Pretreatment and Post Treatment Options

Most treatment options for detoxifying the hazardous constituents from RCRA facilities must have a uniform feed to the process. However, the media in which hazardous constituents are located are not generally homogeneous. Thus, some form of pretreatment of the waste or waste medium will probably be required to prepare the waste for further treatment by chemical, biological or thermal means. 

With few exceptions, treatment technologies are limited to some extent by the size of the material that they are able to process. These limitations can apply to the throat of the feed devices, the inner workings of the equipment, the treatment mechanisms, or the process elements. To make these remedial technologies efficient and cost effective, separation techniques are used to make the feed stream uniform 

In developing a separation strategy, the size distribution of the components found in the contaminated medium can be used as a starting point. As an initial step, debris (such as rocks, etc.) can be separated from the remainder of the waste. After the debris is removed, other separation techniques can be employed to concentrate the waste further or physically manipulate the waste into a form suitable for treatment. 

In order to develop measures for removal of debris from the waste matrix, the general types of debris anticipated need to be identified. A composite list, based on debris found at 29 Superfund sites, was developed. The list includes cloth, glass, ferrous materials, nonferrous materials, metal objects, construction debris, electrical devices, wood existing in a number of different forms, rubber, plastic, paper, etc., as presented in Table 11. Similar types of debris would be expected at RCRA sites. 

Debris with particularly good absorbent qualities such as wood, some paper products, paper, cloth materials, etc., are go candidates for shredding so that they can be included in the remediation process. Materials that are not porous and are not adsorbent are glass, plastic, metal objects, some types of construction debris, tanks, etc., are good candidates for manual or magnetic separation. 

---