Patent Number: 047159928
Section: description

In the drawing, filter cartridges are placed in a chopper or shredder 1 which comminutes them into easily dissolved pieces. The solid material passes through line 2 into dissolution tank 3, while the liquid material passes through line 4 into water purge line 5. Butyrolactone in feed tank 6 is pumped through line 7 by feed pump 8 to line 9 into dissolution tank 3 where it attacks and dissolves in the comminuted filter material. Vapors from tank 3 are collected in line 11 by condenser 12, and the condensed vapors pass through line 13 to feed tank 6, while air in line 14 is exhausted. The dissolved filter cartridges, along with undissolved material, passes as a slurry through line 15 into drum 16. A solidification agent is pumped from tank 17 through line 18 by feed pump 19 to line 20 into drum 16, where the polymerizable material polymerizes and solidifies, entrapping the solid waste material. Water in line 5 passes to water treatment tank 21, where the solids are separated by crystallization or evaporation. The solids can then be passed through line 22 to drum 16 for encapsulation, while the liquid is discharged in line 23 as an affluent. The method of this invention is applicable to any contaminated material that is made with an addition polymerizable organic polymer; such materials contain ethylenically unsaturated double bonds. It is particularly applicable to materials containing large amounts of acrylics and phenolics because these materials are very difficult to dissolve and treat by any other method. A material well suited for treatment according to the process of this invention is one containing about 40 to about 50% by weight acrylic fiber and about 40 to about 50% phenolic resin; filter material may also contain about 5 to 12% wood pulp. While comminution of the material is not required, it is preferred because it greatly reduces the dissolution time. In the first step in the process of this invention, the filter element material is contacted with sufficient butyrolactone to dissolve the organic matter present that is soluble in the butyrolactone. No more butyrolactone should be used than is necessary to dissolve this material since additional butyrolactone will unnecessarily add to the waste volume. Since some of the contaminants in the material, and possibly some of the organic materials themselves, will not be soluble in the butytrolactone, a slurry will be formed. In the next step in the process of this invention, the polymerizable material in the slurry is cross-linked or polymerized to solidfy the slurry. This can be accomplished in the final storage container or it may be accomplished in a reaction vessel. The reactive mixture can then be poured into the final container before it solidifies. Solidification of the slurry is accomplished by the addition thereto of about 0.1 to about 2% by weight, based on the total slurry weight, of an addition polymerization catalyst. Less than 0.1% catalyst is ineffective and more than 2% is unnecessary. Such catalysts are well known in the art and are typically free radical initiators. Examples of suitable free radical initiators include triactin, benzoyl peroxide, and methyl ethyl ketone peroxide. Peroxides are preferred as they have been found to work well. It is preferable to add about 10 to about 50% by weight, based on total slurry weight, of an ethylenically unsaturated monomer to the slurry to reduce the time required for the slurry to solidify. If less than 10% of the ethylenically unsaturated monomer is used, the time required for the slurry to solidify will not be reduced very much, and more than 50% will have minimal additional effect. Suitable ethylenically unsaturated monomers include butadiene, propylene, ethylene, maleic anhydride, and styrene. Styrene is preferred because it has been found to work very well. The ethylenically unsaturated monomer may have any molecular weight and, while it acts as a monomer in this reaction, it may itself be a polymer or an oligomer. The polymerization and solidification of the slurry will occur at room temperature, but it is preferable to heat the slurry between about 70.degree. C. and about the boiling point of the ethylenically unsaturated monomer in order to speed the reaction. While the method of this invention is particularly applicable to filter cartridges, it is also applicable to other materials of similar composition such as ion exchange resins and absorbents. The following examples further illustrate this invention. EXAMPLE 1 Type C-8 and F-8 Cuno filter cartridges manufactured by Robinson Myers were used in these experiments. The following table gives their composition: ______________________________________ Component Type C-8 (wt. %) Type F-8 (wt. %) ______________________________________ Acrylic Fiber 46.7 47.5 Phenolic Resin 45.0 44.0 Wood Pulp 8.3 8.5 ______________________________________ The cartridges were cut into small pieces and placed in beakers containing butyrolactone, tetrahydrofuran, dioxane, and tetrachloroethylene at room temperature. Other pieces were placed in flasks containing N-methyl-pyrrolidone, dimethyl formamide, styrene, or caustic soda, and the solvents were refluxed at their normal boiling point. At the end of 24 hours it was found that butyrolactone was the only solvent that degraded or dissolved the filter cartridge. Specifically, 160 grams of type C-8 and F-8 filters dissolved in 400 cc of butyrolactone, resulting in a final solution volume of about 530 cc. This was a volume reduction factor of about 3:1 over the uncrushed filters. EXAMPLE 2 A contaminant solution was prepared having the following composition: ______________________________________ COMPONENTS WEIGHT PERCENT ______________________________________ Trisodium Phosphate 15.9 Motor Oil 15.9 Co(NO.sub.3).sub.2).6H.sub.2 O 39.2 CsCl 10.0 Sr(NO.sub.3).sub.2 19.0 ______________________________________ The slurry prepared in Example 1 was mixed with the contaminant solution and various curing agents, and the mixture was cured and solidified. Leaching tests were performed on the solid product. The following table describes a solidification procedure and the percent leached of solids and strontium nitrate into deionized (DI) water. ______________________________________ Leaching Results % Solids Solidification Procedure Leached Sr(NO.sub.3).sub.2 ______________________________________ 1. 25 gm Filter Solution .3158 gm = .1411 gm 2 gm Contaminant 15.8% Cured at 32.degree. F. in H.sub.2 O Solid leached for 32 days in DI water 2. 25 gm Filter Solution .6745 gm = .2718 gm 2 gm Contaminant 33.7% 1 gm Triacetin Cured in water at 32.degree. F. Solid leached for 32 days in DI water 3. 25 gm Filter Solution .6231 gm = .2249 gm 25 gm Styrene 31.2% 0.25 gm Benzoyl Peroxide .6267 gm = .3535 gm Cured at 90.degree. C. in oven 31.3% Solid leached for 32 days in 39 ml DI water 4. 25 gm Filter Solution .5869 gm = .2606 gm 5 gm Styrene 29.3% .05 gm Benzoyl Peroxide 2 gm Contaminant Cured at 90.degree. C. in oven Solid leached for 32 days in DI water 5. 50 gm Filter Solution No leaching data 12.5 gm Styrene available 12.5 gm Maleic Anhydride .25 gm Benzoyl Peroxide 2 gm Contaminant Cured at 90.degree. C. in oven 6. 25 gm Filter Solution No leaching data 1 gm Triacetin available 2 gm Contaminant Cured to solid at 0.degree. C. in water Solid cured at 90.degree. C. in oven 7. 20 gm Filter Solution No leaching data 5 gm Maleic Anhydride available .05 gm Benzoyl Peroxide Cured in oven at 140.degree. for 48 hours 8. 20 gm Filter Solution No leaching data 10 gm Maleic Anhydride available .1 gm Benzoyl Peroxide 2 gm Contaminant Cured in oven at 140.degree. C. for 48 hours 9. 20 gm Filter Solution No leaching data 20 gm Maleic Anhydride available 0.2 gm Benzoyl Peroxide 2 gm Contaminant Cured in oven at 140.degree. C. for 48 hours ______________________________________