Abstract:
A remediation system for decontaminating a polluted site that delivers a remediation fluid to the polluted site and receives a contaminated effluent from the polluted site. The system includes a reactor that receives the contaminated effluent and generates an exit fluid stream and a first flow control mechanism coupled to the outlet of the reactor that releases a controlled portion of the exit fluid from the system, and delivers the remaining portion of the exit fluid as the remediation fluid, or delivers the remaining portion to a second flow control mechanism for combination with a controlled quantity of the second reactant to form the remediation fluid.

Description:
PRIORITY INFORMATION 
     CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a 35 U.S.C. §§371 national phase conversion of PCT/US2006/009278, filed Mar. 14, 2006, which claims priority of U.S. Provisional Patent Application No. 60/661,985, filed Mar. 14, 2005, the disclosure of which has been incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to methods of remediating a contaminated site and of destroying contaminants. 
     2. Description of the Related Art 
     Currently steam is being used to clean up contaminated or remediation sites.  FIGS. 9 and 10  show a common configuration of a current art treatment system, in this case the system used to clean up a NASA site at Cape Canaveral. Forming steam using electricity is expensive, so steam is commonly generated using a standard Heat Recovery Steam Generator (HRSG) unit. The generated steam is commonly injected into a delivery well, optionally with the addition of air. This delivers heat into the ground and down to various subsurface levels where the pollutants are located. This steam then passes through the soil toward separate vapor and ground water extraction wells. As it moves it mobilizes and removes a portion of the polluting or contaminant substances. The steam, or steam and air, are driven through the soil by the injection pressure, and optionally by a vacuum at the extraction wells. This vapor containing fluid and aqueous fluid carries with it various soil pollutants, as well as water which may contain dissolved components. As the fluid moves into the extraction wells, up to the surface and on to the treatment system, it can have gaseous and/or liquid phases. 
     The effluent fluid withdrawn from the extraction wells typically passes through a series of process steps to separate gaseous and liquid phases and to remove the pollution contents from the gaseous and liquid components. The removal of the pollution content is typically accomplished by incineration, but other purification processes can be used, instead, or in addition. The resulting purified fluids are then returned to the environment via the air, land, or water. The heat of combustion resulting from the incineration process is typically lost. 
     Normally the fluid is taken from the extraction well into a heat exchanger/condenser to cool it to below the dew point of the water before it passes into a water knock-out tank. This heat exchanger also requires a cooling tower and coolant transfer pump. After separation, the gaseous and liquid streams pass through a complex array of treatment devices. 
     Another practice in soil remediation is to produce steam, mix it with air and inject the mixture into the soil. The Final Report on the clean up of NASA&#39;s Cape Canaveral Launch Site 34, page 10, discusses this in a specific application:
         “The rational for co-injection of air, based on published bench-scale and numerical modeling studies (Betz et al., 1998; Betz et al., 1997; Itamur, 1996; Kaslusky and Udell, 2002; Schmidt, et al. 1998) is that the mixture of steam and air creates a broader thermal front with a larger volume of air saturated with contaminant, thereby inhibiting condensation of the contaminant and formation of NAPL at the leading portion of the thermal front. The principle is that co-air injection produces an extended thermal front, spreading out the isotherms, to create a larger volume within which contaminants can be held in vapor. The air/steam mixture reduces the injection temperatures to the subsurface, and the co-injected air simultaneously increases the carrying capacity of contaminant in vapor. The optimal ratio of air to steam is based on expected concentration of contaminant, and the vapor pressure of the contaminant. Higher concentrations need greater volumes of air in order to have enough carrying capacity to inhibit condensation.”       

