University of British Columbia tests Envron Ozone Odor Control System
In conjunction with the University of British Columbia and the British Columbia Ministry of Agriculture, testing of the Envron odor control system was conducted. A local mushroom composting facility was chosen as the test site and a compost stack was used to gather odorous off-gas. Ozone was then applied to the off-gas using an Envron mixing system. These gases were collected and tested using a full odor panel – the most accurate (and most expensive) way of measuring odors.
The odor panel tests are double-blind experiments in which people are given measured odorous gases or non-odorous gases to sniff through a machine. As the human nose is very sensitive (and also the ultimate test in odor control) the panel indicates whether people would find the odors offensive or not. The odors are then diluted by the machine to see at what levels it becomes non-offensive. As well, Envron used field test equipment to measure percentage gas reductions in the odor stream.
Field Test Results
After running the tests using the destruct stack, Envron’s field testing found an average decrease in total Amines after 48 seconds contact time of 21%. After 303 seconds an average decrease in total Amines of 59% was found. Everyone at the test site sniffed the gases coming out of the stack with Ozone applied and without Ozone applied. Without Ozone everyone agreed that the gases were odorous. With Ozone everyone agreed that the smell was gone.
Field Tests Verified
The reductions in Amines indicated that within a number of seconds, there should have been a very high reduction in odorous (long-chain) compounds. After the tests came back from the UBC odor panel, the odor panel had confirmed the field tests. The untreated samples required dilution rates of between 1701-3043, which is typical of odorous substances. The Ozone treated samples were between 209-264, which is typical of non-odorous substances. As well, the treated samples had a faint Ozone smell, which is an almost antiseptic or sanitary smell.
These results are consistent with commercial uses for Ozone in other industries including home remediation. One of the major markets for Ozone generators in North America is sewage lift stations. Odors at lift stations result from anaerobic processes and Ozone kills these odors quite readily. From work in hog and poultry barns, Envron had already seen Ozone’s ability to quickly kill even very penetrating odors.
One of the main principles in applying Ozone is to thoroughly mix the Ozone with the odorous gases. This can be accomplished in an open air facility through the use of a ventilation system that pushes Ozonated air across the tops of the compost. Or if the composting facility is enclosed, Ozone can be added to the ventilation system at the exhaust. A properly designed “destruct stack” is also used to ensure adequate mixing of the air and the ozone.
If the composting is done in an open-air facility, the Ozone Generators should be slightly oversized to compensate for a less efficient odor/Ozone mix. If the gases are exhausted through a ventilation system, then the generators can be downsized accordingly