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Mercury

6. What can be done to reduce mercury releases?

  • 6.1 What are the possible ways of controlling mercury releases?
    • 6.1.1 Reducing consumption of raw materials and products generating mercury releases
    • 6.1.2 Substitution by non-mercury alternatives
    • 6.1.3 End-of-pipe techniques
    • 6.1.4 Waste management
  • 6.2 What is the best overall approach to reduce emissions?
  • 6.3 What further research and information is needed?
    • 6.3.1 National initiatives
    • 6.3.2 Regional and international initiatives

6.1 What are the possible ways of controlling mercury releases?

    • 6.1.1 Reducing consumption of raw materials and products generating mercury releases
    • 6.1.2 Substitution by non-mercury alternatives
    • 6.1.3 End-of-pipe techniques
    • 6.1.4 Waste management

The source document for this Digest states:

As noted in chapter 6 (of the full assessment), the sources of releases of mercury to the biosphere can be grouped in four major categories. Two of these categories (releases due to natural mobilisation of mercury and re-mobilisation of anthropogenic mercury previously deposited in soils, sediments and water bodies) are not well understood and largely beyond human control.

The other two are current anthropogenic mercury releases. Reducing or eliminating these releases may require:

  • Investments in controlling releases from and substituting the use of mercury-contaminated raw materials and feedstocks, the main source of mercury releases from "unintentional" uses; and
  • Reducing or eliminating the use of mercury in products and processes, the main source of releases caused by the "intentional" use of mercury.

The specific methods for controlling mercury releases from these sources vary widely, depending upon local circumstances, but fall generally under the following four groups:

  1. Reducing mercury mining and consumption of raw materials and products that generate mercury releases;ducim
  2. Substitution (or elimination) of products, processes and practices containing or using mercury with non-mercury alternatives;
  3. Controlling mercury releases through end-of-pipe techniques;
  4. Mercury waste management.

The first two of these are "preventive" measures – preventing some uses or releases of mercury from occurring at all. The latter two are "control" measures, which reduce (or delay) some releases from reaching the environment. Within these very general groupings are a large number of specific techniques and strategies for reducing mercury releases and exposures. Whether or not they are applied in different countries depends upon government and local priorities, information and education about possible risks, the legal framework, enforcement, implementation costs, perceived benefits and other factors.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraphs 112 to 115

For more information, see Chapter 8: Prevention and control technologies and practises 

6.1.1 Reducing consumption of raw materials and products generating mercury releases

The source document for this Digest states:

Reducing consumption of raw materials and products that generate mercury releases is a preventive measure that is most often targeted at mercury containing products and processes, but may also result from improved efficiencies in the use of raw materials or in the use of fuels for power generation. This group of measures could potentially include the choice of an alternative raw material such as using natural gas for power generation instead of coal, or possibly by using a coal type with special constituents (such as more chlorine), because the mercury emissions from burning this type of coal might be easier to control than other coal types.

Another possible approach in some regions might be the use of coal with a lower trace mercury content (mercury concentrations appear to vary considerably in some regions depending on the origin of the raw materials). However, there are some limitations and potential problems with this approach. For example, as in the case of the utility preference for low-sulfur crude oil, it is likely that some utilities might be willing to pay more for low-mercury coal, which effectively lowers the market value of all high-mercury coal, which in turn might lead to higher consumption of high-mercury coal in regions where utilities have less rigorous emission controls. Moreover, data collected recently in the US indicate that coal supplies in the US do not vary significantly in mercury content.

Nonetheless, such preventive measures aimed at reducing mercury emissions are generally cost-effective, except in cases where an alternative raw material is significantly more expensive or where other problems limit this approach.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraphs 116 to 118

For more information, see Chapter 8: Prevention and control technologies and practises 

6.1.2 Substitution by non-mercury alternatives

The source document for this Digest states:

Substitution of products and processes containing or using mercury with products and processes without mercury may be one of the most powerful preventive measures for influencing the entire flow of mercury through the economy and environment. It may substantially reduce mercury in households (and reduce accidental releases, as from a broken thermometer), the environment, the waste stream, incinerator emissions and landfills. Substitutions are mostly cost-effective, especially as they are demanded by a larger and larger market. This group of measures would also include the conversion of a fossil-fueled generating plant to a non-fossil technology.

