Total reduced sulfur compounds

Power boilers at pulp and paper mills are sources of particulate emissions, S02, and NOx. Pollutants emitted from chemical recovery boilers include S02 and total reduced sulfur compounds (TRS). 

By this method it is possible to determine the total concentration of reduced-sulfur compounds or the concentration of TRS compounds, as in a paper pulp plant. The oxidation temperature of the furnace is about 800 °C. The flue gas must contain a minimum of 1% oxygen to ensure that all TRS compounds are fully oxidized to sulfur dioxide. 

The two main sources of air pollutants that may be emitted from basic wastewater treatment plant operations are pulping condensates and bleach plant effluent. The pulping condensates may include total reduced sulfur (TRS) compounds as well as volatile organic compounds (VOCs) such as methanol. The primary pollutants of concern for the bleach plant effluent are chloroform and methanol. Any volatile compounds that could be released as air emissions from basic wastewater treatment plant operations are relatively minor and are generally not subject to specific regulation.65-66... 

Marttila et al. (1995) also examined the relationship between daily exposure to malodorous sulfur compounds (measured as total reduced sulfur [TRS]) from pulp production and experience of symptoms in a small population living in the vicinity of a pulp mill. The major components of the malodorous sulfur compounds are hydrogen sulfide, methyl mercaptan, and methyl sulfides. This work was initiated due to the observation that an unusually high short-term exposure to malodorous sulfur compounds (maximum 4-hour concentrations of hydrogen sulfide at 135 g/m3 [96 ppb]) led to a considerable increase in the occurrence of ocular, respiratory, and neuropsychological symptoms (Haahtela et al. 

The relative contribution that each reduced sulfur compound makes to the total sulfur flux is often of interest because the various compounds behave differently once they enter the atmosphere. Terrestrial biogenic sulfur emissions are dominated by COS (38%), DMS (35%) and H2S (21%). