Waste disposal surface equipment

Condensate from contact units cannot be reused and may constitute a waste disposal problem. Surface condensers can be used to recover valuable condensate. Surface condensers must be equipped with more auxiliary equipment and generally require a greater degree of maintenance. 

Figure 20.2 shows the surface equipment used in a typical subsurface waste-disposal system. Detailed discussion of surface treatment methods can be found in Warner and Lehr.6 The individual elements are listed in the following ... 

The University of California field stations have dealt with dilute pesticide waste disposal on an experimental basis by using lined soil evaporation beds. The beds typically are 20 x 40 x 3 ft pits lined with a butyl rubber membrane and back filled with 12 to 18 Inches of sandy loam soli. Figure 1 Is a cross secton of such a bed. Used containers and spray equipment are washed on an adjacent concrete slab the wastewater drains Into a sedimentation box for trapping particulates, followed by a distribution box In the bed. From the distribution box, the dilute pesticide solutions run underneath the soli surface through leach lines made of 4 Inch perforated PVC pipe. The system Is designed so that water moves up through the soli by capillary action and evaporates off the surface. 

During the past 30 years many new solvents for inorganic deposits were developed. Low hazard corrosion inhibitors have replaced some of the more toxic materials used to protect the structural surfaces during cleaning. Development of nuclear cleaning methods has extended the life of some very valuable nuclear generating plants. New waste disposal methods have enabled the industry to continue to operate, but have required new chemicals to be developed. Modest improvements for cleaning CP/R equipment include ways to remove FeS and we have seen the development of more environmentally friendly solvents. 

The TSDF standards also establish requirements to ensure that hazardous waste management units are closed in a manner that protects human health and the environment. The closure provisions require the facility to stop accepting waste remove all waste from management units and decontaminate all soils, structures, and equipment. Some units (i.e., land treatment units, landfills, and surface impoundments) serve as places for the final disposal of hazardous waste. These land disposal units must comply with additional postclosure requirements to ensure proper long-term unit maintenance. 

Several existing protocols require a solvent (acetone, methanol, isopropanol) rinse as part of equipment decontamination for VOC sampling and 1 10 percent hydrochloric or nitric acid rinse for metal analysis sampling (DOE, 1996 USACE, 1994). These practices, successful as they may be in removing trace level contaminants, create more problems than they are worth. Organic solvents are absorbed by the polymer materials used in sampling equipment construction and appear as interferences in the VOC analysis. Acid destroys the metal surfaces of soil sampling equipment and induces corrosion. The use of solvents and acids is a safety issue and it also creates additional waste streams for disposal. 

Oxidation without UV activation is preferred. The problems associated with UV activation are discussed in Disposal ofNeutralent Wastes (NRC, 2001c). These include the need for special equipment, reduced effectiveness for opaque solutions, and fouling of the optical surfaces. Eor chemical oxidation not catalyzed by UV light, conventional chemical process equipment and procedures are used. 

During any release of radioactive materials, surfaces of objects or equipment may become contaminated. The objective of these measurements is to identify those objects that should be decontaminated, disposed of as waste, or treated in some other controlled fashion. The physical quantity that is generally measured is surface activity. Measurements may be radionuclide-specific or can also be assessed based on dose-rate measurements. The results are generally expressed in Bq/m or Sv/h or equivalent, respectively. 

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