastes
  • aqueous waste streams has long been a difficult problem because of the difficulties associated with removing the liquids or volatiles that typically comprise the majority of such wastes. More often than not aqueous wastes contain volatile components that if not properly treated would cause massive pollution of the environment.
  • the art has recognized a number of processes for treating aqueous waste, several of which involve evaporation steps to concentrate the solids phase prior to further treatment of the concentrated solids. Treatment of harmful volatile components prior to introduction in the environment is also known to the art. An oxidation process is the most typical of treatment processes for volatilized contaminants.
  • oxidation of organic compounds dissolved in wastewater streams is well known in the art. Both liquid phase and vapor phase oxidation processes are known.
  • industrial fluids such as dyestuf f solutions, can be purified using the process disclosed in U.S. Patent No. 4,279,693 (Kuhnlein et al.). This process involves evaporation of impurities from polluted fluids where approximately 90% of the volatile impurities remain untreated or are subjected to flame combustion at temperatures ranging from 800-lOOOt. A small percentage of the impurities (approximately 10%) may be removed from the non volatiles and destroyed in a catalytic oxidation process.
  • U.S. Patent No. 4,141,829 discloses a two step oxidation process. In the first step a contaminated water stream is subjected to a liquid oxidation process to destroy the majority of the organic substances in the liquid stream. Any volatile organics remaining after the liquid oxidation step are heated and catalytically oxidized in a gas phase reactor.
  • U.S. Patent No. 4,021,500 discloses an improved oxidative dehydration system to catalytically remove dissolved hydrocarbons. A hydrocarbon laden liquid water stream is mixed with an air/steam stream and is contacted with a solid catalyst to yield an effluent of water vapor, carbon monoxide and carbon dioxide.
  • U.S. Patent No. 4,699,720 (Harada et al.) teaches a process for treating wastewater wherein a stream containing suspended solids, ammonia and chemically oxidizable substances is subjected to a liquid phase catalytic oxidation reaction. Separation of the suspended or dissolved solids occurs after the oxidation reaction by employing a reverse osmosis process.
  • U.S. Patent No. 4,632,766 discloses a method of treating wastewater wherein a concentrated "slime" containing water is subjected to a noncatalytic multistage oxidation in the presence of air or oxygen.
  • 3,487,016 teaches the oxidation of organic or inorganic materials in liquid or vapor phase using oxygen-containing gas and a catalyst containing either manganese or lead. Oxidation is performed at low temperatures and at atmospheric or less pressure.
  • U.S. Patent No. 3,804,756 (Callahan et al.) teaches that volatile impurities may be steam stripped from wastewaters and then chemically oxidized with a variety of catalyst formulations, with copper oxide being preferred.
  • VOC volatile organic compounds
  • the present invention presents a novel continuous treatment method for concentrating waste solids and chemically oxidizing volatile contaminants. Further, this invention presents a catalytic oxidation process that can be carried out in the presence of steam at gas phase conditions.
  • This invention is directed toward a novel process for the treatment of aqueous waste streams. More specifically the invention provides a means to convert chemically oxidizable volatile pollutants found in a variety of aqueous wastes to harmless inorganic gases. This process also has the potential to produce a useful condensate product of distilled water quality, free of minerals and dissolved organics.
  • Another object of this invention is to provide a process that specifically is designed to dewater slurries and highly mineralized wastewaters and sludges, especially those containing toxic organic and inorganic compounds which, if treated by conventional treating processes, would be considered hazardous if discharged to surface freshwater receiving streams.
  • a broad embodiment of the invention is directed to a process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising the steps of (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuous phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize water and the chemically oxidizable pollutants; (b) removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and a second stream comprising the volatized chemically oxidizable pollutants and steam; and (c) catalytically oxidizing the second stream in the presence of steam, at gas phase conditions to convert substantially all the chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising substantially steam and incondensible gases.
  • Another embodiment of the invention provides for a process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising, in combination, the steps of (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuouse phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize the chemically oxidizable pollutants (b) removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and a second stream comprising volatized chemically oxidizable pollutants and steam (c) separating the first stream into two separate streams, a slip stream and a recycle stream to facilitate removal of the dewatered waste from the process and to maintain the concentration of the dewatered waste in the evaporative reactor in a steady state conditions, the slip stream having a lower volume compared to the recycle stream and having substantially the same composition as both the recycle stream and the first stream (d) recycling the recycle stream to the
  • Figure 1 is a flow diagram of an embodiment of the invention illustrating the treatment of a municipal sludge that uses a stirred tank evaporative reactor.
  • Figure 2 is a flow diagram of an embodiment of the invention that uses a falling film evaporative reactor.
  • the instant invention is capable of processing a variety of aqueous wastes, including sludges, slurries and wastewaters.
  • this invention can process all forms of municipal sludges, rolling mill sludge, radioactive sludge, harbor or other dredgings, PCB contaminated siudges, alum sludges and oily sludges.
  • slurries and wastewaters that can be treated include wastes from coal tar pits, phosphate slimes, leachates, brine concentrates, chelated chemical cleaning solutions, pharmaceutical waste broths and engineered microorganisms.
  • the solids particle size of the aqueous waste treated should be a maximum of about 1/4 inch. Large particles, such as from garbage, can be ground to size or comminuted by existing techniques, thus making this process applicable to all physical forms of aqueous waste materials.
  • Aqueous waste can be generally characterized as a suspension of solid materials containing a high percentage of water. Many such aqueous wastes are contaminated with volatile chemically oxidizable pollutants comprising both organic and inorganic compounds.
  • the aqueous wastes may contain nonvolatile pollutants.
  • the volatile chemically oxidizable pollutants include compounds, such as alcohols, ketones, esters, aromatic hydrocarbons, chlorinated hydrocarbons, ammoniacal compounds, cyanide and sulfur containing compounds, and a variety of other chemicals that are known pollutants.
  • the nonvolatile pollutants typically comprise minerals, which are broadly defined as any element, inorganic compound or mixture occurring or originating in the earth's crust and atmosphere, including all metals and nonmetals, their compounds and ores. Included in the dissolved solids can be compounds of heavy metals, such as, nickel, zinc, cadmium, mercury, arsenic, and lead.
  • the process of the invention is particularly well suited for the treatment of leachates that emanate from landfills.
  • the complex nature of the constituents of such wastewater streams is illustrated by the following compositional profile of a representative landfill leachate.
  • TDS Total Dissolved Solids
  • the particular aqueous waste to be dewatered and detoxified is dispersed into a nonvolatile continuous phase comprising oil in an evaporative reactor. At least two streams are removed from the reactor, the first comprising an admixture of dewatered and detoxified waste solids and second a vapor phase containing primarily steam and, if present, chemically oxidizable compounds.
  • the oils that are preferred for use in this process include inert, relatively nonvolatile oils or fats, or other oil-like materials, including synthetic oils.
  • Typical oils include motor oil, mineral oil, tallow, other animal fats and vegetable oils, all of which often can be derived directly from the process operation; petroleum oils and their fractions and derivatives including fuel oils, glycerines, glycols and mixtures thereof.
  • the quantity of oil is such that its ratio in the system is in the range of about 10 to about 1 by weight, based on each part of non-fat solid. This ratio refers to total oil, i.e., that added plus that derived from the process for reuse.
  • the unit operation performed in the evaporative reactor necessarily includes an evaporation step and details need not be included herein.
  • Any evaporation design that can dewater and detoxify the solids from a dilute solution of waste solids and produce steam substantially free of dissolved solids can be used in the invention.
  • Examples of known evaporator designs include forced circulation, submerged tube forced circulation, Oslo-type crystallizer, short and long tube vertical, horizontal tube, and falling film.
  • Evaporation may be effected with a stirred tank reactor and in particular by using a back-mix reactor design where the concentration of constituents in the effluent of the reactor is equivalent to that in the reactor.
  • a falling film evaporator is the preferred design for the evaporative reactor.
  • the process conditions for the evaporative reactor include a temperature of the oil of from about lOOt (212°F) to about 130t (266°F) and a pressure from about subatmospheric to about 790 kPa (abs) (100 psig), with most preferred temperature and pressure ranges from about 105°C (221 °F) to about 125t (257°F) and from about atmospheric to about 446 kPa (abs) (50 psig), respectively.
  • Waste solids retention time in the evaporative reactor depends upon the water release characteristics of the solids and may be as little as 0.25 hrs. to as much as 6 hrs., more preferably from about 1 hr to about 4 hrs.
  • the waste solids or dewatered waste that accumulates in the hot reaction oil as a result of the vaporization of water and volatile contaminants from the aqueous waste, are withdrawn from the process in a first stream.