At the same time, it would be a mistake to assume that substitution is always a clear winner. For example, in the case of energy-efficient fluorescent lamps, as long as there are no competitive substitutes that do not contain mercury, it is generally preferable from a product-life-cycle perspective to use a mercury-containing energy-efficient lamp rather than to use a less efficient standard incandescent lamp containing no mercury, as a result of current electricity production practises.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraphs 119 & 120

For more information, see Chapter 8: Prevention and control technologies and practises 

6.1.3 End-of-pipe techniques

The source document for this Digest states:

Controlling mercury emissions through end-of-pipe techniques, such as exhaust gas filtering, may be especially appropriate to raw materials with trace mercury contamination, including fossil-fueled power plants, cement production (in which the lime raw material often contains trace mercury), the extraction and processing of primary raw materials such as iron and steel, ferromanganese, zinc, gold and other non-ferrous metals and the processing of secondary raw materials such as iron and steel scrap. Existing control technologies that reduce SO2, NOx and PM for coal-fired boilers and incinerators, while not yet widely used in many countries, also yield some level of mercury control. For coal-fired boilers, reductions range from 0 to 96 percent, depending on coal type, boiler design, and emission control equipment. On average, the lower the coal rank, the lower the mercury reductions; however, reductions may also vary within a given coal rank. Technology for additional mercury control is under development and demonstration, but is not yet commercially deployed. In the long run, control strategies that target multiple pollutants, including SO2, NOx, PM and mercury, may be a cost-effective approach. However, end-of-pipe control technologies, while mitigating the problem of atmospheric mercury pollution, still result in mercury wastes that are potential sources of future emissions and must be disposed of or reused in an environmentally acceptable manner.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraph 121

For more information, see Chapter 8: Prevention and control technologies and practises 

6.1.4 Waste management

The source document for this Digest states:

Mercury wastes, including those residues recovered by end-of-pipe technologies, constitute a special category of mercury releases, with the potential to affect populations far from the initial source of the mercury. Mercury waste management, the fourth "control" measure mentioned above, may consist of rendering inert the mercury content of waste, followed by controlled landfill, or it may not treat the waste prior to landfill. In Sweden, the only acceptable disposal of mercury waste now consists of "final storage" of the treated waste deep underground, although some technical aspects of this method are yet to be finalised.

Mercury waste management has become more complex as more mercury is collected from a greater variety of sources, including gas filtering products, sludges from the chlor-alkali industry, ashes, slags, and inert mineral residues, as well as used fluorescent tubes, batteries and other products that are often not recycled. Low concentrations of mercury in waste are generally permitted in normal landfills, while some nations only allow waste with higher mercury concentrations to be deposited in landfills that are designed with enhanced release control technologies to limit mercury leaching and evaporation. The cost of acceptable disposal of mercury waste in some countries is such that many producers now investigate whether alternatives exist in which they would not have to produce and deal with mercury waste. Mercury waste management, as it is most commonly done today, in accordance with national and local regulations, increasingly requires long-term oversight and investment. Proper management of mercury wastes is important to reduce releases to the environment, such as those that occur due to spills (i.e. from broken thermometers and manometers) or releases that occur over time due to leakage from certain uses (e.g., auto switches, dental amalgams). In addition, given that there is a market demand for mercury, collection of mercury-containing products for recycling limits the need for new mercury mining.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraphs 122 & 123

For more information, see Chapter 8: Prevention and control technologies and practises 

6.2 What is the best overall approach to reduce emissions?

The source document for this Digest states:

A well thought-out combination of emission prevention and control measures is an effective way to achieve optimal reduction of mercury releases. If one considers some of the more important sources of anthropogenic mercury releases, one may see how prevention and control measures might be combined and applied to these sources:

