Deshusses department of civil and environmental engineering duke university, durham, north carolina, usa project team. About supercritical water oxidation or scwo the supercritical phase of water we are often taught that water exists in three phases. A unique addition to the world of supercritical water scw oxidation is generating highpressure flames inside the scw medium. Supercritical water oxidation scwo is an advanced process mainly employed for the treatment of hazardous stable wastes, otherwise treatable by incineration. This process, referred to as supercritical water oxidation scwo, has been developed as a means of waste destruction for aqueous organic wastes.
The objectives were to determine destruction efficiencies of model compounds and industrial waste effluents and to study the feasability of the scwo process. Supercritical water oxidation continued supercritical water oxidation 20 sept. There are currently six fullscale scwo plants operating worldwide, including one at the defense ammunition center at the mcalester army ammunition plant in oklahoma. Co, and water are the fluids used most frequently in reac tions at supercritical conditions. The fluid has a density between that of water vapor and liquid at standard conditions, and. Supercritical water oxidation wastewaters and sludges.
Neighborhoodscale treatment of fecal sludge by supercritical. Download a pdf of metrics for successful supercritical water oxidation system operation at the blue grass chemical agent destruction pilot plant by the national academies of sciences, engineering, and medicine for free. Thus, the supercritical oxidation process was born. Supercritical water oxidation scwo is a high temperature and pressure technology that uses the properties of supercritical water in the destruction of organic compounds and toxic wastes. The technology being employed, supercritical water oxidation scwo, is promising because it works quickly and generates energy in the forms of hot water and steam from the treatment of human waste. A supercritical fluid process employs environmentally benign solvents co 2 and water to extractdestroy. The blue grass plant uses neutralization followed by supercritical water oxidation, known as scwo, to destroy the nerve agent stockpile. The treatment of dilute aqueous streams containing hazardous organic substances has always presented both technical and economic challenges. Supercritical water begins with an introduction that defines supercritical fluids in general. This book systematically presents the technical aspects of supercritical water oxidation and supercritical water gasification for energy and environmental applications, which include reactor design, construction materials, corrosion, salt precipitation, etc. St ate of the art anders gidner and lars stenmark chematur engineering ab box 430, 691 27 karlskoga, sweden e mail.
Supercritical 3400 psia, water 6500c 3206 psia 22 wder 3740c temperature dc supercritical water exists above critical point of 3206 psig and general use of scwoiscwo in an industrial environment iscwo is excellent for the destruction of. Jan 18, 2018 we use thermodynamic models to predict catalyst oxidation and dissolution in supercritical water scw and use experiments to assess the viability of the models for practical scw reaction systems and provide relative rates for these mechanisms. Supercritical water oxidation scwo is a process for destruction of hazardous organic compounds in aqueous waste streams, and does not produce the environmental andor publicity problems produced by the air emissions of waste incinerators. The ehms represent organic materials found aboard navy ships. Pdf supercritical water oxidation scwo for wastewater treatment. Supercritical oxidation in water and carbon dioxide. Supercritical water oxidation, on the other hand, is known to attain nearly complete destruction of various organics such as pcbs, and dioxins in very short time boock, 1996. Supercritical water oxidation for the destruction of hazardous waste. Kinetics of supercritical water oxidation serdp and.
High temperature and pressure systems slightly less than and greater than supercritical water conditions can be used for the efficient destruction of waste biological treatment plant sludges, acetic acid, 2nitro. Supercritical fluid applications in the pharmaceutical. Treatment of fecal sludge in a prototype supercritical. The goal is to sanitize the collected waste of approximately 1200 people, providing a neighborhoodscale solution. Supercritical water oxidation scwo technology presents important environmental advantages for the treatment of industrial wastes and. Supercritical water oxidation scwo, sometimes referred to as hydrothermal oxidation hto, is a highefficiency, thermal oxidation process capable of treating a wide variety of hazardous and nonhazardous wastes. Treatment of fecal sludge in a prototype supercritical water oxidation reactor marc a. Supercritical water oxidation scwo is a process that occurs in water at temperatures and. Supercritical water oxidation scwo is a technology that takes advantage of the special solvation properties of the water above its critical point 374c, 22. When describing supercritical water, it is fundamental to understand the different phases of water.
