United States , Environmental Protection Agency Water Engineering Research Laboratory Cincinnati OH 45268 Research and Development EPA/600/S2-85/096 Sept. 1985 c/ERA Project Summary Application of Adsorptive/ Absorptive Resins and Membranes for Toxic and Hazardous Waste Reduction J. Carl Uhrmacher A study was undertaken to assess the use of membrane separation and ion exchange/adsorption resins for reduc- ing or eliminating toxic and hazardous wastes in the metal finishing and muni- tions manufacturing industries. Data were gathered by means of a literature review and personal interviews with leading researchers in the field. The study examined the capabilities of adsorptive and ion exchange systems using conventional resins, and it also evaluated the newer ion selective and macroreticular non-ionic resins. Similar evaluations were made for the mem- brane separation processes based on the use of conventional size exclusion. ion exchange film-type membranes, and experimental liquid membranes. The process streams and operations involved in the metal finishing and munitions manufacturing industries were studied in detail. All of the impor- tant chemical species normally found in aqueous solutions throughout the plants were identified. Also documented are other chemical and physical character- istics of these streams such as the pH, suspended solids, and the presence of strong oxidizing or reducing agents. The treatment problems encountered in the two industries are quite different, since the species to be removed from the metal finishing wastes are.primarily ionic, whereas the wastes from the munitions industry contain mostly non- ionic, nitrated organic compounds. Both the membrane separation and ion ex- change/adsorption resin systems are evaluated relative to the specific char- acteristics of the hazardous materials to be removed. This Project Summary was developed by EPA's Water Engineering Research Laboratory. Cincinnati. OH. to an- nounce key findings of the research pro/act that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction This study was conducted to assess the state of the art of commercially available and developing technologies for reducing or eliminating hazardous materials from liquid wastes generated in the metals finishing and munitions manufacturing industries. The study examines mem- brane separation systems and ion ex- change/adsorption resin systems for purifying these industrial wastewaters. Toxic and Hazardous Wastes in the Metal Finishing Industry The metal finishing industry uses more than 100 surface finishing and fabricating processes that require aqueous applica- tion and removal of metals. Wastewaters from metal finishing processes contain heavy metal cations that may be toxic and anions that are also a potential hazard to the environment. In addition to the ionic species, organic molecules used as bright - eners, cleaners, and chelating agents are also present and can complicate the wastewater treatment process. Potential ------- pollutants in metal finishing wastes are listed in Table 1. Hazardous Wastes in the Munitions Industry The common explosives produced by the munitions industry contain nitro groups attached to a wide variety of organic structures, which can be aromatic (benzene ring type), heterocyclic (rings containing non-carbon atoms), or ali- phatic (straight or branched chains). The munitions industry also produces nitrated organic compounds of mercury and lead that are used as primers for explosives or propellants. Typical hazardous wastes from Army munitions operations are as follows: RDX (Hexahydro-1,3,5-trmitro- 1,3,5-tnazme) HMX (Octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocme) TNT (Trinitrotoluene) DNT (Dmitrotoluene) NT (Nitrotoluene) TAX (1 -Acetyl-1,2,3,4,5,6-hexahydro- 3,5-dmitro-1,3,5 triazme) SEX (1-Acetyl-1,2,3,4,5,6,7,8- octahydro-3,5,7-trinitro-1,3,5,7- tetraazocine) PETN (Pentaerythntol tetranitrate) Tetryl (N-Methyl-N,2,4,6- tetranitrobenzenamine) Nitroglycerin Nitrocellulose Nitroguanidine PRIMERS Lead Styphnate Pb (C6HN3O8) Lead Azide N6Pb Mercury compounds Two particular effluents from the man- ufacture and processing of TNT (trinitro- toluene) and TNT-containing ordnance constitute a significant problem. Red water is a darkly colored solution that results from selite processing of TNT to remove unwanted isomers and byprod- ucts. This solution can be concentrated and used as an additive in the paper industry or disposed of by incineration. Further washing of the partially purified TNT produces the more dilute and lighter colored solution termed "pink water." Pink water is also produced as a result of general cleaning and washing operations throughout the plant when the carrying stream has a neutral or alkaline pH and is exposed to sunlight. LAP (load, assembly, and