Abstract
Mercury cell chlor-alkali plants in Canada are regulated federally by the National Effluent and Emission Regulations with respect to the release of mercury to the environment.
This status report, covering the years 1986-1989, is part of a continuing series of status reports by Environment Canada on this industry. As such, it reviews and summarizes the loss of mercury from mercury cell chlor-alkali plants to effluents, emissions, products, and solid wastes for the five mercury cell plants operating in Canada over this period.
During 1986-1989, total mercury losses to effluent decreased from 88.07 kg/year (1986) to 46.29 kg/year (1989). This decrease is attributed to the start-up in May 1986 of a new wastewater treatment facility at PPG Canada. Although this plant discharged a total of 4.452 kg of mercury above the regulated limits during a total of 28 effluent regulation exceedances, no prosecutions were undertaken by the regulatory authorities because the plant was in the process of modifying and improving the sewer system and installing a new wastewater treatment plant. Another plant (ICI, Cornwall) had one apparent contravention during April 1988. Because effluent was accumulated over a 3 d period before discharge, however, upon averaging the total mercury release to effluent over this 3 d period, the company was in compliance.
Total mercury emissions over the 4 year period 1986-1989 decreased from 680.56 kg/year (1986) to 547.18 kg/year (1989). Exceedances of the emission regulations were recorded, however, during quarterly compliance testing at three of the five plants. One mercury cell plant (Canadian-Oxy) continues to operate an unenclosed cell area. Consequently, mercury emissions from this plant are determined from amblent mercury concentrations and wind speed over the cells.
Total mercury losses to products and solid wastes for all plants during 1986-1989 were 302.64 kg and 3318.13 kg respectively.
Mercury consumed to produce a tonne of chlorine ranged from 1.78 g to 158.92 g.
All information contained in this report luis been compiled from company data.