Our focus is to measure the primary oxidation steps that occur in the oxidation of methanol, higher alcohols, methylene chloride, aromatics, and some simple organic compounds containing nitro groups. Supercritical water oxidation scwo is an innovative and effective destruction method for organic wastewater and sludge. The scwo reaction takes place at elevated temperatures and pressures above the critical point of water pc 220. The objective of this research was to study the treatment of acetonitrile by catalytic supercritical water oxidation in a compactsized tubular reactor, with an internal volume of 4. Supercritical water oxidation of sewage sludge state of the art anders gidner and lars stenmark chematur engineering ab box 430, 691 27 karlskoga, sweden email. Phenol oxidation in supercritical water sciencedirect. Fecal sludge to energy in a prototype supercritical water.
Abstract this report discusses the replacement of water by carbon dioxide in both the quench stream and the supercritical water oxidation scwo reactor feed in order to reduce the energy utiliza tion in the process. Neutralization followed by supercritical water oxidation. Supercritical water oxidation scwo is a powerful green technology to treat hazardous wastewaters. The process involves bringing together organic waste, water, and an oxidant air, osub 2, etc. Supercritical water oxidation is an exciting waste treatment technology which uses the characteristics of supercritical water to safely treat aqueous waste. This enhancement to the technology eliminates corrosion and accelerates oxidation rates within the reaction chamber such that smaller and lessexpensive units may be constructed. We examined the oxidation and dissolution of noble and transition metals, metal oxide catalyst supports, and transition metal carbides and nitrides. Supercritical water oxidation scwo process is investigated at the institut of technical chemistry, itccpv. Supercritical water oxidation scwo has the potential to be considered a clean energy generation process, as the process effluent is a high temperature, high pressure stream with a high enthalpy. Combustion in supercritical water and subsequent aquifer storage of all coalderived uid e uent removes the need for co 2 separation and compression steps common in other coal red designs with ccs. Two continuous scwo bench scale plants are operated. Rickman general atomics san diego, ca 921211122 abstract in 2000, general atomics was selected by does hydrogen program to perform cooperatively. On the other hand, supercritical water appears to be a unique medium for the safe destruction of dangerous waste by total oxidation due to its special physicochemical properties this is especially true in the case of highly hazardous waste. A comprehensive supercritical oxidation scwo research laboratory, including bench and pilotscale facilities has been developed.
Supercritical water oxidation data acquisition testing. In particular, it focuses on new and emerging applications of supercritical water as a green solvent, including the catalytic conversion of biomass into fuels and the oxidation of hazardous materials. Process fundamentals supercritical water oxidation reactions are carried out above the critical point of water, which is 3740 c and 22. We are placing special emphasis on identifying reaction steps that involve hydroxyl radicals, hydroperoxyl radicals, and hydrogen peroxide. In contrast, supercritical water oxidation can oxidize organic material almost completely.
