Zaouak O.,CAIRPOL |
Daoud A.B.,CAIRPOL |
Fages M.,Ecole des Mines d'Ales |
Fanlo J.-L.,Ecole des Mines d'Ales |
Chemical Engineering Transactions | Year: 2012
H2S is frequently encountered in the field of odour monitoring because of its high odorous power. Hence, different plants, such as water treatment or composting plants, are expected to monitor their emissions. A novel high performance cost effective miniature sensor, named Cairclip, has been developed to detect H2S at the low ppbv level. Based on amperometric detection, it is mainly composed of a dynamic air sampling system, a special filter and a high sensitive electronic circuit containing a data logger. It is able to detect a minimum of 6 ppbv with a RSD of only 1 % (n=5) and a T10-90 response time shorter than 60s. Analytical performances of Cairclips has been validated with a gas chromatography coupled with flame photoionization detector (GC-FPD) for laboratory experiments and total reduced sulphur compounds analyzer (CTRS) for field analyses. Experiments performed with Cairclips were in agreement with both methods. Hence, average sensitivity of sensors differs of less than 9 % compared to the sensitivity of the GC-FPD. Then, field analyses have been performed in a waste water treatment plant (WWTP) in the south of France using the CTRS and Cairclips. These experiments have permitted to determine, using both methods, reduced sulphur compounds contents in the atmosphere in several measurement points of the site. In order to confront Cairclip to a standard apparatus of odour generation, three sensors have been exposed to H2S via an olfactometer. The linear correlation observed between concentrations generated and sensors measurements illustrates the potential of such apparatus in the field of olfactory pollutions and more widely in air quality monitoring. Copyright © 2012, AIDIC Servizi S.r.l.
Pereira-Rodrigues N.,Cairpol |
Guillot J.-M.,Ecole des Mines d'Ales |
Fanlo J.-L.,Ecole des Mines d'Ales |
Rentier C.,Veolia |
Chemical Engineering Transactions | Year: 2010
Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring and process control. International recommendations and laws for limiting environmental pollution (toxic gases) and annoyance (malodorous gases) are becoming stricter for both industrial and domestic sources of pollution. Public organizations for environmental control and industries require therefore new tools for a cheaper and more effective monitoring of gas emissions. Among air pollutants, reduced sulfur compounds and especially hydrogen sulfide (H2S), which mainly results from industrial activities and anaerobic manure decomposition in commercial livestock animal operations, is an offensive malodorous and toxic gas even in small concentrations, causing serious discomfort and health and social problems. There is therefore a need to be able to detect the presence of this pollutant at low concentration (ppb level). Today, the most common industrial gas sensors available on the market are based on semiconductor oxides. However, issues with sensitivity (ppb range), selectivity and stability have limited their use, often in favor of more expensive approaches. Another limitation of these commonly used gas sensors is their lack of reliability while measurements are made on the field, especially during rapid changes of environmental conditions (like sudden variations of relative humidity). We developed an ultraportable and low-cost monitoring gas device that allows the continuous detection of low concentrations of H2S: - The selectivity of measurement was obtained with specific amperometric gas sensors, which have also the advantage to be low consumers of energy and to be miniaturized. - The sensitivity of detection was enhanced (from ppm to ppb range) thanks to a dynamic uptake of the target gas to the amperometric sensor. - The low-cost of the developed monitor provides a higher potential to install arrays of devices to precisely map the levels of this malodorous gas in extended areas. A map reporting H2S real-time levels in the field (location: Wastewater Treatment Plant (WWTP) in the south of France) was carried out. - The reliability of measurement was drastically improved during field measurements (the studied WWTP was close from the sea) by using a filter based on a buffer effect against any environmental interference (like rapid change of relative humidity) during gas monitoring. An evaluation of odorous H2S emissions could be precisely estimated in real-time conditions by performing simultaneous H2S monitoring in the WWTP. Copyright © 2010, AIDIC Servizi S.ri.