United States Environmental Protection Agency Hazardous Waste Engineering Research Laboratory Cincinnati OH 45268 ^'f Research and Development EPA/600/S2-85/069 Jan. 1986 Project Summary Evaluation of Emerging Technologies for the Destruction of Hazardous Wastes Jan Radimsky and Arvind Shah The objective of the full report is to provide detailed information regarding four innovative alternative technolo- gies demonstration projects for treat- ing and destroying hazardous wastes. Under a cooperative agreement be- tween the U.S. Environmental Protec- tion Agency (EPA) and the State of Cal- ifornia, the Department of Health Services (DHS) carried out a pilot-scale test program on the following promis- ing technologies. 1. High Temperature Thagard Fluid-Wall Research 2. Evaluation of Air Resources Emission Tests Board State from SunOhio of California Mobile PCB Treatment Pro- cess 3. Wet Air Oxidation Zimpro 4. Evaluation of Air Resources Emission Tests Board State from Wet Air of California Oxidation Zim- pro Process Discussions of the above processes include project descriptions, results, conclusions, and recommendations. This Project Summary was devel- oped by EPA's Hazardous Waste Engi- neering Research Laboratory, Cincin- nati, OH, to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering infor- mation at back). Introduction On January 20,1981, the State of Cal- ifornia entered into a cooperative agree- ment with the Office of Research and Development, EPA, to evaluate selected promising technologies for destroying hazardous waste. The inclusion of a pro- cess in the report should in no way be considered an endorsement of the pro- cess by either the State of California or the EPA. High Temperature Fluid-Wall, Thagard Research Company Summary The High Temperature Fluid-Wall (HTFW) Reactor was developed origi- nally for the continuous dissociation of methane into carbon fines and hydro- gen. This particular process required the generation of stable temperatures above 1,700°C and the prevention of precipitate formation on the reactor walls. This fact has particular relevance to the project herein. Reactor consists of a tubular core of porous refractory material capable of emitting sufficient radiant energy to ac- tivate the reactants fed into the tubular space. The reactor has been built with cylindrical core diameters of 3", 6", and 12" with heated core lengths of up to '72". The core material is designed to be of uniform porosity to aJlow the perme- ating of a radiation-transparent gas through the core wall into the interior. The core is completely jacketed and in- sulated in a fluid-tight pressure vessel. Electrodes located in the annular space between jacket and core provide the en- ergy required to heat the core to radiant temperatures. To achieve both goals simultaneous- ly, the reacting stream is kept out of physical contact with the reactor wall by means of a gaseous blanket formed by flowing an inert gas radially inward ------- through the porous reactor tube (or core). Both high temperatures and high rates of heat transfer are achieved by heating the porous carbon core to in- candescense so that the predominant mode of heat transfer is by radioactive coupling from the core to the stream. Reactor is heated electrically with six carbon resistance heaters. Because of the extreme temperatures encountered in operation of the device, the insulation package consists not of refractory brick but of a radiation shield made of multi- ple layers of graphite paper backed up with carbon felt. The short residence time associated with the reactor which demands the pulverization of solid feeds also lends itself to a compact sys- tem where a reasonably high through- put is seen for a small installation, and portability becomes an attainable de- sign feature. Four volatile chlorinated hydrocar- bons [(dichloromethane; 1,1,1- trichloroethane; carbon tetrachloride; and Freon-12 (dichlorodifluorometh- ane)] and one nonvolatile chlorinated hydrocarbon (hexachlorobenzene) have been decomposed in the HTFW Reactor in bench-scale tests to assess the appli- cability of the device for efficient de- struction of these particular com- pounds. The hexachlorobenzene, loaded onto a solid radiatiorvtarget, exhibited high (O9.9999 percent) destruction effi- ciency, while the vapors (which could be heated only by secondary thermal conduction from solid radiation