  • the first stream is then split into a recycle stream and a slip stream.
  • the removal of a low-volume slip stream from the evaporative reactor to concentrate the solids eliminates the necessity and cost associated with pumping large volumes of oil throughout the process.
  • the slip stream which comprises an admixture of dewatered solids and oil, is further processed to yield a solid product substantially free of oil and water. Removal of the slip stream is effected by withdrawing the oil and dewatered waste solids from the bottom of the evaporative reactor, removing a low volume of this mixture and returning the balance of the mixture to the top of the reactor.
  • any process that can deoil the dewatered solids may be used.
  • a preferred process involves holding the admixture of dewatered solids and oil in a thickening tank where the solids will settle to form a slurry comprised of about 30 to 40% by weight of solids in oil.
  • This thickened sludge is then washed with a light hydrocarbon, such as pentane, to facilitate extraction of the oil from the solids.
  • the washed solids are then subjected to pressure filtration and further washing with a light hydrocarbon.
  • the resultant filter cake is held at reduced pressure to vaporize any residual light hydrocarbon. Recovered oil and light hydrocarbon are returned to the process for further use.
  • the recovered dry solids may represent a valuable product.
  • the deoiled solid product can be used as a fertilizer, animal feed, or formed into briquets for burning as fuel for the process * or other processes.
  • stabilization is an alternative disposal means, including both physical and chemical stabilization. Any stabilization process known to the art may be used, however, chemical fixation and solidification processes for producing solid wastes suitable for ultimate disposal in landfills or other secure sites are most preferred.
  • stabilizing agents for example, fly ash, asphalts, alkali metal silicates, all forms of cements, pozzolans, gypsum, calcium chloride, kiln dusts, lime, or other known stabilizing agents.
  • the addition of the stabilizing agents can be performed using an in-line or batch process. .After mixing and curing, the mixture forms a solid.
  • the stabilized deoiled solids may then be disposed of following accepted disposal practices. Alternatively, the solid may be used as building materials, as landfill to support buildings, to reclaim coastal lands, or to build levees or dikes.
  • the second stream from the evaporative reactor comprising steam and the volatile chemically oxidizable compounds, is contacted with a solid catalyst in a reaction zone maintained at oxidation reaction conditions.
  • the chemically oxidizable volatile compounds that were volatized when the aqueous waste was contacted with the hot oil are oxidized to produce a gaseous reaction product comprising substantially steam and incondensible gases, primarily carbon dioxide and nitrogen.
  • the second stream typically comprises at least 95 wt% of all of the volatile chemically oxidizable pollutants originally contained in the aqueous waste.
  • the second stream contains at least 96 wt% and more preferably at least 99 wt% of the volatile pollutants present in the aqueous waste.
  • substantially all of the volatile pollutants originally in the aqueous waste are contained in the second stream.
  • substantially all of the volatile pollutants originally present in the aqueous stream are catalytically oxidized in the reaction zone.
  • the second stream from the evaporative reactor contains substantially all of the water originally contained in the aqueous waste fed to the process.
  • the water in the second stream is directed to the catalytic oxidation reactor in the vapor state as steam.
  • the second stream contains significantly more steam than volatile pollutants.
  • the steam-to-organic weight ratio is greater than 2:1. More preferably, the quantity of steam in the second stream is at least 16 times the weight of volatile pollutants contained therein.
  • the volatile pollutant component of the second stream is less than 10% of the total components in the stream.
  • the presence of steam in the oxidation reactor is beneficial to achieving complete oxidation of volatile pollutants. It is believed that the steam directly participates in the oxidation of pollutants either by reacting catalytically, thermally, or through steair. reforming chemistry with partially oxidized compounds. This theory of direct steam participation in pollutant removal could also help explain the apparent lack of a large oxygen effect, since steam is so primarily present. In fact, the oxidation of pollutants can be performed by providing less than the stoichiometric amount of oxygen.
  • each different type of aqueous waste will have a different stoichiometric requirement of oxygen, but because of the high ratio of steam to volatile pollutants present in the reaction zone, high conversions of pollutants are achieved at less than the stoichiometric amount of oxygen.
  • the second stream Prior to the oxidation step the second stream may be compressed by mechanical means or by a steam jet to increase the latent heat value of the second stream.
  • a preferred means to compress the second stream is by compressors powered by steam turbines. These steam turbines can be operated in cogeneration mode using landfill biogas, steam from an incinerator waste heat recovery unit, or other similar source. Energy cost reductions and high cogeneration efficiencies can be realized using steam turbine powered compressors and pumps.
  • the gaseous reaction product that results from the oxidation step may be compressed, in preference to the compression of the second stream, to increase its latent heat value. In either case the latent heat can be used to provide the partial or total heat requirement needed in the evaporative reactor.
  • the catalytic oxidation is performed in a reactor at gas phase conditions using a solid catalyst.
  • the oxidation reaction conditions include a reaction temperature in the range of from about 204 cl C (400°F) to about 1200°C
  • reaction temperature should be maintained in the range from about 371°C (700°F) to about 677°C (1250°F).
  • gas space velocity of the water rich vapor phase stream in the reaction zone is from about 0.1 sec "1 to about 1000 sec "1 , most preferably from about 5 sec " 1 to about 100 sec "1 .
  • the reaction zone pressure preferably is in the operating range of from subatmospheric to about 790 kPa (abs) (100 psig), with a most preferred operating pressure of from about atmospheric to about 446 kPa (abs) (50 psig).
  • the chemically oxidizable compounds in the second stream are catalytically oxidized in the presence of the steam that was formed in the evaporative reactor.
  • the solid catalyst used in the oxidation zone may be selected from any of the known commercially existing oxidation catalyst compositions, or mixtures of known oxidation catalysts, that meet the required standards for stability and activity and that possess a high selectivity for oxidation of volatile organic and inorganic compounds.
  • the active component of the oxidation catalyst is a metal, preferably a nonprecious metal, supported on a solid carrier.
  • the preferred solid carrier is alumina. However, any known carrier may be used, for example, silica, silica-alumina, clay or like materials.
  • the carrier may be in the form of spheres, pellets or extrudates.
  • the amount of active metal on the catalyst is preferably from about 5 to about 50 weight percent, based on the total catalyst weight. More preferably the metal component comprises from about 15 to about 25 weight percent of the catalyst.
  • a preferred oxidation catalyst composition includes chromic oxide and alumina in the form of an extrudate. This preferred catalyst and its method of preparation are more thoroughly described in U.S. Patent No. 4,330,513 (Hunter et al), which is incorporated herein by reference.
  • the oxidation reaction of this invention is exothermic and can cause reaction temperatures to increase to excessive levels.
  • a quench stream may be added to the oxidation reaction zone.
  • a preferred quench medium is the condensate product obtained from the evaporator.
  • additional chemical oxygen can be supplied by any known means, with the injection of air, oxygen enriched air, or O 2 being preferred.
  • This external heat source can be supplied from either direct or indirect sources.
  • Indirect sources include electrical heating and conventional heat exchange equipment.
  • Direct heating includes direct gas fired heating of the second stream.
  • the reactants may be heated by direct fired heat prior to introduction into the oxidation reactor. Any direct fired heating process known to the art may be used.
  • the oxidation reaction step of the invention is capable of catalytically oxidizing a wide range of volatile organic and inorganic compounds, including halogenated organics, organophosphorus compounds, organosulfur compounds and organonitrogen compounds.
  • the gaseous reaction product obtained from the oxidation of such compounds may be highly acidic, containing HC1, PO* SO x and NO x .
  • the acidic nature of the product can have deleterious effects on downstream equipment metallurgy. Neutralization of the acidic gaseous reaction products can prevent corrosion and the eventual destruction of downstream equipment. Any neutralization process known to the art may be used to neutralize the acidic reaction products, including solid scrubbers, liquid scrubbers, or a combination of both.
  • a preferred neutralization method involves the use of a limestone bed located downstream of the oxidation reactor.
  • the inherent alkalinity of limestone will neutralize and remove strongly acidic gases contained in the gaseous reaction stream.
  • multiple limestone beds arranged in series flow may be employed.
  • a preferred type of limestone is dolomitic limestone, which contains a carbonate of calcium and magnesium. The magnesium is better suited to capture volatized borates and arsenates.
  • the limestone bed may also be utilized as a temperature control means when the gaseous reaction product is used to supply the heat of evaporation in the evaporative reactor. Temperature control may be desirable to prevent thermal stress of the reactor. Thermal stress occurs because the gaseous reaction product from the highly exothermic catalytic oxidation reaction can, in some instances, be several hundred degrees higher in temperature than the normal operating temperature of the reactor. Normally it is preferred that the medium used to supply the heat of evaporation be only 5 to 17°C (9 to 30°F) higher than the boiling point of the volatile compounds in the aqueous waste to be evaporated.