     Another known process is referred to as recompression. This process uses a fluid to add further pressure to the injection well to force the wanted fluids to the extraction wells. This is often done with hot gas and/or steam which has been heated on the surface using a combustion system or by combusting a hydrocarbon fuel down within the well. 
     All of these technologies have one or more disadvantages such as complexity leading to reliability problems, high cost, and occupation of large areas. For example, producing the steam needed for the recompression process requires further equipment such as heat exchangers, pumps, compressors, with major quantities of energy needed operate this additional equipment. This increases operating and capital costs, and equipment footprints, while reducing efficiencies. 
     Thus, a need still exists for improvements in the art of decontamination of polluted sites, and safe disposal of the removed contaminants. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to meet this need by providing a system and method which utilizes the contaminants from the pollution site itself to provide part of the energy for the remediation process. Thus, according to one aspect of the invention, an extraction fluid is produced by a suitable reaction process, and is delivered to a pollution site, which may be underground, or on the surface, and may include soil and surface and/or sub-surface water. This may be done using conventional injection wells, or by surface delivery. The extraction fluid is preferably tailored for the specific types of pollutants to be remediated, and may include a quantity of a diluent added during or subsequent to the reaction process. 
     The extraction fluid interacts with the contaminants in the site, and the now polluted extraction fluid is withdrawn. After further processing as needed, at least a portion is added to the reaction process originally used to generate the extraction fluid. 
     According to a second aspect of the invention, when the pollutants include a substantial quantity of combustible hydrocarbons, which is true in most situations, the extraction fluid is generated by a combustion process which utilizes the combustible pollutants as fuel. This not only provides energy for the remediation process, but also incinerates the pollutants. In one preferred embodiment, the remediation system is designed around a combustion process. Other suitable reaction processes and systems are also expressly considered to be within the scope of the invention. 
     According to a third aspect of the invention, the extraction fluid is generated by combustion using a high efficiency, low pollution combustion system capable of burning low grade fuels. This combustion system is also preferably capable of generating large quantities of steam through injection of water in liquid and/or vapor form directly into the combustion process. One especially attractive system for this purpose is the so-called VAST combustion system. This system, and methods of using it for generating heat energy, are described in commonly owned U.S. Pat. Nos. 6,289,666B1 and 6,564,556B2 and PCT/US99/05271 and WO99/46484 and published US Patent Application 2004/0238654, the contents of which are hereby incorporated by reference. 
     Further according to the third aspect of the invention, a fluid including products of combustion and steam generated by a VAST combustor or thermogenerator, along with any additional desired steam and/or liquid water, is introduced into the contaminated site through suitable injection wells, or by other suitable means, and travels through the earth to a point of recovery, extracting liquid and solid pollutants. The resulting polluted effluent fluid which results is drawn out of the ground. After optional separation, and cooling, if necessary, and optional partial decontamination, at least a portion of the effluent fluid is delivered to the combustion system. The combustible components become part of the fuel for the combustion process, thereby destroying most of the extracted liquid or gaseous pollutants, and water content becomes part of the fluid exiting the combustor, along with the water generated by the combustion of hydrogen-containing fuel and pollution components. 
     A major portion of solid non-combustible pollutant components delivered to the combustor are removed after combustion and/or are extracted from any portion of the exit stream that is not delivered to the contaminated site. VAST combustion systems as described above, are very efficient, and the exit stream exhibits very low levels of CO and NOx, and pollutant components from the contaminated site. Any portion of the combustor exit stream which is not delivered to the remediation site is therefore capable of being safely released into the environment in compliance with legislative and/or regulatory requirements. 
     The hot extraction fluid delivered to the contaminated site typically heats up the contaminants, making them less viscous and therefore more mobile, facilitating extraction of the contaminated fluid. 
     According to a fourth aspect of the invention, liquid water or steam may be added to the combustor exit stream at one or more down stream locations for dilution and/or cooling, and to produce additional steam for inclusion in the remediation fluid. 
     According to a fifth aspect of the invention, heat is extracted from the combustor exit fluid, and reused before the extraction fluid is delivered to the contaminated site. This may be accomplished quite efficiently by a system and method in which the reactor exit fluid is split between a HRSG and a “cooling tank”. The heat recovery system transfers heat from the reactor exit fluid into a diluent stream, such as water, which is thereby heated and/or vaporized, and may be mixed with another portion of the combustor exit fluid or delivered into the combustor. The cooled reactor exit fluid stream may then be exhausted. 
     The reactor exit fluid directed to the cooling tank may also transfer heat by direct contact with a diluent to produce a mixture of gas, vapor and optionally liquid. This mixture may be combined with the heated fluid from the heat recovery system to form the remediation fluid. 
     Reuse of a portion of the reactor system exit fluid in the remediation process beneficially reduces the makeup fuel or energy required. It also reduces the equipment required. 
     Where a combustion process is employed, use of the VAST combustion system identified above is preferred, because it can operate efficiently using fluids with a high water content. Thus, effluent streams with high ratios of water to combustibles (whether in liquid or gaseous form), may be recovered from the contaminated site and processed directly without the need to separate out the water. 
     According to a sixth aspect of the invention, utilization of reactive components of the polluted effluent fluid significantly reduces the cost for energy required for generation of the extraction fluid, and may even enable reprocessing contaminant hydrocarbons into a marketable product, (e.g., as a fuel for use off site) where not all the reactive components of the effluent fluid are required to power the remediation process itself. Alternatively, the excess energy available can be used to do mechanical work on site. For example, a combustor can provide an energetic product fluid to drive a turbine to drive a compressor and or generate electricity for use on site or for sale. At the same time, destruction of the contaminants on site eliminates transportation costs and very high off site treatment or disposal costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The exact nature of the invention and other features and advantages thereof will become apparent from the detailed description which follows, and with reference to the drawings, in which: 
         FIG. 1  depicts the basic organization of a remediation system according to the invention which utilizes combustion system and a cooling chamber. 
         FIG. 2  depicts a remediation system according to the invention using a HRSG at wellhead pressure. 
         FIG. 3  depicts a remediation system according to the invention using a HRSG at ambient pressure. 
         FIG. 4  depicts a remediation system using both a cooling chamber and HRSG. 
         FIG. 5  depicts an efficient remediation system incorporating various features according to the invention. 
         FIG. 6  depicts a remediation system according to the invention with a separator and treatment system. 
         FIG. 7  depicts a remediation system with a gas turbine system. 
         FIG. 8  depicts a process flow diagram for a representative preferred embodiment of the invention. 
         FIG. 9  depicts the known In-situ Thermal Remediation Demonstration Project, at Cape Canaveral, Fla. 
         FIG. 10  depicts an example of a known remediation system layout. 
     
    
    
