Toxic organic waste destruction

Hackman, E.E., III. Toxic Organic Chemicals Destruction and Waste Treatment Noyes Data Corp. Park Ridge, NJ, 1978. 

Mediator-Aided Destruction of Organic Wastes (Particularly Toxic, Organic Waste)... 

Thermal processes are typically used for highly toxic waste or highly concentrated organic wastes. If the waste contains PCB, dioxins, or other toxic substances, incineration should be chosen in order to assure destruction. If the wastes contain greater than 1000 parts per million of halogens (chlorinated materials), it would probably be desirable to select incineration of these wastes, after consideration of other options. In any case, a material may be incinerated or used as a fuel if the heat content is greater than 8500 BTUs per pound or, if between 2500 and 8500, it may be incinerated with auxiliary fuel. The waste components of concern are halogens, alkali metals and heavy metals. 

Incinerators are used to bum hazardous waste primarily for waste destruction/treatment purposes however, some energy or material recovery can occur. When performed properly, incineration destroys the toxic organic constituents in hazardous waste and reduces the volume of the waste.3 Since metals will not combust, incineration is not an effective method for treating metalbearing hazardous wastes. 

Incineration has been well organized as one of the best demonstrated and available technologies for waste destruction by direct heat, thus the volume and toxicity of the remaining residuals can be reduced. 

Shaw RW, Dahmen N. Destruction of toxic organic materials using supercritical waste oxidation. J Supercrit Fluids 2000 17 425-437. 

Supercritical Water Oxidation (SCWO) has been proved to be a suitable process for treatment of several toxic and hazardous organic wastes due to its high removal efficiency. SCWO requires of hard reaction conditions (22.1 MPa and over 374°C). Special reactors are needed to support these conditions. An original reactor design is presented here wich has been tested in the treatment of alcohols+ammonia solutions in water. Performance results are presented here for ammonia and alcohols. Destruction efficiency greater than 99.9% are reached for both compounds, probing the correct performance of the reactor. 

Water becomes supercritical above 374°C and 220 atm, becoming less polar. This allows homogenization with non-polar organic materials, thus making them available for chemical reactions. An important potential use is the rapid destruction of toxic organic compounds and waste by oxygen.20... 

The effectiveness of a waste destruction process can be tracked by following the disappearance of a chemical compound that is especially resistant to the process conditions. The working assumption is that, if the tracking compound is completely destroyed, other less stable chemicals will also be absent in the process effluents. The fate of certain chemical species of particular regulatory or public concern, such as persistent organic pollutants (POPs) or toxic heavy metals, may also be used to track the performance of treatment technologies. 

Steele DF (1990) Electrochemical destruction of toxic organic industrial waste. Platin Met Rev 34 10-14... 

The routine monitoring of every hazardous constituent of the effluent gases of operating incinerators is not now possible. EPA has established procedures to characterize incinerator performance in terms of the destruction of selected components of the anticipated waste stream. These compounds, labeled principal organic hazardous components (POHCs), are currently ranked on the basis of their difficulty of incineration and their concentration in the anticipated waste stream. The destraction efficiency is expressed in terms of elimination of the test species, with greater than 99.99 percent removal typically judged acceptable provided that toxic by-products are not generated in the process. 

Waste that is hazardous because it exhibits the toxicity characteristic also must be treated to remove this characteristic prior to disposal. Techniques to remove the toxicity characteristic include, for example, destruction of organic compounds by incineration or incorporation of the waste in an immobilizing waste form (e.g., grout). However, in contrast to ignitable, corrosive, or reactive waste, a properly treated toxic waste may still be considered hazardous in some cases, even if it is not characteristically hazardous after treatment and does not contain any listed substances. For example, a waste that is toxic because it contains high levels of heavy metals could be treated to reduce the leachability of the metals to acceptable levels by incorporation in an appropriate waste form, but the treated waste may still be considered hazardous when the toxic substances of concern are not destroyed by treatment and the possibility exists that their leachability from the waste form could increase substantially after disposal. 

While cathodic processes may produce positive payoffs by recovering metals from waste streams, anodic processes are essentially destructive in nature. Positive payoffs may occur if it is possible to carry out an anodic process which destroys toxic species at the same time that the cathode is recovering metals. For example, during the treatment of a cyanide plating bath, heavy metals are recovered at the cathode while cyanide is destroyed at the anode along with any organic additives and brighteners. 

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