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Publications archive - Waste and recycling
Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.
Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.
CMPS&F - Environment Australia
Appropriate technologies for the treatment of scheduled wastes
Review Report Number 4 - November 1997
Sodium metal is dissolved in liquid anhydrous ammonia to form a characteristic dark blue solution. The blue colour is due to the presence of solvated electrons which are powerful dehalogenating agents.
The formation of solvated electrons can be represented by the reaction:
Solvated electron solutions form rapidly when alkali or alkaline earth metals dissolve in ammonia or certain amines, forming solutions that can be regarded as containing the metal cation and free electrons.
Halogens can be split from organic halides to yield a fully substituted parent hydrocarbon and a metal halide. For example, a PCB molecule can be converted to biphenyl by the reaction:
The application of the technology to waste treatment has been the subject of a 10 year development program by Commodore Environmental Services (US).
This work has resulted in a proprietary re-agent named Agent 313. The technology can be applied as a relocatable system. Information on the process has been provided for this review by Solvents Australia Pty Ltd (1996), the proponent for the process in Australia. Independent information on the process was not available for this review.
Treatment of waste with Agent 313 is carried out without the need for elevated temperatures and the conversion of the waste occurs in a matter of seconds. Solvents Australia states that there is no need for pretreatment, although some dewatering of sludges or sediments may be required.
The proponents claim trials have been carried out on:
The proponents claim materials have been successfully treated in the following forms:
Proving trials on pilot scale equipment have been conducted in the United States for the USEPA, the US Military and the Federal Government. A commercial scale plant is currently under design.
Pilot scale testing has been carried out with Agent 313 in the US on contaminated soil samples from a range of locations and soil types. The following table indicates the reduction in PCB levels attained in one series of tests.
| PCB Concentration | ||
| Soil Type | Before (ppm) | After (ppm) |
| High Level | ||
|
Clay
Organic soil Sandy soil |
290.0
650.0 6,200.0 |
< 1
< 1 < 1 |
| Low Level | ||
|
Clay
Organic soil Sandy soil |
29.0
83.0 130.0 |
< 1
< 1 < 1 |
Source: Solvents Australia submission to CMPS&F, April 1996
The process design employs a cement mixer like reactor in which contaminated material and liquid ammonia are mixed. The ammonia completely disperses the soil, including the clays and washes the contaminant from the soil. After brief mixing, a reactive metal charge is added, typically calcium. Electrons freed from the calcium rapidly dehalogenate the contaminants.
Ammonia is recovered for further use, and in the process the soil is deodorised. The decontaminated soil is claimed to be suitable for return to the site, enriched in nitrogen from trace amounts of residual ammonia.
Treatment of soils with up to 25% water content is possible, suggesting that the process is applicable to sludges and sediments.
The pilot scale plant operates on a batch basis. Continuous processing equipment will be built to suit larger projects.
Care must be exercised to ensure the safe handling of bulk ammonia.
Surface Treatment
Surfaces can be cleaned by Agent 313. Small pieces of equipment and contaminated clothing can be decontaminated in reaction vessels. Larger surfaces can be cleaned in situ; however, effective containment of ammonia vapour is required.
Solvents Australia states that porous contaminated materials such as PCB contaminated concrete can be treated by a variation of the process. This involves a pretreatment of liquid ammonia and a co-solvent on the contaminated concrete surface. The liquid penetrates the surface until the ammonia begins to vaporise, forcing the liquid back to the surface bringing with it dissolved PCBs. Once the PCBs are at the surface, solvated electrons are added and the PCBs are destroyed. It is claimed that this process offers a cost effective alternative to surface scabbling, demolition, burial or sealing.
Transformer Oils
Some of Commodore's earlier work was directed towards decontamination of transformer oils. Solvents Australia states that PCB levels in excess of 20,000 ppm have been successfully reduced to less than 1 ppm, and after treatment, transformer oil is available for further use.
