Mercury Work Group
Phase II Reports >> Hg Management Guidebook

Successfully managing mercury discharges involves the same elements used in any effective environmental management system: commitment, goals, standards, accountability, operational controls, communication, training, and performance metrics. Most facilities have found that many individual actions are needed to achieve success. They have also found that these actions are most efficiently and effectively undertaken if they are specifically developed and coordinated under a written Mercury Management Plan.

Senior management commitment and participation are essential to successful mercury management under a Mercury Management Plan. This commitment provides a framework for integration of the mercury management process into facility strategic plans and for the appropriate and necessary allocation of both human and fiscal resources.

The commitment of senior management is often demonstrated by the creation of a Mercury Management Committee. The initial task of this committee is to develop, publish, and internally distribute a written statement of the management commitment and a facility policy regarding mercury control. Appendix A gives an example of a brief mercury reduction policy statement used by a hospital as part of a Standard Operating Procedure. A separate, stand-alone and comprehensive facility policy statement is recommended.

The Mercury Management Committee should direct the development, communication, and implementation of policies and procedures as necessary and appropriate to establish the facility Mercury Management Plan. These policies and procedures should include a statement of what is expected from each employee concerning mercury discharge control. In addition, the documents could include specific procedures for material procurement, wastewater disposal, and mercury spill response. Appendix A gives an example of a Standard Operating Procedure used by a hospital to implement a mercury reduction policy.

An important part of any Mercury Management Plan is the setting of goals and objectives and the development of a plan and schedule to meet them. While all facilities will have an ultimate goal of achieving and maintaining compliance with the MWRA mercury discharge limit, each facility will have its own set of priorities and directions. As explained below, the planning process to achieve compliance for mercury discharges should be a cross-functional effort.

To maximize its mercury discharge reduction effort, the Mercury Management Committee should assign specific roles and responsibilities to various individuals in developing and carrying out the overall Mercury Management Plan. It is important to include representatives from each discipline or department that could be involved. Organizational structures vary over a wide range; however, for most organizations, the process should include representatives from laboratory, manufacturing, purchasing, environmental health and safety, and maintenance departments. It can be expected that the tasks of plan development and implementation will require cooperation between the responsible departments. These tasks must be coordinated with oversight and follow-up to ensure an orderly and cost-effective mercury discharge reduction effort.

Senior management representatives must also be active participants to ensure such coordination, oversight, and follow-up. These representatives may need to enforce written policies to ensure that they are continuously put into practice. Since a comprehensive effort can involve large commitments of capital and personnel, an important part of the senior management effort will be the allocation and scheduling of those resources to address efficiently the needs of the organization and of regulatory agencies. For example, Standard Operating Procedures of the facility should include descriptions of the authority and responsibilities of each level of staff members.

The selection of, and investment in, a proper Mercury Management Committee will help to ensure a most cost-effective and resource-effective implementation of the steps listed below.

Successful mercury management has often been organized around four major components:

• Source Identification

• Source Reduction and Segregation

• Infrastructure Control and Maintenance

• Pretreatment Systems

Many dischargers have found that actions in each of these areas are needed as part of an ongoing Mercury Management Plan. Control measures span the spectrum of administrative, procedural, and engineered controls. Source reduction, source segregation, infrastructure improvements and, in some cases, pretreatment will be needed. Frequently, more than one measure may be needed to achieve continuously the MWRA mercury discharge enforcement limit of 1.0 µg/L (ppb). While the sequence of actions carried out by different institutions may vary, it has proven helpful to go through the steps listed below when developing a plan for controlling mercury discharges:

• Inventory past and present mercury sources (uses) in the facility.

• Verify and, if possible, quantify suspected mercury sources by reviewing available data and contacting product and chemical manufacturers.

• Track pathways by which mercury enters wastewater and the sewer system.

• Conduct a targeted monitoring program to track the location of mercury sources in the facility and any changes in mercury discharges at permitted monitoring locations that result from source reduction, infrastructure improvements, or pretreatment.

• Identify substitute products and alternative processes to reduce or eliminate current mercury uses through information exchange and contact with manufacturers.

• Evaluate and test possible substitute chemicals, operating procedures, and production processes for effectiveness, and implement those that are feasible.

• For products or chemicals without available substitutes, segregate the associated waste streams for special handling and disposal.