     Throughout the description, like parts and fluid streams bear like reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     General: 
     In the description which follows, the pollutants are assumed to include a substantial quantity of combustible hydrocarbons, and the primary energy generation process will be a combustion process. As such, the presently known best mode of practicing the invention utilizes the VAST combustion system described in the above-identified patents, the invention will be described in that context. It should be understood, however, that other reaction systems and processes capable of generating the needed remediation fluid, and of converting the extracted contaminant into a safely disposable form can alternatively be employed. 
     Turning now to  FIG. 1 , a remediation system according to the invention, generally denoted at  2 A, provides remediation fluid F 62  for delivery into the ground within or near the contaminated site. Remediation fluid F 62  comprises products of combustion and preferably includes steam. It optionally includes a steam-air combination, and optionally liquid water, as described more fully below. 
     For delivery of the remediation fluid, one or more delivery wells may be sunk into the ground, and an effluent fluid containing extracted contaminants is retrieved from one or more extraction wells. A compressor, pump, vacuum pump or similar pressurizing device configured to create a differential pressure is preferably used to facilitate recovery of the effluent fluid. 
     In some instances, the remediation fluid may be delivered directly into the ground, or into contaminated bodies of water. Pollutant-containing effluent may also be recovered from the ground or water surface in some instances. 
     Optionally, separate delivery wells may be used to inject multiple fluids into the soil or water. The delivery wells are preferably configured to provide the desired fluid pressure, flow rate, and/or flow composition, to move the fluid into and through the contaminated site to the desired remediation location to desirably recover contaminants entrained in a contaminant fluid. 
     However recovered, at least a portion of effluent fluid is processed, as described below to separate it into a gaseous/vapor component F 52  and liquid component F 56 . 
     These are fed separately into a reactor  100  as separate fluid streams F 54  and F 58 , respectively. These may be pressurized by a gas compressor  510  and a fluid pump  515  respectively, or similar devices to provide a positive flow through the reaction system. 
     Where the reaction process is combustion, the VAST combustion system described in the above-identified patents is preferably employed as reactor  100 . An oxygen-containing fluid stream F 24  is provided to burn the combustible contaminant components along with any additional fuel to produce an exit fluid stream F 10  containing products of the reaction. e.g., steam, carbon dioxide, other reaction products, and non-condensible or residual gases such as nitrogen, argon and oxygen. Fluid stream F 24  can be ambient air (compressed if desired), oxygen-enriched air, or even pure oxygen under certain circumstances. 
       FIG. 1  also shows an optional splitter  232  which permits a portion of the incoming oxygen-containing fluid F 20  to be diverted to a bypass stream F 28  for delivery to a mixer  637  for adding air to remediation fluid F 62 . 
     Using the VAST combustion system allows precise control of combustion parameters and fluid inputs to produce an exit stream of the desired exit temperature, and containing such low levels of pollutants such as CO and NOx that it can safely be released into the atmosphere under even the most stringent clean air regulations. 
     The combustor exit fluid stream or product fluid F 10  may be processed further, as described below, and then delivered to the remediation site as a remediation fluid F 62  to assist in mobilizing contaminants for extraction. 
     The VAST combustion system is capable of operating with large quantities of injected water (in liquid or gaseous form). Accordingly, a coolant fluid F 40 , which may include water and/or water vapor, and/or steam in selected proportions, may be delivered to a splitter  432 , one outlet of which provides a coolant stream F 42  to combustor  100  to cool the combustion process and produce additional steam in exit fluid F 10  for the remediation process. A second outlet of splitter  42  may provide a coolant stream F 44  to a cooling chamber  650 , as now described. 
     Although the VAST combustor can function even with large quantities of injected water, and accordingly generate large quantities of steam at a desired exit temperature, additional steam and/or cooling may be desired. For that purpose, cooling chamber  650 , which may be of any desired or convenient construction, is used to transfer heat from combustor exit fluid stream F 10  to coolant F 44 , for example, by direct contact, to generate the additional required steam in an diluted outlet fluid stream F 65 . This passes through a splitter  632 , an outlet of which feeds a fluid stream F 78  to a mixer  637 . Mixer  637  may also receive an oxygen-containing fluid stream F 28 . At least a portion of the resulting mixture of the combustor exit fluid F 10 , the additional steam produced in cooling chamber  650 , and any added oxygen-containing fluid F 28  constitutes the remediaton fluid F 62  in this configuration. 
     Any portion of the cooling chamber exit fluid F 65  not needed at the remediation site is bled out of the system via splitter  632  as bleed fluid stream F 79 . Alternatively, a portion of combustor exit stream F 10  can be vented directly (not shown). 
     In some embodiments, it is preferable to adjust the properties of the fluid to be injected into the remediation site. Thus, a portion of air stream F 20  may directed by a splitter  232 , and diverted as a by-pass flow F 28  directly to mixer  637  for combination with fluid stream F 78 . The ratio of exit fluid F 10 , coolant F 40 , F 42  and F 44 , and oxygen-containing fluid or air F 20  and F 28  are preferably controlled to produce a tailored remediation fluid F 62  for delivery to the remediation site to assist in recovery and extraction of contaminated or contaminant fluid. 
       FIG. 2  illustrates a remediation system  2 B which utilizes a heat recover system  700  of any suitable or desired construction, such as a Heat Recovery Steam Generator (HRSG). Here, product or combustor exit fluid F 10  transfers heat to the coolant stream F 46  delivered by splitter  432  to produce a hot fluid F 70 . This may be additional steam beyond that which is provided by combustor  100 . It may be mixed with bypass oxygen-containing fluid F 28  in mixer  637 . 
     Further according to  FIG. 2 , the cooled combustor exit stream F 72  from URSG  700  is delivered to a liquid separator  660 . Here, the coolant and/or other condensibles are separated to provide a liquid stream F 68  and a stream of gaseous components F 67 . A portion F 47  of condensate stream F 68  may be removed from the system through a splitter  434 , with a remainder stream F 48  being recycled into the remediation system via a pump  416 . This may be combined with water from an external source F 40  in mixer  436 . A portion of this coolant flow is directed through splitter  432  to form stream F 42  to cool the combustion process in combustor  100 . The remainder coolant fluid F 46  is delivered to the HRSG  700  to recover heat from combustor exit fluid F 10 . 
     All or part of gaseous stream F 67  from the liquid separator  660  may be returned to the remediation site as part of remediation fluid F 62 . For this purpose, a flow path is provided through splitter  632  and mixer  638 , as in  FIG. 1 , and bleed flow F 79  vents any excess from splitter  632 . The additional steam or other heated diluent F 70  from the HRSG  700  is optionally mixed with the bypass oxygen-containing stream F 28  as previously noted, and the resultant fluid F 69  is then mixed with gas stream F 78  in mixer  638  to form remediation fluid F 62 . Addition of the oxygen-containing fluid F 28  permits tailoring the properties of remediation fluid F 62 , if desired. For example, by varying the oxygen/steam radio based on contaminant composition, improved contaminant extraction efficiency can be achieved. 