Supercritical water oxidation scwo technology holds great promise for treating mixed wastes, in an environmentally safe and efficient manner. Supercritical water oxidation the national academies press. The organic content of the process effluent was examined using three independent procedures chemical oxygen demand. Recent developments of supercritical water oxidation. Supercritical water scw gasification and partial oxidation technology is based on the unique properties of water at conditions near and beyond its thermodynamic critical point of 705f and 3206 psia. R o n mcdowall, a u ckland new zealand for secretariat of the b a sel convention technology description. In all the above mentioned steps, phenol was used as representative of. Supercritical fluid technologies supercritical fluid extraction, sfe, and supercritical water oxidation, scwo are drawing much attention as emerging techniques for soil remediation due to the following attractive features. We use thermodynamic models to predict catalyst oxidation and dissolution in supercritical water scw and use experiments to assess the viability of the models for practical scw reaction systems and provide relative rates for these mechanisms. Under these conditions water becomes a fluid with unique properties that can be used to advantage in the destruction of hazardous wastes such as pcbs. Supercritical water oxidation is a technique for the complete oxidation of organic wastes, based on the physical properties of water in supercritical conditions. It maintained its surface area in subcritical water, although it sintered and lost much of its pore volume in supercritical water. The degradation of phenol was studied as a function of both temperature and residence time.
Supercritical water oxidation process linkedin slideshare. Supercritical water oxidation of a model fecal sludge. The organic content of the waste feed is quickly and efficiently converted to carbon dioxide, water, etc. Neighborhoodscale sewage treatment using supercritical water.
Simulations were made for normal modar operating condi. It does not require prior dewatering or drying of fecal sludge, and it effectively eliminates all types of harmful organisms. Supercritical water oxidation scwo consists of the homogeneous oxidation above the critical point of water 374. Overview of supercritical water oxidation technology.
Operating results from supercritical water oxidation plants. Hydrothermal process engineer supercritical water oxidation. Step 1 was studied at laboratory scale in order to obtain all the required information for modeling the adsorption operation. Destruction of hazardous munitions by supercritical water oxidation pdf.
In addition, funding has been obtained to add a supercritical water oxidation scwo unit at tead for processing of the hppp hydrolysate. Supercritical water oxidation and wet air oxidationtwo moderatetemperature, highpressure processeshave attracted interest because of some potential advantage over components of the baseline system. Additionally, the sri design is constructed from inexpensive materials and operates at a lower temperature than conventional supercritical water oxidation processes. The oxidation of acetonitrile in supercritical water was studied at 400500 oc, 2535 mpa, the flow rate of 24 mlmin, the initial concentration of acetonitrile 0. William jacoby copi, university of missouri, jay golden copi, duke. Manganese dioxide was used as the catalyst and h2o2 was used as the oxidant. Pdf supercritical water oxidation scwo is a technology that takes advantage of the special solvation properties of the water above its critical. The supercritical water oxidation process scwo is of great interest today in recycling toxic andor complexed chemical wastes with very good e ciency. Two supercritical water oxidation scwo plants that utilize transpiring wall reactor designs for processing organic wastes are undergoing testing and operation. Supercritical water has total miscibility with organic fluids and oxygen in supercritical equilibria and presents a reactive environment capable of oxidizing toxic waste.
The oxidation of acetonitrile in supercritical water was studied at 400500 oc, 2535 mpa, the flow rate of 24 mlmin, the. Under supercritical conditions, carbon is converted to carbon. Supercritical water oxidation scwo provisional version. Step two involves a secondary process called supercritical water oxidation scwo, which will be used for final treatment of the hydrolysate at bgcapp. Scwo takes advantage of the unique properties of scw to destroy organic waste. The processes lend themselves to the use of oxygen rather than air. Fouling rates from a sodium sulphate water solution in. Water streams polluted with organic compounds can be treated with co 2 for pollutant recovery. The feedstock is a viscous slurry with a solids content between 520%. The main problem facing toc analysis is ensuring efficient oxidation of the organic carbon. The plant has a nominal waste feed rate of 45 kgh and utilizes compressed air as the oxidant. Resolving these reaction pathways re quires quantitativeinformation,such as the variation of the. Our examination of reaction kinetics in supercritical water undertakes in situ measurements of reactants, intermediates, and products using optical spectroscopic.