• Establish and publicize a facility policy on the sewer disposal of individual wastewater streams.

• Develop and implement an employee training and education program.

• Conduct wastewater characterization studies to obtain specific data regarding problem sources or chemicals, monitor progress in reducing mercury concentrations, and learn of possible interferences with candidate mercury pretreatment systems from, for example, suspended solids, other heavy metals, or complexing agents. Reduce or segregate such interfering waste streams.

• If necessary, clean or replace waste piping infrastructure (traps, drains, and lines) in the facility to remove mercury accumulations from past use and mercury-contaminated bacteriological growth (biomass).

• Implement mercury pretreatment of wastewater, if needed, to achieve compliance.

• Reconsider and implement additional source reduction actions, infrastructure improvements, waste segregations, or pretreatment processes to reduce mercury levels further as needed to remain in compliance, using routine monitoring of operations and of wastewater discharges as guides for action.

For a flow diagram depicting much of this process, refer to Section 3.0, "Step-by-Step Approach to Discharge Compliance" of the MWRA/MASCO Mercury Work Group, Phase II, End-of-Pipe Subcommittee, Pretreatment Guidance Manual, December 1997.

2.5.1 Identifying Sources of Mercury

The first step to manage mercury discharges is to identify how mercury enters the facilities wastewater. Several approaches to accomplish this task are summarized below:

Facilities should use process flow diagrams to develop a conceptual model of the facility as a series of individual processes or unit operations that produce a product or service. All steps in the processes where mercury or mercury-containing materials are either added or discharged should be emphasized in the diagrams to show where opportunities exist for source reduction and control or prevention of mercury in the wastewater before it is discharged from the process. Large, complex facilities with many separate operations can use a combination of different, connecting process flow diagrams. Examples of process flow diagrams for an overall facility and for a specific process (photodeveloping) can be seen in Figure 1A and Figure 1B, respectively.

A second useful way of tracking pollutant sources is to list the production steps and locations and the specific mercury sources and quantities in each step. This approach can be used as a tracking method to ensure that all mercury sources are considered for control and to measure progress of the program at any given time.

Comprehensive process flow diagrams and lists will help identify the large, obvious mercury contributors but may not help to identify all existing sources of mercury. All paths and opportunities for the introduction of mercury from "hidden" sources must be identified.

For hidden sources of mercury, consider the following possible sources:

• process feed materials, pharmaceuticals, reagents, and chemicals (such as ophthalmic and contact lens products, nasal sprays, vaccines, histological fixatives (e.g., B5 and Zenker's Solution) and stains, hematoxylin, and chemicals (e.g., Toxi-Dip B3) used for acidic drug analysis by thin layer chromatography)

Figure 1A
Example Process Flow Diagram
Overall Facility

Figure 1B
Example Process Flow Diagram
Specific Process - Photodeveloping

• medical and biological wastes (blood and blood products, specimen cultures, dental amalgam, and pathological wastes including organs, tissues, and body fluids)⁴

• tissue grinders ⁵

• cleaning materials, soaps and other chemicals used by janitorial services

• contaminated manufacturing or processing equipment

• inputs from an incinerator emission control process such as the fume scrubber.

• facility infrastructure (the Special Waste ⁶  piping system itself)⁷

Mercury sources may be distributed throughout a facility. Institutional processes and activities that occur in decentralized locations present challenges to investigations of sources of mercury-contaminated wastewater. Hospitals and other medical institutions are good examples of this problem because many different types of clinical and research laboratories may occupy adjacent areas or may be spread throughout the facility. For example, a common sink used by individuals from several different departments can be a significant source of mercury contamination.

The following actions can be taken to identify sources of mercury contamination in commercial, industrial, and laboratory products used at your facility:

• Research available information from chemical supply vendors including Material Safety Data Sheets (MSDS) assays and safety information on reagent containers, and if available, certificates of analysis that could suggest the presence of mercury in their products. Vendor information may be limited in usefulness because mercury-bearing substances present in concentrations less than 1 percent or considered proprietary may not be reported in MSDSs or assays.

• Refer to the MWRA/MASCO database of mercury-bearing substances, chemical reagents, and other commercial products that may be in use within a facility. Refer to Section 1.2 and Section 3.0 for information on the database. The database was developed with information obtained from many industries and institutions that have conducted testing of substances commonly discharged to the MWRA sewerage system.