     Still referring to  FIG. 2 , incoming oxidant fluid F 20  may be pressurized using a blower or compressor  220 . This increases the gaseous fluid pressure through the entire system. The compressor is preferably controlled to increase the fluid pressure of remediation fluid F 62  sufficiently for efficient injection. 
     In the remediation system  2 C shown in  FIG. 3 , blower or compressor  690  is placed downstream of combustor  100  and HRSG  700 . Compressor  690  compresses the tailored fluid F 69  from mixer  637 , which may include the cooled gaseous fluid F 78  and bypass oxygen containing fluid F 28 . Once compressed, the gaseous flow F 64  may be mixed with heated diluent/coolant flow P 70  from the HRSG  700  in mixer  638  to form a pressurized remediation fluid F 62 . 
     At least a portion F 24  of oxidant fluid F 20  is drawn into combustor  100 , optionally through a splitter  232 . Any gaseous component F 52  of the effluent fluid is controllably delivered into reactor  100  using compressor  510 . Any liquid component F 56  is controllably delivered using pump  515  as fluid F 58 . Liquid diluent F 40  is controllably delivered using pump  410  via mixer  436  and splitter  432  with a portion to reactor  100  as F 42  and another portion F 46  to heat recovery system  700 . After reacting fluids in reactor  100 , heat is recovered from exit fluid F 10  in heat recovery system  700 . Condensate F 68  is then separated from the cooled product fluid F 72  in separator  660  using pump  416 . A portion of condensate F 68  is preferably returned to the combustor  100  and heat recovery system  700  via splitter  434 , mixer  436  and splitter  432 . Another portion F 47  may be removed from the system by discharging it into the remediation site or into the environment. A portion F 79  of the cooled separated fluid F 67  may be removed from the system using blower or compressor  685  with another portion F 78  delivered to the remediation site. 
       FIG. 4  illustrates another preferred embodiment  2 D which uses both a heat recovery system  700  and a cooling chamber  650 . In this embodiment, combustor exit fluid F 10  is split between the HRSG  700  and a cooling chamber  650  via splitter  630 . 
     The incoming water stream F 40  fed through pump  410  and mixer  436  is delivered to the HRSG  700 , and preferably to one or both of combustor  100  and or cooling chamber  650 . e.g., by using splitters  432  and  439  or the equivalent. As in  FIG. 1 , the portion of combustor exit fluid that is delivered to the cooling chamber  650  is preferably diluted or cooled with a portion of coolant F 41  such as water. In some embodiments, the coolant is changed to vapor and/or entrained or mixed with the diluted exit fluid to form diluted fluid F 63 . The fluid stream F 63  from cooling chamber  650  may be mixed with the gaseous stream F 67  from liquid separator  660  downstream of the HRSG  700 . 
     The use of both the HRSG  700  and a cooling chamber  650  permits use of a smaller HRSG with consequent improved cost efficiency for recovering heat for use in the remediation process. In some instances, with the reduced size of the HRSG greatly reduces the cost of the system. The heated diluent F 70  from HRSG  700  may be mixed with a portion F 28  of oxidant fluid F 20  delivered by blower or compressor  220  via mixer  637 . e.g., steam and air. This heated diluent flow is preferably mixed with the portion of fluid F 63  to form the tailored remediation fluid F 62 . Some of the heat recovered portion F 78  of product fluid F 72  may be mixed with the remediation fluid F 62  via splitter  632 , and mixer  638  to further modify tailored remediation fluid F 62 . The remainder of the heat recovered product fluid F 79  is preferably discharged to the environment. 
     In the embodiment shown in  FIG. 5 , generally denoted at  2 E, the effluent stream F 51  is delivered by a pump,  517 , into a separating system,  550 . Here, the effluent stream F 51  is cooled and at least partially condensed using a heat exchanger. A portion of any solids present may be removed in any suitable or desired manner. The remaining fluid is then preferably separated into several components, including a gaseous component F 52 , an aqueous component F 57 , and a substantially non-aqueous component F 56 . 
     Gaseous stream F 52  may be comprised of a combustible gas such as methane or other hydrocarbons, and nitrogen, carbon dioxide and argon, e.g. when these are injected into the ground as part of remediation fluid F 62 . Aqueous component F 57  comprises at least some water and possibly contaminants and/or dissolved solids. Non-aqueous component F 56  is predominantly comprised of liquid contaminants, and may include some water. 
     The gaseous component is treated as necessary in separating system to remove selected chemical components before delivery as gaseous stream F 52 . This is pressurized by blower or compressor  560 , and delivered to combustor  100  as a compressed gas stream, F 54 . 
     The non-aqueous liquid component is treated as desired, is released as non-aqueous liquid F 56 . This may be further pressurized by pump,  511 , if desired, and preferably injected into combustor  100 , as reactant fluid F 58 . e.g., to provide destroy the contaminant and to provide fuel to the combustion process. 
     A portion F 471  of the aqueous liquid stream F 57  may be returned to the remediation site or discharged to the environment as desired. If needed, the portion F 471  of the water stream leaving splitter  430  may be treated to remove additional chemical components, and if compliant with environmental standards, may be released to the environment. The remainder of the aqueous stream F 430  may be pumped by a liquid diluent pump  410  to form a water stream F 431  having a pressure sufficient to inject the stream into one or more of: the combustor  100  as F 42 , or the liquid injection pressure into the contaminated site as F 47 , or the water injection pressure into cooling chamber  650  as F 435 . This pump pressure includes whatever additional pressure is needed to overcome any pressure losses that occur as this fluid passes through any intervening pipes and equipment. 
     Condensate F 41  from condenser  660  may be mixed in mixer  433  with makeup water F 95  pressurized by pump F 96  to form pressurized diluent or water F 97 . This diluent or liquid water flow F 97 , is preferably supplied through a splitter/mixer  436  as Flow F 432  to pump  411 . A flow of aqueous fluid may also be transferred to/from between mixer/splitter  430  and mixer/splitter  436 . Some of water stream F 431  may be sent to combustor  100  through splitter  431 , mixer  437 , and splitter  438 . A further portion of water stream F 431  may be delivered for injection into the contaminated site as part of fluid stream F 47 , through splitter  431 , and mixer  435 . The remainder is delivered to the cooling chamber  650 , through splitter  431 , mixer  437 , splitter  438 , and mixer  439  as part of water stream F 435 . 
     Some of the water stream F 432  leaving mixer  436  may be pressurized by liquid pump  411  and raised to a pressure equal to at least the gas injection pressure of remediation fluid F 62 , plus additional pressure to overcome any pressure losses that will occur as this fluid passes through any intervening pipes and equipment. The pressurized water F 433  is then sent to an economizer and/or condenser  715 . 
     In some embodiments, a makeup fuel F 32  may be supplied to combustor  100 , pressurized as needed by a pump  310 . The oxidant stream F 20 , which may be ambient air, oxygen-enriched, if desired, or which may even be pure oxygen, is compressed, as necessary, by blower or compressor  200 . This pressurized oxidant fluid F 22  preferably has a pressure equal to at least the gas injection pressure of remediation fluid F 62  plus additional pressure to overcome any pressure losses that will occur as this fluid or any of its reaction products pass through any intervening pipes and equipment. At least a portion of this pressurized oxygen-containing fluid F 22  is delivered as P 24  to combustor  100  through splitter  231 . The rest may be delivered through bypass mixer  637 , and splitter  231 , as bypass stream F 28 . Also, vaporized water stream F 74  may be sent to combustor  100  from splitter  734 . 
     In some embodiments, the fluids entering combustor  100  react to produce the hot exit gas stream F 10 , which contains combustion reaction products and may comprise non-condensible gases such as N2, O2 and Ar, as described above. This is delivered through splitter  630  to a cooling chamber  650  as gas stream F 11 , where it is mixed with a vaporized water stream F 771  from HRSG evaporator/superheater  725 . The hot fluid F 11  is preferably mixed and cooled with water stream F 435 , from mixer,  439 , resulting in a lowering of its temperature and typically, formation of at least some additional steam. In some embodiments, sufficient water is added to provide a liquid phase as well. From cooling chamber  650 , the resulting cooled fluid stream F 63  may be sent to liquid separator  660 , through mixer  636 , as fluid stream F 66 . 
     In some embodiments, part of the combustor exit stream F 10  is delivered through splitter  630  to an HRSG evaporator/superheater,  725 , as gas stream F 71 . There, heat is extracted which lowers its temperature and provides heat for transfer to the diluent or water stream F 77 , which is vaporized and/or possibly superheated to produce vaporized diluent stream F 70 . e.g., steam. Some of this hot vaporized diluent is delivered to cooling chamber  650  as heated or vaporized diluent stream F 771  (e.g., as steam or hot water), and some may be sent to combustor  100 , through splitter  734  as a vaporized coolant stream F 74 . Optionally some of this heated diluent may be discharged from 725 as an outlet stream F 75 , 
     Gas stream F 73  leaving the HRSG evaporator/superheater  725  is preferably sent to an HRSG economizer and/or condenser  715  where further heat is recovered to lower its temperature further and at least partially condenses to produce cooled fluid stream F 72 . At least some of the extracted heat is transferred to liquid water stream F 433  to raise its temperature. Part of the resulting hot liquid coolant F 76  passes through splitter  730  and splitter  732  to form hot liquid streams F 761  and F 762 . The remainder of liquid stream F 76  from splitter  730  goes to the HRSG evaporator/superheater  725  as hot liquid stream F 77 . 
     In some embodiments, the cooled fluid stream F 72  leaving the HRSG economizer/condenser  715  is mixed with a cooled fluid stream F 63  leaving the cooling chamber  650  in mixer  636  to form a cooled fluid stream F 66  for recycling or disposal. Alternatively, the output of  650  may be delivered to mixer  638 . Stream F 66  may be sent to a liquid separator,  660 , from which condensate or liquid water is delivered as stream F 41 , and cooled gas is delivered as stream F 67 . The water stream F 41  may be mixed in mixer  433  with an additional water stream F 95  which is optionally pressurized by pump  409 . 
     In some embodiments, at least some of the cooled gas stream F 67  leaving liquid separator  660  may be treated to remove residual chemical components and may then be discharged through bleed splitter  632 , either directly or through exit blower  780  as discharge flow F 79 . Some of the cooled gas stream F 78 , leaving the splitter  632  may be mixed with the bypass air stream F 28  in mixer  637  to form stream F 69 , which may be compressed by remediation injection compressor  690 . 
     The resulting fluid stream F 64  is mixed with vaporized water F 12 , to form the remediation fluid F 62  for injection into the contaminated site. 
     Other embodiments may include a work unit to use at least a portion of the energy from the reaction process to produce work. The system  2 G in  FIG. 7  illustrates embodiment using an expander  600  to expand a stream of combustor exit fluid F 15  produce mechanical work on shaft  852 . 
     A further embodiment may include an expander-compressor shaft  850  to transfer work to the compressor  220 . This work may be used to compress the air stream F 20 . 
     A portion of the compressed air stream F 24  is used in combustor  100  and the resulting exit fluid F 10  may be split via one or more splitters F 630  and F 633  to form one or more streams F 17  and F 15  such that at least a portion of the hot product fluid goes to the expander  600  from splitter  633 . 
     Once the fluid is expanded in the expander  600 , in some embodiments, the expanded fluid F 16  may be delivered to mixer  634  where further heat may be recovered in the HRSG evaporator/separator  725 . 
     In another embodiment, the work from the shaft  852  may be delivered to an alternator  800 . The electrical energy from this alternator  800 , may be used to supply energy to the pumps or other equipment of the system that require electrical energy. In another embodiment, this electrical energy may be used for energy requirements external to the remediation reaction system. This may also be used to generate further revenue, reducing the cost of system operations. 
     Further work producing embodiments may be configured as known in the art or as described in published U.S. published Patent Application 2004/0238654 or PCT International Application WO 2004/065763. 
     Referring still to  FIG. 5 , control of the delivery of diluent to combustor  100 , cooling chamber  650  and/or economizer  715 , is an important factor in controlling fluid mass, volume, composition, and temperature of the remediation fluid F 62  and the fluids released to the environment. This is relevant to the other described embodiments as well, and to the delivery of non-aqueous diluents, such as for non-combustion reaction processes. 
     One or more of the mass flow, temperature and/or ratio of gaseous and liquid flows of water or other diluent are preferably controlled to provide temperature control. In system  2 E of  FIG. 5 , water flow is preferably controlled by controlling splitter  731  in the heated diluent exit stream from evaporator  720  and/or a splitter  730  in exit stream F 76  of economizer  715 . Electrically, hydraulically, or pneumatically controlled valves may also be used for this purpose. 
     Water delivery may also be controlled after separation of the aqueous component of the effluent stream from the remediation site such as after a separator  550  (see  FIG. 5 ). The ratios between at least two of these diluent streams upstream of combustor  100  are preferably controlled to control the temperature, composition, and/or flow rate of fluid F 10  exiting the combustor. 
     Coolant flow to cooling chamber  650  is used to control temperature and/or composition of the remediation fluid F 62 . Liquid or vaporized water may be controlled and injected to control the temperature of the remediation fluid F 62 , or of a hot fluid F 75  delivered to site, to improve or optimize the recovery of contaminants. 
     Water delivery into the remediation site is used to replace at least some and preferably all the volume of effluent fluid removed from the site and/or to dispose of diluent and/or condensate that has been collected in the remediation process. Excess diluent may be separated and released into the environment. This may be used to maintain the material balance within the remediation process and/or in the remediation site. 
     Further details concerning diluent control may be found in U.S. Pat. Nos. 6,289,666B1 and 6,564,556B2 and PCT/US99/05271 and WO99/46484 and published US Patent Application 2004/0238654. 
     As previously noted, a feature of the invention is use of components of the removed contamination as in the remediation process, along with make-up reactant, as necessary. For combustion, the flow of fuel to combustor  100  should be controlled relative to the delivered oxygen to provide stable combustion. Pumps and/or compressors, optionally with flow controls, may be used for this purpose. 
     Makeup reactant or fuel may be needed to provide better combustion (or for a non-combustion process) when the heating value of the contaminant used for the primary reactant is not great enough to raise the temperature of the reaction as high as required for the desired remediation. Makeup fuel may also provide heat for transfer to water in cooling chamber  650  to produce additional steam beyond what can be provided by combustion and water injection to combustor  100 . 
     In embodiments combusting hydrocarbons in the reactor, this makeup fuel may be liquid fuel (such as diesel oil, bunker oil, jet fuel, etc) and or gaseous fuel (such as methane, natural gas, etc). This may be provided through a pump  310  from a source F 30 . 
