The present invention relates to a waste processing system for and method of processing waste product, such as municipal solid waste (MSW) and processed waste, for example, refuse-derived waste (RDF), including human waste, waste which contains organofluorines, such as perfluorocarbons (PFCs), including perfluoroalkyl and polyfluoroalkyl substances (PFAS), such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS), and also fluorinated gases (F-gases). The waste product can be a solid, liquid or gas, or combinations thereof, and can be supplied in many forms, for example, sludge, plastic and biomass, and includes tires and flooring material and tiles.

PFAS are substances having a chain of linked carbon and fluorine atoms, and, because the carbon-fluorine bond is one of the strongest, these substances are recalcitrant and not easily degraded.

Waste product typically contains a significant percentage of water, which gives rise to problems in processing, especially in systems using high- temperature combustion. The present inventors have, however, recognized that this contained water can advantageously be employed in processing of the waste product itself, in that the contained water can be extracted to provide for supercritical oxidation or combustion.

In one configuration the contained water can be extracted to generate supercritical water, and this supercritical water can be utilized for supercritical water oxidation (SCWO), which has been found to reduce the PFAS content by greater than 99% (Krause et al, Supercritical Water Oxidation as an Innovative Technology for PFAS Destruction, Journal of Environmental Engineering, 148, 10.1061/(ASCE)EE.1943-7870.0001957). The PFAS content of the waste product would otherwise have to be converted thermally at high temperature, typically above 1200 C, and moisture arising from water in the waste product would have to be carefully regulated. In another configuration the contained water can be extracted to generate superheated steam, which can be utilized in supercritical combustion. Supercritical combustion is a controlled detonation technique exhibiting low viscosity, high heat transfer, low surface tension, and, in turn, yields high combustion efficiency, high temperature output and reduced pollutant formation. As with supercritical water oxidation (SCWO), supercritical combustion can reduce the PFAS content by greater than 99%.

In one aspect the present invention provides a waste processing system, comprising: a drying chamber which includes a cavity which is supplied with waste product and heated to dry the waste product and generate steam, optionally flash steam, optionally the drying chamber is supplied with a heated gas, optionally recirculated exhaust gas, to heat the waste product; a gasification chamber which includes a cavity which receives the waste product from the drying chamber and in which the waste product is heated to generate synthetic gas or syngas within a gasification zone, optionally the gasification chamber is supplied with a heated gas, optionally recirculated exhaust gas, to heat the waste product; and a thermal converter which receives the steam and the syngas or residual or tail gas from the syngas, and is configured to cause supercritical oxidation or combustion of the syngas or tail gas to provide a stream of heated gas.

In another aspect the present invention provides a method of processing waste product, comprising: heating waste product in a drying chamber to generate steam, optionally flash steam, optionally the waste product is heated in the drying chamber with a heated gas, optionally recirculated exhaust gas; transferring the waste product from the drying chamber to a gasification chamber, optionally the waste product which is transferred from the drying chamber is transferred through the gasification chamber; heating the waste product within a gasification zone of the gasification chamber to generate synthetic gas or syngas, optionally the waste product is heated in the gasification chamber with a heated gas, optionally recirculated exhaust gas; and providing the steam and the syngas or residual or tail gas from the syngas to a thermal converter to cause supercritical oxidation or combustion of the syngas or tail gas to provide a stream of heated gas.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:

Figure 1 illustrates a waste processing system in accordance with one embodiment of the present invention;

Figure 2 illustrates a horizontal sectional view (along section I-I) of the system of Figure 1;

Figure 3 illustrates an alternative hydrogen purifier for the system of Figure 1;

Figure 4 illustrates a waste processing system in accordance with another embodiment of the present invention;

Figure 5 illustrates a vertical sectional view (along section II-II) of the system of Figure 4;

Figure 6 illustrates a perspective view (part cut-away) of the combustion chamber of the system of Figure 4; and

Figure 7 illustrates an alternative hydrogen purifier for the system of Figure 4.

