4.4.1.6 Environmental International Process
Head Office: Environmental International Inc.
912 Scott
Kansas City, Kansas 66105
Contact: William McGaugh, Senior Vice-President
(913) 281-0057
Environmental International Inc., has devised a process for treating waste capacitors and transformer oils contaminated with PCBs that can be used as an alternative to incineration. The process involves the mechanical rinsing of the capacitors to remove all PCBs. The capacitors are taken apart and thoroughly rinsed and cleaned. The metal salvaged is sold as scrap. The PCB fluid is removed to a storage tank for treatment.
The PCBs, removed from the capacitors, and any transformer oil contaminated with 570 000 ppm PCBs are treated chemically with a proprietary reagent. The treated oil is recycled and the waste by-products (which are considered non toxic) are landfilled.
The Environmental International process is capable of treating "out of service" capacitors at a rate of 100/shift as well as contaminated transformer oil. The chemical treatment process is not presently mobile, but the company is considering developing one if they should find a demand for such a process.
Environmental International is approved to accept PCB-contaminated capacitors and does so at a cost of $1.10/kg, for non-leaking capacitors crated in wood crates, or $1.65/kg for capacitors in steel drums (these do not include transportation costs). On receipt of the capacitors, the company takes over legal responsibility for the proper treatment and/or disposal of the PCBs and capacitor shell. The crated capacitors are kept in an on-site storage facility until they can be treated.
The process has obtained a 3 year approval in EPA Region VII, and the company has approval to accept PCBs from any location as long as they are treated at their Kansas City site.
Reference: (McGaugh, pers. comm., 1982).
4.4.1.7 Other Sodium Type Dechlorination Processes.*
| Company Name |
Process Type |
Status |
| Life Enterprises Inc., Barto, PA |
- modified sodium naphthalide process |
- review of process by EPA
- region III has been requested but no follow-up has been made |
| General Electric Corp., Philadelphia, PA |
- standard sodium process
- exact constituents of reagent are confidential |
- approved to conduct a test of the process at the company's leisure in EPA Region III |
| British Columbia Hydro |
- sodium metal dechlorination process |
- in the process of researching scale-up potential of the lab.process |
| Ontario Hydro |
- sodium metal dechlorination process |
- pilot plant scale testing |
| PCB Destruction Co. Kansas City, MO |
- sodium type dechlorination process |
- testing of process done for EPA Region VII; results showed problems with process |
| PCB Eliminators Kansas City, MO |
- chemical dechlorination |
- under review by EPA Region VII |
| Radium Petroleum Kansas City, MO |
- chemical dechlorination waste oils |
- bench scale
demonstration completed for EPA with satisfactory results; process under review |
* A number of other sodium dechlorination processes were identified. Most of these processes are at an early stage of development and little new information was forthcoming over that found for those already reviewed. The processes follow, for completeness.
4.4.2 Radiant Energy Processes
The promotion of chemical reaction, and therefore destruction of PCB can take place by the application of radiant energy. A number of processes are being evaluated which are based fundamentally on some radiative process that initiates the process reaction. In these radiative processes energy either interacts directly with the PCB molecule promoting its reaction, or interacts with an intermediate species which subsequently attacks the PCB molecule. In both cases, the question of temperature becomes relatively unimportant; these processes operate from within a few degrees of room temperature to temperatures that reduce the waste to basic molecular fractions.
4.4.2.1 Thagard High Temperature Fluid Wall Reactor
Head Office: Thagard Research Corporation
2712 Kelvin Avenue
Irvine, California 92714
Contact: E. Matovich
(714) 556-4470
The High Temperature Fluid Wall (HTFW) reactor is a radiant energy process, because the driving force for the reactor is a series of carbon rods electrically heated to high temperature such that they emit (infrared) radiation. This radiation is focused in a manner described below on waste material contained in a pourous tube. The tube material, which is transparent to the IR radiation, is protected from the heated waste by a fluid curtain of gas that is caused to flow over its surface.
The reactor configuration is given in Figure 10. The reactor consists of a jacketed insulated cylinder typically 30 cm in diameter. Inside the cylinder six carbon electrodes are arranged as shown in Figure 11. When electrically heated to about 2000°C, these electrodes emit infrared radiation. The inside walls of the reactor are lined with insulation and a carbon radiation heat shield which reflects the energy back towards the centre of the reactor.
A porous tube made of a ceramic material that is transparent to the IR radiation runs down the centre of the cylinder. Inside this cylinder, energy is absorbed by a slurry of carbon particles in the waste. Absorbed energy creates high surface temperatures which break the waste molecules into simple molecular fragments, in the case of PCBs; HCI, CO, CO2, CH4 and H2 (note: water may have to be added to provide enough hydrogen and oxygen to produce gaseous products). The whole inside of the reactor is bathed in nitrogen which is drawn through the porous central reaction tube to form a fluid film on the inside of the reaction tube to prevent contact from the heated waste.
