Mercury regulation

So, maybe it doesn t really matter that we have been so tardy in developing mercury regulations. What do you think ... 

Although CAIR is a favorable development in clean air regulation, EPA s recently announced mercury regulations represent a step backwards on existing air toxic provisions of the Clean Air Act. Each year, uncontrolled coal-fired power plants in the United States emit nearly 50 tons of mercury to the air in addition to an estimated 33 tons disposed of in the waste left over after power plants bum coal. In 1997, the U.S. EPA estimated that coal-fired power plants accounted for about 33% of all U.S. emissions, with municipal, medical and hazardous waste combustors accounting for another 33% combined. 

Mercury. EPA responded to the judicial remand of the Bush Administration s Mercury regulation in March 2011 by proposing to establish a hazardous emission standard under section 112 of the Clean Air Act reflecting the maximum degree of reduction in emissions that was achievable (MACT). EPA predicted that compliance with these standards would reduce mercury emissions from power plants by about 91 percent, and this would in turn prevent 17,000 premature deaths, 11,000 heart attacks, and 120,000 asthma attacks per year. ... 

Mercury salts are highly toxic and must be handled carefliUy. It is necessary to consult the material safety data sheet prior to handling. Strict adherence to OSHA/EPA regulations is essential. The ACGIH adopted (1991—1992) TLV for mercury as inorganic compounds is TWA 0.1 mg/m and for fluorides as F 2.5 mg/m. ... 

Coalition ofJSlortheast Governors. The CONEG model heavy-metal guideline is implemented through state regulations and limits total metal content of lead, chromium, mercury, and cadmium. The limitation of 100 parts per million total is aimed at protecting the environment from the disposal of post-consumer waste. 

Regulations. In order to decrease the amount of anthropogenic release of mercury in the United States, the EPA has limited both use and disposal of mercury. In 1992, the EPA banned land disposal of high mercury content wastes generated from the electrolytic production of chlorine—caustic soda (14), accompanied by a one-year variance owing to a lack of available waste treatment faciUties in the United States. A thermal treatment process meeting EPA standards for these wastes was developed by 1993. The use of mercury and mercury compounds as biocides in agricultural products and paints has also been banned by the EPA. 

California and Minnesota have placed restrictions on the disposal of fluorescent light tubes, which contain from 40—50 mg of mercury per tube, depending on size. After batteries, fluorescent lamps are the second largest contributor of mercury in soHd waste streams in the United States (3,14). A California law classifies the disposal of 25 or more fluorescent lamp tubes as hazardous waste. In Minnesota, all waste lamps generated from commercial sources are considered hazardous waste. Private homes are, however, exempt from the law (14). Other states have proposed similar regulations. Several companies have developed technologies for recovering mercury from spent lamps (14). 

This secondary reaction starts at about 180°C, but the mass must be heated to 350—400°C to bring the reaction to completion and produce a nitrate-free product. The off-gases are extremely corrosive and poisonous, and considerable attention and expense is required for equipment maintenance and caustic-wash absorption towers. Treatment of the alkaline wash Hquor for removal of mercury is required both for economic reasons and to comply with governmental regulations pertaining to mercury ia plant effluents. 

Metal compounds, particularly compounds of the heavy metals, have a history of importance as antimicrobial agents. Because of regulations regarding economic poisons in the environment they are no longer widely used in this appHcation. Mercury, lead, cadmium, uranium, and other metals have been imphcated in cases of poisoning that resulted in government response. The metals whose compounds have been of primary interest as antimicrobials are mercury, silver, and copper. 

CFR Part 61 (Appendix B) NESHAP regulations Method lOlA Mercury... 

Although the petrochemical and metals industries were the primai y focus of the toxic air pollutants legislation, approximately forty of these substances have been detected in fossil power plant flue gas. Mercury, which is found in trace amounts in fossil fuels such as coal and oil, is liberated during the combustion process and these emissions may be regulated in the future. EPA issued an Information Collection Request (ICR) that required all coal-fired plants to analyze their feed coal for mercury and chlorine. Since these data will be used in making a regulatory decision on mercury near the end ot the year 2000, it is critical that the power industry provide the most accurate data possible. 

A float-type FM regulator type is primarily employed on packaged FT boilers. It has a float chamber located at the NOWL and is connected to the steam-water areas of the boiler. When the water level falls, the float drops and mechanically moves a mercury switch (or electronic switch), which in turn actuates the FW regulator valve. 

A cylinder of carbon monoxide equipped with a suitable regulator calibrated in pounds per square inch (p.s.i.g.) is connected to the three-way stopcock. All joints and the septum must be secured with clamps or wire. A vertical tube containing mercury was connected to an exit tube from the reaction flask by the checkers. A pressure of carbon monoxide was maintained against a 500-mm. column of mercury. 

Romans mined the mineral cinnabar (HgS) from deposits in Spain 2000 years ago, and in the sixteenth century the Spanish shipped mercury obtained from the same ore deposits to the Americas for the extraction of silver. Mercury is an important component of street lamps and fluorescent lights. It is used in thermometers and barometers and in gas-pressure regulators, electrical switches, and electrodes. 

To keep to a minimum the current flowing through the mercury it is best to employ a valve circuit with a relay, so that the regulator current only controls the grid potential of a valve. 

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