target) exhibited destruction efficiencies re- lated inversely to the compound heats of formation, indicating that vapor- phase reaction temperatures were lower than the solid reaction. Destruc- tion efficiencies ranged from 99.999965 percent for dichioromethane to 84.99 percent for Freon-12. Heat transfer anal- ysis indicated that vapor heating is de- pendent on the solid particle density, and that efficient heating (and destruc- tion) of vapors can be achieved simply by increasing the particle density. Results and Conclusions Chlorinated Hydrocarbon Vapor Samples The most important conclusion drawn from the work completed is that chlorinated hydrocarbons introduced into the reactor in the vapor form are much more difficult to destroy than sim- ilar materials loaded onto solids, given identical residence times and reactor temperatures. While the governing factor in the case of the solids was the direct absorption of radiation by the solid surfaces and consequent extremely rapid heating, the governing factor in the case of the vapors was the conduction of the heat from the particle surface into the vapor—a much slower process limited in rate by the thermal conductivity of the vapor itself. Thus, as might be anticipated, the temperature levels achieved in the va- pors for a given residence time will not, in general, be as high as the tempera- tures achieved on the solids. The exper- imental result of this behavior will be that minimum temperatures and mini- mum residence times for complete de- struction of the vapor-phase substances will not be achieved, and that the ob- served destruction levels will now be critically dependent on the heat of for- mation of the substance being investi- gated. Chlorinated Hydrocarbons Solid Sample The results for hexachlorobenzene (HCB) in soil are in agreement with HCB results on carbon, thus duplicating both the destruction and analytical methods and further substantiating the conclu- sion that the solids are rapidly heated and the toxic material effectively de- composed. Despite some data problems, the frac- tion of HCB remaining on the solids and in the effluent gases was approximately 10~6, corresponding to a destruction ef- ficiency of approximately 99.9999 per- cent. The demonstration of gettering of chlorine (from decomposition of HCB) with calcined lime (CaO) mixed with the soil produced no identifiable results. Since gettering of halogens and sulfur with lime and subsequent fixing into a vitreous slag has been previously dem- onstrated on numerous occasions with other materials we must conclude that some deficiency in the experimental procedure was introduced (inadequate mixing of the lime in the soil, too low a CaO/CI ratio for this particular applica- tion, etc.). Subsequent experimental work will seek to quantify this parame- ter which is an important system con- sideration of on-site disposal. Air Resources Board's (ARB) Evaluation to Determine Emissions from SUNOHIO's Mobile PCB Treatment Process Three evaluation tests were con- ducted to allow determination of emis- sions from SUNOHIO's mobile PCB treatment process. The mobile unit was tested while treating contaminated oils at three locations: Chevron's USA refin- ery at El Segundo, California; Pacific Gas and Electric (PG&E) Company's fa- cility at Union City, California; and Maxwell Laboratory's facility in San Diego, California. PCBs were not detected in samples of emissions taken at two of the tests. However, relatively high benzene and aliphatic hydrocarbon concentrations were measured in the units' uncon- trolled exhaust gases. Measured con- centrations ranged from 18 to 7,000 ppm for benzene and 700 to 2,700 ppm for aliphatic hydrocarbons. Low process volumetric flow rates resulted in the mass emission rates for benzene and the aliphatic hydrocarbons to values of approximately 0.1 Ib/hr. and below. Data from samples taken by the South Coast Air Quality Management District (SCAQMD) staff during the El Segundo test indicate that dioxins and furans are not present above the limit of detect- ability. The efficiency of the carbon adsorp- tion control system for preventing emis- sions to the atmosphere of benzene and aliphatic hydrocarbons was found to have varied from approximately 99 to 30 percent, indicative that carbon ad- sorption breakthrough occurred. The 30 percent efficiency calculation was based upon concentration measure- ments from the evaluation