Hazard reduction Waste treatment methods

The treatment of waste is the third element of the hierarchy and should be utilized only in the absence of feasible source reduction or recychng opportunities. Waste treatment involves the use of chemical, biological, or physical processes to reduce or eliminate waste material. The incineration of wastes is included in this categoiy and is considered preferable to other treatment methods (i.e., chemical, biological, and physical) because incineration can permanently destroy the hazardous components in waste materials (Ref. 4). It can also be employed to reduce the volume of waste to be treated. 

This book analyzes alternatives to land disposal of hazardous metal waste streams, focusing on methods that prevent waste generation. Source reduction, recycling, and treatment strategies are examined. 

Incineration is a well-known process that involves the conversion of toxic and hazardous waste into a less or nontoxic waste by heating at a very high temperature to convert them into gaseous and particulate matter. Incineration is considered an attractive option after source reduction, and recycling. This method is sometimes preferred over the other treatment methods because it destroys permanently the hazardous components in the waste material. 

Because endrin and endrin aldehyde are listed as hazardous substances, disposal of wastes containing these compounds is controlled by a number of federal regulations (see Chapter 7). Land disposal restrictions apply to wastes containing endrin or endrin aldehyde (EPA 1986d, 1987b). Chemical treatment (reductive dechlorination) or incineration are possible disposal methods (HSDB 1995 IRPTC 1985). Past disposal... 

The WRH in column one has been completed by the authors for each option. If you have an option that is not included in the list of options you may add it to the list and assign it an appropriate WRH value. Source reduction has the greatest point value because source reduction is usually the easiest and cheapest methods of waste reduction to implement. Treatment, on the other hand, is on the lower end of the scale and is considered to be the least desirable option. Treatment is discouraged as the first alternative in hazardous waste management. These point values are selected by the authors. If you feel that they should be modified you should feel free to change them when you use the WRAM. 

Waste minimization generally considers all of the methods in the EPA hierarchy (except for disposal) appropriate to reduce the volume or quantity of waste requiring disposal (e.g., source reduction). The definition of source reduction as applied in the Pollution Prevention Act, however, is "any practice that reduces the amount of any hazardous substance, pollutant, or contaminant entering any waste stream or otherwise released into the environment.. . prior to recycling, treatment or disposal (Ref. 1). Source reduction reduces the amount of waste generated it is therefore considered true pollution prevention and has the highest priority in the EPA hierarchy. 

In most waste streams, either hazardous or radioactive, only a small amount of harmful contaminants is found in a large volume of otherwise harmless waste, and the treatment is aimed at reduction of the effect of these contaminants on the environment. Possible treatments include separation and recycling of the contaminants, destruction of the waste, and if these methods fail, isolation of the entire waste volume and disposal or safe storage. The decontamination and recycling of waste is a good strategy, provided it is economical. Where recycling is not economical, destruction of the wastes takes precedence over any... 

As mentioned before, subsequent phosphate treatment does not affect the stable sulfide, and TCLP results show excellent stabihzation of Cr in any oxidation state. Alternatively, a small amount of reductant in the waste will convert chromate into lower oxidation states. Such methods, however, are not preferred, because the reductant may also affect the solubility of other hazardous compounds. The exception is technetium-containing radioactive waste, in which chromate is also a contaminant. As we shall see in Chapter 17, a reductant is essential for stabihzation of technetium, and that will also help in stabilization of chromium. 

---