Wood preservation facilities, ammoniacal copper zinc arsenate: chapter C-9

9. Waste, Process Emissions and Disposal

For general information on process emissions and disposal, consult Section 9 of Part I, Chapter A - General Recommendations for All Wood Preservatives.

9.1 Control, Treatment and Disposal

Potential process emission sources at ACZA wood preservation facilities were described in Section 5.2 Figure 1. The main categories of process wastes or emissions that may be encountered at ACZA facilities, along with their recommended disposal methods, are presented in Chapter A Table 23.

Federal and provincial regimes address hazardous waste and hazardous recyclable material in different manners. Provincial requirements may also differ from province to province. Consult your provincial authority for more information.

9.2 Liquids Containing ACZA

Liquid solutions containing ACZA, such as drips and washwaters, should be routinely collected and reused as makeup in preparing new treatment solutions. If unusual circumstances (such as prolonged plant shutdown) prevent on-site reuse, transport to another ACZA facility (for reuse) should be arranged. The chemical supplier may be able to suggest another facility that uses ACZA. Disposal should be considered only as a last alternative.

9.3 Solids with High ACZA Concentrations

Consult Section 9 of Part I, Chapter A - General Recommendations for All Wood Preservatives.

9.4 Miscellaneous Solid Wastes

Miscellaneous solid wastes (e.g. cuttings from ACZA-treated lumber) from ACZA wood preservation plants may be disposed of at designated sanitary landfills as approved by the provincial regulatory agency.

Containers should be rinsed thoroughly (triple rinsed - see Section 9.4 of Chapter A) with water prior to disposal, and the rinse water should be used for the preparation of work solutions.

Do not use ACZA treated wood as a compost or mulch.

Incineration of ACZA-contaminated materials is not permitted except in facilities authorized for disposal of such products because of the formation of toxic combustion by-products.

9.5 Air Emissions

Air emissions at ACZA facilities are normally localized; effects, if any, would be confined within the boundaries of the facilities. Air emissions from ACZA facilities may include the following:

• vapours from ammonia storage tank vents
• vapours from ACZA mixing and storage tank vents
• vapours from vacuum pump discharge
• vapours from opening of retort cylinder doors
• vapours from freshly treated charges
• vapours from kiln-drying operations

Vapours from ammonia storage tanks, ACZA working solution tanks and vacuum pump discharge, should be captured and redirected to a common vent line prior to passing through a scrubber and exiting the building.

Recent air monitoring at one ACZA plant equipped with a scrubber revealed that levels of ammonia were very low and barely detectable by smell. Scrubber or any similar air pollutant control device is a necessity to ACZA plants since measured airborne ammonia concentrations up to 250 ppm were detected in the past at one ACA facility (9).