  • Mercury emissions from municipal and medical waste incinerators may be reduced by separating the small fraction of mercury containing waste before it is combusted. For example, in the USA, free household mercury waste collections have been very successful in turning up significant quantities of mercury-containing products and even jars of elemental mercury. Also, separation programmes have proved successful in the hospital sector and a number of hospitals have pledged to avoid purchasing mercury-containing products through joint industry-NGO-Government programmes. However, separation programmes are sometimes difficult or costly to implement widely, especially when dealing with the general public. In such cases a better long-term solution may be to strongly encourage the substitution of non-mercury products for those containing mercury. As a medium term solution, separation programmes may be pursued, and mercury removed from the combustion stack gases. Mercury emissions from medical and municipal waste incineration can be controlled relatively well by addition of a carbon sorbent to existing PM and SO2 control equipment, however, control is not 100% effective and mercury-containing wastes are generated from the process;
  • Mercury emissions from utility and non-utility boilers, especially those burning coal, may be effectively addressed through pre-combustion coal cleaning, reducing the quantities of coal consumed through increased energy efficiency, end-of-pipe measures such as stack gas cleaning and/or switching to non-coal fuel sources, if possible. Another potential approach might be the use of coal with a lower mercury content. Coal cleaning and other pre-treatment options can certainly be used for reducing mercury emissions when they are viable and cost-effective. Also, additional mercury capture may be achieved by the introduction of a sorbent prior to existing SO2 and PM control technologies. These technologies are under development and demonstration, but are not yet commercially deployed. Also, by-products of these processes are potential sources of future emissions and must be disposed of or reused in an environmentally acceptable manner;
  • Mercury emissions due to trace contamination of raw materials or feedstocks such as in the cement, mining and metallurgical industries may be reduced by end-of-pipe controls, and sometimes by selecting a raw material or feedstock with lower trace contamination, if possible.
  • Mercury emissions during scrap steel production, scrap yards, shredders and secondary steel production, result primarily from convenience light and anti-lock brake system (ABS) switches in motor vehicles; therefore a solution may include effective switch removal/collection programmes;
  • Mercury releases and health hazards from artisanal gold mining activities may be reduced by educating the miners and their families about hazards, by promoting certain techniques that are safer and that use less or no mercury and, where feasible, by putting in place facilities where the miners can take concentrated ores for the final refining process. Some countries have tried banning the use of mercury by artisanal miners, which may serve to encourage their use of central processing facilities, for example, but enforcement of such a ban can be difficult;
  • Mercury releases and occupational exposures during chlor-alkali production may be substantially reduced through strict mercury accounting procedures, "good housekeeping" measures to keep mercury from being dispersed, properly filtering exhaust air from the facility and careful handling and proper disposal of mercury wastes. There are a number of specific prevention methods to reduce mercury emissions to the atmosphere. The US chlor-alkali industry invented the use of ultraviolet lights to reveal mercury vapour leaks from production equipment, so that they could be plugged. Equipment is allowed to cool before it is opened, reducing mercury emissions to the atmosphere. A continuous mercury vapour analyser can be employed to detect mercury vapour leaks and to alert workers so that they can take remedial measures. The generally accepted long-term solution is to encourage the orderly phase-out of chlor-alkali production processes that require mercury, and their substitution with technologies that are mercury free;
  • Mercury releases and exposures related to mercury-containing paints, soaps, various switch applications, thermostats, thermometers, manometers, and barometers, as well as contact lens solutions, pharmaceuticals and cosmetics may be reduced by substituting these products with non-mercury products;
  • Mercury releases from dental practices may be reduced by preparing mercury amalgams more efficiently, by substituting other materials for mercury amalgams, and by installing appropriate traps in the wastewater system;
  • Mercury emissions from dental amalgams during cremation may only be reduced by removing the amalgams before cremation, which is not a common practice, or by filtering the gaseous emissions when the practice takes place in a crematorium. Since a flue gas cleaner is an expensive control technique for a crematorium, prevention by substituting other materials for mercury amalgams during normal dental care might be a preferred approach;
  • In cases of uncontrolled disposal of mercury-containing products or wastes, possible reductions in releases from such practises might be obtained by making these practices illegal and adequately enforcing the law, by enhancing access to hazardous waste facilities, and, over the longer term, by reducing the quantities of mercury involved through a range of measures encouraging the substitution of non-mercury products and processes.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 8, paragraph 124

