Electronic noses track down odor nuisances
Posted by Thierry Page on Sat, Jul 23, 2011 @ 05:06 PM
SIVOS has equipped the 60 Bornes WWTP in Vendée (French Atlantic coast) with an OdoWatch system to measure and model the dispersion of odors. The idea behind it is to lower the complaints from neighboring citizens and to have more targeted interventions.
After repeated complaints from tourists bothered by the smell, they didn't want to hear of it anymore! Yet, elected officials representing SIVOS (inter-municipal body formed to construct and run the 60 Bornes plant) and managers at Saur (the company now managing the 60 Bornes purification plant located in the districts of Saint-Hilaire-de-Riez and Saint-Jean-de-Monts in Vendée) still didn’t know how to fight the odor pollution, a common problem with many industries (waste treatment centers, rendering plants, chemical plants, digestion plant, distilleries, etc.). The 60 Bornes plant processes wastewater from 17,000 inhabitants during winter, but has to handle wastewater from over 100,000 people during summer.
And, despite several investments made to minimize odors, its technical managers could not resolve the problem. SIVOS decided to set up a system to diagnose the spread of odors. Between 2004 and 2007, many projects to eliminate odors were tried. These projects ranged from deodorization by UV photocatalysis applied to primaries and sludge odor emissions, fat and drainage effluent treatments, and even an odor absorbing caulking ... they tried everything. To investigate further, they had to know where the smell came from.
SIVOS then decided to call Odotech, specializing in odor measurement and analysis technologies. They performed a diagnosis of the different sources. Sixteen were identified within the treatment plant, but also outside, within a radius of three kilometers.
In June 2008, the WWTP was finally equipped with Odotech's Odoscan system. Stage One: various odor samplings are carried out onsite the plant and around the site in the sewer system. The samples were then processed at the Odotech Lab by dynamic dilution olfactometry: they are diluted with odorless air and the resulting dilutions are then presented to a panel using sniffing ports.
The panel members indicate whether or not they detect an odor. The odor concentration values for each sources are then incorporated into the odor dispersion modeling software and merged in real-time with the weather data (wind direction, temperature, brightness, etc.) provided by a weather tower installed on site.
INVESTMENTS TO BE MADE WERE OPTIMIZED
Finally, SIVOS now has a real-time odor plume 24/7 (odor units per m3 of air) and can track continuously the dispersion of odors. The software uses AERMOD, a US-EPA approved model.
According to Jean-Michel Martin - Plant Manager, “This allows us to have an idea of how it spreads, where it goes, its intensity, even when the nose does not detect anything.” Operators are then able to make any necessary decisions: improve the capture of odors, decide the best time to remove the waste... “The technology allows us to better target the investments to be made”. One year after the implementation of the system, Saur is quite satisfied with it: only two complaints were recorded last year.
Following its proactive approach, SIVOS has since installed electronic noses on the most fluctuating sources, this time to set up a continuous measurement.
