Patent Number: 058624945
Section: description

DETAILED DESCRIPTION OF THE INVENTION The encapsulating material used in the hazardous waste treatment systems of the present invention includes polyacrylic acids and all salts thereof. The encapsulates are typically utilized in powder or granular form. When added to a moisture bearing waste product, the encapsulates react with the moisture in the waste material to form a stable gel-like matrix. The liquids in the waste material are entrapped within the matrix and the waste material is left with no free standing liquids. The particular encapsulate used in a hazardous waste treatment system is selected according to the characteristics of the waste material being processed. The encapsulates used in the encapment process of the present invention preferably are non-biodegradable, non-toxic, incinerable materials which retain many times their own weight in moisture at elevated pressures. The encapsulates also are preferably compatible with most chemicals and are effective at a wide pH range and a wide temperature range. It is desirable that the encapsulates be transparent so that the waste material containing the encapsulates may be X-rayed using Real Time Radiography techniques required by many regulated disposal sites. Suitable encapsulates for use in the encapment process of the present invention include polyacrylates sold under the tradename ECsorb by Technical Solutions & Systems, 328 East Elk Avenue, Elizabethton, Tenn. 37643. Referring now to FIG. 1, there is shown the pressurized vessel containment system of the present invention, designated generally as 1, wherein a pressurized vessel or tank 2 is filled with encapsulating material 3 for dispensing directly onto the hazardous waste 4. The pressurized tank 2 may be any vessel designed to dispense its contents under pressure from a gas or other suitable propellent. The pressurized tank 2 may range in size from small aerosol-type cans to large commercial or industrial sized tanks. The pressurized containment system 1 is particularly useful for controlling leaks and spills of low-level radioactive and mixed moisture bearing waste material. The nozzle 5 on the tank 2 is pointed at the leaking waste material 4 and the encapsulating material 3 is dispensed directly into the hazardous waste 4. Within seconds, the encapsulating material 3 reacts with the moisture in the waste material 4 to form a stable gel-like matrix 6, preventing any further flow of the waste 4. The gel-like matrix can then be disposed of in a safe and suitable manner. In addition, the pressurized containment system 1 can be used to form dikes or barriers which contain larger volumes of waste material until appropriate clean-up measures can be implemented. As shown in FIG. 2, the solid waste treatment system of the present invention, designated generally as 7, includes a conveyor 8 for transporting solid waste material 9 to a fuser 10. The conveyor 8 may be a belt conveyor, a screw auger, or any other suitable means for transporting the solid waste 9 into the fuser 10. The fuser 10 is preferably a commercial mixer which is provided with a high speed rotary hammer. In a particularly preferred embodiment, the high speed rotary hammer rotates at a minimum speed of 2500 rpm, and more preferably at a speed of 3500 rpm. However, any means for breaking up the solid waste 9 and blending the solid waste 9 with the encapsulating material 3 is suitable for use in the fuser 10. The fuser 10 may be a portable unit which can be transported to the solid waste clean-up site. The fuser 10 also is preferably provided with load cells 12 or other means for weighing the solid waste 9 within the fuser 10. When utilized for treating radioactive solid waste material, the fuser 10 is preferably provided with detectors 11 to monitor the level of radioactivity within the fuser 10. The detectors 11 may be a germanium detector a passive/active neutron measuring device or any other suitable means for monitoring the level of radioactivity within the fuser 10. In a typical application, the solid waste treatment system 7 is assembled at a contaminated soil clean-up site. The soil 9 is tested for moisture content and levels of hazardous contaminants to determine the appropriate amount of encapsulating material 3 to add to the soil 9. The solid moisture bearing soil waste 9 is transported on the conveyor 8 through hopper 13 into the fuser 10. A predetermined amount of encapsulating material 3 is added to the fuser 10. The amount of the encapsulating material 3 is determined by the moisture content of the soil, as well as government regulations regarding radioactive and hazardous waste disposal. The fuser 10 is started and the solid waste 9 and the encapsulating material 3 are