v-xEPA United States Environmental Protection Agency Industrial Environmental Research Laboratory Cincinnati OH 45268 Research and Development EPA-600/S7-81-081 May 1981 Project Summary Assessment of Oil Shale Retort Wastewater Treatment and Control TechnologyPhases I and II J. R. Klieve, G. D. Rawlings, and J. R. Hoeflein Oil shale retorting is a synthetic fuel production technology on the verge of commercialization in the United States. In order to ensure that the emerging oil shale industry will have minimal adverse effects upon surface and/or groundwater where recover- able reserves of oil shale are found, demonstrated technologies to upgrade oil shale wastewaters must be available to developers. To this end, the U.S. Environmental Protection Agency has contracted with Monsanto Research Corporation (MRC) to conduct a three-year, five-phased study to: (1) summarize known information concerning oil shale retort wastewater sources and characteris- tics; (2) identify potentially applicable control technologies capable of treat- ing the identified wastewater streams; and (3) design, construct, and operate pilot-plant facilities to evaluate the selected technologies. This report presents results Of Phases I and (I, in which literature and other information sources were surveyed to obtain rele- vant data about oil shale retorting technologies, wastewater sources and characteristics, potential waste- water uses, and potentially applicable treatment technologies. As a result of the study, data gaps were identified, and recommendations for bench- scale treatability studies were made. This Project Summary was develop- ed by EPA's Industrial Environmental Research Laboratory, Cincinnati. 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 information at back). Technical Discussion In-situ retorting, which consists of heating shale underground after modification of the permeability of the rock formation, is being investigated by Dow Chemical Co., Equity Oil Co., Geo- kinetics, Irfc., Occidental Oil Shale, Inc., and Rio Blanco Oil Shale Co., all of which are now conducting process development efforts. Processes being developed by Paraho Development Corp., Superior Oil Co., TOSCO Corp., and Union Oil Co., are classified as surface retorting, in which mined, crushed shale is heated in above- ground metal vessels to produce crude oil. Although many process variations exist within the two major retorting process categories, in-situ and surface, distinct wastewater streams are common to most processes within each category. From in-situ retorting, three major streams emanate: mine water, retort water, and gas condensate. Mine water is thatwater pumped from a shale formation prior to ignition. Retort water is formed when water vapor condenses in cool, rubblized shale ahead of the flame front during retorting. Gas con- densate is that water which leaves the ------- retort as a gas and is recovered when gas from the in-situ retort is cooled. From surface retorting, three major streams are envisioned: gas conden- sate, product water, and spent shale pile leachate. Water normally leaves the surface retort in the vapor phase and is recovered as gas condensate when the retort gas is cooled prior to purification. In addition, water separates from the product oil following oil/gas separation and is termed product water. Since spent shale from surface retort- ing is to be disposed of above ground, leachate through the shale pile is another potential wastewater stream. Mine water has been found to exhibit high levels of alkalinity, chemical oxygen demand (COD), chloride, fluo- ride, sulfate, boron and sodium. Exis- tence of trace metals are of particular concern, since some mi'ne water will be discharged to the environment. Retort wastewater and product wastewater contain high levels of most pollutants identified. Gas condensate wastewaters exhibit high levels of ammonia, alkalinity, and organics; however, concentrations of trace metals are significantly lower in gas condensate than in retort wastewater. Limited data are available to character- ize leachate; however, high levels of organics, total dissolved solids (IDS), sulfate, and sodium have been exhibited. Water-use schemes developed by industry and government contractors have been reviewed. Most water-use schemes suggest use of wastewater within the retorting facility; however, there appears to be little technical information to support this approach. Available information relating to the treatability of individual retort streams was summarized and significant data were obtained only for the treatability of mine water and combined retort/prod- uct water. In the case of mine water, activated alumina