  • An alternative means to prevent thermal stress is to quench the gaseous reaction products, preferably using a portion of the condensate product stream.
  • oxidation of the chemically oxidizable compounds in the second stream is preferably performed using a solid supported metal catalyst, it is within the scope of the invention to perform the oxidation step by any catalytic means or combination of means known to the art.
  • the oxidation reaction may be performed by ultraviolet light catalyzed peroxide or ozone oxidation.
  • the composition of the gaseous reaction product exiting from the oxidation reactor comprises substantially steam and incondensible gases, primarily carbon dioxide and N-.
  • the gaseous reaction product can optionally be condensed to produce a useful condensate of substantially liquid water. Condensation can be performed by any method known to the art. One method is to pass the gaseous reaction product through an economizer to utilize its latent heat to effect the evaporation of the volatiles contained in the aqueous waste. Alternatively, the condensation of the gaseous reaction product can be performed in an evaporator while simultaneously utilizing its latent heat to effect the evaporation of the volatiles contained in the aqueous waste.
  • a condensate product stream produced by the process of the invention is comprised of substantially liquid water that is free of minerals and organics and is reusable as a condensate for other processes.
  • the condensate may be directly disposed of to existing surface water receiving streams without the need for additional treatment.
  • the inventive concept of this invention provides the basis for solving important environmental engineering problems.
  • toxic chlorinated organics that are nonvolatile such as certain polychlorinated biphenyl (PCB) congeners
  • PCB polychlorinated biphenyl
  • This invention provides an environment for simultaneous destruction of these PCBs using chemical dehalogenation processes because the heat and the low moisture content is a favorable environment for dechlorination.
  • Any chemical dehalogenation process known to the art may be advantageously used to destroy halogenated nonvolatile organics present in the continuous oil phase.
  • a slip stream of the halogenated organic containing oil dispersion medium is routed to a reactor where the chemical dehalogenation reaction is carried out. After the reaction is complete, all reaction products are routed back to the evaporative reactor. Volatile chlorinated organic fragments are volatized in the evaporative reactor and are completely destroyed when passed over the oxidation catalyst.
  • waste materials containing heavy metals can be processed in this invention by adding oil soluble metal extractants, such as tributyl phosphate, 2-ethylhexyl phosphoric acid, trioctylphosphine oxide, etc. to the continous oil phase.
  • the metal extractants solubilize the metals in the oil and allow for easy extraction from the process.
  • a slip stream of the continuous oil phase is treated to recover the metals and the oil and organic extractant is recirculated to the evaporative reactor.
  • the inventive concept of this process provides a source of high temperature to remove high boiling water residuals. For example, fresh water evaporates at about lOOt (212°F) however, as the water gets more brackish the boiling point can increase substantially.
  • the horsepower for vapor reco pressi ⁇ n evaporation at 212°F is about double when brine is evaporated at 235°F.
  • Using a slip stream of the recirculating continuous oil phase to desuperheat the hot off -gases from the catalystic oxidation provides higher oil temperatures to evaporate this higher boiling water.
  • the evaporative reactor can be operated in a more energy efficient temperature range for evaporting most of the water and evaporation of the much smaller amount of high boiling point water is achieved by using the energy released by catalytic oxidation.
  • FIG. 1 is a flow diagram of one preferred embodiment of the invention illustrating the treatment of municipal sewage or equivalent waste materials.
  • the sewage is carried by line 1 to heat exchanger means 10 where the sewage is heated indirectly with hot gaseous oxidation reaction product carried in line 12.
  • the heated sewage is carried via line 2 to evaporative reactor 3 where it is contacted with hot nonvolatile oil maintained at a temperature in the range from about 240-250°F.
  • the water and other volatile compounds contained in the sewage are vaporized into a mixture of steam and chemically oxidizable compounds and are continuously removed from the evaporative reactor via line 11.
  • the mixture of steam and chemically oxidizable compounds is indirectly heated in heat exchanger means 20, mixed with oxidizing agent introduced through line 14 and contacted with a solid nonprecious metal oxidation catalyst in reactor 13.
  • the amount of oxidizing agent added to the steam and chemically oxidizable compounds will vary depending on the oxygen demand of the chemically oxidizable component.
  • the oxidation reaction that occurs in reactor 13 produces gaseous products that are removed from the reactor via line 12, indirectly heat exchanged in heat exchanger means 20 and 10 and then removed from the process via line 15.
  • An homogenous admixture of oil and dewatered and detoxified waste solids, equivalent to the concentration in the evaporative reactor is removed from the reactor via line 4.
  • Recycle oil from line 22 is added to the admixture in line 4 and indirectly heated in furnace 5.
  • Line 6 recycles the heated admixture of oil and waste solids back to reactor 3.
  • the admixture in line 6 is split to form slip stream 7 and recycle stream 24.
  • Slip stream 7 is a low volume stream having the same composition of the admixture in line 6 and the slip stream is carried to settling tank 8. Volatiles from settling tank 8 are removed via line 9 and combined with the admixture in line 24 prior to recycle to reactor 3.
  • the settled admixture in tank 8 is removed by line 16 combined with a light hydrocarbon as a wash and fed to pressure filter 18.
  • Filtrate 20 comprising oil and light hydrocarbon is removed from the pressure filter via line 20 and carried to flash drum 21 where the light hydrocarbon is vaporized and removed overhead via line 17, condensed and collected in wash tank 23.
  • Recycle oil is removed from the flash drum via 22.
  • the pressure filter produces a filter cake or briquette that is removed via line 19 and subsequently burned as a fuel in furnace 5. Ash product formed in the furnace is removed for disposal via line 23.
  • the aqueous waste to be dewatered and detoxified is carried by line 30 to heat exchanger means 31 where it is heated indirectly with the condensate product stream 37.
  • the heated aqueous waste is carried by line 32 to sump 33 of evaporative reactor 34.
  • a concentrate or slurry of oil and dispersed dewatered waste solids is contained in sump 33. Upon contact with the hot oil in sump 33, water and volatile compounds are vaporized.
  • the slurry of oil and dispersed dewatered waste solids is continuously circulated through lines 35 and 45 to the top of evaporative reactor 34 where water and volatile chemically oxidizable pollutants are recirculated to the heat exchanger section of evaporative reactor 34, where they are heated and vaporized.
  • a slip stream 44 is removed from the slurry in line 35 and treated in a manner similar to that described for the slip stream described in the embodiment illustrated in Figure 1.
  • the steam and chemically oxidizable pollutants generated in the reactor are substantially free of all dissolved solids and are removed from the reactor by line 36.
  • the steam and chemically oxidizable compounds in line 36 are compressed by compression means 39 and returned to line 40.
  • the compressed steam and chemically oxidizable compounds in line 40 are then combined with an oxygen containing stream 41 prior to entering oxidation reactor 42.
  • the degree of conversion of volatile pollutants in the oxidation reactor depends on 1) the degree of contamination of the aqueous waste fed to the process, and 2) the tolerable level of pollutants in the stream ultimately exiting the process. The higher the level of pollutants in the incoming aqueous waste, the greater degree of conversion will be achieved in the oxidation reactor. Similarly, if the level of contaminants allowable in the stream exiting the process is high, then a lower degree of conversion is required in the oxidation reactor.
  • the goal to be accomplished by the oxidation reactor is not the percentage removal of pollutants, but rather is the removal of a sufficient quantity of pollutants such that the discharge stream from the process is not harmful to human health or the environment.
  • the oxidation reactor can achieve at least 95% conversion, and in some instances 99.9+% conversion, of the chemically oxidizable compounds in the second stream.
  • This produces a gaseous reaction product of substantially steam and incondensible gases, primarily carbon dioxide.
  • the gaseous reaction product is removed from the oxidation reactor by line 43.
  • a portion of the gaseous reaction product in line 43 can be used as a preheat means for maintaining the temperature of the reactants entering the oxidation reactor.
  • a steam compressor may be used to compress the gaseous reaction products in line 43 to increase their heat value.
  • Condensation of the gaseous reaction product is accomplished upon introduction of the gaseous reaction product in line 43 to the shell side of the heat exchanger element of evaporative reactor 34.
  • the condensate formed in the heat exchanger is continuously removed through line 37, heat exchanged with incoming aqueous waste and removed from the process via line 38.
  • a laboratory test unit comprising a stirred glass reactor and a reaction product condenser.
  • the glass reactor was operated at atmospheric pressure and was heated externally with an electric heating mantle.
  • the reactor contained approximately 700 ml. of oil, the oil being nonvolatile when heated to 100-125%.
  • aqueous waste was added incrementally to the reactor below the surface of the oil using a metering pump.
  • the waste was added at the rate of about 3 ml./30 sec.
  • Volatiles were collected and condensed using a cold water reaction produced condenser.
  • the condensate was analyzed using gas chromotography techniques. Dewatered waste was extracted from the oil using light hydrocarbon extraction techniques. Results from several test runs are shown below.
  • Thickened reactor oil product solids % 45-52
  • Reactor oil temperature °C 110
  • Feed Composition 20% oil, 35% solids and 45% water Reactor oil temperatures, °C 107 Reactor oil solids at equilibrium, % 15