Since phenol oxidation in supercritical water results in the formationof a large number of individual reaction products, then it is quite possible that the oxidation of or ganics in supercritical water involves a complex set of re action pathways. Reactors, kinetics and catalysis reactions at supercritical conditions. The agent will then be mixed with either a caustic solution or water to destroy the chemical agent before being temporarily stored for later treatment. The supercritical water oxidation reactor runs at temperatures up to 600 c and pressure of 34003500 psi or 230240 bar. This new equipment will provide tead with the technology necessary to demil obsolete aluminumbodied cartridge actuated devices cads currently in. Purpose of scwop is to develop and demonstrate supercritical water oxidation as a viable technology for treating doe hazardous and mixed wastes and to coordinate scwo research, development, demonstration, testing, and evaluation activities. Extensively trained, knowledgeable, skilled workers and stateoftheart robotics systems ensure the safe destruction of the stockpile. Metrics for successful supercritical water oxidation system. Supercritical water oxidation scwo is a process that occurs in water at temperatures and pressures above a mixtures thermodynamic critical point. Oxidation of hazardous wastes by supercritical water oxid.
Neighborhoodscale sewage treatment using supercritical water oxidation engineers at duke university are developing a system to treat human waste and reuse some of the byproducts. Supercritical water oxidation scwo provisional version page 2 of 14 pops technology specification and data sheet john v ijgen, i n ternation a l hch and p e sticides a ssociation and dr. Supercritical water oxidation energy scwoe for operation at temperatures above the ignition, supercritical water oxidation scwo with hydrothermal flame as internal heat source allows to use air or oxygen and the faster kinetics minimizes the reactor volume. Even though the entire oxidation process in carbon dioxide is still. The aqueous phase from wet air oxidation will require further treatment. Science has since shown that there are fifteen 15 states of matter, including super critical. Supercritical water oxidation reaction pathway and. Supercritical water oxidation technology safely disposes. In scwo, organic materials, including materials containing heteroatoms such as chlorine, can be effectively oxidized by o2 in an aqueous medium above the critical point of pure water, that is, at 374ac 705af and 3,205 psi 221 bars. Supercritical water oxidation for the destruction of toxic. This process has been extensively studied for decades from laboratory scale studies of model.
Fluent was used to generate the input requirements and aspen plus was used to model the scwo process. Tavlarides department of chemical engineering and materials science, 220 hinds hall, syracuse. This process has been extensively studied for decades from laboratory scale studies of model compounds to several demonstration and industrial plants under construction worldwide. The process dissolves organics and an oxidizer into high pressure 25 mpa and high. This new equipment will provide tead with the technology necessary to demil obsolete aluminumbodied cartridge actuated devices cads currently in storage at tead.
Oxidation of hazardous wastes by supercritical water oxidation scwo supercritical water oxidation scwo is an end of pipe technology applicable to industrial waste effluents or sludges breaking down the hazardous toxic compounds into carbon dioxide and water. The aqueous phase from supercritical water oxidation may not. Solubility of inorganic salts in sub and supercritical. Laboratory alternate fluid to improve energy efficiency of. More recently, however, sc co, has begun to attract attention as an envi. It is well known that water above its critical point is an effective solvent for organic compounds. Treatment of acetonitrile by catalytic supercritical water. Pdf recent developments of supercritical water oxidation. Co, which has a critical temperature near ambient conditions, has often been used because of this experimental convenience. Nov 17, 2016 the agent will then be mixed with either a caustic solution or water to destroy the chemical agent before being temporarily stored for later treatment. One plant is designed to destroy navy excess hazardous materials ehm.
Operating results from supercritical water oxidation. Supercritical water oxidation technology description. Supercritical water technology applied to the purification of. Supercritical water oxidation american institute of chemical. At typical scw reactor conditions of 1200f and 3400 psi densities are only onetenth that of normal liquid water.
While the unique properties of nearcritical and supercritical water have been utilized. Army medical research and developmen command fort detrick, frederick, maryland 217015012 contract no. Supercritical water technology applied to the purification. Catalyst oxidation and dissolution in supercritical water.
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