absorption, precipitation with phosphoric acid and lime, and ion exchange have been demonstrated in bench-scale screening tests to remove fluoride and/or boron. Additional tech- nologies should be used for dissolved gas removal, suspended solids removal, IDS removal, and disinfection, particu- larly if the water is discharged or used for. potable needs. Many research studies have focused on the treatment of retort/product water. There remain, however, key technical questions in the area of emul- sified oil separation and organics removal. Steam stripping has been identified as a promising technology for dissolved gases removal. Granular acti- vated carbon and polymeric resins have been demonstrated for gross organics removal; however, for cost considera- tions, aerobic biological treatment should be the focus for gross organics removal, with carbon and polymeric resins used to remove refractory organics. No research activity in the area of gas condensate treatment was identified; however, steam stripping should ade- quately treat gas condensate for in- plant use. In the case of leachate, it is recom- mended that funds be used to identify leachate as a major wastewater stream and characterize it, rather than investi- gate treatment alternatives. If leachate is found to be a significant wastewater stream, serious questions regarding leachate collection arise. Several treatability screening studies have been conducted to fill many treat- ment step needs identified in Figures 1 and 3, particularly in the case of mine water and retort water treatment. Be- cause of their design and intent, these studies have generally been useful to screen some potential technologies and eliminate others. Many key technical questions still remain unanswered such as: How should emulsified oil be separated in retort and product water? What is the best system for re- moval of organics from retort and product water? Will state-of-the-art technologies treat gas condensate and leachate? To answer these questions, and to size pilot-plant equipment, MRC recom- mends conducting additional bench- scale treatability studies. Presently, there are several opportunities for MRC to obtain relevant samples of retort wastewaters with which to conduct these studies, namely: Rio Blanco mine water and retort water Tosco gas condensate Geokinetics retort water Occidental retort water and gas condensate In the case of mine water treatment, only Battelle N.W. has conducted bench-scale treatability studies for the removal of fluoride and boron which are of primary concern if the excess mine water is to be discharged or used for potable purposes. Activated alumina absorption and precipitation with phos- phoric acid and lime were identified as promising technologies for the removal of boron. The literature reported that electrodialysis and reverse osmosis could produce a more than adequate effluent; however, reverse osmosis appears to be more cost-effective at the high TDS levels expected and has other technical advantages as well. Thus, additional research is needed to demonstrate the feasibility of reverse osmosis treatment of mine water and to size pilot-plant equipment in the case of other treatment steps. Suggested technology options to be investigated in these studies are listed in Figure 1. Many more studies have been con- ducted with retort water; however, key technical questions remain; e.g., no studies have been conducted to investi- gate emulsified oil separating from retort and product water. Steam strip- ping has been identified by several investigators as the best technology for dissolved gases removal, though fouling of column packings has been experi- enced. Emulsified oil separation may alleviate the problem. Although many studies have been conducted to assess technologies for organics removal, many questions remain. Aerobic bio- logical treatment has classically been the most cost-effective method of organics removal from municipal wastes, but various pretreatments are required for these systems to operate with retort water; also, a large portion of the organics (50%) appear to be refrac- tory. Therefore, additional studies are needed to identify methods which would enhance -the ability of aerobic biological treatment to remove organic compounds. The sensitivity of biological systems to variations in retort water composition has serious implications for commercial operations. If it is found that wastewater cannot be treated bio- logically, it may become necessary to test physical/chemical methods such . as wet air oxidation and granular' ------- Potential End Use Reinfection Treatment Steps Mine Water Treatment Options Dissolved Gases Removal Clarification Fine