Figures 1 and 2 illustrate a waste processing system in accordance with one embodiment of the present invention. The system comprises a primary waste product supply 3 for supplying waste product, a secondary waste product supply 5 for supplying waste product, a drying chamber 7 which is supplied with the waste product from the primary waste product supply 3 and heats the waste product to dry the waste product and generate steam, a gasification chamber 9 which receives the waste product from the drying chamber 7 and in which the waste product is heated to generate synthetic gas or syngas, a treatment unit 10 for treating steam vented from the drying chamber 7 and residual gas and particulate from the gasification chamber 9, a hydrogen extraction unit 11 which receives the syngas from the gasification chamber 9 and extracts hydrogen from the syngas, a thermal converter 12 for generating a stream of heated gas, and a heat exchanger 14 which receives the stream of heated gas from the thermal converter 12 and extracts heat therefrom.

In one embodiment the waste product is municipal solid waste (MSW) or processed waste, for example, refuse-derived waste (RDF), including human waste.

In one embodiment the waste product contains organofluorines, such as perfluorocarbons (PFCs), including perfluoroalkyl and polyfluoroalkyl substances (PFAS), for example, perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS).

In one embodiment the waste product contains fluorinated gases (F-gases).

In one embodiment the waste product comprises a solid, liquid or gas, or combinations thereof.

In one embodiment the waste product is supplied in many forms, for example, sludge, plastic and biomass, and includes tires and flooring material and tiles. In this embodiment the primary waste product supply 3 comprises a container 15, here in the form of a hopper, which contains waste product, in one embodiment in the form of a solid or sludge or mixtures thereof, and a waste feed 17 which feeds waste product from the container 15 to the drying chamber 7.

In this embodiment the waste feed 17 comprises a ram 19 which is actuated reciprocally between a first, material-receiving position, in which waste product can fall from the container 15 in front of the ram 19, and a second, feed position, in which the waste product ahead of the ram 19 is fed, here pushed, into an upstream end of the drying chamber 7. With this action of the ram 19, the feeding of fresh waste product into the drying chamber 7 causes waste product at a downstream end of the drying chamber 7 to be fed into an upstream end of the gasification chamber 9.

In this embodiment the drying chamber 7 comprises an elongate cavity 21 along which waste product is displaced with operation of the waste feed 17.

In this embodiment the drying chamber 7 includes a heated gas source 23 which supplies a heated gas into the cavity 21 thereof, which heated gas can be a recirculated exhaust gas, and an outlet 24, here including a plurality of vents 26, through which steam, in this embodiment flash steam, is vented from the drying chamber 7. With this configuration, the heated gas supplied to the drying chamber 7 and heat from the gasification chamber 9 acts to heat the waste product within the cavity 21 of the drying chamber 7.

In this embodiment the temperature of the drying chamber 7 is controlled such that the upstream end of the cavity 21 is maintained at a temperature of less than 600 C, which is sufficient to yield steam from the moisture within the waste product.

In this embodiment the treatment unit 10 heats the steam which is received from the drying chamber 7 to a temperature above 374 C and a pressure above 22.1 MPa, which represents the critical point, in order to generate supercritical water.

In this embodiment the treatment unit 10 includes an inlet 27 which is fluidly connected to the outlet 24 of the drying chamber 7 and an outlet 28 which is fluidly connected to the thermal converter 12.

In this embodiment the treatment unit 10 includes a heated gas source 29 which supplies a heated gas to the treatment unit 10 to heat the received steam, which heated gas can be a recirculated exhaust gas.

In this embodiment the treatment unit 10 includes a reactor 30, which generates supercritical water from the received steam.

In this embodiment the treatment unit 10 includes an oxidant supply 31 which supplies an oxidant, here air, to the generated supercritical water. With the addition of oxidant, the supercritical water provides for supercritical water oxidation of material, here in the thermal converter 12, which, as noted above, has been found to reduce the PFAS content by greater than 99%.

In this embodiment the gasification chamber 9 comprises a cavity 33 having an outlet 34, here in an upper section thereof, and a floor assembly 35, here at lower section thereof, over which waste product is transferred.

In this embodiment the floor assembly 35 comprises a transfer mechanism 39 which provides a grate at the floor of the gasification chamber 9 and transfers waste product which is received from the drying chamber 7 through a gasification zone GZ.

In this embodiment the transfer mechanism 39 comprises a stepped assembly 45 over which waste product is transferred. In this embodiment the stepped assembly 45 comprises a plurality of steps 47, here of fixed position, which are arranged in staggered downward relation, and a plurality of movable members 49 which are movable reciprocally in relation to the steps 47 to transfer waste product along and over the steps 47.