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

A process is presented for dewatering and detoxifying aqueous wastes, especially those containing volatile chemically oxidizable organic and inorganic pollutants. The process combines an efficient evaporative reactor using hot oil as a heat transfer medium to concentrate waste solids and a catalytic oxidation reaction to convert the volatilized organic and inorganic pollutants. A condensate product may be obtained from the aqueous waste according to the inventive process that is of distilled water quality and substantially free of minerals and organics.

Description

ADIABATIC PROCESS FOR THE EXTRACTION OF AQUEOUS WASTES
BACKGROUND OF THE INVENTION A. Field of Invention
This invention relates generally to the treatment, dewatering, and detoxifying of contaminated aqueous wastes including wastewaters, slurries, and sludges. The treatment of these contaminated streams has become a national environmental priority, since such streams are being created by so many sources, such as landfills, research, industry, power plants, government and many other chemical, pharmaceutical, biological, plating, and photographic processes.
More specifically this invention involves a novel process that concentrates solid waste materials and catalytically oxidizes volatile pollutants, both of which are contained in the aqueous wastes that can be treated by this invention. Further, this invention has the capability of providing a useful condensate product. The novel process disclosed herein couples efficient evaporation with gas phase catalytic oxidation. Optionally, this process can provide for the recapture of distilled quality water that is substantially free of minerals and organics and that may, therefore, be safely returned to rivers and streams or reused in industrial processes.
B. Description of Prior Processes
The treatment and purification of aqueous waste streams, such as sewage and animal and human wastes, has long been a difficult problem because of the difficulties associated with removing the liquids or volatiles that typically comprise the majority of such wastes. More often than not aqueous wastes contain volatile components that if not properly treated would cause massive pollution of the environment.
The art has recognized a number of processes for treating aqueous waste, several of which involve evaporation steps to concentrate the solids phase prior to further treatment of the concentrated solids. Treatment of harmful volatile components prior to introduction in the environment is also known to the art. An oxidation process is the most typical of treatment processes for volatilized contaminants.
Evaporation processes for treating polluted waste streams are well known to the art. In particular vertical tube falling film evaporation with vapor recompression has been suggested to efficiently concentrate wastewater streams containing a high concentration of total dissolved solids. The use of such evaporators is described in an ASME publication entitled "Development History of the RCC Brine Concentrator For Concentrating Cooling Tower Blow Down", by J.H. Anderson, 1976.
Distillation of water and catalytic oxidation of residues in sewage and other contaminated liquids by contacting the wet waste with a molten salt is disclosed in U.S. Patent No. 3,642,582 (Greenberg et al.). The molten salt provides two functions. The first is a heat transfer medium to effect evaporation of the water in the waste and the second is to catalyze the oxidation of organic residue remaining after evaporation. Likewise, in U.S. Patent No. 3,688,120 (Patterson) molten metal is used to convert human organic waste into harmless gases. A bath of molten lead, maintained at 620°F to 900°F, is the preferred metal to effect evaporation of water and oxidation of organic compounds in the waste stream.
Alternative methods for recovering clean water from aqueous waste streams are disclosed in U.S. Patent Nos. 3,716,458 (Greenfield et al.) and 3,947,327 (Greenfield et al.). These two patents disclose processes that utilize both volatile and nonvolatile oil to assist in the transfer of concentrated waste streams from successive evaporation stages. The waste stream of the processes is the continuous phase, and the oil is merely a carrier fluid used to move the waste from one evaporator stage to another. Such processes require a large inventory of oil and are frequently plagued with operational problems involving pumping of a "gummy" phase as the waste solids are concentrated. Neither of these patents recognizes that a slip stream of dispersed waste solids can effectively be processed to remove concentrated nonvolatile pollutants. Further, these patents are silent as to how to minimize oil inventory and maintain the waste solids in steady state within the evaporative reactor. In addition, these patents fail to recognize catalytic oxidation of volatile organic vapors.
In general, oxidation of organic compounds dissolved in wastewater streams is well known in the art. Both liquid phase and vapor phase oxidation processes are known. For example, industrial fluids, such as dyestuf f solutions, can be purified using the process disclosed in U.S. Patent No. 4,279,693 (Kuhnlein et al.). This process involves evaporation of impurities from polluted fluids where approximately 90% of the volatile impurities remain untreated or are subjected to flame combustion at temperatures ranging from 800-lOOOt. A small percentage of the impurities (approximately 10%) may be removed from the non volatiles and destroyed in a catalytic oxidation process. The catalytic oxidation process operates in a nonsteam environment with a low water-to-organic ratio. U.S. Patent No. 4,141,829 (Thiel et al.) discloses a two step oxidation process. In the first step a contaminated water stream is subjected to a liquid oxidation process to destroy the majority of the organic substances in the liquid stream. Any volatile organics remaining after the liquid oxidation step are heated and catalytically oxidized in a gas phase reactor. U.S. Patent No. 4,021,500 (Rogers) discloses an improved oxidative dehydration system to catalytically remove dissolved hydrocarbons. A hydrocarbon laden liquid water stream is mixed with an air/steam stream and is contacted with a solid catalyst to yield an effluent of water vapor, carbon monoxide and carbon dioxide.
U.S. Patent No. 4,699,720 (Harada et al.) teaches a process for treating wastewater wherein a stream containing suspended solids, ammonia and chemically oxidizable substances is subjected to a liquid phase catalytic oxidation reaction. Separation of the suspended or dissolved solids occurs after the oxidation reaction by employing a reverse osmosis process. Likewise, U.S. Patent No. 4,632,766 (Firnhaber et al.) discloses a method of treating wastewater wherein a concentrated "slime" containing water is subjected to a noncatalytic multistage oxidation in the presence of air or oxygen. Yet another wastewater treatment process using liquid phase catalytic oxidation is disclosed in U.S. Patent No. 4,294,706 (Kakihara et al.). This reference suggests the removal of suspended solids prior to treatment (Column 3, lines 12-15). Extraction of volatile contaminates from waste streams followed by catalytic destruction of the volatized contaminates has been practiced in the art. For example, U.S. Patent No. 3,127,243 (Konikoff) teaches a process whereby human waste is subjected to a noncontinuous vacuum distillation process to produce vaporized materials that are passed to a high temperature catalytic reactor containing a noble metal catalyst. The reaction product is then condensed to produce potable water. Likewise, U.S. Patent No. 3,487,016 (Zeff) teaches the oxidation of organic or inorganic materials in liquid or vapor phase using oxygen-containing gas and a catalyst containing either manganese or lead. Oxidation is performed at low temperatures and at atmospheric or less pressure. U.S. Patent No. 3,804,756 (Callahan et al.) teaches that volatile impurities may be steam stripped from wastewaters and then chemically oxidized with a variety of catalyst formulations, with copper oxide being preferred.
The elimination of volatile organic compounds (VOC) from industrial/commercial waste gases is also well known in the art. Destruction of VOC is accomplished by catalytic incinerators. A recent article entitled, "Destruction of Volatile Organic Compounds Via Catalytic Incineration" authored by B.H. Tichenor and MA. Paiazzol, Environmental Progress, Volume 6, No. 3, August, 1987, reports the results of an investigation into various catalytic incinerator designs. Tests were performed by evaporating organic compounds into clean air streams and then passing the streams across a monolithically supported precious metal catalyst. Catalytic incineration of noxious industrial fumes is also disclosed in U.S. Patent No. 4,330,513 (Hunter et al.). This reference discloses a process where fumes and waste gases containing hydrocarbons are contacted with a fluidized bed of nonprecious metal solid catalyst. Additionally, a series of U.S. Patents (Nos. 3,823,088; 3,992,295; 3,997,440; 4,062,772; 4,072,608 and 4,268,399) teach that waters containing minor amounts of dissolved organic materials can be purified by contacting either a liquid or gaseous phase with a promoted zinc aluminate catalyst.
Although the art has understood the need and has attempted the treatment of aqueous waste streams and contaminated gas streams, it has failed to solve the problem of efficiently treating such contaminated streams, especially when these streams contain volatile chemically oxidizable contaminants. The present invention presents a novel continuous treatment method for concentrating waste solids and chemically oxidizing volatile contaminants. Further, this invention presents a catalytic oxidation process that can be carried out in the presence of steam at gas phase conditions.
SUMMARY OF THE INVENTION
This invention is directed toward a novel process for the treatment of aqueous waste streams. More specifically the invention provides a means to convert chemically oxidizable volatile pollutants found in a variety of aqueous wastes to harmless inorganic gases. This process also has the potential to produce a useful condensate product of distilled water quality, free of minerals and dissolved organics.
It is an object of this invention to provide a process that eliminates the environmental problems commonly associated with the disposal of dilute solutions of contaminated waste solids.
Another object of this invention is to provide a process that specifically is designed to dewater slurries and highly mineralized wastewaters and sludges, especially those containing toxic organic and inorganic compounds which, if treated by conventional treating processes, would be considered hazardous if discharged to surface freshwater receiving streams.
Yet another object of the present invention is to provide a treatment process that eliminates the need for costly incineration of contaminated aqueous streams. Still another object of the present invention is to provide a treatment process that is environmentally safe and a cost effective substitute for deep well disposal or biological treatment of contaminated aqueous wastes.