pack) plants, where artillery shells are cleaned by steam and repacked with fresh explosives, also produce pink water. This waste stream contains RDX and HMX, two heterocyclic nitrated explo- sives, as well as TNT. The wastewaters encountered in these two industries are quite different in physical and chemical characteristics and also in the type of hazard they present relevant to the general population and to the environment. In metal finishing, the species to be removed are ionic and amenable to treatment based on either ion exchange or membrane-type separa- tion techniques. The munitions waste- waters contain mostly non-ionic, nitrated organic compounds that have so far resisted ion exchange treatment. The various organic compounds encountered should be able to be concentrated through the use of reverse osmosis or even ultrafiltration membrane systems, since these separation techniques are based on size discrimination. Removing organics from aqueous streams with adsorptive materials such as activated carbon is quite common, and resin systems with high adsorption capacities, such as those Table 1. Potential Pollutants in Metal Finishing Wastes Cations (Valence) Cr (+3 +6) CuM +2) Ni(+2+3) Sn (+2 +4) Pb (+2 +4) Au f+1 +3; AgM) Zn (+2) Anions (Valence) Cr207 (-2) CNf-1 ) SO. (-2) BFt(-1) Clf-1) SiOe (-2) P207<-4) Other Materials Organics Brighteners Cleaners Chelates Detergents Cd(+2] with macroreticular resins, should have the potential for treating munitions wastes. Use of Membrane Separation Systems Osmotic membranes have been a lab- oratory curiosity since the 1920's, but practical membranes were not commer- cially available until the 1 960's. The full report evaluates the classic thin-skinned polymeric membranes used in ultrafiltra- tion and reverse osmosis systems today, and it examines dynamic inorganic mem- branes. The full report also evaluates processes that use ion exchange mem- branes, such as electrodialysis and Don- nan dialysis. Finally, the full report con- siders potential applications of an emerg- ing liquid membrane technology that uses both supported and emulsion liquid mem- branes. Use of Resin Systems A wide range of ion exchange/adsorp- tion-type resins have been used in indus- trial water purification systems over the years. The new types of resins being developed for both ion exchange and adsorption applications are presented in this report. Both microreticular and macro- reticular divinylbenzene/polystyrene res- ins are included. Also examined are chelating and reductive resins that react with the metallic ions. Finally, recently developed ion exchange precoats are examined for potential applicability. Methods Sources of Information A wide range of publications dealing with the separation sciences was re- viewed to develop a list of experts from industry, government, and academia who would be knowledgeable in this field. Appropriate trade publications were re- viewed to identify companies actively engaged in metal finishing, munitions manufacturing, producing or supplying membranes or membrane separation systems, producing or supplying ion exchange/adsorption resins or treatment systems, or conducting research in these areas. Evaluation of Information Information from these sources was compiled to give an overall history and general picture of the state of the art for the different types of membrane separa- tion and ion exchange/adsorption resin systems. The data available on the per- ------- formance of individual products in the treatment of hazardous wastes from the metals finishing and munitions manu- facturing industries were then evaluated Combined information from all of these sources was then assessed to determine the potential of these technologies in the treatment of waste streams from the target industries. Results A considerable body of data and tech- nical information was compiled as a result of the literature .review, telephone and personal interviews, and visits to various research facilities. The data are present- ed'primarily ir> the form of tables that describe (1) the characteristics of the various waste streams and plating solu- tions encountered in the metal finishing and munitions manufacturing industries, and (2) the performance characteristics of specific types of membrane separation systems, membrane materials, commer- cial membrane modules, ion exchange/ adsorption systems, resin materials, and commercially available resin formula- tions. The full report presents a complete discussion of data available on the com- mercial uses of these wastewater treat- ment technologies and for the treatment of similar aqueous solutions. In addition, the full report reviews and evaluates the results of advanced research projects on the development of new or novel mem- brane systems and resin formulations that are potentially