Management of Wastes from Wood Preserving Facilities

INTRODUCTION Wood preserving is a significant, diverse and well established industry with five hundred forty-seven known operating plants in the United States. (1) The principal product of these plants is chemically treated wood for use as railroad ties, utility poles, and construction materials. In 1984, the industry treated about 500 million cubic feet of wood products. (2) Wood is chemically treated to reduce or prevent decay by microorganisms, attack by insects and to increase its resistance to fire. Adequate preservation requires the use of large quantities of toxic chemicals which could cause environmental damage and may even result in adverse health effects. Wastewaters from these plants contain not only the normal sanitary wastes, but unusable and contaminated preservatives which no longer can be used for the processes. Two other sources of wastewater are stormwater surface runoff and excess process water. Solid residues include sludges from wastewater treatment, insoluble organic materials from waterborne salts, and contaminated soils from spills or from drippage. In older plants, the discharge of wastewaters requires treatment, which has proven to be costly and technically difficult. As a result, many small plants have chosen to close their doors instead of invest the money in treatment processes. This has been because the capital simply has not been available to them due to their small size and independent operation. These abandoned plants probably represent serious future clean-up problems for the regulatory agencies. The newer facilities, constructed in the past ten years, have incorporated within their design various pollution prevention technologies that satisfy environmental regulations and provide greater efficiency in operation. In reviewing the records of this industry, it is clear that early recognition of the "zero discharge" or "total containment" allowed the industry to modernize and flourish in North Carolina. The objective of this paper is to review the status of this industry in North Carolina, to describe the evolution and use of pollution prevention strategies for wood preservation plants, and finally to suggest strategies for existing plants for attaining self containment and zero discharge which will ultimately result in economic benefit to the plants. HISTORICAL DEVELOPMENT The need to protect wood from various forms of decay and physical weathering has been recognized since ancient times. Noah was commanded to use pitch while constructing the ark, and accounts of the use of similar agents are found in other passages of ancient history. In modern times, different chemicals and treatments …