Compliance with Chlor-Alkali Mercury Regulations, 1986-1989: Status Report

• 5.1 General
• 5.2 Company Related

5.1 General

1. During the years 1986-1989, there were five operational mercury cell chlor-alkali plants in Canada producing chlorine and caustic soda from the electrolysis of brine using a mercury cathode. This is a significant reduction from the number of mercury cell plants that were operating in the mid-1970s.
   
   
2. Offsetting this decline in the number of mercury cell plants has been a corresponding increase in the number of nonmercury-based chlor-alkali processes, specifically membrane and diaphragm cells. In 1986 and 1989, for example, diaphragm cells accounted for approximately 75% and 83%, respectively, of total chlorine production, whereas mercury cells accounted for 20% and 14%, respectively, of total chlorine production.
   
   
3. From 1986 to 1989, chlorine production from mercury cell chlor-alkali plants decreased from 210 278 tonnes to 189 577 tonnes, a decrease of almost 10%.
   
   
4. Primarily, mercury from mercury cell plants is lost to process effluents, emissions, products, and solid wastes. Emission losses, which continue to represent the largest actual operational release to the environment, come from cell room ventilation, end boxes, hydrogen filters, and retorts. Of these sources, the largest mercury release results from cell room ventilation. Although mercury lost as solid waste is, in absolute terms, the largest loss, this waste is either buried in secure landfills (with associated groundwater monitoring) or is chemically stabilized off-site by various commercial (proprietary) processes. In this way, mercury is not released to the environment. Mercury losses to effluents and products are low compared with those losses to emissions and solid wastes.
   
   
5. From 1986 to 1989, mercury losses to effluents decreased from 88.07 kg in 1986 to 46.29 kg in 1989, a decrease of 47%.
   
   
6. From 1986 to 1989, mercury losses to emissions decreased front 680.56 kg in 1986 to 547.18 kg in 1989, a decrease of 19.6%.
   
   
7. The demand for chlorine by the papermaking sector continues to decline as this sector adopts nonchlorine bleaching processes to eliminate the formation and release of potentially toxic organochlorine compounds. This decline in the demand for chlorine is expected to be long term.
   
   
8. In November 1990, PPG Canada Inc. ceased operations as a mercury cell plant and converted to membrane cell technology. As of January 1, 1991, there were four operating mercury cell plants in Canada.

5.2 Company Related

5.2.1 Canadian-Oxy Ltd.

1. Over the period 1986-1989, Canadian-Oxy was in compliance with effluent regulations.
   
   
2. Over the period 1986-1989, Canadian-Oxy was in compliance with emission regulations except for 1987, when 130.5 kg of mercury were emitted above the allowable limit. This loss occurred during the third quarter of 1987 and is attributed to a combination of a change of ownership (and consequent loss of expertise), very high operating and production levels, increased electrical capacity, seawater cooling deficiencies (caused by high temperatures), and equipment malfunction.
   
   
3. Canadian-Oxy continues to operate an open cell room with mercury emissions calculated from ambient mercury concentrations (obtained from six samplers located between the cells) and the average vertical velocity at each sampler.
   
   
4. Mercury losses per tonne of chlorine produced ranged from 3.52 g in 1988 to 8.58 g in 1987. Average losses over the period 1986-1989 were 5.28 g per tonne of chlorine produced.
   
   
5. Mercury consumption per tonne of chlorine produced ranged from 8.89 g in 1988 to 14.16 g in 1987.

5.2.2 ICI Ltd., Cornwall

1. Over the period 1986-1989, ICI, Cornwall, was in compliance with effluent and emission regulations.
   
   
2. Although within regulated release amounts, mercury losses to emissions increased each year from 85.09 kg in 1986 to 91.72 kg in 1989. This increased mercury release was not matched by an increase in chlorine production. In fact, there was a decrease in total chlorine production from 1987 to 1989.
   
   
3. The increase in mercury losses in 1988 and 1989, as explained earlier, was due to the disposal of sludge (i.e., solid waste) that had accumulated on-site since 1983 or earlier. This accumulated material was disposed of during 1988 and 1989.
   
   
4. Mercury losses per tonne of chlorine produced ranged from 3.36 g in 1986 to 18.55 g in 1988. Average losses over the period 1986-1989 were 9.96 g per tonne of chlorine produced.
   
   
5. The consumption of mercury per tonne of chlorine produced ranged from 4.74 g in 1987 to 29.0 g in 1986. The high value for 1986 was due to the large mercury input for chat year (4 364 kg) compared with far lower mercury inputs for the other years.

5.2.3 ICI Ltd, Dalhousie

1. Over the period 1986-1989, ICI, Dalhousie, was in compliance with effluent regulations.
   
   
2. Violations of emission regulations were recorded from various sources during 1986-1989. Over this period, only the end box system was in compliance for all quarterly testing.
   
   
3. Mercury losses to emissions declined from 90.45 kg in 1986 to 40.60 kg in 1989, with total chlorine production remaining at a fairly constant level over the 4 years.
   
   
4. Mercury losses to solids did not show any particular trend over the period 1986-1989, ranging from a minimum of 258.01 kg in 1988 to a maximum of 665.00 kg in 1989.
   
   
5. Mercury losses per tonne of chlorine produced ranged from 11.14 g in 1988 to 24.99 g in 1989.
   
   
6. Mercury consumption per tonne of chlorine produced decreased significantly from 121.16 g in 1986 to 1.78 g in 1988. Mercury consumption for 1989 could not be determined due to zero mercury input for this year, which gave a negative mercury consumption figure.

5.2.4 ICI Ltd, Dalhousie

1. Over the period 1986-1989, Canso Chemicals was in compliance with effluent and emission regulations.
   
   
2. Mercury losses to effluent and emissions decreased from 1986 to 1989. At the same time, however, chlorine production decreased significantly from 21 887 tonnes in 1986 to 12 847 tonnes in 1989.
   
   
3. Total mercury lost in 1989 (46.99 kg) was significantly lower than that lost in the years 1986-1988. This is reflected in significant reductions in mercury losses to effluent, emissions, and solids.
   
   
4. Mercury losses per tonne of chlorine produced ranged from 3.45 g in 1986 to 5.08 g in 1988. Losses for 1986, 1987, and 1989 are similar.
   
   
5. Mercury consumption per tonne of chlorine produced ranged from 6.59 g in 1989 to 11.52 gin 1988.

5.2.5 PPG Canada Inc

1. Over the period 1986-1989, PPG Canada violated effluent regulations a total of 28 d in 1986 and a total of 3 d in 1988. In 1987 and 1989, the company was in compliance with effluent regulations. During the 1986 and 1988 violations, PPG Canada discharged 4.452 and 0.909 kg of mercury, respectively, above the allowable limit.
   
   
2. Over the period 1986-1989, several violations of emission regulations were recorded from various sources. Only during 1988 were all sources in compliance. The majority of violations were associated with cell room ventilation, with one violation being recorded for each of the hydrogen stream and end box.
   
   
3. Mercury losses to effluent decreased significantly after 1986 (45.1 kg), following installation and start-up of the effluent treatment plant, to 12.51 kg in 1987 and 11.69 kg in 1989.
   
   
4. Mercury losses to emissions decreased noticeably after 1986 (306.53 kg), but ranged between 160.54 kg in 1987 and 199.68 kg in 1989. Compared with other plants, these emissions are high.
   
   
5. Total mercury input to PPG Canada over the period 1986-1989 was significantly greater at 24 150 kg than for the other plants.
   
   
6. Mercury consumption per tonne of chlorine produced ranged from 107.37 g in 1988 to 158.92 g in 1989.