applicable to the treatment of these wastes. The conclu- sions and recommendations presented in the report are based on assessment of the accumulated data. Conclusions Treatment of Metal Finishing Wastes Use of Ion Exchange Resin Technology Ion exchange resin technology is a mature technology for the removal of contaminants from plating solutions, the recovery of precious metals, and the freshening of plating baths for reuse. This technology is being used by both manu- facturers and firms that collect and rejuvenate spent solutions from small companies. Research is being performed by private industry and government on process improvements in areas such as producing more highly selective resins and developing better removal and re- covery techniques. The economics of using ion exchange technology in the treatment of these wastes varies widely for specific applications, depending on the type of plating system involved, the configuration of rinses, and the configura- tion of the waste treatment system. Use of Membrane Technology Reverse osmosis and ultrafiltration are mature technologies for treating metal finishing wastes. Zero-sludge and re- duced-sludge systems are available and are used extensively throughout the industry. Reverse osmosis has a partic- ularly high utilization rate in the treatment of nickel plating wastewaters. Although zirconium oxide dynamic membranes are commercially available and appear promising, they have not been used to any extent in the treatment of hazardous wastes. The newer membrane separation systems based on liquid and ion exchange membranes, Donnan dial- ysis, and emulsion liquid membranes are not sufficiently developed to assess their potential for application to the treatment of hazardous wastes. The economics of using membrane separation systems in the treatment of these wastes generally depends on: • the amount of water to be treated, • the fouling index (SDI) of the water to be treated, • pretreatment requirements for the wastewater before introduction to the membrane separation process, and • the potential for resource recovery. Potential savings and capital payback depend on. • the value of recovered materials, • the potential for reusing the treated water in the process, • potential reductions in sewer dis- charge charges, and • potential savings in sludge removal and disposl charges. Electrodialysis and other electrolysis processes have been used to a moderate degree in the treatment of these waste streams. Supported liquid membranes have been demonstrated in the field and show some promise, and the combination of Donnan dialysis with other technol- ogies has demonstrated potential for the treatment of these wastes. However, insufficient data are available at this time to assess the potential economics of these systems in the treatment of metal finish- ing wastes. Of the various pollutants from electro- plating processes, hexavalent chromium is probably the most difficult material to treat, since it is an anion and a powerful oxidizing agent. Claims of successful treatment have not been fully substan- tiated by the data available at this time. Treatment of Munitions Wastes Use of Ion Exchange/Adsorption Resin Technology Granular activated carbon (GAC) has been shown to be more cost effective in the treatment of munitions wastes than currently available macroreticular resins. However, recent laboratory studies indi- cate that the use of these resins in a two- bed system has significant potential for being more cost effective than GAC mthe future. Use of Membrane Technology Very little effort has been made to apply membrane separation technology to the treatment of wastewaters from the muni- tions manufacturing industry. Concern over the potential for accumulating dan- gerous concentrations of explosive mater- ials has been a major impediment to research in this area. Also, very little work has been done on the application of membrane separation technology for treating the unique wastes from military installations. Although the data available indicate mixed results, this technology is considered to have a high potential for the treatment of these wastes in the future. The full report was submitted in fulfill- ment of Contract No. 68-03-3214 by Carltech Associates, Inc., under the spon- sorshipof theU.S. Environmental Protec- tion Agency. ------- J. Carl Uhrmacher is with Car/tech Associates, Inc., Columbia, MD21045. Thomas J. Powers is the EPA Project Officer (see below). The complete report, entitled "Application of Adsorptive/Absorptive Resins and Membranes for Toxic and Hazardous Waste Reduction," (Order No. PB 85-241 776/AS; Cost: $13.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Water Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 EPA/600/S2-85/096 QOOO'529 PS CHICAGO PROTECTION AGENCY ------- |