test con- ducted at the PG&E facility. An alternative control system was tested that utilized an oil fired furnace, a component of the PCBX process, to in- cinerate the emissions. Furnace exhaust gas samples indicate a general reduc- tion in concentration of compounds measured across the furnace. Benzene and toluene were not detected in the furnace exhaust gas. Introduction On December 2 and 10, 1982 and No- vember 30,1983, the ARB's Engineering Evaluation Branch conducted evalua- tion tests on chemical processing equipment designed to reclaim trans- former oils contaminated with PCBs. The process tested is known as the ------- "PCBX" process and was developed by SUNOHIO, a partnership between the Sun Company of Radnor, Pennsylvania and the Ohio Transformer Corporation of Louisville, Ohio. The equipment is in- stalled on two mobile trailers and can be driven to different geographical lo- calities to treat contaminated oils on site. The first test was conducted on De- cember 2,1982 at Chevron's USA El Se- gundo refinery. This was a joint venture between SCAQMD and the ARB. The second test was conducted on Decem- ber 10, 1982 at a PG&E facility in Union City. The third test was conducted on November 30,1983 at the San Diego fa- cility of Maxwell Laboratory. The objectives of the evaluation tests were to allow determination of emis- sions from the unit's vacuum degasser and determination of the efficiency of two prototype emission control sys- tems. One control system consists of an oil mist eliminator, in combination with an activated charcoal filter to control emissions from the vacuum degasser's vent pipe. The other control system uti- lizes an oil fired furnace that is a compo- nent of the PCBX process to incinerate the emissions. Conclusions and Recommendations Based on the analytical results and staff experience obtained from the ARB's evaluation test conducted on the SUNOHIO PCBX process, the following observations are made: 1. The activated carbon adsorption canister used during testing is not big enough to provide effective emissions control for an extended period of time, the control system should be (1) redesigned to have a larger activated carbon adsorption unit, or (2) revise the maintenance schedule for the present carbon canister to require canister re- placement with a frequency com- mensurate with a demonstrated breakthrough* time. 2. If emissions are to be prevented from the carbon canister, the car- bon canister breakthrough should be monitored with a continuous analyzer. 3. Based upon the results of this test, the oil fired furnace as a control device appears to,be effective. Results and Discussion 1. Results From the Test Conducted at Chevron's USA El Segundo Re- finery Results of analyses performed on samples taken from the PCBX pro- cess during the ARB evaluation test conducted at Chevron's USA El Segundo refinery indicate that Benzene and Ca-C^ hydrocarbons were the predominant compo- nents measured in the gases vented directly out of the vacuum degasser during the treatment of transformer oil. Benzene concen- trations ranged from 400 ppm to 7,000 ppm and hydrocarbon con- centrations from 7 ppm to 1,600 ppm. TRW's analytical results for samples taken at the same location as the ARB, show benzene concen- trations exceeding 5,000 ppm and C5 hydrocarbon concentrations as being 1,400 ppm. TRW results for benzene are in the range of con- centrations determined by the ARB and the hydrocarbon concentra- tions, while not directly compara- ble to the ARB results, are proba- bly not inconsistent. SCAQMD did not take samples from the vacuum degasser outlet. PCBs were not detected above the detection limit of the analytical method for any of the ARB sam- ples taken. TRW also sampled for and could not detect PCBs above the limit of detection for their ana- lytical method (1 ppm). As discussed previously, SCAQMD took samples before and after the activated carbon adsorber and an- alyzed those samples for PCBs, furans, and dioxins. Because they sampled at a different location and the emphasis of their analytical work was different, no direct com- parison can be made between the SCAQMD and ARB test results. Test results indicate that furans and dioxins are not present above the detectable limits, less than 4-30 parts per trillion. However, in two samples taken from the centrifuge vent at the inlet and outlet of the carbon cannister, detectable amounts of PCBs were measured; 1..7 (10~3) ppm at the inlet and 8.7 (10~6) ppm at the outlet. 