• Request Certificates of Analysis from all suppliers. The request should specify that Certificates of Analysis list mercury contents in micrograms per liter (µg/L) or parts per billion (ppb), not as percentages. For nondetectable concentrations, the Certificates of Analysis should report the respective analytical detection limit.

• Perform mercury analyses on reagents disposed to drains in significant quantities if mercury content information is unavailable. Initial analyses could be done on products found in and around sinks in the facility. Continuous and intermittent discharges from automatic instruments or machines should also be tested. Note that many domestic cleaning agents available at retail stores, such as soaps, detergents, and bleaches, are known often to contain mercury.

In facilities where mercury was or is being used, the infrastructure itself may be a significant source of discharge pollution. The waste plumbing system should be examined for residual mercury by conducting a sampling and testing program from the point of discharge, including any existing pretreatment systems, all the way back to points of process discharges into system. Consider the following:

• Passive pH neutralization systems, i.e., limestone chip tanks, can accumulate mercury-containing deposits often in association with organic substances. Even when a chip tank is acceptable, the tank must be inspected and serviced monthly.⁸  Such tanks are not allowed for recombinant DNA biomedical research or production laboratories.⁹

• Active pH neutralization systems may also accumulate metallic mercury or mercury-containing deposits and may introduce additional mercury by using low-grade mercury-containing alkaline (NaOH) or acidic (H₂S0₄ or HCl) neutralization and treatment chemicals.

• Sampling ports in the wastewater piping system should be located to segregate areas by operations and (if necessary) by discrete activities in individual units.

• Inspect sink traps for accumulations of elemental mercury from past disposal practices. A sink trap cleaning and replacement program could be conducted when suspected source areas have been isolated by other means. Contents from sink traps, both liquid and sediment, can be analyzed for mercury as a record of past and (after the initial cleaning) recent mercury-bearing material disposal to the drain. The traps should be thoroughly cleaned or replaced before reinstallation. Refer to Section 2.5.4 and Appendix B for further information on infrastructure control measures.

• Inspect waste piping systems, particularly laterally running pipes, for accumulations of sediment or bacteriological growth (biomass). Refer to Section 2.5.4 and Appendix B for further information on infrastructure control measures in Special Waste piping systems.

This section addresses the planning process from the point where the processes using mercury have been characterized and mercury sources have been identified and quantified. Once a better understanding of mercury sources and uses has been developed for the facility, the process of identifying and evaluating source reduction options can be started.

The information in this section is summarized in part from "A Practical Guide to Toxics Use Reduction" prepared by the Massachusetts Office of Technical Assistance (OTA). OTA provides free assistance to Massachusetts industries that wish to set up a source reduction program at their manufacturing facilities. Additional sources for information on source reduction are listed in Section 3.0 of this document.

Mercury source reduction can be achieved by many methods, ranging from complete redesign of processes to simple changes in work habits and chemical handling practices. These methods can be categorized into six generic types of source reduction options as follows:

1. Input Substitution
2. Product Reformulation
3. Process Redesign/Modification
4. Process Modernization
5. Improved Operation and Maintenance
6. Recycling and Reuse

1. Input Substitution
This source reduction method or technique involves substituting materials or equipment that contain mercury with non-mercury replacements. Examples of this technique include replacement of elemental mercury with Galinstan^TM,¹⁰ changing chemicals to higher grades (e.g., changing sodium hydroxide and sulfuric acid that may be used in wastewater neutralization and treatment), and replacing thimerosal containing reagents with non-thimerosal containing products. Additional examples of successful input substitution can be found in Case Studies 1, 3, and 7 in Appendix F.

2. Product Reformulation
This technique focuses on reducing or eliminating mercury in the final manufactured products. Beyond reducing mercury discharges, this method may permit companies to increase sales by appealing to growing consumer demand for "green" products. If your product formulation is specified by your customers, consider negotiating with them to change their specifications. Customers may need to be educated to realize the potential benefits of sound environmental practices. Case Study 4 is a good example of this source reduction technique.

3. Process Redesign/Modification
When source reduction is achieved by developing and using new and different equipment or processes than those currently in use, it falls under the category of process redesign. This technique focuses on alternative ways of conducting a process (e.g., manufacturing a product, analyzing a sample) that will reduce or eliminate the use of mercury in the process and the generation of a mercury- containing discharge. One example of this technique is replacing mercury thermometers with digital units. Case Study 6 presents another use of this option.