S.S. Removal Cooling Tower Makeup Discharge TDS/Trace Metals Removal Residual Inorganics Removal Boiler Feed Potable Use Aeration Chemical Addition/ Flocculation/ Sedimentation Multimedia Filtration Reverse Osmosis Ion Exchange Ion Exchange Cl2 retort water are envisioned. Bench- scale studies conducted at this time are still recommended to complete a retort treatability data base which would be used by industry and government in making water-use decisions. Although no known studies exist for the treatment of gas condensate, this stream should not be difficult to treat, compared to retort water. At this time, the extent to which emulsions are present in gas condensate is not known. If present, they will have to be removed prior to subsequent treatment steps. Steam stripping studies are necessary to assess organics removal as well as inorganic dissolved gases removal. If organics remain following steam strip- ping, studies for their removal will have to be initiated. Suggested technology options for gas condensate treatment are listed in Figure 3. Since it is not known whether leachate from spent-shale piles will be present in significant quantities, and leachate quality is still not fully understood, research funds should be directed to address these issues rather than investigating treatment alterna- tives. If spent-shale piles are found to be porous, and the leachate from percolation through the piles is toxic or unacceptable for groundwater discharge, serious questions about leachate collection in full-scale systems exist. This report was submitted in partial fulfillment of Contract No. 68-03-2801 by Monsanto Research Corporation under the sponsorship of the U.S. Environmental Protection Agency. This report covers the period May 1979 to March 1980; work was completed as of February 1980. Figure 1. Mine water treatability options. activated carbon adsorption. It is unlike- ly that retort water would be discharged from a full-scale retorting facility; how- ever, if discharge is necessary, treatment for trace organics, trace metals, and TDS will become necessary. Several investigators have used granular activated carbon and polymeric resins for gross organics removal; however, studies are needed to assess these technologies for their , ability to remove refractory organics present in the effluent from the gross organics removal treatment step. Studies of TDS and trace metals removal by reverse osmosis and ion exchange would also become neces- sary. Suggested treatment options to treat retort water to discharge quality are shown in Figure 2. Treatment to discharge quality will probably not be necessary in full-scale systems since many in-plant uses for ------- Potential End Use Treatment Steps Retort Water, Product Water Steam Generation Via Thermal Sludge Oxidizer Emulsified (?) Oil Separation Dissolved Gases Removal Organics Removal Fine S.S. Removal Dust Control Shale Moistening Scale Control Cooling Tower Makeup Discharge Gravity Separation Chemical Addition/DAF Chemical Emulsion Breaking/Separation Ultrafiltration Steam Stripping Aerobic Biological Treatment With One or More Pretreatments: -pH Adjustment -Chemical Coagulation -Wet Air Oxidation -Ozonation -PAC Addition Wet Air Oxidation Granular Activated Carbon Multimedia Filtration Chemical Addition Trace Organics Removal TDS/Trace Metals Removal Granular Activated Carbon Polymeric Resins Reverse Osmosis Ion Exchange Figure 2. Retort wastewater treatability options. ------- Potential End Use"1 Treatment Steps Technology Options Gas Condensates Cooling Tower ' Makeup Dust Control Shale Moistening Discharge Emulsified (?) Oil Separation Dissolved Gases Removal Organics Removal Fine S.S. Removal Trace Organics Organics Gravity Separation Chemical AdditionYDAF Chemical Emulsion Breaking/Separation Ultrafiltration Steam Stripping Aerobic Biological Treatment (See Figure 2) Multimedia Filtration Granular Activated Carbon Polymeric Resins Figure 3. Gas condensate wastewater treatability options. ------- J. R. Klieve. G. D. Rawlings, and J. R. Hoeflein are with Monsanto Research Corporation, Dayton, OH 45407. W. W. Liberick. Jr.. is the EPA Project Officer (see below). The complete report, entitled "Assessment of Oil Shale Retort Wastewater Treatment and Control TechnologyPhases I andII, "(Order No. PB 81-187 288; Cost: $9.50, 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: Industrial Environmental Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 » US GOVERNMENT PRINTING OFFICE. 1981 -757-01Z/7H7 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use $300 RETURN POSTAGE GUARANTEED PS 0000329 U S EWVIR PROTECTION REGION 5 LIBRARY 230 S DEARBORN STREET CHICAGO IL 60604 ------- |