In this embodiment the steps 47 are arranged substantially in spaced, parallel relation, and the movable members 49 are configured such that upper and lower surfaces of the movable members 49 are in close relation to adjacent surfaces of the steps 47, whereby the action of withdrawing the movable members 49 acts to scrape material therefrom.

In this embodiment ones or groups of ones of the movable members 49 are movable independently of one another, so as to enable control of an amount of waste product in the gasification zone GZ. This manner of control allows readily for use with different kinds of waste product, with the rate of transfer being controlled accordingly.

In this embodiment the gasification chamber 9 includes a heated gas source 51 which supplies a heated gas to the gasification chamber 9, which heated gas can be a recirculated exhaust gas, and heats the waste product to generate synthetic gas or syngas, with the temperature within the gasification zone GZ being controlled so as to prevent combustion, here to a temperature of less than 600 C.

In this embodiment the heated gas source 51 supplies the heated gas to the gasification chamber 9 through the transfer mechanism 39.

In this embodiment the gasification chamber 9 includes a combustion zone CZ at a downstream region thereof, at which a temperature is maintained to provide for starved combustion of the waste product thereat, which waste product has passed through the gasification zone GZ and from which syngas has been extracted. In this embodiment the gasification chamber 9 includes a flow restrictor 55, here in the form of an apertured refractory member, at the outlet 34 thereof through which the flow of the generated syngas and heated gas is restricted, in order to provide for controlled generation and supply of syngas from the gasification chamber 9.

In this embodiment the hydrogen extraction unit 11 includes an inlet 56 which is fluidly connected to the outlet 34 of the gasification chamber 9 and an outlet 57 which is fluidly connected to the thermal converter 12.

In this embodiment the hydrogen extraction unit 11 comprises a heat exchanger 58 for rapidly cooling the syngas as received from the gasification chamber 9, and a hydrogen purifier 59 which receives the cooled syngas from the heat exchanger 58 and purifies the syngas by removing other components or impurities, including carbon monoxide, carbon dioxide, hydrocarbon derivatives and water vapor, to yield purified hydrogen, with the residual or tail gas passing to the outlet 57 of the hydrogen extraction unit 11.

In this embodiment the heat exchanger 58 is configured to cool the syngas to a temperature of less than 60 C, optionally less than 50 C, optionally less than 40 C, and optionally less than 35 C.

In this embodiment the hydrogen extraction unit 11 comprises a chiller 60, here an absorption chiller, which supplies a cold input to the heat exchanger 58.

In this embodiment the hydrogen purifier 59 comprises a pressure swing adsorber (PSA), which incorporates beds of adsorbent to adsorb impurities from the syngas, including carbon monoxide, carbon dioxide, hydrocarbon derivatives and water vapor, to yield purified hydrogen, typically having a purity greater than 99.99 vol/vol%, with the tail gas providing a fuel for the thermal converter 12. In an alternative embodiment the hydrogen purifier 59 comprises a gas membrane separator, for example, a PRISM (RTM) membrane (as supplied by Air Products, Allentown, PA, USA), a POLYSEP (RTM) membrane (as supplied by Honeywell UOP, Des Plaines, IL, USA) or a HISELECT (RTM) membrane (as supplied by Evonik, Essen Germany), which, by differential pressure from a higher pressure on a feed side to a lower pressure on a permeate side and the difference in permeation rates of hydrogen and other molecules, including carbon dioxide and methane, yields purified hydrogen, with the tail gas providing a fuel for the thermal converter 12.

In another embodiment, as illustrated in Figure 3, the hydrogen purifier 59 could comprises a gas membrane separator 59a and a pressure swing adsorber (PSA) 59b in combination, with the gas membrane separator 59a being upstream of the pressure swing adsorber 59b, in order to perform preliminary separation of the syngas and yield a gas richer in hydrogen to the pressure swing adsorber 59b.

In this embodiment the hydrogen extraction unit 11 further comprises a hydrogen reservoir 63, which stores the purified hydrogen, here under pressure.

In this embodiment the thermal converter 12 is fluidly connected to the outlets 28, 57 of the treatment unit 10 and the hydrogen extraction unit 11.

In this embodiment the outlet 28 of the treatment unit 10 is fluidly connected to the thermal converter 12 downstream of the outlet 57 of the hydrogen extraction unit 11.