4. Process Modernization
This technique is similar to process redesign, but does not involve a total redesign of the equipment or processes being used. Instead, existing equipment/processes are modified or replaced with newer, more efficient approaches based upon the same technology as the old. Because fundamental changes in process technology are not made, process modernization options will often pay for themselves more quickly than process redesign options. Examples of this technique are more precise metering of chemicals and reagents into a process, and new sample analyzers that use smaller quantities of reagents. Additional examples are shown in Case Studies 1, 3, and 7.

5. Improved Operation and Maintenance
This source reduction technique applies to all industries and should be pursued by all facilities using mercury or mercury-containing materials. Improved operation and maintenance often results in significant reductions in mercury discharge, and bottom-line savings, without major up-front costs. Improved operation and maintenance has three primary categories: Inventory Controls, Materials Handling Improvements/Housekeeping and Personnel Training. Examples of the first two categories are discussed below. More detailed information on personnel training programs can be found in Section 2.8 and Appendix E of this Guidebook.

Inventory Controls

• Train personnel on how to identify and order/purchase mercury-free materials

• Purchase chemicals and supplies as they are needed to reduce storage time.

• Computerize purchasing to improve inventory control.

• Install inventory management software to track supplies.

• Offer incentives to reduce rates at which stocks of chemicals and supplies expire.

• Control cleaning chemicals used by contractors.

Housekeeping/Materials Handling Improvements

• Improving housekeeping procedures (e.g., prohibiting water used in floor washing in non-process areas from being poured down drains connected to the Special Waste system).

• Develop a spill control plan for mercury-containing materials, including the use of mercury cleanup kits. Make sure spills and leaks are not discharged to the sewer.

• Loading docks - repair or replace any leaking valves, pipes, pumps, containers, and fill hose or fill line connections.

• Storage areas - ensure that tank overfill alarms are working, storage containers are properly sealed and curbed, and workers are trained in proper chemical transfer procedures.

• Laboratory stockrooms - protect containers to eliminate breakage.

• Production areas/laboratories - repair or replace leaking tanks and equipment.

• Work with employees to reduce leaks and spills during material transfers or equipment operation (e.g., mixing batches of reagents.)

• Institute a program to have employees separate mercury- containing materials from the waste stream (e.g., fixatives with thimerosal, mercury thermometers, and batteries).

• Production areas/laboratories - place portable thermoplastic screens in sinks to keep medical or biological solids out of drains.

Personnel Training

Improve employee awareness of mercury discharge issues, sources of mercury in the facility, and proper handling and disposal procedures. Post signs near all sinks and drains in work areas stating that disposal of any mercury-containing compounds to the sewers is prohibited. Refer to Figure 2 for an example "Waste Water Alert!" sticker used at some facilities. Replace the signs regularly with different background colors or revised text to maintain a high level of awareness and compliance. Develop and periodically update specific lists of mercury-containing compounds for each work area.

Figure 2
Example AWaste Water Alert! Sticker

Develop standard and improved operating and maintenance procedures. Set up personnel training and retraining programs. Case Studies 1, 2, 3, 4, 6, and 7 provide examples of improved operating and maintenance procedures. Refer also to the Example Standard Operating Procedure in Appendix A.

6. Recycling and Reuse
This type of source reduction technique has the potential to provide significant reductions in chemical purchase and disposal costs, and includes recycling both treated water and recovered mercury. An example of this technique is given in Case Study 3.

Source reduction programs usually include the development of formal procedures for identification of source reduction options, evaluation of the identified options, and implementation of favorably evaluated options. The following are summaries of these three steps:

Source Reduction Options: Identification
One commonly used technique for developing a list of source reduction options is a series of brainstorming sessions involving several individuals at the facility. The group should consist of facility management, engineering, maintenance, equipment operators, manufacturing and laboratory personnel as appropriate. All options generated should be initially listed, without judging feasibility. Developing an extensive list of options is beneficial since it will then be more likely that the best options for the facility will be identified. After the list is generated, the screening process can begin.

Source Reduction Options: Evaluation
The initial consideration of options need not be very detailed, but it should be documented and structured to show why a given option is considered infeasible, worthy of further study, or ready for implementation. Using an "option screening table" is often helpful in structuring the evaluation. The screening table lists the options for each part of the process, ranks them for technical and economic feasibility¹¹ and pollution prevention potential, and shows what action will be taken.