2. Results From the Test Conducted at PG&E's Union City Facility Benzene and aliphatic hydrocar- bons were the major components measured in the ARB samples taken from the degasser vent dur- ing the treatment of PCB- contaminated oils stored in a tank at a PG&E facility located in Union City. The range of concentrations determined for benzene and Ce-C^ hydrocarbons was 50 to 950 ppm and 1,900 to 2,700 ppm, respec- tively. Benzene and aliphatic hydrocar- bons were also the significant components in the treated vacuum degasser vent gas as sampled at the outlet from the control sys- tem's activated charcoal adsorber. The range of benzene concentra- tions was 600-700 ppm and the range of Ce-C^ hydrocarbons was 1,400 to 1,800 ppm. BAAQMD also took samples at the charcoal ad- sorber outlet and test results showed: a comparable benzene concentration of 840 ppm (aver- age); a comparable C6-Ci2 hydro- carbon concentration of 1,500 ppm; and total organic and non- methane organic compound con- centrations of 2,600 ppm (average) and 2,400 ppm (average), respec- tively. The control system's charcoal can- ister was the same one used at the El Segundo test. Results of a com- parison between the concentra- tions determined for the inlet and outlet of the control system are in- dicative of carbon adsorption breakthrough. The reduction of both benzene and aliphatic hydro- carbons was approximately 30 percent across the control system. PCBs were not detected above the detection limit of the analytical method for any of the ARB sam- ples taken. 3. Results From the Test Conducted at the Maxwell Laboratory in San Diego Concentration values for emis- sions were measured during two distinct phases of the PCBX pro- cess: (i) degassing and (ii) dechlo- rination. Benzene concentrations in the uncontrolled vacuum de- gasser emissions, measured at the common inlet to both control sys- tems, ranged from 18 ppm to 220 ppm. Toluene was also measured at concentrations ranging from 0.1 ppm to 290 ppm. At the outlet from the condenser/ carbon control systems, measured benzene concentrations ranged from 10 ppm to 23 ppm and toluene from 0.1 ppm to 26 ppm. Benzene and toluene were not ------- measured above the 0.1 ppm limit of detection in the exhaust gases from the combustion control de- vice. Products of combustion in the fur- nace exhaust gas were monitored when the furnace was fired on fuel oil only and when it was fired with a mixture of fuel oil and vacuum degasser vapors. When combust- ing fuel oil only, the following compounds were measured: 75 ppm S02, 72 ppm NOx, 9.3 ppm THC, 133 ppm CO, 10.2 percent C02 and 9.7 percent 02. When vac- uum degasser vapors were added for combustion in the furnace, measured concentrations were: 78 ppm S02, 92 ppm NOx, 24 ppm THC, 200 ppm CO, 10.2 percent C02, 9.1 percent 02, 0.1 ppm ben- zene and 0.1 ppm, toluene. Samples taken before and after the control devices were speciated to determine the types of compounds present in the emissions. For com- parison purposes, a sample of am- bient air was taken. The com- pounds detected in the ambient sample were all at the part per bil- lion (ppb) level. The magnitude of the other concentration values measured in the uncontrolled and controlled emissions were at the part per million level. Commercial Demonstration of Wet Air Oxidation of Hazardous Wastes Summary Wet Air Oxidation by Zimpro, Inc., is a process which has been used to oxidize dissolved or suspended organic sub- stances at elevated temperature and pressures. The process is thermally self-sustaining with relatively low or- ganic feed concentrations and is, there- fore, most useful for wastes which are too dilute to incinerate economically yet too toxic to treat biologically. The purpose of this project was to demonstrate wet air oxidation of toxic and hazardous wastes at a full-size in- stallation which was located at Cas- malia Resources, a commercial waste treater in California. In the operation of the full-scale Zimpro Wet Air Oxidation unit, wastes selected from classified groups of organic wastes were detoxi- fied. These classified groups were: phe- nolic wastes, organic sulfur wastes, general organic wastes, cyanide wastes, pesticide wastes, and solvent still bottoms wastes. This section con- tains detail evaluation of these six clas- sified