Sawdust: Surprisingly Eco-Friendly and Sustainable

What is Sawdust and how is it Made?

The term 'sawdust' may bring to mind images of a woodshop or construction site but, what exactly is sawdust, and how is it made? Sawdust is a byproduct of wood processing activities, such as sawing, milling, or drilling. It consists of tiny wood particles, which are typically discarded after the wood processing is completed. Despite its reputation as waste, sawdust holds significant potential as a sustainable eco-friendly product.

The basic act of cutting wood creates sawdust either by a simple handsaw or an electrical power saw, the process of sawing wood results in tiny particles of fiber being released into the air. These particles, which we know as sawdust, vary in size and shape depending on the type of wood, the kerf of the blade and the sawing technique used. While often regarded by many as bothersome waste, a closer look reveals that sawdust is far from useless.

Any cut through wood creates sawdust beginning when a tree is cut down, cut into sawlogs and transferred to a sawmill. There, the tree is cut into planks, boards, or other products. Approximately 5% of a tree’s volume is turned into sawdust by this process. This 'waste' material is often collected and disposed of, but as we'll see, it can also be repurposed in a variety of surprising and eco-friendly ways.

Different types of Sawdust: Hardwood, Softwood, and Composites

There are different types of sawdust, classified based on the species of tree from which the wood originates. Hardwood sawdust is made from deciduous trees like oak or maple, while softwood sawdust comes from coniferous trees such as pine or spruce. The type of sawdust produced from deciduous and coniferous trees affects its properties and potential uses.

Hardwood sawdust is generally denser and has a higher energy content (BTU) than softwood sawdust. This makes it suitable for uses that require a dense, long-burning fuel, such as is required for biomass energy production. Sawdust from hardwoods can be compressed or added to make insulating wood panels. On the other hand, softwood sawdust is lighter and less dense, making it ideal for uses that require a lightweight, absorbent material, like animal bedding, insulation or as a floor mop up compound.

Composite sawdust is another category, produced when composite wood products like plywood or particleboard are cut or sanded. This type of sawdust can contain a mixture of different types of wood, as well as adhesives and other materials used in the manufacture of the composite product. While composite sawdust has unique properties due to its mixed composition, it isn't suitable for some applications such as a compost mix, due to potential chemical contaminants.

The Sustainability Potential of Sawdust

As mentioned previously, sawdust is often seen as waste, but its potential for sustainability is more than a little significant. As a byproduct of the wood industry, sawdust is produced in large quantities. In fact, literal mountains of sawdust are created by lumber mills. Rather than being discarded, it can be repurposed in a variety of ways, contributing to a circular economy where waste is minimized.

One of the key sustainability potentials of sawdust lies in its role as a renewable resource. Unlike fossil fuels, sawdust is produced continuously as long as trees are grown and harvested. This makes it a potentially sustainable source of energy, particularly in regions like Canada where forestry is a major industry.

Moreover, sawdust can be used in ways that reduce the demand for other, less sustainable resources. For instance, using sawdust as a soil amendment can reduce the need for synthetic fertilizers, while using it as a building material can lessen the demand for concrete or plastics. The sustainability potential of sawdust is not only about reusing waste but also about reducing the carbon footprint of various industries.

Uses for Sawdust for Building Materials

Sawdust has found a place in the construction industry as an ingredient in building materials. Its properties, such as its light weight, thermal insulation ability, cheap cost, and abundance, make it an attractive option for sustainable building.

One of the most common uses of sawdust in building materials is in the production of particle board. Here, sawdust and other wood waste are combined with adhesives and pressed into sheets. The result is a versatile and affordable material that can be used in a variety of construction applications, from furniture to flooring.

Another innovative use of sawdust in building materials is in the creation of 'sawdust concrete.' This involves mixing sawdust with cement and water to create a light, insulating material that can be used for walls or floors. While not as strong as traditional concrete, sawdust concrete has the advantage of being more environmentally friendly, as it uses a waste product and reduces the amount of cement required.

Sawdust as Animal Bedding

Sawdust is widely used as bedding for animals, particularly in livestock farming and pet care. Its absorbent properties make it ideal for soaking up animal waste, keeping the animals dry and comfortable while they sleep.

One of the advantages of using sawdust as animal bedding is its low cost. As a byproduct of the wood industry, sawdust is often available at a lower price than other bedding materials. In addition, the use of sawdust helps to reduce waste, as the used bedding can be composted or used as a fertilized soil amendment.

However, not all sawdust is suitable for animal bedding. For instance, sawdust from treated wood or composite materials can contain harmful chemicals that could be dangerous to animals. Therefore, it's important to ensure that the sawdust used for bedding is naturally sourced.