blended until the encapsulating material 3 and the solid waste 9 form a homogenous mixture. The soil waste 9 entering the fuser is generally soft and moist in appearance. Some soil wastes may even be in the form of a slurry. The encapsulating material 3 reacts with the moisture in the soil waste 9 to form stable gel-like matrix. Upon completion of the blending operation, the solid waste 9 has a granular appearance similar to grainy sand. The treated solid waste material 9 then is placed in appropriate storage containers 14 for hazardous waste disposal. The solid waste 9 is processed in the fuser 10 in individual batches until all of the contaminated solid waste 9 has been treated and sealed in containers 14. After treatment with the solid waste treatment system 7 of the present invention, the waste material is tested by the paint filter test or the Environmental Protection Agency ("EPA") Method 9095. Upon completion of the encapment process, the solid waste material 9 meets all current waste acceptance criteria for no free standing liquids. As shown in FIG. 3, the encapment process of the present invention also includes an aqueous liquid waste minimization system, designated generally as 15. The waste minimization system 15 includes a liquid waste tank 16 and an encapsulate tank 17. Both the liquid waste tank 16 and the encapsulate tank 17 empty into a pipe 18 which transports a predetermined amount of liquid waste 19 and encapsulating material 3 to an in-line mixer 20. The mixer 20 may be a ribbon mixer or any other suitable means for blending and mixing the encapsulating material 3 with the liquid waste 19 until the mixture forms a gel-like matrix. In a preferred embodiment, the gel-like mixture of liquid waste 19 and encapsulating material 3 is transported through an enclosed conveyor 21 and into an evaporator 22 or other suitable means for removing the moisture from the gel-like matrix. Discharge pipe 23 or other suitable means for removing the vapor or distillate from the evaporator 22 is provided on evaporator 22. An outlet port 24 is provided on the evaporator 22 for removing the processed waste material. Preferably, the outlet port 24 empties directly into an appropriate hazardous waste container 14. The liquid waste minimization system 15 also may be provided with a temperature control panel not shown detectors not shown for monitoring the level of radioactivity in the waste material, load cells (not shown) or other means for weighing the materials being processed, and an automated control system for regulating the operation of the system 17. The liquid waste minimization system 15 may be configured as a permanent installation for continuously processing liquid waste material in an industrial setting or as a mobile unit for processing liquid waste material at various locations. In a typical application, radioactive liquid waste 19 is tested for levels of contaminants. After determining the appropriate amount and type of encapsulating material 3 to add to the liquid waste 19, the liquid waste 19 is pumped into the liquid waste tank 16. As the liquid waste 19 travels through pipe 18, the encapsulating material 3 is added to the liquid waste 19 in pipe 18. The mixture is transported through the in-line mixer 20 which blends the encapsulating material 3 with the liquid waste 19 to form a gel-like matrix. The gel-like matrix is transported through the enclosed conveyor 21 to the evaporator 22 which removes substantially all of the moisture from the gel-like matrix. The vapor or distillate is removed from the evaporator 22 through discharge pipe 23. Substantially all of the radioactive contaminants in the liquid waste material are entrapped in the remaining matrix material, which is now in the form of a crusty ash-like material. The volume of remaining matrix material is generally about 50% to about 90% less than the original volume of liquid waste 19 prior to treatment by the liquid waste minimization process. Since substantially all of radioactive contaminants are entrapped in the matrix material, the distillate is generally free of any significant levels of radioactive contaminants. The distillate can then be disposed of by depositing in waste streams or other waste disposal methods for non-hazardous waste material. In the event the distillate contains higher levels of contaminants, the distillate can be recycled through the liquid waste minimization system 15 or disposed of in less costly disposal sites for lower level contaminated waste material. Although the invention is described with respect to the preferred embodiments, it is expected that various modifications may be made thereto without departing from the spirit and scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims which follow.