wastes' treatment, the effective- ness of the wet air oxidation unit, and sample analysis of feed and effluent. Description of Wet Air Oxidation Process The Zimpro Wet Air Oxidation unit for this demonstration processed aqueous wastes at a designed reactor tempera- ture of 550°F, a designed reactor pres- sure of 2,000 PSIG, a liquid waste flow rate of 10 GPM, and a compressed air rate of approximately 190 SCFM. In the wet oxidation process, liquid waste, ex- iting from a high pressure pump, is combined with compressed air and di- rected through the cold, heat-up side of the heat exchanger. The incoming waste-air mixture exits from the heat-up side of the heat exchanger and enters the reactor where exothermic reactions increase the temperature of the mixture to a desired value. The waste-air mix- ture exits the reactor and enters the hot, cool-down side of the heat exchanger and, after passage through the system pressure control valves, is directed to the separator. In the separator, the spent process vapors (noncondensible gases) are separated from the oxidized liquid phase and are directed into a two-stage water scrubber-carbon bed adsorber, vapor treatment system. In the wet air oxidation process, or- ganic substances can be completely ox- idized to yield highly oxygenated prod- ucts and water. For example, organic carbon-hydrogen compounds can be oxidized to carbon dioxide and water, while reduced organic sulfur com- pounds (sulfides, mercaptans, etc.) and inorganic sulfides are easily oxidized to inorganic sulfate, usually present in the oxidized liquor as sulfuric acid. Inor- ganic cyanides and organic cyanides (nitriles) are easily oxidized to carbon dioxide, ammonia, or molecular nitro- gen. It should be noted that oxides of nitrogen such as NO or N02 are not formed in wet air oxidation. When incomplete oxidation of or- ganic substances occurs, the easily oxi- dized reduced sulfur and cyanides are usually still oxidized to sulfate and car- bon dioxide-ammonia provided a suffi- cient degree of oxidation is accom- plished. However, incomplete oxidation of other organic compounds results in the formation of low molecular weight compounds such as acetaldehyde, ace- tone, and acetic acid. These low molec- ular weight compounds are volatile and are distributed between the process off-gas phase and the oxidized liquid phase. The concentration of these low molecular weight compounds (mea- sured as total hydrocarbons (THC) ex- pressed as methane) in the process of off-gas is dependent on their concentra- tion in the oxidized liquid phase, which is determined by the degree of oxida- tion accomplished, the waste being oxi- dized, and the influent organic concen- tration of the waste. Results and Conclusion Wet air oxidation of phenolic and or- ganic sulfur classes of waste has been demonstrated at the Casmalia Re- sources, Inc., full-scale wet air oxidation installation. Oxidation of a petroleum refining spent caustic waste at a process temperature of 515°F (268°C) and a nominal residence time of 113 minutes resulted in 99.77 percent total phenols reduction, 94.0 percent organic sulfur reduction, and 89.3 percent chemical oxygen demand (COD) reduction. Gas chromatographic/mass spectroscopic (GS-MS) analysis identified acetic acid, benzoic acid, and several sulfide deriva- tives as the major components present in the effluent oxidized waste. Analysis of treated process off-gases indicated a total hydrocarbon (THC) concentration of only 84.5 ppm (expressed as methane). Oxidation resulted in >99.7 percent sulfide sulfur reduction, 98.8 percent total phenols reduction, and 81.3 per- cent COD reduction. Sulfide sulfur and total phenols concentrations were re- duced to > 1.0 mg/l and 66 mg/l, respec- tively, upon oxidation. Further reduc- tion in residual total phenols concentration would likely be achieved by postoxidation treatment with ozone or hydrogen peroxide. The raw spent caustic wastewater had a BODs/COD ratio of 0.49 compared to 0.64 for the oxidized product indicat- ing a slight increase in biodegradability following oxidation. The oxidized prod- uct would likely be easily biodegradable since highly biodegradable materials generally have BODs/COD ratios in the range of 0.5 to 0.6. The wastewater pH decreased from 12.6 in the raw waste to 8.7 upon oxidation, likely due to the conversion of reduced sulfur com- pounds to sulfuric acid. An