# Organic chemical manufacturer reduces odor complaints by over 60 percent by changing biofiltration media

Environmental management for a major organic chemical producer reports reduction of odor complaints by over 60 percent by replacing its natural wood chip biofiltration odor removal media with a special synthetic type. Meanwhile, its operations management is projecting dramatically reduced odor control costs through the new media’s considerably longer expected service life, building on savings already gained by substituting biofiltration for an afterburner.

“We’ve been using the new media for almost a year now, and are very happy with it,” reported Robin S. Hart, P.Eng., the safety, health and environmental engineer for Cognis Canada Corporation in Toronto. “Last year, we had 11 odor complaints from up to a mile away, but this year only four, both from a location that is only about 50 yards from us.”

Hart said odor removal effectiveness had also been documented by the company’s own odor patrol, which has detected far less high-level odor intensity. Odor sources are short-chain fatty acids, especially caprylic acid, deriving from the company’s hydrolysis of animal fats and vegetable oils into fatty acids and glycerin.Cognis’ latest upgrade is the deployment of BIOSORBENSä biofiltration media, manufactured by BIOREM Technologies of Guelph, Ontario, and expected to last for 10 years before requiring replacement. In addition to its use for the successful treatment of volatile fatty acids here, BIOREM reports effective treatment elsewhere of aldehydes, ketones, alcohols, and aliphatic and aromatic hydrocarbons.

Michael Stein, operations manager, noted that while the previous wood chip media was controlling odor, its rapid decay rate undermined its performance while increasing odor control costs.

“We’re expecting net savings of $20,000/yr over the projected new service life of 10 years,” he said. “Previously, we were only getting about a year out of the wood chips before they decayed into fine grain, started channeling, and lost treatment effectiveness. In addition to the cost of replacing it, we didn’t like the extra burden it gave us during shutdowns that were scheduled for a variety of other needs.”

Stein said the plant’s odor-rich gases derived from natural oils and fats and their products, heated up to 180 degrees F, with odor increasing with temperature. Air drying and tank cleaning practices also contribute to odor generation. To control odor, the company has depended primarily on incineration of odor-rich gases in both a process boiler and a separate gas-flame afterburner. Presently, about half of the odor-rich stream is still routed to the process boiler for incineration in the firebox, while the balance is sent to the biofilter, which can handle 60% of the stream at full capacity. The 20 foot x 15 foot x 10 foot biofilter, containing 2000 cubic-feet of the new media, has a design capacity of 6,000 acfm/min. of odor-rich gas, with typical operation running at 4,000 acfm/min. Pressure drop across the filter is 1 in. water gauge differential pressure.

“We realized very significant fuel savings, about $10,000/month, by shutting down the afterburner and changing to biofiltration, and now we’re looking at further reduction in odor control costs through the change in biofiltration media,” Stein concluded.