     A second reactant for the reaction process (e.g., air, in the case of combustion) may also be controlled to provide needed cooling. With the addition of diluent for cooling, the co-reactant may be controlled to near stoichiometric ratios to improve the efficiency, net power, and/or to minimize the cost of the remediation process. This may readily be achieved in a VAST combustion system using controlled valves and one or more microprocessors or controllers. 
     Additional makeup fuel flow F 58  can be provided to compensate for fluctuations in heat released by combustion of fuel stream F 52 . Fuel stream F 58  is preferably controlled to maintain the combustor temperature within a prescribed temperature range. This temperature range is preferably selected with a lower temperature sufficient to adequately destroy the contaminants delivered to the reactor  100  while constraining the temperature to not greater than an upper temperature to limit formation of byproduct emissions such as NOx. 
     Referring to  FIG. 6 , in remediation system  2 F, heat from combustor exit fluid F 10  is recovered through a heat recovery system  1000  comprising an evaporator or boiler  720  (preferably including a superheater), an economizer  710 , a condensor  640  and a liquid separator  660 . The heat recovery system  1000  transfers heat to a gaseous fluid F 70  and/or a hot liquid F 76 , such as steam and/or hot water. This heat recovery system preferably recovers liquid diluent F 411  from the gaseous downstream exit fluid F 66  after heat has been recovered from the portion F 71 , e.g., as warm to cool water F 411 . 
     This warm water F 411 , is preferably pressurized by a pump  415  to form pressurized coolant F 412  for delivery back through heat recovery system  1000 . e.g., to the condenser  640  and/or economizer  710  to form a warm or hot water flow F 611  and/or F 76 . A portion F 77  of the hot water F 76  is preferably separated and delivered to the evaporator  720 . Another portion F 42  of the hot water F 76  is preferably delivered to the reactor  100  to help control one or more of the reactor temperature, the temperature of the reaction, and/or the temperature of the hot product fluid F 10 . 
     Where the diluent or water stream F 47  is sufficiently hot to be beneficially mixed with the compressor exit gas F 12 , this is done in the dilution or cooling chamber  650 . 
     Excess hot water F 47  is preferably delivered to the remediation site, or it be discharged to the environment. 
     The cooled portion of the combustor exit fluid may be discharged or bled to the environment as a Bleed Fluid F 79  to balance the overall non-condensible flows within the remediation system, e.g. discharging a portion of the nitrogen, argon, carbon dioxide and possibly excess oxygen. Under startup conditions or as desired, the flow F 79  may be controlled to deliver a larger portion or all of the non-condensibles to the remediation site. Conversely, near the end of the project or as desired a smaller portion or none of the non-condensibles may be delivered to the remediation site. The flows F 62  and/or F 79  may be controlled to give fluctuating or pulsate flows to enhance contaminant recovery in some conditions. 
     Fluid stream F 11  from splitter  630  is preferably used as the primary source for remediation fluid F 62 . This is preferably mixed with at least a portion of hot gaseous diluent fluid F 70  or steam from heat recovery system  1000  to provide the desired steam volume and fluid temperature. The resultant fluid F 12  may be further cooled, if necessary, by mixing a portion of water F 44  separated from the extractant fluid F 51 . Hot water F 761  from a splitter  440  downstream of the economizer  710  may also be used. 
     A contaminant or extractant fluid F 51  comprising mobilized contaminants, is preferably extracted from the remediation site. This may be assisted by a pump  517  to form a pressurized or compressed contaminant fluid F 54 . 
     The effluent fluid F 51  generally comprises one or more gaseous, liquid, and solid components and mixtures thereof, as previously described. These may include steam, water vapor, water, non-condensible gases, dissolved entrained or suspended solids, and contaminants. The contaminants may comprise one or more of hydrocarbons, halogenated compounds, oxygenated hydrocarbons, and nitrogen comprising compounds or fertilizers. 
     With further reference to  FIG. 6 , in this configuration, effluent fluid P 51  recovered from the remediation site is preferably separated into multiple separated fluid streams of differing density using a centrifugal separator system  555  or any other suitable separation system. A settling tank may be used to separate fluid stream F 51  into multiple phases generally comprising a plurality of a gaseous fluid, a light liquid phase, a medium liquid phase, a dense liquid phase, and solids. 
     Preferably, the separator system  555  comprises one or more centrifuges to separate the extractant fluid into multiple partially or fully separated fluids based on density. More preferably, separator system  555  comprises at least one decanter centrifuge capable of separating a composite fluid into three streams based on density. e.g., into a light fluid, a medium fluid and a dense fluid and/or a solids stream. Similarly, the decanter may form a medium fluid, dense fluid and solids stream. 
     The separated streams F 85 -F 89  are preferably treated in separate treatment units. These may include a gaseous fluid treatment system  952 , a light fluid treatment system  954 , and medium fluid treatment system  956 , a dense fluid treatment system  958 , and a solids treatment system  960 . In some applications, a gaseous fluid comprising non-condensibles is generally recovered as the lowest density stream. Where the contaminants include components which have a relatively high vapor pressure (low boiling point), the gaseous component will comprise a portion of these high vapor pressure compounds. Where this concentration exceeds prescribed emission rates, this light contaminant gaseous fluid is preferably treated in a gaseous fluid treatment system  952  to reduce these contaminants to satisfactory levels. 
     In some applications, the gaseous fluid treatment system  952  may comprise an activated absorption system such as activated carbon or an activated mineral. E.g., this may be useful where the gaseous fluid comprises a small fraction of volatile contaminants that are readily absorbed. 
     In other applications, gaseous treatment system  952  preferably cools or chills the gaseous separated fluid F 85  to condense and separate out a portion of the contaminant using a direct contact condenser, a chiller, or refrigerator as appropriate to the desired cooling temperature. 
     Heat from cooling the light separated fluid F 85  is preferably transferred to a heat exchange fluid for subsequent use in heating other combustor components, such as air F 22  and/or water F 411 . Where the heat exchanger fluid is water and is sufficiently hot, it is preferably delivered to a mixer  639  or cooling chamber  650  to mix in with the combustor exit fluid F 11 . 
     Where the resulting chilled gas stream satisfies emission limits, a portion F 80  is preferably discharged to the atmosphere. Such discharge F 80  facilitates controlling buildup of non-condensibles within the remediation system, and may be desirable with heavier hydrocarbons or with lighter fuels where a portion of the volatile hydrocarbon fraction has already evaporated. Such discharge beneficially avoids having to further treat the extracted non-condensibles through the reactor  100  thereby reducing the flow through the reactor by about half in some instances. This also eliminates the need to heat fluid P 80 , and avoids loss of heat in non-condensible discharge or of recovering heat from the non-condensibles downstream of the combustor. 
     Any condensed contaminant is preferably recovered and may be further treated as appropriate to its composition. 
     The residual treatable (combustible) contaminant stream F 52  is preferably delivered to combustor  100 . If treatment system  952  is not used, gaseous contaminant fluid F 85  may be delivered directly to combustor  100 . 
     Where condensed contaminant stream F 36  may be used as a fuel, it is preferably delivered to a fuel buffer tank  340  from which a controlled makeup fuel F 56  is pressurized by pump  511  and then delivered to the reactor  100  as pressurized makeup fuel F 58 . This light fuel may be further supplemented by makeup fuel F 38  from a light fluid treatment unit  954  as described below. 
