by Paul Crumpler, Pollution Prevention Engineer
[From the Source - Fall 1996]
Almost every business or organization has some wood waste. Most businesses dispose pallets. Hotels, schools, hospitals, warehouses, and manufacturers dispose of approximately 16 million pallets in Georgia annually. Other businesses also generate and dispose wood waste such as sawdust and short unusable boards. Companies that manufacture lumber or build a wood product such as furniture or millwork generate significant amounts of wood waste that is almost always sent to a landfill for disposal. There are approximately 1,500 wood products manufacturers in Georgia generating and disposing from one to 1,500 cubic yards of waste per month. Pulp mills and similar industries can generate as much as 60 tons per day. Large companies such as paper mills sometimes burn wood waste to generate steam and electric power. A number of small companies also burn wood for energy. Some large companies also landfill wood waste in mill-owned landfills.
Cost is a primary concern. Approximately 150 wood product manufacturers who recently attended The Wood Finishers and Furniture Manufacturers Workshop were surveyed on solid waste generation and disposal. They reported disposal costs alone ranged from about $50 per month up to $8,000 per month. Several small companies with under 50 employees reported disposal costs of more than $1,000 monthly. These companies usually send wood waste to municipal landfills where hauling and tipping fees are charged. Several had found alternative methods of handling their wood waste, such as supplying horse stables with sawdust and wood fuel to homes and businesses.
Landfill depletion and avoiding the need to build new landfills is a major concern of public and private landfill operators. For pulp mills and similar companies, disposal cost per ton in their own private landfills is relatively low. However, these landfills are rapidly filling up, requiring construction of new landfills which can cost millions.
Waste wood does not pose a specific environmental threat other than filling landfill space that could accept more noxious waste. Recently, disposal of residential yard clippings, leaves, and tree branches was prohibited in lined landfills in Georgia to decrease the necessity of building new landfills. Residential yard trimmings are similar and sometimes exactly the same as industrial wood waste.
Wood product and furniture manufacturers generate sawdust, offcuts, and dust. Offcuts are generated from cutting a shorter length from a long board. The remaining short board is of good quality, but is too short to make a useful part. Other offcuts are generated due to defects such as knots or splitting; some furniture companies scrap up to 40% of purchased lumber due to defects. Sawdust is generated from cutting, drilling, and milling (shaping) operations where wood is removed from a finished product. Dust is very fine flour-like wood particles generated during sanding and other machining operations. Wood dust is explosive, irritates workers, causes quality problems by settling on fresh paint, and is a nuisance to neighbors. For these reasons, dust is often collected in filter bags or dust collectors. In general all of these materials are landfilled. Offcuts, sawdust, and dust generated by wood products manufacturers is typically clean material containing little sand, soil, or water.
Lumber yards and pulp mills generate other waste wood. When logs are delivered to a mill, they are checked for size and metal contamination. Logs that are too large to fit processing equipment are sometimes landfilled. Logs containing nails, wire, and bullets are also often landfilled. Bark is removed from logs prior to processing; it is usually burned for energy recovery or sold to a dealer. Some bark falls off the trees in the logyard where it becomes mixed with soil; this dirty material is often landfilled. Wood waste generated by pulp mills and lumber yards contains more foreign material and moisture than that generated by wood products manufacturers since it usually is not kiln dried and is handled outdoors.
Pallets are sometimes in perfect condition when they are disposed. Typically pallets are made of hardwood and sometimes pine board with a low moisture content. A typical pallet is roughly 42" x 48" x 6", weighs approximately 50 pounds, and contains about 3 pounds of steel nails.1 As mentioned above, 16 million or 800,000,000 pounds of pallets are disposed in Georgia each year. It is unclear how these pallets are disposed. However, if they were landfilled whole, they would fill 4,200,000 cubic yards of landfill space. This is equal to a football field stacked 2,400 feet high. Pallets contain at least 60% open volume; most of this material is air. Many companies grind or chip their waste wood, whether pallets, offcuts, or tree limbs. Grinding reduces overall volume and sometimes makes material easier to sell. The size and shape of the ground wood is dependent upon the type of equipment used, the manufacturer, and equipment settings. Ground wood can range in size from less than 1/4" chips to 10" strings.
