Essential Oils and Odor Control

The most commonly used odor-control approach is to collect the foul air in a ductwork system or stack and treat it with one of a variety of technology alternatives—the three most popular being chemical wet scrubbing, activated carbon, and biofiltration. All of these treatment technologies have proved effective at removing odorous compounds when applied correctly, although each has specific limitations.

Aside from their individual limitations there is one problem common to all. The air must be captured for them to treat effectively. For many sites, however, capture is impossible. There is, for example, no possible way to capture all the air at a landfill, compost site, wastewater-treatment plant, wastes lagoon or transfer station. Also it is not cost effective for many processing plants to use the mechanical, chemical, or biological methods.

What possible methods exist to treat such odors effectively and efficiently? One is to use essential oils.

The Essential-oils Alternative
The development of commercially available products known as odor neutralizers is recent. In the past many of the odor-control products were either masking agents or "snake-oil" products.

Masking agents operate on the principle of overpowering an offensive odor with a stronger, allegedly, less-offensive odor. Masking agents are nothing more than industrial-strength perfumes, which, by combining and increasing the odors present, often actually worsen the situation. There is no actual reaction's taking place between the masking agent and the original odor as occurs with odor neutralizers.

The full mechanics of how essential oils work is complex. Basically, it involves weak electrostatic bonding. When a mix of essential oils and water is sprayed into the air, the oil separates out to form a thin film over the water droplet itself. This "skin" creates an electrostatic charge over its outer surface, and this charge attracts the odor molecules. Although the water droplet is quite minute, it is still large enough to capture the malodor molecules and effect the neutralization.

Benefits
Compared with using the more conventional technologies, essential-oil technology provides the following benefits:

• A neutralization system can be installed more quickly, not incurring as much time or capital costs.
• The treated air does not require a collection system of any kind.
• A neutralizing system can be mobile, enabling the equipment to be moved as the sources of emission moves.
• The equipment necessary for applying the technology has a small footprint, is simple, and completely automated.
• There are no resulting byproducts of essential-oil neutralizing agents, and therefore special post treatment or disposal is not required.
• The essential-oil-neutralizing agent is CFC free, ozone free, non-toxic, and safer than chemicals typically used in scrubbers.

Conclusions
The use of an odor-control technology known as neutralization provides a viable option in controlling odor. It is, compared with other methods, cost effective and in many circumstances the only technology that can effectively control odors in areas where odors are elusive and hard to contain or are emitted from large odor sources.

The previous article was adapted from the presentation, "Odour Control—Traditional Methods vs Essential Oils," which appeared in the May 1999 issue of Canadian Environmental Protection.

About the Authors: E. Paul Chapple and Ian Howard work for Ecolo Odor Control Systems Worldwide, 1222 Fewster Drive, Unit 9, Mississauga, ON L4W 1A1. Tel: 905-625-8664; Fax: 905- 625-8892; Email: info@ecolo.com.