     In configurations where treatment  952  by condensation or chilling is insufficient to separate out contaminant below prescribed emission limits, the gaseous fluid is preferably delivered to the reactor  100  for treatment, either as a treated contaminant comprising gas F 52 , or directly as the separated contaminant comprising gas F 85 . 
     In some applications, the separated gas P 85  may comprise halogenated compounds that exceed emission limits. In such configurations, the separated gas treatment  952  is designed and constructed to accommodate the halogenated compounds. For example, trichloro ethylene is preferably delivered to a reactor where the light halogenated compounds are reacted with a co-reactant such as oxygen in air or oxygen enriched air. The resulting halide acids may be preferably scrubbed with alkaline solution or slurry to reduce acidic halide emissions. This process may be combined with that of treating a dense liquid phase. 
     The light fluid component F 86  separated in separator  555  often comprises hydrocarbons less dense than water. This may include substantial quantities of hydrocarbons that may be beneficially used as fuel. For this, a light fluid treatment unit  954 , is preferably used to separate out suspended solids. This may be a filter or more preferably a centrifuge. 
     In applications where the aqueous component F 87  has little dissolved solids, the light to medium fluid separation performed in separator  555  is preferably adjusted to recover a desired fraction of the light fluid F 86 . This separation may include a small portion of the medium or aqueous phase sufficient to achieve the desired degree of light liquid recovery. 
     The treated light fluid F 38  may be delivered to the buffer fuel tank  340  for use as part of makeup fuel F 58  as described above. Excess treated hydrocarbons may be recovered as flow F 34  for other applications. 
     In some applications, the light fluid component F 86  may be contaminated with one or more of salts, salt water, or water with dissolved solids. Sometimes it is desirable to use the recovered hydrocarbon F 38  for fuel and to reduce slag accumulation or hot section corrosion. In such cases, light fluid F 38  may be further treated by washing with clean water to reduce salt concentrations, especially sodium and chloride ions. This may be done using condensate or water recovered from cooling a portion of the product fluid F 71  in a condenser  640  and/or separator  660 . 
     For applications which require a fuel without water, the washed hydrocarbon may further centrifuged to separate out an aqueous portion and reduce the residual aqueous content. Where the contaminant level in removed aqueous portion is too high to permit discharge, the separated aqueous phase may be returned to the separator system  555  for further processing. 
     A separated medium density liquid component F 87  is preferably delivered to a medium density liquid treatment system  956 . The component will typically be an aqueous phase possibly comprising undesirably high levels of dissolved and/or entrained solids. This medium liquid F 87  is preferably centrifuged to separate out any solids, which may then be discharged as F 82 . For example, these may be returned in a slurry to the remediation site. The treated aqueous phase fluid F 44  is preferably delivered to a cooling chamber  650  where it is used to cool a portion of the hot product combustor exit fluid comprising FP 0 , F 1  and/or F 12  downstream from the combustor. 
     In some cases, the medium density liquid F 87  may comprise combustible contaminants but negligible solids. In such situations, the contaminant medium density aqueous fluid F 44  may be delivered to the combustor  100  to destroy the combustible contaminants. 
     In other cases, the medium density liquid F 87  may comprise combustible contaminants and dissolved solids. In such configurations, the liquid is preferably injected into the combustor  100  with sufficient makeup fuel F 58  as needed to combust or react the contaminants. 
     In some cases, there may also be a higher density liquid component F 88  separated in  555 , which is preferably delivered to a high density liquid treatment system  958 . The dense fluid F 88  may comprise a halogenated compound. In such configurations, the dense fluid is preferably delivered to dense fluid treatment system  958  as required. 
     For solid components F 89  separated from the extractant fluid, when high density liquids are also present, the solids F 89  may be further treated in a solids treatment system  960 . 
     Solids with residual dense fluid F 89  may be heated to evaporate the dense fluid. The dense fluid vapor may be separately condensed and recovered. The recovered dense fluid vapor is preferably delivered to a dense fluid treatment system  958 . 
     The separated and treated solids F 84  may be discharged, preferably to the remediation site. This may be conveniently accomplished by merging them with any solids discharged from the light fluid treatment F 82 . 
     The remediation system is preferably configured or controlled such that the flow of the cooled fluid comprising non-condensibles discharged to the environment F 79  is similar to that of the noncondensible gases in the effluent fluid F 52  that are separated and delivered to the combustor  100 . Where the noncondensible gas flow is controlled, the control is preferably provided by a valve at the gaseous discharge outlet from the heat recovery system  1000 . e.g., the separator  660 . These discharge flows may be negligible on startup, but increase to about half the total flow from the reactor under steady state operations (normalized for temperature.) At end of operations, the flow F 62  to the site may be shut down while continuing to pump residual gas comprising fluid from the remediation site. 
     In some applications, the carbon dioxide formed by a combustion reaction may be sequestered underground while the remaining fluid flows may be balanced. 
     In highly recycled remediation processes, critical material and energy flows are preferably balanced within the system to avoid accumulating gases in the reaction system or the remediation site, and to avoid other instabilities. This may put some additional constraints on the selection of design variables that may not otherwise be obvious. e.g., while the contaminated site may not be a closed system, non-condensible gas flows within the remediation system and the contaminated site are preferably balanced on the average. This helps avoid a potentially disruptive or explosive gas buildup. It further helps to reduce pumping work. 
     More preferably, the net liquid volumetric flows to and from the site and within the remediation system should be balanced. This provides the further benefit of reducing the tendency to push contaminant or water containing contaminant outward from the original contaminated region. 
     Most preferably, material flows for all atomic species and energy flows are balanced over all the streams entering and leaving the combined system of the remediation system and the contaminated site. Writing the material balances at this level provides guidance for important flow and power controls. 
     With reference to  FIG. 5 , in one embodiment, there are eight unknown variables in six overall material balances if a material flow balance for water and non-condensibles is desired for the combined remediation site system, including the remediation system and the contaminated site. (e.g., this would increase to 10 unknowns and eight material balances if hydrogen and carbon and a hydrocarbon contaminant were included.) 
     That means, on an overall basis, that if two material balances are preferably specified or else calculated from any other combination of design variables, then the overall material balances preferably determine all the rest of these unknown variables no matter what the details of the internal process are. This fact restricts the choice of preferred design variables under average conditions, except for startup and shutdown or pulsating flows. 
     Furthermore, these preferred design restrictions are even more stringent, because not all of these variables appear in all the overall material balance equations. Each of the rows in the following table corresponds to one of the material balance equations. The columns refer to a particular unknown variable. The X&#39;s denote the appearance of a variable in an equation. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 A Flow Balance Variable Matrix 
               