eight-hour wet air oxidation dem- onstration of a general organic waste- water was performed at the Casmalia ------- Resources, Inc., full-scale wet oxidation installation on July 28, 1983. The general organic wastewater was processed continually during the eight- hour wet air oxidation demonstration. During the demonstration period, the wet air oxidation unit was operated at an average reactor temperature of 531°F (277°C), a compressed air flow rate of 190 SCFM and a reactor pressure of 1,515 PSIG. Waste was processed at an average liquid flow rate of 5.0 GPM re- sulting in a nominal residence time of 120 minutes. Residual oxygen concen- trations in the process off-gas averaged 4.1 percent during the demonstration period. The data indicates the waste to be rel- atively high strength with a chemical oxygen demand (COD) of 76.0 g/l and a dissolved organic carbon (DOC) con- centration of 20,830 mg/l. The raw waste had a pH of 1.9. Very effective treatment of the general organic waste was obtained by wet air oxidation. Oxi- dation resulted in 96.7 percent COD re- duction with the waste COD reduced to 2.5 g/l. A DOC reduction of 96.7 percent was obtained with the oxidized waste having a DOC concentration of 685 mg/l. Analysis of the off-gas sample indi- cated carbon dioxide, oxygen, nitrogen, and carbon monoxide concentrations of 12.9, 5.9, 81.2, and 0.3 percent, respec- tively. Total hydrocarbon (THC) and methane concentrations of 29.1 ppm (expressed as methane)'and 10.0 ppm, respectively, were determined for the process off-gas sample. Treatment of cyanide wastewafers by wet air oxidation has been demon- strated at the Casmalia Resources, Inc., full-scale wet air oxidation installation. The wet air oxidation demonstration was performed on July 29 and August 18,1983 during a combined six-hour pe- riod of steady state operation. The wastewater processed during the wet air oxidation demonstration was a mixture of cyanide wastes generated by various metal plating processes. Labo- ratory screening tests performed by Zimpro, Inc., indicated the individual wastes contained in the wastewater mixture to be treatable by wet air oxida- tion and compatible with respect to ma- terials of construction. During the combined demonstration period, the wet air oxidation unit was operated at an average reactor temper- ature of 495°F (257°C), a compressed air flow rate of 190 SCFM, and a reactor pressure of 1,220 PSIG. Waste was pro- cessed at an average liquid flow rate of 7.5 GPM, resulting in a nominal resi- dence time of 80 minutes. Residual oxy- gen concentrations in the process off- gas averaged 7.1 percent during the demonstration period. The analyses in- dicate the composite raw waste to be a typical high strength cyanide waste with a cyanide concentration of 25,390 mg/l, chemical oxygen demand (COD) of 37.4, g/l and pH of 12.6. Wet air oxidation resulted in very ef- fective treatment of the cyanide waste. The cyanide concentration of the raw waste was reduced to 82 mg/l, repre- senting a cyanide reduction of 99.7 per- cent. A COD reduction of 88.8 percent and a dissolved organic carbon (DOC) reduction of 88.4 percent were obtained by wet air oxidation. COD and DOC con- centrations in the composite oxidized waste were 4.2 g/l and 1,710 mg/l, re- spectively. The scale formation which occurred in the oxidation unit during the cyanide demonstration period is reflected by the total ash data. The composite raw waste had a total ash concentration of 112.9 g/l compared to only 77.4 g/l for the com- posite oxidized waste. Since the ash is expected to pass through the oxidation unit as inert material, the data indicates as much as 35 g/l of inert solids were deposited in the oxidation system dur- ing treatment of the cyanide waste. Analysis of the off-gas sample indi- cated 1.5 percent carbon dioxide, 8.5 percent oxygen, and 82.8 percent nitro- gen. Carbon monoxide was not de- tected in the off-gas sample. A total hy- drocarbon (THC) concentration of 61.1 ppm (expressed as methane) and a methane concentration of 9.0 ppm was determined for the process off-gas sam- ple. Wet air oxidation of four pesticides— dinoseb, methoxychlor, carbaryl, and malathion—was evaluated in a full- scale demonstration at Casmalia Re- sources, Casmalia, California, on March 28, 1984. Since wastewaters containing relatively high concentrations of a vari- ety of pesticides were not easily avail- able, the