In this embodiment the thermal converter 12 includes an elongate cavity 71, with the outlet 57 of the hydrogen extraction unit 11 being located at an upstream region of the cavity 71. In this embodiment the thermal converter 12 includes a flow accelerator 73 which is fluidly connected to the outlet 57 of the hydrogen extraction unit 11 and acts to provide a flow of the tail gas of increased velocity from the hydrogen extraction unit 11.

In this embodiment the thermal converter 12 includes a burner 75 which acts to ignite and provide for burning of the tail gas as delivered from the hydrogen extraction unit 11 at start-up.

In this embodiment the thermal converter 12 includes a suction fan 77 which acts to draw the tail gas into the cavity 71 of the thermal converter 12.

In this embodiment the suction fan 77 is regulated to control temperature and residence time within the thermal converter 12.

In this embodiment the thermal converter 12 is controlled such that a temperature of at least 1000 C, in one embodiment at least 1100 C, is maintained in the cavity 71 thereof. In this embodiment the temperature within the cavity 71 of the thermal converter 12 is maintained at a temperature of less than 1400 C.

In this embodiment the secondary waste product supply 5 comprises a container 81, here in the form of a chamber, which contains waste product, in one embodiment in the form of a particulate, liquid or gas or mixtures thereof, and a waste feed 83 which feeds waste product from the container 81 into the cavity 71 of the thermal converter 12.

In one embodiment the container 81 is adapted separately to contain particulate, liquid and gas or mixtures thereof.

In one embodiment the waste feed 83 comprises one or more injectors 85. With this configuration, the thermal converter 12, in addition to generating a stream of heated gas, acts further to destroy substances which are delivered thereto, including residual hydrocarbons, organofluorines and fluorinated gases, and also waste product which is delivered directly by the secondary waste product supply 5 into the cavity 71 of the thermal converter 12.

Figures 4 to 6 illustrate a waste processing system in accordance with another embodiment of the present invention.

The system comprises a waste product supply 103 for supplying waste product, a drying chamber 107 which is supplied with the waste product from the waste product supply 103 and heats the waste product to dry the waste product and generate steam, a gasification chamber 109 which receives the waste product from the drying chamber 107 and in which the waste product is heated to generate synthetic gas or syngas, a hydrogen extraction unit 111 which, when operative, receives the syngas from the gasification chamber 109 and extracts hydrogen from the syngas, a thermal converter 112 for generating a stream of heated gas which receives steam vented from the drying chamber 107 and gas, in this embodiment either residual or tail gas and particulate from the hydrogen extraction unit 111 when operative or syngas from the gasification chamber 109 when the hydrogen extraction unit 111 is inoperative.

In one embodiment the waste product is municipal solid waste (MSW) or processed waste, for example, refuse-derived waste (RDF), including human waste.

In one embodiment the waste product contains organofluorines, such as perfluorocarbons (PFCs), including perfluoroalkyl and polyfluoroalkyl substances (PFAS), for example, perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS). In one embodiment the waste product contains fluorinated gases (F-gases).

In one embodiment the waste product comprises a solid, liquid or gas, or combinations thereof.

In one embodiment the waste product is supplied in many forms, for example, sludge, plastic and biomass, and includes tires and flooring material and tiles.

In this embodiment the primary waste product supply 103 comprises a container 115, here in the form of a hopper, which contains waste product, in one embodiment in the form of a solid or sludge or mixtures thereof, and a waste feed 117 which feeds waste product from the container 115 to the drying chamber 107.

In this embodiment the waste feed 117 comprises a ram 119 which is actuated reciprocally between a first, material-receiving position, in which waste product can fall from the container 115 in front of the ram 119, and a second, feed position, in which the waste product ahead of the ram 119 is fed, here pushed, into an upstream end of the drying chamber 107. With this action of the ram 119, the feeding of fresh waste product into the drying chamber 107 causes waste product at a downstream end of the drying chamber 107 to be fed into an upstream end of the gasification chamber 109.

In this embodiment the drying chamber 107 comprises an elongate cavity 121 along which waste product is displaced with operation of the waste feed 117.

In this embodiment the drying chamber 107 includes a heated gas source 123 which supplies a heated gas into the cavity 121 thereof, which heated gas can be a recirculated exhaust gas, and an outlet 124, here including a plurality of vents 126, through which steam, in this embodiment flash steam, is vented from the drying chamber 107. With this configuration, the heated gas supplied to the drying chamber 107 and heat from the gasification chamber 109 acts to heat the waste product within the cavity 121 of the drying chamber 107.