This technology is in relatively early stages of development. A 30 cm by 9 m reactor has been tested on hexachlorobenzene; tests on PCBs under US EPA auspices are planned for later in 1982. The company has spent some five years developing the reactor to this stage and demonstrating process chemistry.
The reactor will likely be able to handle both solids and liquids provided solid PCB waste is shredded finely enough. The concept at this time is to add lime and silica to neutralize HCI produced and immobilize ash in a vitreous state. Reactor by-products from this high temperature pyrolysis will be simple gas molecules which can be burned to innocuous products. The company feels that waste throughputs of 130-180 Mg per day can be achieved with this technology.
As previously mentioned, this technology is still in early stages of development. Although previously tested on many waste products including a surrogate for PCB, a test on PCB material is still pending.
Capital and operating costs, and in turn unit destruction costs, are difficult to estimate and cannot be included in this study. Capital investment in a large air pollution control system could be minimized because off gases are in the low to moderate temperature range; however, the high level of electrical energy input required would contribute significantly to operating costs.
Reactors of this type, with cylindrical core diameters of up to 120 cm, are presently being scaled to treat 150-250 Mg/day of toxic waste. Apart from the reactor itself, ancillary equipment for larger sized units is readily available. Cooling water pumps, for instance, can be purchased off the shelf.
Final impacts on natural and worker environments will only be defined after scale-up and testing. The reaction of the US EPA is positive as they will be supporting additional waste testing in the Spring of 1982.
References: (Thagard Research Corp., 1981; Oppelt, 1981).
Figure 10 Vertical Cross-Section of a Typical Fluid-Wall Reactor
(Thagard Research Corp., 1981)
Click image to view a full size version.
Figure 11 Horizontal Cross-Section of a Typical Fluid-Wall Reactor
(Thagard Research Corp., 1981)
Click image to view a full size version.
4.4.2.2 Plasma Arc Pyrolysis Process
Royal Military College
Department of Civil Engineering
Kingston, Ontario
Contact: Dr. T.G. Barton
(613) 545-7395
The Plasma Arc Pyrolysis Process makes use of the energy in ionized gas molecules to cause the dissociation of PCB molecules. The ionized gas molecules exist in a plasma created by the discharge of electrical current through a collimated vortex of low pressure gas. As these ionized gas molecules decay they transfer energy to the PCB molecule in a number of ways. The ultraviolet radiation given off as the ionized species decays is thought to be one of the major energy transfer mechanisms, thus this process is included as a radiant energy process.
The major innovative feature of the Plasma Arc Pyrolysis Process is the plasma generator called the plasma torch. This device produces a toroidal vortex of low pressure gas through which electrical current is passed, creating the plasma. The torch acts as one electrode, and a hearth in the bottom of the reactor acts as the other electrode, Figure 12. The power supplied to the torch is capable of delivering 1000 V at up to 300 A. Centreline temperatures equivalent to 50 000 K are achieved in the plasma.
Gas volumes supplied to the torch are small fractions (>5%) of the gas volume required if the waste were to be combusted. The gas composition is not critical. The waste PCBs are pyrolyzed with the main products being CO, CO2, HCI, H2 and H2O. Typical energy requirements are: 1.26 MJ/kg of PCB waste producing outlet temperatures in the range of 1110 K.
At present, tests are being run to determine the destruction efficiency of PCBs in the reactor. The PCBs are injected as a stream directed at the reactor hearth. PCB destruction efficiencies in excess of 99% were demonstrated in previous preliminary work.
Destruction of solid waste awaits further testing although the process itself was originally designed and tested on non-PCB solid wastes. Processing rates will fall in the 100-1000 kg/h range.
The capital costs involved for a reactor capable of destroying 15 kg/min of PCB fluid are estimated to be approximately $700 000 for a system that includes a 600 kW power feed; scrubber, air compressor, water cooling system; water treatment system, feed system, building and laboratory.
Supervisory and operating personnel would be the main reason for high operating costs, likely in the neighbourhood of $1 200 000 per year including cost of capital investment. This figure is based on a 4 shift, 7 day week schedule with a standard receiving and storage schedule of 40 hours. Unit cost of destruction over a one year period would be $0.26/kg.
Components of the system are readily available, with the exception of land which is not included in the aforementioned capital cost.
The unit costs would be reduced if destruction were performed by a contractor destroying PCBs on-site with plasma reactor and accessories mounted on highway trailers. To increase the capacity of such a system, modules of the same capacity (15 kg/min) could be run side by side rather than increasing the capacity of a single unit.
Environmental impacts are likely to be slight. By-product gases can be flared and solid residues are likely to be inert inorganics. Occupational risks are those of any hazardous materials handling facility. |