above compounds were spiked into an acidic distillate waste- water which had previously been pro- cessed in the Casmalia wet air oxidation unit. Prior to the full-scale pesticides wet air oxidation demonstration, bench scale autoclave oxidations of a variety of pesticides had been evaluated. Greater than 99 percent destruction was observed for seven pesticides, includ- ing the four subsequently demon- strated in the Casmalia full-scale unit. Removals of the four pesticides ranged from 98.0 to greater than 99.8 percent. Analyses of pesticides in the feed and effluent composites were by gas and liquid chromatography. COD, BOD5, and DOC removals were quite similar to results obtained during oxidation of the acidic distillate waste alone. COD, BOD5, and DOC removals of 95.3, 93.8, and 96.1 percent were ob- served. Carbon dioxide, oxygen, nitro- gen, and carbon monoxide concentra- tions of 14.2, 3.5, 79.0, and 0.7 percent, respectively, were observed. Total hy- drocarbon (THC) and methane concen- trations of 153 ppm (expressed as methane) and 61.9 ppm, respectively, were determined for the process off-gas sample. Wet air oxidation of a solvent still bot- toms type waste was evaluated in a full- scale demonstration at Casmalia Re- sources, Casmalia, California, on March 29, 1984. The wastewater was pro- cessed continuously during the eight- hour wet air oxidation demonstration. Soluble chloride analyses for feed and effluent indicated 7,860 and 505 mg/l, respectively. These data indicate material in the feed causing a positive interference 'in the chloride analysis. Oxidation of this material resulted in an apparent decrease in -soluble chloride. This behavior is frequently seen in the wet air oxidation of industrial wastes. Soluble fluoride increased from 7.5 to 42.7 mg/l upon oxidation, likely due to the destruction of fluorinated organic compounds. This fluoride content was not observed in previous bench scale screening of this wastewater. Fluoride levels much higher than this may not be acceptable in the Casmalia wet air oxi- dation unit because of corrosive effects on titanium system components. Carbon dioxide, oxygen, nitrogen, and carbon monoxide concentrations of 11.8, 3.8, 81.2, and nil percent, respec- tively, were observed. THC and methane concentrations of 217 ppm (expressed as methane) and 80 ppm, re- spectively, were determined for the pro- cess off-gas sample. However, on-line off-gas THC measurements indicated increasing THC concentrations through- out the demonstration run as the vapor phase activated carbon adsorption bed became exhausted. ------- Air Resources Board's Evaluation Test Conducted on a Wet Air Oxidation Process to Treat Hazardous Wastes Summary The California Air Resources Board (ARB) conducted six evaluation tests on a wet air oxidation unit manufactured by Zimpro, Inc. The unit designed to treat toxic wastes is installed and oper- ated at a Class I waste disposal facility managed by Casmalia Resources and located in Casmalia, California. The test results of the four category wastes, namely—phenols, sulfides, acid organ- ics, and cyanides—are discussed in the full report. The ARB evaluation tests were initi- ated in response to a request by Santa Barbara County Air Pollution Control District for emission data with which to properly establish and assess the wet air oxidation unit's waste processing ca- pabilities and the effectiveness of the air pollution control devices. Results and Discussion 1. Wet Air Oxidation Process Wet air oxidation appears to be an effective method for reducing the concentration of liquid phase cyanide and phenol compounds. Cyanide concentrations measured at the inlet and outlet of the wet air oxidation process were 46,300 parts per million by weight (ppm W) and 6.94 ppm W, respectively. Inlet and outlet phenol concentra- tions were 18,700 micrograms per milliliter (jjig/ml) and 2.35 (jig/ml. The reduction in concentration for both compounds treated by the wet air oxidation process was over 99 percent. However, wet air oxidation of acid- organics was somewhat less con- sistent. Two sets of inlet-outlet samples were taken across the process with one indicating a 64 percent reduction of the initial con- centration and the other, a 97 per- cent reduction. Each value was ob- tained by ratioing the GC/FID generated total peak areas for an inlet-outlet sample pair taken across the wet air oxidation pro- cess. When the output sample's GC/FID trace was compared to that for the inlet sample, some peaks had disappeared, some were no- ticeably reduced, and in some in- stances, new peaks appeared. Be- 6 cause the availability of standards to identify each peak was limited, the ratio of total peak areas was used to give a relative indication of the wet air oxidation process. 