When identifying options, the important thing is not to get the category of option correct, but to know what makes up good versus bad source reduction methods. For example, if a proposed option will increase worker exposure to safety and health hazards, it is not a viable source reduction option.

Source Reduction Options: Implementation
As in any planning process, careful scheduling and anticipation of results are needed for effective implementation. Once the mercury reduction options are identified and chosen, an implementation schedule and task list should be developed and responsibilities should be assigned.

Such a schedule is particularly important if your facility is currently in noncompliance with the MWRA mercury discharge limit. Compliance with MWRA limits is a task and schedule driven process. The MWRA enforcement staff defines and negotiates specific compliance dates based on discussions and documents from the facility and their knowledge of what is needed. If a facility does not define the actions and schedule that it wishes to follow to achieve compliance, the MWRA may define them for the facility. The MWRA approach may not be as convenient or as cost-effective as a proactive plan developed by the facility itself.

Be practical in scheduling: allow a reasonable amount of time for foreseeable and unexpected delays such as receiving results from analytical testing laboratories, receiving price quotes, or completing construction activities.

Source Reduction Summary
In cases where source reduction alone will not be sufficient to bring the facility into compliance with the current MWRA enforcement action threshold of 1.0 µg/L (ppb) for mercury, additional infrastructure, source segregation, and/or pretreatment actions may be warranted. However, when source reduction is incorporated into a Mercury Management Plan, the need for pretreatment will often be significantly reduced. This often results in a lower overall cost than if pretreatment alone is pursued. Case Study 7 shows how a clinical testing laboratory could significantly reduce the size of a pretreatment system by including source reduction and segregation measures into its successful efforts to achieve compliance.

As part of its Phase II effort, the MWRA/MASCO Mercury Work Group studied mercury loadings from five groups of facilities that had MWRA discharge permits: clinical laboratories, medical waste incinerators, hospital laundries, medical and biotech research laboratories, and other related facilities (including college laboratories, steam suppliers, pharmaceutical manufacturers, and testing laboratories). The study used discharge flow estimates and available mercury concentration data to calculate estimates of average mercury loadings (in pounds per day) for 242 of these facilities having 355 permitted discharges or sampling locations.¹²

One finding of the study was that many of these facilities had sporadic peak mercury discharges during the study period. Frequently, the peak discharges seriously affected the average mercury concentrations from the facility. For example, a hospital laundry was found to have discharged mercury at an average of about 400 µg/L (ppb) for six daily composite samples collected during a six month period. Two of the six samples were measured at about 1,000 µg/L (ppb) and 1,400 µg/L (ppb), but three samples were at or below 1.0 µg/L. The 1,400 µg/L (ppb) sample suggested that the hospital laundry discharged more than 0.1 pounds of mercury in that one day.¹³  Since the overall loading to the MWRA sewerage system is estimated to be between 0.75 and 1.0 pounds per day,¹⁴  the discharge from this one facility represented a very significant one-day loading of mercury.

To limit such sporadic peak discharges, facilities should develop and carry out a source reduction program as outlined in the previous section. For many facilities, peak discharges are likely to be associated with individual daily activities of material handling, operations, and maintenance. Therefore, continuous training and monitoring of personnel are essential activities to assure that proper material handling, processing, and disposal procedures are practiced at all times.

For facilities that continue to experience sporadic peak discharges after implementation of an intensive source reduction program, segregation of problem waste streams from the sewer discharge should be considered. Since the source reduction program should help to identify the problem waste streams, control of peak discharges could become a matter of selection of alternate disposal methods (offsite disposal) for the identified waste streams. Refer to Section 1.3 in Appendix C for a discussion of procedures and permits required for offsite disposal of various waste streams. Refer also to the following section for the possible contributions of biomass accumulations to sporadic peak mercury discharges.

If a pretreatment system is to be installed, limiting the mercury concentration peaks remains an important consideration. Problem waste streams can be segregated from the influent to the pretreatment system. Also, a mixed equalization tank can be used to reduce variations in both the wastewater flow and concentration. To limit concentration peaks, the equalization tank would be operated in a partially full mode so that a volume of liquid would exist within the tank at all times. The liquid volume would serve to dilute short-term peaks in incoming mercury concentrations. A mixer would ensure that concentrations remain uniform throughout the liquid volume in the tank.¹⁵ Refer to Section 2.5.5 for a discussion of pretreatment systems.

