Mercury Controls

Chlor-alkali chemical manufacturing facilities using mercury cells must meet tougher air pollution standards for mercury under a rule EPA issued last month.

The new Clean Air Act regulation is expected to cut emissions of mercury from the nine affected U.S. chlor-alkali plants by about 73%, from 1,764 to 487 lb annually, according to EPA. The rule also sets out new work practices, such as regular inspections for leaks and requirements that rooms holding mercury cells be coated with a material that resists absorption of the toxic metal.

According to EPA, the rule should have no significant impact on the market for products made using chlorine or sodium hydroxide, which are produced by chlor-alkali plants.

Collectively, the rule will require an estimated $1.6 million in capital costs and $1.4 million per year in operating costs for the nine plants. EPA adds, "Overall, the economic impact of the final standards is minimal for the facilities producing chlorine."

In addition to chlor-alkali production facilities, the regulation's new emissions standards apply to units that recover mercury from waste.

As EPA issued the new regulation, it also announced that it will not regulate air emissions of chlorine and hydrochloric acid from plants manufacturing chlorine and NaOH, regardless of whether the facilities use mercury cells to produce these chemicals. Emissions of chlorine and HCl from these plants are low enough not to threaten the public health or the environment, EPA says.

The rule controlling mercury from chlor-alkali facilities follows an EPA proposal to cut mercury, sulfur dioxide, and nitrogen oxides from coal-fired power plants through emissions controls and pollutant trading (C&EN, Dec. 22, 2003, page 12).