2. Condensible, Noncondensible Separator With the exception of acid- organics, the amount of noncon- densible cyanide, phenols, and sulfide measured at the separator was at the microgram level. The quantity of CN, phenol, and sulfide captured was 3.23 |xg, and 713 jxg, respectively. These values also represent the prescrubbed gas concentrations at the inlet to the scrubber. The total volume drawn for each sample was 45 cubic feet. A "less than" symbol (<) preced- ing a value implies that it is below the detection limit of the analytical method with respect to the total volume sampled. Noncondensible acid-organic samples taken at the separator were used to identify and semi- quantitate the major organic com- ponents present in the gas stream prior to entering the control equip- ment. The results show that for the treatment of this particular waste, halogenated (bromo-, chloro-) alkenes and benzene appear to be the major compounds in the gase- ous effluents from the separator. 3. Scrubber The scrubber was effective in re- moving sulfide from the gas stream but did not afford any greater control advantage for cyanide and phenols than was achieved by the wet air oxidation process. The calculated cyanide concentra- tion at the inlet was very low, 0.0025 jxg/l or 0.0034 ppm. The measured scrubber efficiency for controlling noncondensible sulfide was 93.4 percent. The scrubber reduced the inlet concen- tration of 0.555 |jig/l, or ppm, to 0.037 (i.g/1, or ppm. The outlet cyanide concentration of 0.0026 jig/l, <0.0025 ppm is comparable to the inlet concentra- tion and indicates that the scrub- ber has no apparent effect on cyanide when this compound is in- troduced into the scrubber at such low levels. It appears that a major portion of the residual phenols and cyanides remaining after the wet air oxida- tion process is retained in the sep- arator's liquid phase and pumped to the facility's water discharge pond. Any liquid phase reactions that may be occurring are un- known. There is a minimal contri- bution of cyanide and phenols to the gas phase for control by the scrubber. However, whether the scrubber would be an effective control device at higher inlet con- centrations of cyanide and phe- nols, as might occur during an upset condition, is yet to be deter- mined. 4. Carbon Bed The carbon bed was most effective in controlling the discharge to at- mosphere of gas phase bromi- nated compounds. The inlet con- centration of 450 ppm was reduced to 0.18 ppm at the outlet of the carbon bed, representing a removal efficiency of over 99 per- cent. Note that these concentration values are order of magnitude esti- mates based on (a) the qualitative speciatipn data that identified brominated hydrocarbons as the major noncondensible hydrocar- bons present and (b) quantitative analysis that normalized all significant GC peaks to 1,2- dibromomethane, which was the major identifiable compound for which a standard was available. The normalization technique was performed because standards were not available for the other major peaks. A comparison of these values will give a relative ef- ficiency performance of the carbon adsorber. The percentage control for cyanide and sulfide was minimal: 17.8 per- cent and 26.8 percent, respec- tively. The full report was submitted in par- tial fulfillment of Cooperative Agree- ment No. R-808908 under sponsorship of the EPA and the State of California, DHS. U. S. GOVERNMENT PRINTING OFFICE:1986/646-l 16/20750 ------- Jan Radimsky and Arvind Shah are with Department of Health Services, Sacramento. CA 95814. Harry M. Freeman is the EPA Project Officer (see below). The complete report, entitled "Evaluation of Emerging Technologies for the Destruction of Hazardous Wastes," fOrder No. PB 86-128 717/AS; Cost: $16.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield. VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Hazardous Waste Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 Official Business Penalty for Private Use $300 EPA/600/S2-85/069 ------- |