Pesticides
Solvents Australia advises that Agent 313 is effective in the destruction of a range of pesticides, and results obtained are summarised in Table 12.3.
| Pesticide | % Destroyed |
| Altrazine | 100.0 |
| Bromacil | 100.0 |
| Carbaryl | 92.8 |
| 2,4-D | 100.0 |
| Dalapon | 100.0 |
| DBCP | 100.0 |
| DDT | 100.0 |
| Decamba | 100.0 |
| Dieldrin | 100.0 |
| Diuron | 100.0 |
| Dinosab | 100.0 |
| Malathion | 100.0 |
| Paraquat | 99.9 |
| Pichloram | 100.0 |
| PMA | 86.0 |
| Trifluralin | 100.0 |
| 2,4,5-T | 100.0 |
| Vernolate | 100.0 |
| Zineb | 99.4 |
Source: Solvents Australia submission to CMPS&F, April 1996
Operating Costs
While costs are to a large extent determined by the nature of the waste and will be application specific, the following indicative costs have been provided by Solvents Australia:
Concentrated Wastes: $12,000 - $20,000/tonne
PCB contaminated soils $300 - $350/tonne
The indicative costs for concentrated wastes are based on preliminary cost estimates for destroying waste CFCs. The estimate for treating PCB contaminated soils was generated from a comprehensive study carried out in the United States. The estimates are based on using a rotary drum reactor which could be transported on a truck. The concept involves two reactors on trucks or trailers, with the processing equipment on a third truck or trailer. Capital cost of the truck or trailers are not included in the estimate.
Note that the cost estimates are based on the results of pilot scale trails and preliminary designs for a commercial scale unit.
Estimates for the treatment of PCBs in soils indicate an energy requirement of the order of 150 kWh per tonne of soil treated.
Nature of the Treated Material
The products resulting from treatment and the disposal options suggested by Solvents Australia are listed in Table 12.4. Further review and confirmation of site-specific disposal options will be required with reference to the applicable regulatory controls on landfilling.
| Material Treated | Products | Disposal Options |
| Concentrated PCBs | Biphenyl, calcium hydroxide, calcium chloride. | Landfill as salts. |
| PCBs in soils | Biphenyl, calcium hydroxide, calcium chloride, clean soil. | Return soil to ground. |
| PCBs on surfaces | Biphenyl, calcium hydroxide, calcium chloride. | Collect salts and landfill. |
| PCB/oil mixtures | Biphenyl, calcium hydroxide, calcium chloride, oil. | Reuse oil. Landfill salts. |
| Concentrated HCB | Benzene, sodium chloride, sodium hydroxide. | Separate benzene and landfill salts. |
| HCB in soils | Benzene, sodium chloride, sodium hydroxide, clean soil. | Separate benzene and return soil with salt to ground. |
Source: Solvents Australia submission to CMPS&F, April 1996.
The technology has not been previously demonstrated in Australia. However, Solvents Australia advises that a demonstration plant currently under construction in the US will be installed in Australia for high concentration wastes and surface treatment. Solvents Australia states that commercial scale treatment of soil is to be fast tracked.
(a) Proponents (in Australia)
Solvents Australia Pty Ltd (NSW)
(b) Wastes Applicable
Waste materials that can be successfully treated include:
(c) Contaminants Applicable
Scheduled and non-scheduled contaminants successfully treated with Agent 313 include:
(d) Status
Solvated electron technology has not been demonstrated in Australia to date.
(e) Timing for Commercialisation
A small processing plant is currently under construction in the US. This will have the capacity to process a minimum 25 kg/hr of liquid or gaseous contaminated material.
(f) Cost (Example Only)
While costs are to a large extent determined by the nature of the waste and will be application specific, the following are provided as indicative costs:
Concentrated Wastes: $12,000 - $20,000/tonne
PCB contaminated soils $300 - $350/tonne
The indicative costs for concentrated wastes are based on preliminary cost estimates for destroying waste CFCs.
(g) Safety/Environmental Risk
Solvents Australia advises that tests on a wide range of materials on both laboratory scale and pilot scale have indicated consistently high destruction efficiencies, and there are currently no indications that factors exist that would adversely impact on sustained destruction efficiencies in commercial use.
The process is designed to be contained and to have no process emissions. Ammonia and calcium metal are potentially hazardous and must be handled with due care. Ammonia is a volatile liquid, and is toxic and flammable. Calcium metal is highly reactive, and can react with water to form explosive gas mixtures of hydrogen.
(h) Non-technical Impediments
None known at this stage.
(i) Preferred Mode of Implementation
The treatment process can be transported relatively easily and given statutory approvals, development of a mobile treatment unit is considered the most likely form of implementation.
(j) Limitations
There appear to be no significant limitations to the implementation of this treatment technology.
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