In some cases, the following have been recognized as significant contributors to chronic mercury contamination in wastewater discharges from wastewater piping systems that carry Special Waste:

1. Quantities of elemental mercury that have collected in Special Waste piping traps that serve sinks and other fixtures.

2. Organic mercury accumulations in the bacterial biomass growth on the interior walls of the Special Waste piping infrastructure.

The presence of elemental mercury in traps and other collection points of the Special Waste piping infrastructure of a facility can result from past inappropriate disposal practices. The deposits of elemental mercury can contaminate the wastewater passing through the Special Waste system for indefinite periods.

Large quantities of bacterial biomass growth within the Special Waste piping infrastructure of a facility may be very important because mercury and mercury compounds can be converted by bacteria into very toxic methyl mercury that becomes accumulated and highly concentrated in the biomass. This phenomenon is called bacterial "bioaccumulation" and "bioconcentration" of mercury. Then, dislodged pieces of the mercury-laden biomass may be carried into the wastewater stream. In this way, large accumulations of biomass within a Special Waste piping system can lead to instances of high mercury concentrations in the discharged wastewater.

Therefore, infrastructure control measures may have to be addressed in the Mercury Management Plan developed by a facility. Specific infrastructure control measures are outlined in Appendix B and its subsections: Special Waste Piping Design (Appendix B-1), Special Waste Trap Cleaning/ Replacement (Appendix B-2), and Special Waste Piping Power Washing (Appendix B-3). The guidelines and procedures outlined in these appendices relate to mercury and biomass and their removal from Special Waste traps and piping systems. However, these guidelines can be followed by any facility where the discharge of mercury-containing materials to waste piping systems is suspected or has been confirmed.

It must be noted, however, that the biomass removal procedures have been found totally ineffective in reducing mercury concentrations in wastewater from metal waste piping systems such as copper,¹⁶ high silicon cast iron and stainless steel. The reason may be that mercury cannot easily be removed from most metal surfaces because of the strong tendency of mercury to react with metals and form an amalgam (or alloy). From the amalgam, the mercury can still be released and metabolized by bacteria in the Special Waste piping system.

For all waste piping systems, depending upon the approach specified in the facility's Mercury Management Plan, infrastructure control measures may include some or all of the following steps:

• source reduction

• source segregation, waste piping modifications

• waste trap sampling, cleaning, or replacement

• waste piping replacement or cleaning (power washing)

• wastewater collection for offsite disposal¹⁷

• wastewater pretreatment (possibly consisting of solids sedimentation, multistage filtration, or other process steps).

While these measures are listed in a possible chronological order, some of them could be eliminated depending upon a facilities specific Mercury Management Plan.

Before any infrastructure control measures (as detailed in Appendices B and B-1, B-2, and B-3) are started, however, a facility should take all steps needed to prevent any elemental mercury or mercury-containing compounds from being disposed to the Special Waste drains of the facility. Continued disposal of any amount of mercury to the drains may mean that the waste trap and piping cleaning procedures would be totally ineffective or effective only for a short period. Then, the waste trap and piping cleaning procedures would have to be done again to reduce effluent mercury concentrations.

The MWRA is currently formulating requirements for data collection during power washing. As part of this process, a facility must notify the MWRA of its intention to do power washing and participate in a study of power washing effects according to specific conditions and protocols. The results of the study will be used to finalize a MWRA guidance on acceptable power washing procedures. Currently, the MWRA is concerned that:

• Power washing may be improperly considered by some facilities as a substitute for comprehensive mercury management that would include source reduction (including purchasing and inventory controls), source segregation (including training and supervision of waste disposal practices), and/or pretreatment.
   

• Power washing may lead to greater mercury violations for an indefinite period as small particles of loosened mercury-laden biomass are discharged with normal wastewater flows for several days or weeks after the power washing procedure.

Refer to Appendix B-3 for details on the interim MWRA power washing requirements.

