United States Office of Research and EPAl625lR971004 Environmental Protection Development July 1997 Agency Washington DC 20460 Technology Transfer GEPA Capsule Report Aqueous Mercury Treatment EPA/625/R-97/004 July 1997 Capsule Report: Aqueous Mercury Treatment National Risk Management Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Cincinnati, OH 45268 @ Printed on Recycled Paper Acknowledgements This capsule report was prepared under contract number 68-C3-0315 by Eastern Research Group, inc. (ERG) for the U.S. Environmental Protection Agency’s (USEPA) Office of Research and Development (ORD). Edwin Barth served as the work assignment manager and provided technical direction. Linda Stein of ERG directed the editing and production of this report. James Patterson, of Patterson and Associates, Inc., Chicago, IL was the primary author. Technical reviewers of this report were: Richard Osantowski, Radian international Corporation, Milwaukee, WI Thomas Sorg, National Risk Management Research Laboratory, USEPA, Cincinnati, OH Donald Sanning, National Risk Management Research Laboratory, USEPA, Cincinnati, OH Jerry Stober, Environmental Services Division, USEPA, Athens, GA Notice This document has been reviewed in accordance with the U.S. Environmental Protection Agency’s peer and administrative review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 111 Contents Page Chapter 1 Executive Summary l-l 1.1 Purpose ......................................... l-l 1.2 Summary ........................................ l-l Chapter 2 Precipitation Treatment Processes . 2-l 2.1 Sulfide Precipitation ................................ 2-l 2.2 Coagulation/co-precipitation .......................... 2-2 Chapter 3 Adsorption Processes . 3-l 3.1 Activated Carbon Adsorption ......................... 3-l 3.2 Xanthate Treatment ................................ 3-3 3.3 Other Adsorption Processes .......................... 3-4 3.3.1 BPHC Adsorption ............................. 3-5 3.3.2 MHBB Adsorption ............................. 3-5 3.3.3 Coal Fly Ash Adsorption ........................ 3-5 3.3.4 Forager Sponge Adsorption ..................... 3-5 Chapter 4 Ion Exchange Treatment . , . , . 4-l Chapter 5 Other Processes . 5-l 5.1 Chemical Reduction ................................ 5-l 5.2 Membrane Separation .............................. 5-l 5.3 Emerging Technologies ............................. 5-5 5.3.1 Macrocycles Adsorption ........................ 5-5 5.3.2 Biological Detoxification ........................ 5-5 5.3.3 Membrane Extraction .......................... 5-5 iv Contents (Continued) Page Chapter 6 Comparison of Treatment Processes . ,. , . 6-l 6.1 Treatment Effectiveness ............................. 6-l 6.2 Residuals Management ............................. 6-l 6.2.1 Mercury Sludges .............................. 6-l 6.2.2 Spent Activated Carbon ........................ 6-l 6.2.3 Concentrated Brine Solutions .................... 6-l 6.3 Economics . 6-2 Chapter 7 Casestudy............................................. 7-l 7.1 Ion Exchange Removal of Mercury from Wastewater at DOE’s Savannah River Site Effluent Treatment Facility . 7-l 7.1.1 The ETF ..................................... 7-l 7.1.2 ETF Feed Streams ............................ 7-3 7.1.3 ETF Discharge Limits .......................... 7-3 7.1.4 Ion Exchange Role in the ETF ................... 7-3 7.2 Effluent Treatment Facility Economics , . 7-5 Chapter 8 References . 8-l V List of Tables Table No. Page 2-l Sulfide Precipitation treatment for mercury .......................... 2-2 2-2 Coagulation/co-precipitation treatment results for mercury .............. 2-3 3-l Activated carbon mercury treatment results .......................... 3-3 3-2 Starch xanthate treatment for mercury .............................. 3-4 3-3 Freundlich isotherm parameters for mercury adsorption ................ 3-5 4-l Summary of mercury-selective chelate resins ........................ 4-2 4-2 Ion exchange treatment for mercury in drinking water .................. 4-2 5-l Performance of reduction processes for mercury treatment .............. 5-2 5-2 Performance of membrane processes for mercury treatment ............ 5-3 6-l Summary of achievable effluent mercury concentrations ................ 6-1 6-2 Operating costs (U.S. $/year 1987) of processes for mercury removal from chlor-alkali wastewaters .............................. 6-3 7-l Nonradioactive contaminants and discharge limits ..................... 7-4 7-2 Radioactive contaminants and discharge limits ....................... 7-4 List of figures Figure no. Page 2-l Sulfide precipitation ............................................ 