Accordingly a broad embodiment of the invention is directed to a process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising the steps of (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuous phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize water and the chemically oxidizable pollutants; (b) removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and a second stream comprising the volatized chemically oxidizable pollutants and steam; and (c) catalytically oxidizing the second stream in the presence of steam, at gas phase conditions to convert substantially all the chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising substantially steam and incondensible gases.
Another embodiment of the invention provides for a process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising, in combination, the steps of (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuouse phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize the chemically oxidizable pollutants (b) removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and a second stream comprising volatized chemically oxidizable pollutants and steam (c) separating the first stream into two separate streams, a slip stream and a recycle stream to facilitate removal of the dewatered waste from the process and to maintain the concentration of the dewatered waste in the evaporative reactor in a steady state conditions, the slip stream having a lower volume compared to the recycle stream and having substantially the same composition as both the recycle stream and the first stream (d) recycling the recycle stream to the evaporative reactor and (e) catalytically oxidizing the second stream in the presence of steam by contacting the second stream with a solid catalyst at gas phase conditions to convert the chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising substantially steam and incondensible gases, the solid catalyst comprising an inorganic oxide support containing at least one metal oxide.
These as well as other embodiments of the present invention will become evident from the following, more detailed description of certain preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate preferred embodiments of the invention. Specifically, Figure 1 is a flow diagram of an embodiment of the invention illustrating the treatment of a municipal sludge that uses a stirred tank evaporative reactor. Figure 2 is a flow diagram of an embodiment of the invention that uses a falling film evaporative reactor.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The instant invention is capable of processing a variety of aqueous wastes, including sludges, slurries and wastewaters. For example, this invention can process all forms of municipal sludges, rolling mill sludge, radioactive sludge, harbor or other dredgings, PCB contaminated siudges, alum sludges and oily sludges. Examples of slurries and wastewaters that can be treated include wastes from coal tar pits, phosphate slimes, leachates, brine concentrates, chelated chemical cleaning solutions, pharmaceutical waste broths and engineered microorganisms. The solids particle size of the aqueous waste treated should be a maximum of about 1/4 inch. Large particles, such as from garbage, can be ground to size or comminuted by existing techniques, thus making this process applicable to all physical forms of aqueous waste materials.
Aqueous waste can be generally characterized as a suspension of solid materials containing a high percentage of water. Many such aqueous wastes are contaminated with volatile chemically oxidizable pollutants comprising both organic and inorganic compounds. In addition, the aqueous wastes may contain nonvolatile pollutants. The volatile chemically oxidizable pollutants include compounds, such as alcohols, ketones, esters, aromatic hydrocarbons, chlorinated hydrocarbons, ammoniacal compounds, cyanide and sulfur containing compounds, and a variety of other chemicals that are known pollutants. The nonvolatile pollutants typically comprise minerals, which are broadly defined as any element, inorganic compound or mixture occurring or originating in the earth's crust and atmosphere, including all metals and nonmetals, their compounds and ores. Included in the dissolved solids can be compounds of heavy metals, such as, nickel, zinc, cadmium, mercury, arsenic, and lead.
The process of the invention is particularly well suited for the treatment of leachates that emanate from landfills. The complex nature of the constituents of such wastewater streams is illustrated by the following compositional profile of a representative landfill leachate.
Parameter Concentration. mκ/ι
Total Dissolved Solids (TDS) 10,000 - 30,000
Chemical Oxygen Demand (COD) 1,000 - 50,000 Total Organic Carbon (TOC) 300 - 15,000
Iron 5 - 2,000
Nickel, Zinc, Cadmium, Mercury High
Arsenic, Lead, etc.
Chloride, Sulfate, etc. 1000+ Priority Organic Pollutants High According to the invention, the particular aqueous waste to be dewatered and detoxified is dispersed into a nonvolatile continuous phase comprising oil in an evaporative reactor. At least two streams are removed from the reactor, the first comprising an admixture of dewatered and detoxified waste solids and second a vapor phase containing primarily steam and, if present, chemically oxidizable compounds. The oils that are preferred for use in this process include inert, relatively nonvolatile oils or fats, or other oil-like materials, including synthetic oils. Typical oils include motor oil, mineral oil, tallow, other animal fats and vegetable oils, all of which often can be derived directly from the process operation; petroleum oils and their fractions and derivatives including fuel oils, glycerines, glycols and mixtures thereof. The quantity of oil is such that its ratio in the system is in the range of about 10 to about 1 by weight, based on each part of non-fat solid. This ratio refers to total oil, i.e., that added plus that derived from the process for reuse.
The unit operation performed in the evaporative reactor necessarily includes an evaporation step and details need not be included herein. Any evaporation design that can dewater and detoxify the solids from a dilute solution of waste solids and produce steam substantially free of dissolved solids can be used in the invention. Examples of known evaporator designs include forced circulation, submerged tube forced circulation, Oslo-type crystallizer, short and long tube vertical, horizontal tube, and falling film. Evaporation may be effected with a stirred tank reactor and in particular by using a back-mix reactor design where the concentration of constituents in the effluent of the reactor is equivalent to that in the reactor. When treating municipal sludge, the use of a back-mix reactor design avoids the "gummy" phase that is typically encountered by processes that use multistep evaporation. A falling film evaporator is the preferred design for the evaporative reactor. The process conditions for the evaporative reactor include a temperature of the oil of from about lOOt (212°F) to about 130t (266°F) and a pressure from about subatmospheric to about 790 kPa (abs) (100 psig), with most preferred temperature and pressure ranges from about 105°C (221 °F) to about 125t (257°F) and from about atmospheric to about 446 kPa (abs) (50 psig), respectively. Waste solids retention time in the evaporative reactor depends upon the water release characteristics of the solids and may be as little as 0.25 hrs. to as much as 6 hrs., more preferably from about 1 hr to about 4 hrs.
The waste solids or dewatered waste that accumulates in the hot reaction oil as a result of the vaporization of water and volatile contaminants from the aqueous waste, are withdrawn from the process in a first stream. The first stream is then split into a recycle stream and a slip stream. The removal of a low-volume slip stream from the evaporative reactor to concentrate the solids eliminates the necessity and cost associated with pumping large volumes of oil throughout the process. By constantly removing the slip stream, a steady state amount of accumulated waste solids is maintained in the evaporative reactor, which permits operation at the solids retention time required for dewatering. The slip stream, which comprises an admixture of dewatered solids and oil, is further processed to yield a solid product substantially free of oil and water. Removal of the slip stream is effected by withdrawing the oil and dewatered waste solids from the bottom of the evaporative reactor, removing a low volume of this mixture and returning the balance of the mixture to the top of the reactor.
To obtain a solid product free of oil and water, any process that can deoil the dewatered solids may be used. A preferred process involves holding the admixture of dewatered solids and oil in a thickening tank where the solids will settle to form a slurry comprised of about 30 to 40% by weight of solids in oil. This thickened sludge is then washed with a light hydrocarbon, such as pentane, to facilitate extraction of the oil from the solids. The washed solids are then subjected to pressure filtration and further washing with a light hydrocarbon. The resultant filter cake is held at reduced pressure to vaporize any residual light hydrocarbon. Recovered oil and light hydrocarbon are returned to the process for further use. Other hydrocarbon extraction processes known to the art can also be used for recovering the light hydrocarbon. Depending on the aqueous waste treated, the recovered dry solids may represent a valuable product. For sewage solids, the deoiled solid product can be used as a fertilizer, animal feed, or formed into briquets for burning as fuel for the process* or other processes. For hazardous deoiled solid product, for example, radioactive solids, stabilization is an alternative disposal means, including both physical and chemical stabilization. Any stabilization process known to the art may be used, however, chemical fixation and solidification processes for producing solid wastes suitable for ultimate disposal in landfills or other secure sites are most preferred. These processes involve adding stabilizing agents, for example, fly ash, asphalts, alkali metal silicates, all forms of cements, pozzolans, gypsum, calcium chloride, kiln dusts, lime, or other known stabilizing agents, to the deoiled solid product. The addition of the stabilizing agents can be performed using an in-line or batch process. .After mixing and curing, the mixture forms a solid. The stabilized deoiled solids may then be disposed of following accepted disposal practices. Alternatively, the solid may be used as building materials, as landfill to support buildings, to reclaim coastal lands, or to build levees or dikes. The second stream from the evaporative reactor, comprising steam and the volatile chemically oxidizable compounds, is contacted with a solid catalyst in a reaction zone maintained at oxidation