In this embodiment the temperature of the drying chamber 107 is controlled such that the upstream end of the cavity 121 is maintained at a temperature of less than 600 C, which is sufficient to yield steam from the moisture within the waste product.

In this embodiment the gasification chamber 109 comprises a cavity 133 having first and second outlets 134, 135, here in an upper section thereof, and a floor assembly 135, here at lower section thereof, over which waste product is transferred.

In this embodiment the floor assembly 135 comprises a transfer mechanism 139 which provides a grate at the floor of the gasification chamber 109 and transfers waste product which is received from the drying chamber 107 through a gasification zone GZ.

In this embodiment the transfer mechanism 139 comprises a stepped assembly 145 over which waste product is transferred.

In this embodiment the stepped assembly 145 comprises a plurality of steps 147, here of fixed position, which are arranged in staggered downward relation, and a plurality of movable members 149 which are movable reciprocally in relation to the steps 147 to transfer waste product along and over the steps 147.

In this embodiment the steps 147 are arranged substantially in spaced, parallel relation, and the movable members 149 are configured such that upper and lower surfaces of the movable members 149 are in close relation to adjacent surfaces of the steps 147, whereby the action of withdrawing the movable members 149 acts to scrape material therefrom. In this embodiment ones or groups of ones of the movable members 149 are movable independently of one another, so as to enable control of an amount of waste product in the gasification zone GZ. This manner of control allows readily for use with different kinds of waste product, with the rate of transfer being controlled accordingly.

In this embodiment the gasification chamber 109 includes a heated gas source 151 which supplies a heated gas to the gasification chamber 109, which heated gas can be a recirculated exhaust gas, and heats the waste product to generate synthetic gas or syngas, with the temperature within the gasification zone GZ being controlled so as to prevent combustion, here to a temperature of less than 600 C.

In this embodiment the heated gas source 151 supplies the heated gas to the gasification chamber 109 through the transfer mechanism 139.

In this embodiment the gasification chamber 109 includes a combustion zone CZ at a downstream region thereof, at which a temperature is maintained to provide for starved combustion of the waste product thereat, which waste product has passed through the gasification zone GZ and from which syngas has been extracted.

In this embodiment the gasification chamber 109 includes a flow restrictor 155, here in the form of an apertured refractory member, through which the flow of the generated syngas and heated gas is restricted, in order to provide for controlled generation and supply of syngas from the gasification chamber 109.

In this embodiment the hydrogen extraction unit 111 includes an inlet 156 which is fluidly connected to the first outlet 134 of the gasification chamber 109 and an outlet 157 which is fluidly connected to the thermal converter 112. In this embodiment the hydrogen extraction unit 111 includes a valve 158 at the first outlet 134, which is opened to allow syngas to flow therethrough when the hydrogen extraction unit 111 is operative.

In this embodiment the hydrogen extraction unit 111 comprises a cooler 159, here an injection cooler, and a cooled gas supply 160 which supplies a cooled gas, which can be a recirculated exhaust gas, to cool the syngas as received from the gasification chamber 109.

In this embodiment the hydrogen extraction unit 111 comprises a particulate separator 161, here a cyclone separator, to separate particulate from the cooled flow of syngas as received from the cooler 159.

In this embodiment the hydrogen extraction unit 111 comprises a heat exchanger 163 which acts further rapidly to cool the syngas as received from the particulate separator 161.

In this embodiment the hydrogen extraction unit 111 comprises a chiller 165, here an absorption chiller, which provides a cold output to the heat exchanger 163.

In this embodiment the heat exchanger 163 is configured to cool the syngas to a temperature of less than 60 C, optionally less than 50 C, optionally less than 40 C, and optionally less than 35 C.

The hydrogen extraction unit 111 comprises a hydrogen purifier 169 which receives the cooled syngas from the heat exchanger 163 and purifies the syngas by removing other components or impurities, including carbon monoxide, carbon dioxide, hydrocarbon derivatives and water vapor, to yield purified hydrogen, with the residual or tail gas passing to the outlet 157 of the hydrogen extraction unit 111. In this embodiment the hydrogen purifier 169 comprises a pressure swing adsorber (PSA), which incorporates beds of adsorbent to adsorb impurities from the syngas, including carbon monoxide, carbon dioxide, hydrocarbon derivatives and water vapor, to yield purified hydrogen, typically having a purity greater than 99.99 vol/vol%, with the tail gas providing a fuel for the thermal converter 112.