Cultivating Mushrooms with Sawdust

One of the more surprising uses of sawdust is in the cultivation of mushrooms. Certain types of mushrooms, particularly gourmet varieties like shiitake and oyster mushrooms, can be grown on a substrate of sawdust. The process involves inoculating the sawdust with mushroom spores, then keeping it in the right conditions for the mushrooms to grow. The sawdust provides the necessary nutrients for the mushrooms, while also helping to retain moisture. Growing mushrooms on sawdust is a sustainable way to repurpose this byproduct of the wood industry. Not only does it reduce waste, but it also creates a valuable product – gourmet mushrooms – that can be sold at great profit in most markets.

Using Sawdust as a Natural Cleaning Agent

Sawdust's absorbent properties make it a useful natural cleaning agent. It can be used to clean up spills, particularly oil or other liquids that are difficult to remove using traditional cleaning methods. For example, sawdust can be used to clean up oil spills in a workshop or garage. Simply sprinkling the sawdust over the spill will cause the oil to be absorbed, making it easier to clean up. The oil-soaked sawdust can then be safely disposed of, reducing the environmental impact of the spill.

In addition to oil spills, sawdust can also be used to clean up other types of messes. For instance, it can be used to absorb paint, varnish, or other liquid waste materials. It can even be used to clean greasy tools or machinery, as the sawdust will absorb the grease and leave the surface clean.

Sawdust as a Sustainable Energy Source

One of the most exciting uses of sawdust is as a material that can generate renewable energy. Sawdust can be burned directly as a fuel, or it can be processed into pellets, briquettes, or other forms of biofuel.

Burning sawdust for heat or energy dates back centuries. Modern technologies however, have made it possible to use sawdust as a fuel in a more efficient and environmentally friendly way. For instance, hardwood sawdust can be compressed into pellets that burn more cleanly and consistently than raw sawdust.

Sawdust can also be converted into biofuel through a process known as gasification. This involves heating the sawdust in a low-oxygen environment to produce a gas that can be used as a fuel. This gas, known as syngas, can be used to generate electricity or heat, making sawdust a potential source of renewable energy.

Gardening Compost: The Role of Sawdust in the Garden

Sawdust can play a crucial role in gardening, particularly as a component of compost. When mixed with other organic materials and allowed to decompose, sawdust can contribute to a rich, nutrient-filled compost that can greatly benefit plants. In the compost pile, sawdust serves as a source of carbon, which is needed to balance the nitrogen-rich materials like kitchen scraps or grass clippings. The sawdust also helps to aerate the compost, preventing it from becoming too compacted and allowing the beneficial organisms to do their work.

However, when using sawdust in compost, it's important to remember that it can take a long time to decompose, particularly if it's from hardwood. Therefore, it's best to use sawdust in combination with other, faster-decomposing materials that include worms and other invertebrates to speed up the decomposition process.

Scented sawdust

A relatively new use of sawdust is in the production of scented products. By infusing sawdust with essential oils or other fragrances, it can be used to create sachets, potpourri or air fresheners for the home or car.

The process involves mixing the sawdust with the chosen fragrance, then allowing it to dry. The result is a natural, eco-friendly product that can be used in various ways to scent the home, the shop or other spaces.

Scented sawdust can also be used in pet care, as a deodorizer for animal bedding or litter boxes. This provides a double benefit, as the sawdust not only absorbs waste, but also helps to control odors.

Pros and Cons Using Sawdust

Like any material, sawdust has its pros and cons. On the pro side, sawdust is abundant, cheap, and versatile. It can be used in a variety of ways, from building materials to animal bedding to energy production. Moreover, using sawdust can contribute to sustainability by reducing waste and replacing less eco-friendly materials.

However, there are also cons to using sawdust. One of the main concerns is the potential for dust and respiratory issues. Sawdust can be fine and easily airborne, which can lead to respiratory problems if inhaled. Therefore, it's important to handle sawdust with care, using appropriate protective equipment such as safety glasses and masks.

Another concern is the potential for contamination. Sawdust from treated wood or composite materials can contain harmful chemicals, which can pose risks to health and the environment. Therefore, it's crucial to know the source of the sawdust and ensure it's safe for the intended use.

The Potential of Sawdust

Dismissed as waste, sawdust holds significant potential as an environmentally friendly product. Its versatility and abundance make it a valuable resource that can be repurposed in numerous ways, from building materials to energy production and more. With continued research and innovation and the move to becoming carbon neutral by 2050, new uses for this underappreciated byproduct are likely to emerge, further enhancing its role in promoting sustainability and reducing the environmental impact of industry.

Article posted, Jan 18