reaction conditions. The chemically oxidizable volatile compounds that were volatized when the aqueous waste was contacted with the hot oil are oxidized to produce a gaseous reaction product comprising substantially steam and incondensible gases, primarily carbon dioxide and nitrogen. The second stream typically comprises at least 95 wt% of all of the volatile chemically oxidizable pollutants originally contained in the aqueous waste. Preferably, the second stream contains at least 96 wt% and more preferably at least 99 wt% of the volatile pollutants present in the aqueous waste. In the most preferred embodiment, substantially all of the volatile pollutants originally in the aqueous waste are contained in the second stream. As such, substantially all of the volatile pollutants originally present in the aqueous stream are catalytically oxidized in the reaction zone. The second stream from the evaporative reactor contains substantially all of the water originally contained in the aqueous waste fed to the process. The water in the second stream is directed to the catalytic oxidation reactor in the vapor state as steam. The second stream contains significantly more steam than volatile pollutants. Typically the steam-to-organic weight ratio is greater than 2:1. More preferably, the quantity of steam in the second stream is at least 16 times the weight of volatile pollutants contained therein. In other words, in the most preferred embodiment the volatile pollutant component of the second stream is less than 10% of the total components in the stream. Although not completely understood and not wishing to be bound by a particular theory it is believed that the presence of steam in the oxidation reactor is beneficial to achieving complete oxidation of volatile pollutants. It is believed that the steam directly participates in the oxidation of pollutants either by reacting catalytically, thermally, or through steair. reforming chemistry with partially oxidized compounds. This theory of direct steam participation in pollutant removal could also help explain the apparent lack of a large oxygen effect, since steam is so overwhelmingly present. In fact, the oxidation of pollutants can be performed by providing less than the stoichiometric amount of oxygen. Of course, each different type of aqueous waste will have a different stoichiometric requirement of oxygen, but because of the high ratio of steam to volatile pollutants present in the reaction zone, high conversions of pollutants are achieved at less than the stoichiometric amount of oxygen.
Prior to the oxidation step the second stream may be compressed by mechanical means or by a steam jet to increase the latent heat value of the second stream. A preferred means to compress the second stream is by compressors powered by steam turbines. These steam turbines can be operated in cogeneration mode using landfill biogas, steam from an incinerator waste heat recovery unit, or other similar source. Energy cost reductions and high cogeneration efficiencies can be realized using steam turbine powered compressors and pumps. Likewise, the gaseous reaction product that results from the oxidation step may be compressed, in preference to the compression of the second stream, to increase its latent heat value. In either case the latent heat can be used to provide the partial or total heat requirement needed in the evaporative reactor.
The catalytic oxidation is performed in a reactor at gas phase conditions using a solid catalyst. The oxidation reaction conditions include a reaction temperature in the range of from about 204clC (400°F) to about 1200°C
(2192°F). Most preferably the reaction temperature should be maintained in the range from about 371°C (700°F) to about 677°C (1250°F). The gas space velocity of the water rich vapor phase stream in the reaction zone is from about 0.1 sec"1 to about 1000 sec"1, most preferably from about 5 sec" 1 to about 100 sec"1. The reaction zone pressure preferably is in the operating range of from subatmospheric to about 790 kPa (abs) (100 psig), with a most preferred operating pressure of from about atmospheric to about 446 kPa (abs) (50 psig). The chemically oxidizable compounds in the second stream are catalytically oxidized in the presence of the steam that was formed in the evaporative reactor.
The solid catalyst used in the oxidation zone may be selected from any of the known commercially existing oxidation catalyst compositions, or mixtures of known oxidation catalysts, that meet the required standards for stability and activity and that possess a high selectivity for oxidation of volatile organic and inorganic compounds. The active component of the oxidation catalyst is a metal, preferably a nonprecious metal, supported on a solid carrier. The preferred solid carrier is alumina. However, any known carrier may be used, for example, silica, silica-alumina, clay or like materials.
The carrier may be in the form of spheres, pellets or extrudates. The amount of active metal on the catalyst is preferably from about 5 to about 50 weight percent, based on the total catalyst weight. More preferably the metal component comprises from about 15 to about 25 weight percent of the catalyst. A preferred oxidation catalyst composition includes chromic oxide and alumina in the form of an extrudate. This preferred catalyst and its method of preparation are more thoroughly described in U.S. Patent No. 4,330,513 (Hunter et al), which is incorporated herein by reference.
The oxidation reaction of this invention is exothermic and can cause reaction temperatures to increase to excessive levels. To prevent temperatures from exceeding approximately HOOt (2192°F), a quench stream may be added to the oxidation reaction zone. A preferred quench medium is the condensate product obtained from the evaporator. Depending upon the chemical oxygen content of the second stream and the level of chemically oxidizable compounds to be reacted, it may be necessary to supply additional chemical oxygen as a reactant to achieve the high level of conversion required in the oxidation reaction. Additional chemical oxygen can be supplied by any known means, with the injection of air, oxygen enriched air, or O2 being preferred. On initial start-up of the oxidation reactor it may be necessary to use an external heat source to increase the temperature of the reactants to a point where the oxidation reaction will begin. This external heat source can be supplied from either direct or indirect sources. Indirect sources include electrical heating and conventional heat exchange equipment. Direct heating includes direct gas fired heating of the second stream. To maintain the appropriate inlet reactor temperature of the reactants during the process it may be necessary or desirable to perform indirect heat exchange of the reactants with a portion of the reaction products. Alternatively, the reactants may be heated by direct fired heat prior to introduction into the oxidation reactor. Any direct fired heating process known to the art may be used.
The oxidation reaction step of the invention is capable of catalytically oxidizing a wide range of volatile organic and inorganic compounds, including halogenated organics, organophosphorus compounds, organosulfur compounds and organonitrogen compounds. The gaseous reaction product obtained from the oxidation of such compounds may be highly acidic, containing HC1, PO* SOx and NOx. The acidic nature of the product can have deleterious effects on downstream equipment metallurgy. Neutralization of the acidic gaseous reaction products can prevent corrosion and the eventual destruction of downstream equipment. Any neutralization process known to the art may be used to neutralize the acidic reaction products, including solid scrubbers, liquid scrubbers, or a combination of both. A preferred neutralization method involves the use of a limestone bed located downstream of the oxidation reactor. The inherent alkalinity of limestone will neutralize and remove strongly acidic gases contained in the gaseous reaction stream. Depending upon the amount of acidic gas present, multiple limestone beds arranged in series flow may be employed. A preferred type of limestone is dolomitic limestone, which contains a carbonate of calcium and magnesium. The magnesium is better suited to capture volatized borates and arsenates.
In addition to the neutralization of acidic gases in the gaseous reaction product, the limestone bed may also be utilized as a temperature control means when the gaseous reaction product is used to supply the heat of evaporation in the evaporative reactor. Temperature control may be desirable to prevent thermal stress of the reactor. Thermal stress occurs because the gaseous reaction product from the highly exothermic catalytic oxidation reaction can, in some instances, be several hundred degrees higher in temperature than the normal operating temperature of the reactor. Normally it is preferred that the medium used to supply the heat of evaporation be only 5 to 17°C (9 to 30°F) higher than the boiling point of the volatile compounds in the aqueous waste to be evaporated. An alternative means to prevent thermal stress is to quench the gaseous reaction products, preferably using a portion of the condensate product stream. Although oxidation of the chemically oxidizable compounds in the second stream is preferably performed using a solid supported metal catalyst, it is within the scope of the invention to perform the oxidation step by any catalytic means or combination of means known to the art. For example, the oxidation reaction may be performed by ultraviolet light catalyzed peroxide or ozone oxidation.
The composition of the gaseous reaction product exiting from the oxidation reactor comprises substantially steam and incondensible gases, primarily carbon dioxide and N-. The gaseous reaction product can optionally be condensed to produce a useful condensate of substantially liquid water. Condensation can be performed by any method known to the art. One method is to pass the gaseous reaction product through an economizer to utilize its latent heat to effect the evaporation of the volatiles contained in the aqueous waste. Alternatively, the condensation of the gaseous reaction product can be performed in an evaporator while simultaneously utilizing its latent heat to effect the evaporation of the volatiles contained in the aqueous waste. As the hot gaseous oxidation reaction product releases its heat to evaporate the volatiles, condensation occurs and the condensate produced is drawn off as a liquid water product stream. A condensate product stream produced by the process of the invention is comprised of substantially liquid water that is free of minerals and organics and is reusable as a condensate for other processes. Alternatively the condensate may be directly disposed of to existing surface water receiving streams without the need for additional treatment.
