Wood preservation facilities, alkaline copper quaternary: chapter G-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 ACQ wood preservation facilities were described in Section 5.2, Figure 1. The main categories of process wastes and emissions that may be encountered at ACQ facilities, along with their recommended disposal methods, are presented in Chapter A, Table 23.

9.2 Liquids Containing ACQ

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

9.3 Solids with High ACQ Concentrations

For the purpose of this document, solids with high ACQ concentrations include sludge from sumps and cylinders, and disposable cartridge filters used to filter recycled waters. Recovery of the components (copper and quat) would be ideal, but this option is not commercially feasible in Canada at this time. The preferred means of disposal depends on the local or provincial jurisdiction that applies. It is the responsibility of the waste generator to obtain and comply with approvals required by the jurisdiction in which the facility is located.

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

9.4 Miscellaneous Solid Wastes

Miscellaneous solid wastes (e.g. empty copper concentrate and quat drums, cuttings from ACQ-treated lumber) from ACQ wood preservation plants may be disposed of at designated sanitary landfills as approved by the provincial regulatory agency. The ingredient drums should be rinsed thoroughly (triple-rinsed) with water prior to disposal, and the rinse water should be used for the preparation of work solutions.

Do not use ACQ-treated wood as a compost or mulch.

Incineration of materials contaminated with ACQ 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 ACQ facilities are normally localized; effects, if any, would be confined within the boundaries of the facilities. Air emissions from ACQ facilities include vapours from the following:

• ammonia/copper or amine/copper storage tank vents
• ACQ mixing and storage tank vents
• vacuum pump discharges
• opening of retort cylinder doors
• freshly treated charges
• vapours from kiln-drying operations

Although information is not yet available for ACQ facilities, there have been studies on the preservative ammoniacal copper arsenate (ACA). Monitoring of mists (28) in the vicinity of several ACA retorts during cylinder door openings has shown arsenic and copper concentrations below published ACGIH threshold limit values (24). Ammonia emissions in the vicinity of ACA retort cylinder door openings and in the vicinity of freshly treated wood have been reported at concentrations above occupational health limits. For example, Todd and Timbie (25) measured airborne ammonia concentrations of up to 250 ppm within localized areas of one ACA facility. These concentrations were much higher than occupational health limits of 35 ppm for a 15-minute exposure and 25 ppm for an 8-hour exposure. Concern about ammonia releases and control measures at an ACA facility also has been expressed in an Environment Canada report (28).