2-l 3-l Types of GAC column design .................................... 3-l 3-2 GAC process flowsheet ......................................... 3-2 5-I Principles of the crossflow microfilter ............................... 5-4 5-2 Filtrate polishing using microfiltration ............................... 5-4 5-3 Schematic representation of mercury extraction with an emulsion liquid membrane .............................................. 5-6 5-4 Schematic representation of mercury ion extraction with an emulsion liquid membrane ....................................... 5-6 6-l Flow chart of unit operations utilized for technical-economical analysis ..................................................... 6-2 7-l F/H effluent treatment facility process flow sheet ...................... 7-2 7-2 ETF facility O&M cost breakdown ................................. 7-5 Vi Chapter 1 Executive Summary 1 .I Purpose investigated to date only at bench or pilotscale. The literature, however, provides only limited information on This report describes established technologies and actual full-scale treatment technology performance and identifies evolving methods for treating aqueous mercury. almost no full-scale economic data or information on The information provided encompasses full-, pilot- and mercury recovery. bench-scale treatment results as presented in the technical Well-established and widely reported full-scale literature. The report describes alternative technologies in technologies are precipitation, coagulation/co-precipitation, terms of (1) governing physical and chemical principles and activated carbon adsorption. Representative data from (e.g., solubility, oxidation-reduction potential, volatility), (2) aqueous mercury treatment operations using these key treatment parameters (e.g., speciation, pH, methods are provided in this report. precipitating agent type and dosage, or adsorbent type and Another technology is ion exchange treatment, which dosage), (3) pretreatment requirements, treatment has historically been limited to the use of anion resins to performance, advantages and disadvantages, design process industrial wastewater that contains inorganic considerations, and economics when available. This mercury in the complex mercuric chloride form. Chapter 8 information can be useful for evaluating mercury treatment provides a case study illustrating the use of an ion alternatives for industrial wastewater, groundwater, and soil exchange system for mercury removal. washing extract. Other, less-established methods for treating aqueous This document assumes that the reader is already well mercury that are discussed in this report include chemical versed with the technologies described and is using this reduction, membrane separation, and emerging report to better understand each technology’s applicability technologies involving macrocycles adsorption, biological for aqueous mercury removal. Thus, the report does not treatment, and membrane extraction. provide basic descriptions of each technology; such Each of the mercury treatment technologies described information can be found elsewhere in the literature. In in this report achieves different effluent mercury addition, the report does not present recommended values concentrations. The effectiveness of treatment provided by for the common design parameters of technologies. each type of technology depends on the chemical nature Values for such parameters as (1) contact time, (2) and initial concentration of mercury as well as the presence volumetric loading rates, (3) dosages, (4) reaction times, of other constituents in the wastewater that may interfere (5) breakthrough times, and (6) mixing requirements can with the process. As indicated by example data provided, be determined by conducting treatability studies using the co-precipitation and ion exchange achieve the lowest wastewater to be treated. effluent mercury concentrations for many waste streams, ranging from 0.5 to 5.0 ,ugIL. Membrane technology 1.2 Summary typically achieves 80 to 90 percent rejection of mercury. A broad spectrum of mercury treatment technologies Other factors, however, such as residuals management has been described in the technical literature, ranging from and costs, weigh heavily in selecting the appropriate established full-scale applications to innovative approaches treatment approach. l-l Chapter 2 Precipitation Treatment Process This chapter presents information on precipitation and tion). A typical process flow diagram for sulfide precipita- coagulation/co-precipitation technologies, which are among tion is shown in Figure 2-l. The sulfide precipitant is the most well-established approaches for removing added to the wastewater in a stirred reaction