The inventive concept of this invention provides the basis for solving important environmental engineering problems. For example, toxic chlorinated organics that are nonvolatile, such as certain polychlorinated biphenyl (PCB) congeners, accumulate in the oil dispersion medium when PCB containing wastes are treated. This invention provides an environment for simultaneous destruction of these PCBs using chemical dehalogenation processes because the heat and the low moisture content is a favorable environment for dechlorination. Any chemical dehalogenation process known to the art may be advantageously used to destroy halogenated nonvolatile organics present in the continuous oil phase. A slip stream of the halogenated organic containing oil dispersion medium is routed to a reactor where the chemical dehalogenation reaction is carried out. After the reaction is complete, all reaction products are routed back to the evaporative reactor. Volatile chlorinated organic fragments are volatized in the evaporative reactor and are completely destroyed when passed over the oxidation catalyst.
Similarly, waste materials containing heavy metals can be processed in this invention by adding oil soluble metal extractants, such as tributyl phosphate, 2-ethylhexyl phosphoric acid, trioctylphosphine oxide, etc. to the continous oil phase. The metal extractants solubilize the metals in the oil and allow for easy extraction from the process. A slip stream of the continuous oil phase is treated to recover the metals and the oil and organic extractant is recirculated to the evaporative reactor. Additionally, the inventive concept of this process provides a source of high temperature to remove high boiling water residuals. For example, fresh water evaporates at about lOOt (212°F) however, as the water gets more brackish the boiling point can increase substantially. The horsepower for vapor reco pressiσn evaporation at 212°F is about double when brine is evaporated at 235°F. Using a slip stream of the recirculating continuous oil phase to desuperheat the hot off -gases from the catalystic oxidation provides higher oil temperatures to evaporate this higher boiling water. Thus, the evaporative reactor can be operated in a more energy efficient temperature range for evaporting most of the water and evaporation of the much smaller amount of high boiling point water is achieved by using the energy released by catalytic oxidation.
A more complete understanding of the inventive concept of this invention may be obtained by a review of the accompanying drawings, which present two preferred embodiments of the invention. The presentation of these embodiments is not intended to exclude from the scope of the inventive concept those other embodiments set out herein or other reasonable and normal modifications of the inventive concept. Details, such as miscellaneous pumps, heaters, coolers, condensers, start-up lines, valving and similar hardware, have been omitted as being nonessential to a clear understanding of the preferred embodiments of the invention.
Figure 1 is a flow diagram of one preferred embodiment of the invention illustrating the treatment of municipal sewage or equivalent waste materials. The sewage is carried by line 1 to heat exchanger means 10 where the sewage is heated indirectly with hot gaseous oxidation reaction product carried in line 12. The heated sewage is carried via line 2 to evaporative reactor 3 where it is contacted with hot nonvolatile oil maintained at a temperature in the range from about 240-250°F.
Upon contact with the hot oil, the water and other volatile compounds contained in the sewage are vaporized into a mixture of steam and chemically oxidizable compounds and are continuously removed from the evaporative reactor via line 11. The mixture of steam and chemically oxidizable compounds is indirectly heated in heat exchanger means 20, mixed with oxidizing agent introduced through line 14 and contacted with a solid nonprecious metal oxidation catalyst in reactor 13. The amount of oxidizing agent added to the steam and chemically oxidizable compounds will vary depending on the oxygen demand of the chemically oxidizable component. The oxidation reaction that occurs in reactor 13 produces gaseous products that are removed from the reactor via line 12, indirectly heat exchanged in heat exchanger means 20 and 10 and then removed from the process via line 15. An homogenous admixture of oil and dewatered and detoxified waste solids, equivalent to the concentration in the evaporative reactor is removed from the reactor via line 4. Recycle oil from line 22 is added to the admixture in line 4 and indirectly heated in furnace 5. Line 6 recycles the heated admixture of oil and waste solids back to reactor 3. The admixture in line 6 is split to form slip stream 7 and recycle stream 24. Slip stream 7 is a low volume stream having the same composition of the admixture in line 6 and the slip stream is carried to settling tank 8. Volatiles from settling tank 8 are removed via line 9 and combined with the admixture in line 24 prior to recycle to reactor 3. The settled admixture in tank 8 is removed by line 16 combined with a light hydrocarbon as a wash and fed to pressure filter 18. Filtrate 20 comprising oil and light hydrocarbon is removed from the pressure filter via line 20 and carried to flash drum 21 where the light hydrocarbon is vaporized and removed overhead via line 17, condensed and collected in wash tank 23. Recycle oil is removed from the flash drum via 22. The pressure filter produces a filter cake or briquette that is removed via line 19 and subsequently burned as a fuel in furnace 5. Ash product formed in the furnace is removed for disposal via line 23.
Referring now to the embodiment illustrated in Figure 2, the aqueous waste to be dewatered and detoxified is carried by line 30 to heat exchanger means 31 where it is heated indirectly with the condensate product stream 37. The heated aqueous waste is carried by line 32 to sump 33 of evaporative reactor 34. A concentrate or slurry of oil and dispersed dewatered waste solids is contained in sump 33. Upon contact with the hot oil in sump 33, water and volatile compounds are vaporized. The slurry of oil and dispersed dewatered waste solids is continuously circulated through lines 35 and 45 to the top of evaporative reactor 34 where water and volatile chemically oxidizable pollutants are recirculated to the heat exchanger section of evaporative reactor 34, where they are heated and vaporized. A slip stream 44 is removed from the slurry in line 35 and treated in a manner similar to that described for the slip stream described in the embodiment illustrated in Figure 1. The steam and chemically oxidizable pollutants generated in the reactor are substantially free of all dissolved solids and are removed from the reactor by line 36. The steam and chemically oxidizable compounds in line 36 are compressed by compression means 39 and returned to line 40.
The compressed steam and chemically oxidizable compounds in line 40 are then combined with an oxygen containing stream 41 prior to entering oxidation reactor 42. The degree of conversion of volatile pollutants in the oxidation reactor depends on 1) the degree of contamination of the aqueous waste fed to the process, and 2) the tolerable level of pollutants in the stream ultimately exiting the process. The higher the level of pollutants in the incoming aqueous waste, the greater degree of conversion will be achieved in the oxidation reactor. Similarly, if the level of contaminants allowable in the stream exiting the process is high, then a lower degree of conversion is required in the oxidation reactor. The goal to be accomplished by the oxidation reactor is not the percentage removal of pollutants, but rather is the removal of a sufficient quantity of pollutants such that the discharge stream from the process is not harmful to human health or the environment. Depending on the makeup of the aqueous waste the oxidation reactor can achieve at least 95% conversion, and in some instances 99.9+% conversion, of the chemically oxidizable compounds in the second stream. This produces a gaseous reaction product of substantially steam and incondensible gases, primarily carbon dioxide. The gaseous reaction product is removed from the oxidation reactor by line 43. A portion of the gaseous reaction product in line 43 can be used as a preheat means for maintaining the temperature of the reactants entering the oxidation reactor. Optionally, a steam compressor may be used to compress the gaseous reaction products in line 43 to increase their heat value.
Condensation of the gaseous reaction product is accomplished upon introduction of the gaseous reaction product in line 43 to the shell side of the heat exchanger element of evaporative reactor 34. The condensate formed in the heat exchanger is continuously removed through line 37, heat exchanged with incoming aqueous waste and removed from the process via line 38.
In order to more fully demonstrate the attendant advantages arising from the present invention the following example is set forth. It is to be understood that this example is not intended as a limitation on the otherwise broad scope of the invention. g AMPLE
To demonstrate the effectiveness of dewatering aqueous waste streams, laboratory test runs were performed in accordance with the dewatering process of the invention. A laboratory test unit was used comprising a stirred glass reactor and a reaction product condenser. The glass reactor was operated at atmospheric pressure and was heated externally with an electric heating mantle. The reactor contained approximately 700 ml. of oil, the oil being nonvolatile when heated to 100-125%.
An aqueous waste was added incrementally to the reactor below the surface of the oil using a metering pump. The waste was added at the rate of about 3 ml./30 sec. Volatiles were collected and condensed using a cold water reaction produced condenser. The condensate was analyzed using gas chromotography techniques. Dewatered waste was extracted from the oil using light hydrocarbon extraction techniques. Results from several test runs are shown below.
Test Run 1 - Anaerobically Digested Municipal Sewage Sludge
Feed, Digested sludge containing 3.34 wt % total solids Feed Rate (approximate evaporation rate), % of reactor oil weight per minute 0.6 Reactor oil temperature, °C 107
Reactor oil solids at equilibrium, % 12-15
Thickened reactor oil product solids, % 45-52
Deoiled product solids, moisture, % 5-8
Test Run 2 - Belt Pressed, Anaerobically Digested Muncipal Sewage Sludge
Feed, Belt pressed sludge containing 17% solids
Feed rate, % of reactor oil rate per minute 0.7
Reactor oil temperature, °C 110
Reactor oil solids at equilibrium, % 10-12 Thickened reactor oil product solids, % 45-50
Deoiled product solids, moisture, % 2-5
Test Run 3 - Steel Rolling Mill Wastewater Sludge
Feed Composition; 20% oil, 35% solids and 45% water Reactor oil temperatures, °C 107 Reactor oil solids at equilibrium, % 15
Product Solids, % water less than 1
% oil less than 1
Product oil, water free essentially total recovery
The present invention has been described in terms of certain preferred embodiments. Of course, numerous other embodiments not specifically described may fall within the spirit or scope of the following claims.

