The Evolution of Odor Control in the Organic Waste Processing Industry

Odor control is a crucial element of waste processing facilities across the country. Failing to prevent or mitigate odor can make operations significantly more complicated as well as invite complaints from nearby residents.

Strategies for how to best handle odor have evolved along with the waste processing industry, with technological advances fueling much of that evolution. Naturally, strategies will differ across different types of facilities; the best process for a landfill will differ from the best process for an anaerobic digestion or a composting facility.

Just as technology and research have allowed odor control to advance over the past 10 years, there is reason to hope that the next 10 years will bring exciting new developments to the field.

At the upcoming Global Waste Management Symposium (GWMS), which is being held at the Hyatt Regency Indian Wells Resort & Space in Indian Wells, Calif., February 11-14, Kyle Muffels, US-West solid waste manager at GHD, will discuss his paper on the evolution of odor control in the food and source separated organic waste processing industry. He recently sat down with us to provide a preview of his session.

Waste360: Going off the title of your session, what would you say have been the biggest developments in odor control technology over the last 10 years?

Kyle Muffels: In terms of the technology, I would say the level of sophistication in odor treatment has increased. Historically, we typically used biofiltration systems, with organic media, simple humidification systems and no temperature or ammonia control. In the last 10 years, there have been advances in biofiltration with the use of inorganic media, humidifiers and scrubbers for humidity and ammonia control prior to biofiltration and temperature control to maintain mesophilic conditions. We have also added discharge stacks to improve dispersion of treated air. Additionally, there have been advances in physical removal systems to reduce reliance on biological systems, such as thermal and photoionization / UV treatment technologies.

Waste360: What would you like attendees of your session to take away?

Kyle Muffels: When we designed the abstract, our intentions were that we want people to take away an understanding of the characteristics of odor at organic processing facilities. What are the processes that exist to help mitigate those odors? What are some of the criteria or regulatory standings and challenges that these facilities are facing in different geographic regions? What are some of the existing organic processing facilities using? We’d like to answer these questions.

Odors from organic processing facilities vary depending on the feedstock, aerobic versus anaerobic organic process and operating conditions, and there is a wide range of odor-causing compounds such as ammonia, hydrogen sulfide and mercaptans.

The odor treatment train needs to be adapted to the odor characteristics of the airstream as well as the applicable regulatory thresholds and objectives. I would like to cover the main technologies that we have seen in this industry that achieve this. In addition, the selection of the odor treatment process train will also depend on the available space onsite and a bit of strategy as it relates to offsets from property lines or certain public uses. I’d like to provide some insight from a few sites in North America that have successfully navigated these choices.

Waste360: How would these challenges vary by geographic location?

Kyle Muffels: A couple of ways. There are the physical characteristics of the site location, but I was mostly referring to the different regulatory regimes in my abstract. These conditions can vary from state to state and country to country.

The quantification and treatment of odors is actually interesting.  Most jurisdictions have some kind of general prohibition clauses–‘nobody shall cause an odor nuisance’–but these are open to subjective interpretation. Many jurisdictions also impose concentration limits on individual compounds, such as hydrogen sulfide, but they do not address the potential synergistic or masking effects of gas mixtures. Another interesting regulatory approach is based on ambient odor concentration or odor units, which can be measured onsite using a device called a nasal ranger or samples collected and measured by a certified panel of eight or more people.

Waste360: Where do you see the odor control evolution progressing in the next 10 years? Have we reached a plateau or have we barely scratched the surface?

Kyle Muffels: I think it’s certainly going to improve in economy and in efficiency. What I mean by that is as we move into some of these more energy-intensive control techniques, we should end up with more compact systems that are less capital intensive, so there may be an ability to see greater economy in the site selection of organic processing facilities or related odor control infrastructure. This should help with building facilities in dense urban areas, which is going to be required as more and more states implement landfill diversion requirements. When considering dense urban areas, I think it is going to be worth it for us to keep an eye on technologies that have been used in other related industries such as wastewater, food and beverage, as well as what other countries in Europe or Asia are doing. I also think the industry will continue to largely use traditional biofiltration and chemical scrubbing systems with improvements in performance and efficiency. These systems are becoming more compact, which will also help in developing new or existing sites.