In an alternative embodiment the hydrogen purifier 169 comprises a gas membrane separator, for example, a PRISM (RTM) membrane (as supplied by Air Products, Allentown, PA, USA), a POLYSEP (RTM) membrane (as supplied by Honeywell UOP, Des Plaines, IL, USA) or a HISELECT (RTM) membrane (as supplied by Evonik, Essen Germany), which, by differential pressure from a higher pressure on a feed side to a lower pressure on a permeate side and the difference in permeation rates of hydrogen and other molecules, including carbon dioxide and methane, yields purified hydrogen, with the tail gas providing a fuel for the thermal converter 112.

In another embodiment, as illustrated in Figure 7, the hydrogen purifier 169 could comprises a gas membrane separator 169a and a pressure swing adsorber (PSA) 169b in combination, with the gas membrane separator 169a being upstream of the pressure swing adsorber 169b, in order to perform preliminary separation of the syngas and yield a gas richer in hydrogen to the pressure swing adsorber 169b.

In this embodiment the thermal converter 112 comprises a swirl chamber 171, a combustion chamber 175 which is fluidly connected to the swirl chamber 171, an oxidant supply 177 which supplies an oxidant to the swirl chamber 171 and the combustion chamber 175, a heated gas supply 179 which supplies a heated gas to the swirl chamber 171 and the combustion chamber 175, which heated gas can be a recirculated exhaust gas, and a burner 181 which acts to ignite and provide for burning of the gas as received by the swirl chamber 171 at start-up. In this embodiment the swirl chamber 171 includes a first inlet 183 which is fluidly connected to the drying chamber 107 to receive steam from the drying chamber 107, a second inlet 185 which is selectively fluidly connected to one of the second outlet 135 of the gasification chamber 109 to receive syngas and the outlet 157 of the hydrogen extraction unit 111 to receive residual or tail gas therefrom, and a third inlet 187 which is fluidly connected to the oxidant supply 177 and the heated gas supply 179.

In this embodiment the second inlet 185 includes a flow accelerator 188 which acts to provide a flow of the syngas or tail gas of increased velocity to the swirl chamber 171.

In this embodiment the swirl chamber 171 includes an outlet 189 from which a gas swirl passes to the combustion chamber 175.

In this embodiment the fluid connection from the second outlet 135 of the gasification chamber 109 to the second inlet 185 of the swirl chamber 171 includes a valve 191, which is closed when the hydrogen extraction unit 111 is operative and opened when the hydrogen extraction unit 111 is operative, whereby the second inlet 185 receives syngas directly from the gasification chamber 109 when the hydrogen extraction unit 111 is inoperative and residual or tail gas from the hydrogen extraction unit 111 when the hydrogen extraction unit 111 is operative.

In this embodiment the combustion chamber 175 includes a first inlet 193 which is fluidly connected to the outlet 189 of the swirl chamber 171, and a second inlet 195 which is fluidly connected to the oxidant supply 177 and the heated gas supply 179.

In this embodiment the combustion chamber 175 includes an outlet 197 from which a stream of heated gas is supplied for energy conversion. This configuration of the swirl chamber 171 and the combustion chamber 175 provides for supercritical flash combustion, which provides for combustion of pollutants, including residual hydrocarbons, organofluorines and fluorinated gases - so reducing pollutant emissions, and, as noted above, has been found to reduce the PFAS content by greater than 99%.

The swirl chamber 171 acts as a pre-mixing chamber which combines syngas and other residual or tail gases, superheated steam from the drying stage, oxidant and a heated gas, in this embodiment recirculated exhaust gas, to induce a swirl, and also results in pre-combustion, which substantially reduces ignition delay within the combustion chamber 175 - so achieving a shortest combustion duration, and thereby higher temperatures and reduced emissions.

In this embodiment the combustion chamber 175 includes swirl gates 199, here defining a meandering, interdigitated path, which act to increase both mixing and retention time.

In this embodiment the combustion chamber 175 is configured to provide a retention time of greater than 3 seconds.

Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the present invention as defined by the appended claims.

For example, in the first-described waste processing system, the secondary waste product supply 5 could be omitted.