Facilities that experience difficulties in complying with sewer discharge limits after implementing aggressive source reduction, source segregation, and infrastructure control measures may find that "end-of-pipe" pretreatment systems may be needed to achieve compliance. Since mercury discharges to the environment have recently received considerable attention from national (EPA), regional (Great Lakes), and local (Boston, San Diego) regulatory agencies, several vendors of wastewater pretreatment technologies have conducted research, development, and marketing activities related to mercury removal systems.

The MWRA/MASCO Mercury Work Group, End-of-Pipe Subcommittee, Technology Identification Subgroup, conducted a Bench-scale Feasibility Testing Project in 1997 for which six vendors of mercury pretreatment technologies volunteered to participate. The participating vendors offered mercury removal systems in the following main process technology areas:

• Activated / Modified Carbons - Barnebey & Sutcliffe Corporation and ICET, Inc.

• Other Specialized Adsorbents - Aero-Terra-Aqua (ATA) Technologies Corporation, ICET, Inc. (a second offering), KDF Fluid Treatment, Inc., and SolmeteX, Inc.

• Electrolytic Precipitation Systems - Soils N.V. (Zwijndrecht, Belgium).

Besides these vendors and process technologies, the Subgroup found other vendors that offered enhanced filtration systems for mercury removal applications. Facilities that are considering the installation of mercury pretreatment systems are encouraged to refer to the Technology Identification Subgroup Report¹⁸ that details the methods and results of the Bench-Scale Feasibility Testing Project and to its companion document, the Pretreatment Guidance Manual.¹⁹ As a follow-up to the MWRA/MASCO effort, the Massachusetts Strategic Envirotechnology Partnership (STEP), operating under the Massachusetts Executive Office of Environmental Affairs (EOEA), has been conducting a pilot-scale project of four mercury removal technologies at three wastewater generating facilities. The STEP project report is expected to be published in late 1999.

One of the most important steps in the selection of a pretreatment system is to learn the physical and chemical characteristics of the process wastewater stream in question. The study of wastewater characteristics may help identify the presence of contaminants from each contributing industrial or laboratory process. Based upon analytical testing of representative waste stream samples, the levels of contaminants can be compared with the limits of applicable sewer discharge regulations. The scope of the characterization effort will vary from simple to complex depending upon the nature and size of the facility and upon the type and extent of the discharge problem.

For wastewater containing mercury, a wastewater characterization study could include determination of the chemical species and physical forms of mercury that may be present. Mercury in wastewater may exist in three chemical species: metallic, ionic, and organic. In addition, the various species of mercury may bind to particulate matter in the wastewater to form physical agglomerates containing mercury.

In analytical testing of wastewater samples, total mercury concentrations are usually determined by analytical laboratories using EPA Method 245.1 with a method detection limit of 0.2 µg/L (ppb).²⁰ Besides meeting current regulatory requirements, this EPA method is usually the analytical method of choice because most applicable federal, state, and local regulations typically address total mercury concentrations.

Of the various mercury species that may be present in a wastewater stream, concentrations of particulate mercury are the easiest to quantify. Particulate mercury concentrations in wastewater samples are not directly measured, however, but are determined as mathematical differences in analytical test results of total mercury and dissolved mercury. Dissolved mercury concentrations are determined using EPA Method 245.1 on wastewater samples that have been initially filtered through a 0.45 micron (mm) filter. Additional tests on samples filtered through larger and smaller (such as 0.2 mm) filters are sometimes recommended because particulate mercury is such an important species of mercury in wastewater.

Contaminants in the wastewater (such as suspended solids; metals like copper, lead, and zinc; solvents and other organic compounds; or metal-complexing agents like ammonia and detergents) can interfere with the proper operations of certain wastewater pretreatment systems. If individual process waste streams contain these interfering contaminants, the waste streams could be either reduced, segregated from the other streams, or eliminated. If this is not possible, the pretreatment system must be designed to work effectively with the identified interfering contaminants.

A wastewater characterization study that examines these issues can help to set an overall approach to achieving compliance with regulations. Such an overall approach may involve a combination of source reduction, source segregation, and pretreatment. If the facility does not have qualified technical staff, an experienced consulting engineering firm should be employed to perform the wastewater characterization study and to help in the development and execution of the overall approach.

Guidance for managing mercury wastes according to federal and Massachusetts regulations is presented in Appendix C. This Appendix also deals with regulatory issues of collection and offsite disposal of industrial wastewater from a facility in an area served by a sewer system (see Section 1.3.2).