             
          
           
               
                   
                 Mass of Fluid 
                 Mass of 
                 Mass of 
                   
               
               
                   
                 Entering 
                 Fluid 
                 Fluid 
               
               
                   
                 contaminated 
                 Exiting 
                 Exiting 
                 Mole Fraction in Fluid returned to the 
               
               
                   
                 site from 
                 HRSG into 
                 430 into 
                 contaminated site 
               
             
          
           
               
                   
                 Envir. 
                 Envir. 
                 Envir. 
                 O2 
                 N2 
                 H2O 
                 CO2 
                 Ar 
               
               
                   
                   
               
             
          
           
               
                 O2 
                 X 
                 X 
                   
                 X 
                   
                   
                   
                   
               
               
                 N2 
                 X 
                 X 
                   
                   
                 X 
               
               
                 CO2 
                   
                 X 
                   
                   
                   
                   
                 X 
               
               
                 Ar 
                 X 
                 X 
                   
                   
                   
                   
                   
                 X 
               
               
                 H2O 
                   
                 X 
                 X 
                   
                   
                 X 
               
               
                 Mole 
                   
                   
                   
                 X 
                 X 
                 X 
                 X 
                 X 
               
               
                 Fraction 
               
               
                   
               
             
          
         
       
     
     As Table 1 shows, not all variables appear in all equations. For example, only three unknown variables appear in the CO2 equations. Thus, if one of these is fixed, then another variable may also be fixed by the preferred overall material balance. Such a fixed parameter is no longer available to be chosen as an independent design variable for steady state operation. This may cause other variables to become fixed because of other preferred steady state material balance equations that may now contain only one unknown variable. Prescribing or controlling a potential design variable may take place by direct choice. It may also be achieved by prescribing or controlling some combination of other design variables such that there is some equation that has only one potential design variable as an unknown. The overall material and energy balance equations are among the most likely to be in that category. 
     As should be clear from this discussion the desired choice of design variables is important in the analysis of such a preferred steady state process. 
     An exemplary VAST remediation process is demonstrated in a flow chart shown in  FIG. 8 . 
     At step S 1 , oxygen-containing fluid is pressurized and delivered to the combustor. At step S 2 , the combustible pollutants are delivered to the combustor, and burned to produce steam and to destroy the pollutants. Additional makeup reactant or fuel may be used to maintain reaction stability. Diluent is preferably used to adjust the temperature of a portion of the combustor exit fluid to within a desired range. This reaction or combustion typically produces a combustor exit fluid comprising products of reaction, vaporized diluent and non-condensible gases. 
     At step S 3 , remediation fluid is injected into the contaminated site. Additional water is added, as necessary, to control the remediation fluid temperature to within a desired temperature range. At least a portion of the exit fluid is mixed with hot water as needed, producing further steam. The resultant hot treatment fluid comprising products of reaction and diluent is then injected into the contaminated site. 
     At step S 4 , the soil is heated with treatment fluid to mobilize pollutants. At least a portion of the hot remediation fluid passes through the soil to heat the contaminants, mobilize them, and carry them to extraction wells. 
     At step S 5 , an effluent fluid comprising liquid and/or vapor contaminant is recovered from the contaminated site. This commonly comprises water, and may comprise non-condensible gas including one or more of nitrogen, oxygen, carbon dioxide and argon. 
     At step S 6 , the effluent is preferably separated into gaseous and residual fluids. In one embodiment, the extracted mixture is preferably separated into a gaseous fluid comprising gases and/or vapor, and a residual fluid comprising diluent and contaminant liquids and any dissolved materials and/or solids entrained in the extractant flow. 
     At step S 7 , liquids are condensed from the extracted vapor. The gaseous stream is preferably cooled in a condenser to liquefy a portion of contaminants and/or diluent from the gaseous stream. A direct contact condenser using a cold diluent, e.g., water, is preferably used to condense out these liquids. This preferably uses a heat pump to recover the exchanged heat and deliver it to the remediation site. 
     At step S 8 , entrained liquid is extracted from the gaseous extracted fluid and delivered to a condensed liquid buffer tank. e.g., using a mist eliminator or centrifuge. 
     At step S 9 , residual fluid comprising recovered liquids is preferably separated into multiple liquids, and optionally residual solid stream, based on density. 
     One or more contaminant fluids are preferably delivered into one or more buffer tanks, while the residual diluent fluid may be delivered back to the separator chamber, to fluid discharge, or to a solids discharge. e.g., separating one or more of a Dense Non-Aqueous Phase Liquid (DNAPL such as a predominantly chlorinated compound which may comprise other components), an aqueous phase that may comprise other components, and Light Non-Aqueous Phase Liquid (such as a predominantly hydrocarbon fluid that may comprise water) and storing them in one or more buffer tanks. Further liquid that has been cooled and condensed in step S 7 , then separated from the vapor/gaseous stream in step S 8 , may be added to at least one of the buffer tanks. 
     At step S 12 , liquid contaminant separated from extracted fluid is preferably pumped to the combustor. 
     At step S 14 , makeup fuel and/or water are mixed in or sprayed along with the contaminant liquid being delivered to the combustor. The flow rates for makeup fuel and water are preferably controlled relative to the delivered oxygen and contaminant liquid to keep the reaction stable and/or provide further heat sufficient to react the contaminant to a desired degree. 
     At step S 11 , extracted vapor/gas remaining after condensing and extracting the condensibles and liquids ( 8 ,  9 ) is delivered to the combustor and its contaminants are burned. Non-pollutant components may be discharged to the environment. 
     At step S 13 , prior to delivery into the combustor, the gaseous/vapor fluid may be mixed with air and/or makeup fuel to help keep the reaction stable and/or provide further heat. 
     After combustion in step S 2 , a portion of the reaction product stream is preferably injected into the soil at step S 3 . At step S 15 , a portion of the reaction product stream may be removed and treated for any remaining pollutants before being used for other purposes, and/or a portion may be exhausted in step S 19 . 
     At step S 16 , after treatment, pollutants removed from the effluent fluid are discharged or disposed of as appropriate. 
     Step S 17 , is configured or controlled as to whether water should be recovered or not. 
     Step S 18  preferably includes heat recovery and water condensation. Heat is preferably recovered from a portion of the exit fluid comprising reaction products. Water is preferably condensed and separated from the predominantly non-condensible fluid portion. 
     At step S 19 , a portion of non-condensible fluid is discharged from the remediation system to help balance fluid flows. Non-condensibles may be discharged after the combustor, but more preferably after recovering heat from at least a portion of the exhausted gas, non-condensibles may be discharged upstream of the reactor after separating them from the extractant fluid and preferably after removing any contaminants. Alternatively, non-condensibles may be removed from oxidant fluid such as air and be discarded before processing. 
     At step S 20 , water condensed from the heat recovery system is preferably filtered and stored. 
     At step S 21 , liquid water and/or steam is delivered to the combustor and/or mixed with one or more of the fuel, oxygen containing fluid and combustor exit fluid to cool them and prevent formation of pollutants. 
     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. For example, the splitters herein may comprise simple openings or bifurcations in a fluid duct, or they may form valved outlets, or they may be actively controlled diversion between two or more flows. It is intended, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.