Effects of H2S Loading Rate on the Performance of Reactive Absorption with Electrochemical Oxidation

The odor released from environmental facilities is recognized as a major problem in environmental industries. In this study, reactive absorption, using an electrolyzed water solution (electrolyzed water scrubber, EWS), was developed to treat the odorous gases H2S and NH3, which are representative odorous substances. In addition, a numerical model composed of mass transfer coefficients and zero-order kinetic constants was established to predict the performance of EWS. The model was verified through experiments and data fittings. In the experiments, the concentration of H2S varied from 500 to 2000 ppm, while NH3 was fixed at 500 ppm. The results revealed that the H2S removal rate varied depending on the inlet H2S concentration, but no changes were observed for NH3. The numerical model appropriately described the experimental results to further predict the performance of EWS. The model prediction results for the shock loading of H2S indicated that a 100% removal rate can be achieved by increasing the current density to 70 mA cm−2 or higher. Finally, the EWS can be used to reduce the odor, owing to its flexible operation that responds to fluctuating loading rates.

Organic side streams: using microbes to make substrates more fit for mass producing insects for use as feed

Microbes, combined with insects, convert organic waste into products of value. Resulting insects can be harvested and used as a high-quality protein resource, while the residues can be used as fertiliser. Microbes play an important role in the conversion process. This review’s aim was focused on how microbes promote insects such as black soldier fly (Hermetia illucens L.), house fly (Musca domestica L.), waxworm (Plodia interpunctella) and yellow meal worm (Tenebrio molitor L.), to convert organic waste, while also harmlessly reducing organic waste pollution. The novelty is reflected in some core gut microbiota and their secreted enzymes degrade macromolecules such as protein, fat, polysaccharide, cellulose, polystyrene and polyethylene. Gut microbiota also could help insects degrade hazardous substances such as antibiotics, mycotoxin, odorous substances, and inhibit pathogens in organic wastes to make substrates more fit for insects.

Distribution and characteristics of geosmin and 2-MIB-producing actinobacteria in the Han River, Korea

Actinobacteria can be one of the causes of earthy and musty odors in drinking water. In this study, the distribution and odor producing ability of actinobacteria isolated in the Han River as a source of tap water were investigated. Actinobacteria were detected in low concentration from December to February and this gradually increased in March and April. The number of actinobacteria detected was particularly high in April (63 CFU/mL), July (45 CFU/mL), and October (39 CFU/mL) due to the influence of rainfall. Actinobacteria with geosmin-producing genes were detected mainly in March and July. In contrast, actinobacteria with 2-MIB-producing genes were detected mainly in October. There was a difference in the time when actinobacteria with the geosmin and 2-MIB-producing gene were highly detected in the river. Also, the types of actinobacteria with the geosmin and 2-MIB-producing gene were different. More than 70% of the geosmin inducer gene was isolated in Streptomyces, but the 2-MIB inducer gene was detected in various genera of actinobacteria as well as Streptomyces. The detection of odorous substances in March and October when cyanobacteria were not detected, or the detected number was low, suggested that actinobacteria could be a cause of odor inducers in the Han River.

Effect of UV light on food quality and safety

The recent years have seen a great number of instances when ultraviolet (UV) radiation was used in the preservation process of all sorts of foods. Since the purine and pyrimidine bases of DNA and RNA absorb well the 254 nm radiation, its application with the use of a correct dosage can result in disinfections of various orders of magnitude. It can be particularly effective in cases where technology does not allow a more intensive heat treatment. When used properly, UV treatment can be a competitive procedure in the case of foodstuffs where the large surface area allows for UV rays to penetrate the entire volume of the substance. Incorrectly applied UV treatment may change the composition of foods. Free-radical as well as photochemical reactions can digest the proteins, damage the antioxidants, oxidize the lipids, make changes to the colour and substance, and produce undesirable flavourings and odorous substances. Some vitamins are particularly sensitive to UV irradiation in the course of which losses could reach even 50%. Photosensitive water-soluble vitamins are vitamin C, B12, B6, B2 and folic acid, while vitamins A, K and E are the fat soluble sensitive to light, carotene being the only provitamin with such properties. On the other hand, UV treatment can be a useful tool of food safety because of the photosensitivity of fungal toxins.

Cytogenetic status of children in the hygienic assessment of the air pollution by odorous substances

For the first time the impact of odorous emissions from the enterprise for the production of chewing gum on the cytogenetic status of children, residing in the distance of 0,9 and 6 km, was studied. Specific weak mint and fruity odour in the air in the placement of the enterprise may be related to the presence of menthol, menthone, pinene, limonene, ethyl acetate and other compounds containing in the emissions. There were no differences in cytogenetic status of children in both groups (by frequency of micronuclei, protrusions, binucleated cells, apoptosis).

Application of factor and cluster analyses to determine source–receptor relationships of industrial volatile organic odor species in a dual-optical sensing system

Most odor nuisance investigations rely on either human olfactory examination or on-site sampling and analytical techniques, but these methods are often subject to spatial and temporal limitations and thus impractical for locating odor emission sources. This study developed an alternative approach with a dual-optical sensing system, a meteorological station, and the combination of factor and cluster analyses to identify and characterize emission sources of multiple air contaminants. Factor and cluster analyses were employed to establish the emission profile of multiple odorous substances from each emission source. Both receptor and source monitoring data were collected to characterize the emission sources of various odorous substances. Open-path Fourier transform infrared (OP-FTIR) as a receptor path detected concurrent trends of several organic solvents with concentrations higher than the reference odor threshold values, indicating that these compounds were potential causes of odor nuisance. Qualitative source apportionment by factor and cluster analyses suggested that these odorous substances were used as organic solvents in surface coating or painting processes. Closed-cell Fourier transform infrared (CC-FTIR) at two nearby surface-coating companies indicated that only one company's stack exhibited the same odorous substance profile found by the OP-FTIR receptor path. The major odor emission source was thus identified in this study. This study demonstrated the feasibility of using the alternative investigative framework to successfully identify emission sources from an industrial odor nuisance site. The major emission sources were identified, and future enforcement plans can be conducted to enhance odor investigation efficiency and improve overall air quality.