The information in Appendix C may be helpful in mercury source identification and waste reduction efforts. Wastes that exceed the current MWRA enforcement limit for mercury may be generated when activities such as waste stream segregation and infrastructure control measures are carried out.

Communication is key to the pursuit of a cost-effective reduction effort. Because many tasks will cross departmental lines, regular planning and review meetings are necessary to ensure the proper exchange of information and progression of effort. Intra-departmental communication must also take place as direction and training for the generators and managers of the waste streams. Finally, an organization must maintain good communication with the regulatory agency including a compliance schedule and routine progress reports. This reporting relationship can also become a pathway for exchange of information as new products or reduction methods are identified.

To keep personnel up-to-date on all waste management issues, the facility may want to develop newsletters and informational posters, distribute published articles, or implement other appropriate means of communication.

Once a facility has identified its sources of mercury and has determined what methods it will use to control those sources, it is imperative that all staff be trained in the new waste management techniques the facility has adopted. Each staff person should be made aware that the actions of each individual throughout the workday can directly affect the compliance status of the facility wastewater discharge.

The mercury management committee should play an integral role in developing the training program. While the training program should be tailored to each facility's needs, each program should include an overview of the following topics:

• regulatory requirements and responsible agencies

• sewer discharge regulations/prohibitions

• air emission regulations

• solid and hazardous waste regulations

• plumbing infrastructure information

• treatment systems information

• mercury source list

• policies and procedures for purchasing mercury-containing and mercury-free materials

• product substitution/source reduction

• proper handling techniques

• wastewater sampling protocols

• pH monitoring

• distinguishing and segregating sanitary waste from Special Waste

• waste management

• recycling opportunities

• waste minimization techniques

• waste disposal protocols and required permits

The training program should be presented to all affected facility personnel as soon as all new waste management techniques are in place. Newly hired personnel should be trained within thirty days of hire. All staff should be provided with refresher training annually, at a minimum. Refer to Appendix E for an example of a mercury awareness "Training Packet."

To monitor the effectiveness of a Mercury Management Plan and maintain a continuous improvement effort, regular periodic reviews are needed. These reviews would have a dual intent:

• ensure control of mercury discharges and compliance with regulatory standards, and

• ensure continuing adherence to internal mercury management policies and procedures.

The periodic reviews should target the key areas of the Mercury Management Plan and should be scheduled accordingly for review and repetition. Annual reviews could be done for facilities that have successfully set up their Mercury Management Plan. More frequent reviews should be done during the first year, when changes are made to the system, or when deficiencies are found. Priorities should be based on the facility's assessment of its particular risks and vulnerabilities.

The periodic reviews should include assessments of source reduction and waste management practices, employee training and communication, and wastewater monitoring and pretreatment programs. Additional factors that may affect topics, complexity, and frequency of the reviews could include regulatory changes, new processes or operations, and personnel changes.

Review observations should identify deficiencies and omissions in the Mercury Management Plan and should also identify and emphasize its strengths. The reviews could include unannounced site visits to observe work practices. Reviewers may recommend actions that address ways to ensure or improve staff compliance with written mercury management procedures.

Plan review findings and recommendations should be documented and shown to senior and operations managers for their examination and action. Copies should also be distributed to operations, environmental, engineering, maintenance, and other staff as appropriate. Additionally, managers of the reviewed operations should develop and execute any needed corrective action plans that set timetables and assign responsibilities for implementation. Periodic follow-up is recommended to ensure completion of any remedial actions.

For a regulatory agency, an ongoing Plan review program at a facility may show the facility's awareness and intent to address mercury compliance issues. Thus, review results could be made available to the MWRA or other regulators as appropriate. It is recommended that a facility discuss their Plan review process with the regulating authority so that a mutual and written understanding can be reached regarding the release and use of review reports.

Because the results of periodic reviews of a Mercury Management Plan can greatly help a facility to identify Plan accomplishments and deficiencies, periodic reviews serve as mechanisms for providing feedback into the Plan. With the support of management, the Plan can then be modified and improved to meet the goal of total success. Therefore, a successful Mercury Management Plan is usually one that includes a regular iterative process of investigation, action, measurement, review, and revision.

The Mercury Management Subcommittee of the MWRA/MASCO Mercury Work Group hopes that this Guidebook can help many facilities to properly address, successfully and efficiently achieve, and continuously improve the management of mercury.

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