Community Research and Development Information Service - CORDIS

Periodic Report Summary 1 - ODOURCOB (OdourCOB - Odour Characterization of Odorants from Biosolids)

The aim of the project OdourCOB is to identify the major contributing odorants produced from wastewater biosolids to odour annoyance. In order to achieve this goal biosolids emissions were characterized using gas chromatography-mass spectrometry/olfactory technique (GC-MS/ODP) to determine the olfactory impact of odours in terms of their odour character and intensity. In that research GC-MS/ODP system was used for separation, isolation and identification of compounds from biosolids emissions. The combine analytical and data analysis techniques were enabled to establishment the specific odour fingerprints for biosolids emission.
The researcher is going to determine relationship between chemical composition and odour character. It assumed to confirm the hypotheses:
1. Odorous emissions from wastewater biosolids are composed of a complex mixture of odorants.
2. The identification of odour annoyance of wastewater biosolids can be achieved by taking into account odorant quality characters and intensity.
3. There are a number of key odorants whose formation can be related to the operational and biochemical processes.
4. GC-MS/ODP technique can characterize odours by allowing a full identification of the volatile compounds presents in the environmental emissions from both chemical and sensory viewpoints.
During two years of the project researcher identified volatile organic compounds (VOCs) associated with anaerobically stabilised biosolids, map emissions as the biosolids are stored and to identify sensorially relevant VOCs which have the potential to contribute to nuisance emissions from the biosolids at the wastewater treatment plants. VOCs were measured to identify compounds that could contribute to the overall odour character of nuisance emissions. Compounds emitted varied as the biosolids cakes were stored for a period of 35 days. The range of VOCs identified as the anaerobically stabilised cakes are aged during storage suggests they are present due to a range of factors; biotic and/or abiotic production as well as household or industrial inputs to the sewer catchment. Variations between the types and concentration of compounds emitted from different biosolids emphasises the impact of upstream processes on biosolids emissions. Sensorially important VOCs such as trimethylamine (TMA), acetic acid, limonene and ethyl methyl benzene were identified at levels above their detection thresholds. However, TMA was the only compound to exceed the sulfur compounds being detected with a concentration four orders of magnitude greater than its odour detection threshold.
Moreover, emissions from 218 biosolids cakes have been analyzed to show the variation between ODP assessors for the identification and intensity assessment of odorous VOCs. The ODP assessors detected 32 different odorous VOCs from biosolids emission. Some of those compounds are still unknown. The frequencies of positive responses and the intensities assigned by each assessor to particular VOCs varied. Moreover, some of odorous VOCs were not detected by all assessors. For example, the geosmin was detected by only two of them. The use of GC-MS/ODP system for the analysis of odorous VOCs could be valuable when analysed by different assessors, allowing a range of responses to specific odorants in a populations to be investigated.
Researcher has identified new odorants from biosolids emissions which have not being reported in the literature: 2-isopropyl methoxypyrazine, Sulfide allyl methyl, Methyl propyl sulfide. Moreover, some of the odorants are still unidentified yet. To correctly find relationship between odour and chemical composition will be absolutely necessary to find those unknown chemicals. During third year of the project the Marie Curie fellow will try to identify those unknown odorants.

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Life Sciences
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