Odors treatment : biological technologies

Physical-chemical waste gas cleaning techniques have proven their effi ciency and reliability and will continue to occupy their niche, but several disadvantages remain. Among them are high investment and operation costs and the possible generation of secondary waste streams. With biological waste treatment techniques, reactor engineering is often less complicated and consequently costs are less. In addition, usually no secondary wastes are produced. Biological methods are nonhazardous and benign for the environment. Possible drawbacks are restricted knowledge about the biodegradation processes, limited process control, and relatively slow reaction kinetics. Anyway, the biological methods for the removal of odors and volatile organic compounds (VOCs) from waste gases are cost-effective technologies, when low concentrations (below 1-10 g/m -3 ) are to be dealt with (Kosteltz et al., 1996). Therefore, decision making can be based merely on economical analysis. Like the treatment of liquid effl uents, gaseous streams will be more often considered for biological treatment. For organic compounds, the biological reaction can be described as: CHO + O 2 + nutrients C 5 H 7 O 2 N (cell dry weight) + CO 2 + H 2 O + heat When heteroatoms are present (e.g., chlorine, sulfur), end-products like HCl or H 2 SO 4 can be formed. For effi cient pollutant removal, target pollutants have to be suffi ciently biodegradable and bioavailable. A major advantage in the case of odor treatment is that biocatalysts have high affi nity for the substrates, which allows effi cient treatment of low infl uent concentrations. Biocatalysts also operate at room temperature and they have innocuous fi nal products (e.g., carbon dioxide and water). Provided that you have the right inocula, microorganisms can metabolize almost every compound there is. In general, odors consist of a very complex mixture of volatile organic as well as inorganic compounds. The most relevant compounds regarding odors in the food industry are nitrogencontaining compou(undefined

The future European standard to determine odour in ambient air by using field inspection

peer reviewedThis paper presents the methodologies to determine odour in ambient air by field inspection that will be a new European standard. The objective is to characterize the odour in a defined area. Without making a link with potential annoyance due to the presence of odours, the described methods propose the way to characterize an exposed environment. Two approaches are defined in the new standard: the grid method and the plume method. The grid method can be used determine the exposure to ambient odours in a defined area of study, using direct observation of recognizable odours in the field by human panel members. This method must be applied over a sufficiently long period of time (6 or 12 months) to be representative for the meteorological conditions of that location. The result is the distribution of the frequency of exposure to odours within the assessment area. The plume method can be used to determine the extent of detectable and recognizable odours from a specific source using direct observation in the field by human panel members under specific meteorological conditions