Claims

I Claim as My Invention:
1. A process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising, in combination, the steps of: (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuous phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize water and the chemically oxidizable pollutants;
(b) continuously removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and removing from the reactor a second stream comprising the volatized chemically oxidizable pollutants and steam; and
(c) catalytically oxidizing the second stream in the presence of steam at gas phase conditions to convert substantially all the chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising substantially steam and incondensible gases.
2. The process of Claim 1 further characterized in that the oil is maintained at a temperature from about 100% to about 130%.
3. The process of Claim 1 further characterized in that the dewatered waste is concentrated by settling, filtration or centrifugation.
4. The process of Claim 3 further characterized in that residual nonvolatile oil is extracted from the concentrated dewatered waste with a light hydrocarbon.
5. The process of Claim 1 further characterized in that the quantity of steam in the second stream is at least 2 times the weight of the chemically oxidizable pollutants.
6. The process of Claim 1 further characterized in that the second stream is admixed with an oxygen containing stream.
7. The process of Claim 1 further characterized in that the second stream is heated by direct fired heating prior to catalytic oxidation.
8. The process of Claim 1 further characterized in that the gas phase conditions comprise a reaction temperature from about 371% to about 677%, a gas space velocity from about 5 to about 100 sec"1 and a pressure of from about atmospheric to about 446 kPa (abs).
9. The process of Claim 1 further characterized in that the second stream is contacted with a solid catalyst.
10. The process of Claim 9 further characterized in that the solid catalyst comprises an inorganic oxide support containing at least one metal oxide catalyst.
11. The process of Claim 10 further characterized in that the metal oxide catalyst is formed from a nonprecious metal.
12. The process of Claim 10 further characterized in that the metal oxide catalyst comprises chromium and the inorganic support comprises alumina.
13, The process of Claim 1 further characterized in that a portion of the energy required for heating the oil used to volatize the chemically oxidizable pollutants is supplied by condensing the gaseous reaction product.
14. The process of Claim 1 further characterized in that the second stream is compressed to increase its heat value.
15. The process of Claim 1 further characterized in that the gaseous reaction product is compressed to increase its heat value.
16. A process for dewatering and decontaminating an aqueous waste containing volatile chemically oxidizable pollutants comprising, in combination, the steps of: (a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuous phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize the chemically oxidizable pollutants;
(b) continuously removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and a second stream comprising the volatized chemically oxidizable pollutants and steam;
(c) separating the first stream into two separate streams, a slip stream and a recycle stream, to facilitate removal of the dewatered waste from the process and to maintain the concentration of the dewatered waste in the evaporative reactor in a steady state condition, the slip stream having a lower volume compared to the recycle stream and having substantially the same composition as both the recycle stream and the first stream;
(d) recycling the recycle stream to the evaporative reactor; and
(e) catalytically oxidizing the second stream in the presence of steam by contacting the second stream with a solid catalyst at gas phase conditions to convert the chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising substantially steam and incondensible gases, the' solid catalyst comprising an inorganic oxide support containing at least one metal oxide as a catalyst.
17. The process of Claim 16 further characterized in that the dewatered waste is concentrated from the oil by sedimentation, iltration or centrif ugation.
18. The process of Claim 17 further characterized in that residual oil is extracted from the concentrated dewatered waste with a light hydrocarbon.
19. The process of Claim 16 further characterized in that the metal oxide comprises chromium and the inorganic support comprises alumina.
20. The process of Claim 1 or 16 further characterized in that at least a portion of the slip stream is routed to a reaction vessel such that any nonvolatile chlorinated organics present in the continuous phase are destroyed using a chemical dehalogenation process.
21. The process of Claim 1 or 16 further characterized in that a portion of the slip stream is heat exchanged with the gaseous reaction product to decrease the temperature of the gaseous reaction product and to heat the portion of the slip stream, the heated portion of the slip stream being flashed to separate water vapor from the heated portion of the slip stream.
22. The process of Claim 1 or 16 further characterized in that an oil soluble metal extractant is added to the first stream prior to removal of the slip stream to extract metal contaminants present in the aqueous waste.
23. A process for dewatering and decontaminating an aqueous waste comprising, in combination, the steps of:
(a) continuously dewatering the aqueous waste by dispersing a stream of the aqueous waste into a continuous phase comprising oil circulating in an evaporative reactor maintained at a temperature sufficient to volatize water contained in the aqueous waste;
(b) continuously removing from the reactor a first stream comprising a dispersion of dewatered waste and oil and simultaneously removing from the reactor a second stream comprising steam;
(c) separating the first stream into two separate streams, a slip stream and a recycle stream, to facilitate removal of the dewatered waste from the process and to maintain the concentration of the dewatered waste in the evaporative reactor in a steady state condition, the slip stream having a lower volume compared to the recycle stream and having substantially the same composition as both the recycle stream and the first stream; (d) recycling the recycle stream to the evaporative reactor; and
(e) concentrating the dewatered waste in the slip stream by extracting residual oil from the slip stream with a light hydrocarbon.
PCT/US1991/004278 1990-09-17 1991-06-14 Adiabatic process for the extraction of aqueous wastes WO1992005119A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58366990A 1990-09-17 1990-09-17
US583,669 1990-09-17

Publications (1)

Publication Number Publication Date
WO1992005119A1 true WO1992005119A1 (en) 1992-04-02

Family

ID=24334103

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1991/004278 WO1992005119A1 (en) 1990-09-17 1991-06-14 Adiabatic process for the extraction of aqueous wastes

Country Status (1)

Country Link
WO (1) WO1992005119A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3716458A (en) * 1970-09-18 1973-02-13 Carver Greenfield Corp Process and apparatus for recovering clean water from dilute solutions of waste solids
EP0354656A1 (en) * 1988-08-08 1990-02-14 Chemical Waste Management, Inc. Process for the catalytic treatment of wastewater

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3716458A (en) * 1970-09-18 1973-02-13 Carver Greenfield Corp Process and apparatus for recovering clean water from dilute solutions of waste solids
EP0354656A1 (en) * 1988-08-08 1990-02-14 Chemical Waste Management, Inc. Process for the catalytic treatment of wastewater

Similar Documents

Publication Publication Date Title
US5205906A (en) Process for the catalytic treatment of wastewater
US5160636A (en) Process for the treatment of mixed wastes
KR101243605B1 (en) Waste to energy by way of hydrothermal decomposition and resource recycling
KR920007881B1 (en) Process for the catalytic treatment of waste water
US3741890A (en) Solid waste disposal and water purification method and apparatus
JPH11100243A (en) Conversion treatment of waste into cement raw material
CN101343137A (en) Method for innocent treatment of bottom oil sludge, scruff and active sludge in petro-chemical industry
CN110734164A (en) ship wastewater treatment system and treatment method thereof
JP3626459B2 (en) Organohalogen compound processing apparatus and processing method thereof
Tucker et al. Deactivation of hazardous chemical wastes
US5453202A (en) Method for treatment of impounded sludges, soils and other contaminated solid materials
HUT54197A (en) Process for recovering components, elements of compounds from material mixtures
US5514352A (en) Apparatus for high speed air oxidation of elemental phosphorous wastes in aqueous medium
CN109437350B (en) Chemical three-waste comprehensive treatment system and method
GB2034684A (en) Wet Oxidation Treatment
Patterson et al. Pilot-scale supercritical water oxidation of sewage sludge
US11807565B2 (en) Remediation of per- and poly-fluoroalkyl substances in wastewater
WO1992005119A1 (en) Adiabatic process for the extraction of aqueous wastes
JP2002138057A (en) Halogen-based organic waste treatment method and treatment apparatus
RU2783358C2 (en) Method for neutralizing landfill filtrate and other liquid wastes with a high content of difficult-to-oxidize organic substances (in terms of cod) based on supercritical water oxidation and a device for its implementation
JP2001179074A (en) Treatment method and apparatus of organic substance containing nitrogen and phosphorus
JPH0757358B2 (en) Wastewater treatment method
JP4003084B2 (en) Detoxification method for dredged soil
ADU ASAMOAH et al. PLANT DESIGN FOR THE TREATMENT OF PHENOLIC WASTEWATER FROM TOR USING MODIFIED SPENT FCC CATALYST
JP2001252697A (en) Method and apparatus for treating night soil and / or septic tank sludge

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): DE

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载