For more information, see Chapter 8: Prevention and control technologies and practises 

6.3 What further research and information is needed?

    • 6.3.1 National initiatives
    • 6.3.2 Regional and international initiatives

6.3.1 National initiatives

The source document for this Digest states:

The environmental authorities in a number of countries consider mercury to be a high-priority substance with recognised adverse effects. They are aware of the potential problems caused by use and release of mercury and mercury compounds, and therefore have implemented measures to limit or prevent certain uses and releases. Types of measures that have been implemented by various countries include:

  • Environmental quality standards, specifying a maximum acceptable mercury concentration for different media such as drinking water, surface waters, air and soil and for foodstuffs such as fish;
  • Environmental source actions and regulations that control mercury releases into the environment, including emission limits on air and water point sources and promoting use of best available technologies and waste treatment and disposal restrictions;
  • Product control actions and regulations for mercury-containing products, such as batteries, cosmetics, dental amalgams, electrical switches, laboratory chemicals, lighting, paints/pigments, pesticides, pharmaceuticals, thermometers and measuring equipment;
  • Other standards, actions and programmes, such as regulations on exposures to mercury in the workplace, requirements for information and reporting on use and releases of mercury in industry, fish consumption advisories and consumer safety measures.

Although legislation is the key components of most national initiatives, safe management of mercury also includes efforts to reduce the volume of mercury in use by developing and introducing safer alternatives and cleaner technology, the use of subsidies to support substitution efforts and voluntary agreements with industry or users of mercury. A number of countries have through implementation of this range of measures obtained significant reductions in mercury consumption, and corresponding reductions of uses and releases.

The table below gives a general overview of some of the types of implemented measures of importance to management and control of mercury, as related to its production and use life-cycle and an indication of their status of implementation, based on information submitted for this report. More detailed descriptions of most of these measures are provided in chapter 9 and the separate Appendix to this report.

TYPE AND AIM OF MEASURE STATE OF IMPLEMENTATION
Production and use phases of life cycle
P
O
I
N
T

S
O
U
R
C
E
Prevent or limit the intentional use of mercury in processes General bans implemented in very few countries
Prevent or limit mercury from industrial processes (such as chlor-alkali and metallurgic industry) from being released directly to the environment Implemented in many countries, especially OECD countries
Apply emission control technologies to limit emissions of mercury from combustion of fossil fuels and processing of mineral materials Implemented in some OECD countries
Prevent or limit the release of mercury from processes to the wastewater treatment system Implemented in some OECD countries
Prevent or limit use of obsolete technology and/or require use of best available technology to reduce or prevent mercury releases Implemented in some countries, especially OECD countriesImplemented in some countries, especially OECD countries
P
R
O
D
U
C
T
S
Prevent or limit products containing mercury from being marketed nationally General bans implemented in a few countries only. Bans or limits on specific products are more widespread, such as batteries, lighting, clinical thermometers
Prevent products containing mercury from being exported Only implemented in a few countries
Prevent or limit the use of already purchased mercury and mercury-containing products Only implemented in a few countries
Limit the allowable content of mercury present as impurities in high-volume materials Only implemented in a few countries
Limit the allowed contents of mercury in commercial foodstuffs, particularly fish, and provide guidance (based on same or other limits values) regarding consumption of contaminated fish Implemented in many countries, especially OECD countries
Disposal phase of life cycle
Prevent mercury in products and process waste from being released directly to the environment, by efficient waste collection Implemented in some countries, especially OECD countries. WHO guidelines used by some countries.
Prevent mercury in products and process waste from being mixed with less hazardous waste in the general waste stream, by separate collection and treatment Implemented in many countries, especially OECD countries
Prevent or limit mercury releases to the environment from incineration and other treatment of household waste, hazardous waste and medical waste by emission control technologies Implemented or implementation ongoing in some countries, especially OECD countries.
Set limit values for allowable mercury contents in sewage sludge spread on agricultural land Implemented in a number of countries
Restrict the use of solid incineration residues in road building, construction and other applications Implemented in some OECD countries
Prevent the re-marketing of used, recycled mercury Only implemented in a few countries

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 9, paragraphs 125 to 127

For more information, see Chapter 9: Initiatives for controlling releases and limiting use and exposures 

6.3.2 Regional and international initiatives

The source document for this Digest states:

It is also apparent that because of mercury’s persistence in the environment and the fact that it is transported over long distances by air and water, crossing borders and often accumulating in the food chain far from it’s original point of release, a number of countries have concluded that national measures are not sufficient. There are a number of examples where countries have initiated measures at regional, sub-regional and international levels to identify common reduction goals and ensure coordinated implementation among countries in the target area.

Three regional, legally binding instruments exist that contain binding commitments for parties with regards to reductions on use and releases of mercury and mercury compounds:

  • LRTAP Convention on Long-Range Transboundary Air Pollution and its 1998 Aarhus Protocol on Heavy Metals (for Central and Eastern Europe and Canada and the USA);
  • OSPAR Convention for Protection of the Marine Environment of the North-East Atlantic; and
  • Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea.

All these three instruments have successfully contributed to substantial reductions in use and releases of mercury within their target regions.

The regional and sub-regional cooperation is, however, not limited to legally binding agreements. Six initiatives exist at regional or sub-regional levels that inspire and promote cooperative efforts to reduce uses and releases of mercury within the target area without setting legally binding obligations on the countries/regions participating. The initiatives are: the Arctic Council Action Plan, the Canada-US Great Lakes Binational Toxics Strategy, the New England Governors/Eastern Canada Premiers Mercury Action Plan, the North American Regional Action Plan, the Nordic Environmental Action Programme and the North Sea Conferences. Important aspects of these initiatives are the discussion and agreement on concrete goals to be obtained through the cooperation, the development of strategies and work plans to obtain the set goals and the establishment of a forum to monitor and discuss progress. Although these initiatives are not binding on their participants, there is often a strong political commitment to ensure that the agreements reached within the initiative are implemented at national/regional level.

There are also a number of examples of national/regional initiatives being taken by the private sector in the form of voluntary commitments that can be seen as an adjunct to public sector initiatives and as having a good chance of success as they have, by definition, the support of the primary stakeholders. All these voluntary initiatives are valuable supplements to national regulatory measures and facilitate awareness raising, information exchange and the setting of reduction goals that benefit the target region.

At the international level, two multilateral environmental agreements (MEAs) exist that are of relevance to mercury and mercury compounds: the Basel Convention on Control of Transboundary Movements of Hazardous Wastes and their Disposal and the Rotterdam Convention on the Prior Informed Consent Procedure for Certain Chemicals and Pesticides in International Trade. These instruments regulate trade in unwanted chemicals/pesticides or hazardous wastes. However, they do not contain specific commitments to reduce uses and releases of mercury directly. The most recently negotiated agreement relevant to chemicals, the Stockholm Convention on POPs, does not cover mercury. In addition, a number of international organizations have ongoing activities addressing the adverse impacts of mercury on humans and the environment.

A more detailed compilation of national initiatives, including legislation, in each individual country is contained in an appendix to this report, entitled "Overview of existing and future national actions, including legislation, relevant to mercury". The Appendix is published in a separate document. The information compiled therein has been extracted from the national submissions received from countries under this project.

Source & ©: UNEP Global Mercury Assessment report, Summary of the Report, 
Chapter 9, paragraphs 128 to 133

For more information, see Chapter 9: Initiatives for controlling releases and limiting use and exposures 


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