1 Information from a paper prepared by Georgia Tech EDI, "Pallet Disposal and Opportunities for Recycling", C. Bouffier, C. Downing, B. W. Rial
There are companies and individuals in Georgia that will take your wood waste for beneficial reuse. Some will pay for wood waste; others will charge for pickup and transportation. Whether a particular company can use your waste wood depends on the condition of the wood. Moisture content, contamination with soil or nails, size of the pieces, variation in piece size, and quantity can all make wood waste useful or not useful to a particular company.
Pulp mills can use large quantities of chipped wood as fuel to power steam and generate electricity. Some mills burn wood exclusively because it provides a clean burning, low sulfur fuel. Others burn coal and fuel oil in addition to wood. Lumber yards that kiln dry wood sometimes burn wood as a heat source. Plywood, particle board, and timber-derived chemical businesses also burn wood for power generation. Keeping the moisture and foreign material content low improves marketability as fuel.
Some companies will buy or accept wood waste. They then sell the wood to manufacturers that use wood as a raw material or fuel. They provide the service of pooling smaller amounts of wood waste in order to provide large quantities to other companies. Some buyers of wood from brokers include particle and fiber board manufacturers, pulp mills, chemical plants, chicken farms, and mulch manufacturers.
Mulching and Composting
Wood waste is sometimes mulched or composted to create beneficial products. Mulching consists of grinding wood waste into smaller pieces that can be used as ground covering or outdoor decoration. For example, Christmas trees are often collected and mulched after the holidays. The value of mulch is greatly dependant upon appearance. For example, large pine bark nuggets and cypress mulch are saleable products; Christmas tree mulch is almost never sold.
Composting is essentially allowing biological waste such as wood to decay into soil. Wood, grass clippings, vegetable matter, and mineral wastes can be blended and allowed to decay. The resulting soil can be sold in truckload or bag quantities. Some companies such as Hyponex sell composted soils at garden supply stores as a primary business.
Mulching and composting can be done on a large or small scale. Some companies and individuals mulch and compost for their own use. Information on these processes can be obtained from the library, county extension agents, universities, and trade magazines such as BioCycle, Waste Age, and Resource Recycling.
Waste exchanges are essentially classified ads for waste. A company will list a description, quantity, and availability of a waste on an exchange listing which is published via mail, computer bulletin boards, or the Internet. Other companies list the type of waste materials that they need on the same listing. Some waste exchanges list many different types of waste; others list only a particular waste such as wood. The Georgia Forestry Commission has a wood waste exchange accessible through a computer bulletin board.
Pallet recyclers take used or unwanted pallets from a business, inspect, recondition, and sell the used pallet for reuse. There are numerous pallet recyclers in Georgia. These recyclers also generate large amounts of waste wood. Broken boards and unusable pallets are their largest wastes. See the Spring/Summer 1996 issue of From the Source for a list of pallet recyclers.
Some manufacturers repair pallets for their own shipping needs. Simple inspection can identify reusable pallets. Flexibility in using different sizes of pallets often aids in reuse. Some companies have found that adding one or two employees who only repair and inspect incoming pallets for reuse in shipping finished goods is cost effective. Munekata of Dalton, GA has added two employees to their pallet recovery and reuse program. The program has reduced overall cost to the company and reduced disposal of waste.
Altering processes and material may help reduce waste generation, thus avoiding disposal or recycling. Gailey Industries of Americus, GA reduced wood waste generation by switching from kiln-dried board lumber to plywood in frame construction of upholstered furniture. Approximately, 40% of all hardwood purchased had to be scrapped due to cracks and other defects. Even though plywood costs more per board foot than hardwood board, overall production cost were reduced since the scrap rate was reduced to 2%, fewer board feet of lumber needed to be purchased, and waste wood disposal decreased from 80 cubic yards to less than 2 cubic yards. A additional benefit was increase product quality; plywood construction increased the furniture's strength and durability.
Other source reduction methods can be used to reduce waste and cost. Planning cuts carefully can reduce offcuts. Buying lumber closer to finished product size can reduce chip generation from machining.
In addition to providing technical assistance directly to Georgia industry, P2AD can help your company locate other businesses, trade organizations, and university resources that can assist in solving your wood waste problems. Some publications that may offer more information on mulching, composting, and recycling wood waste are provided below.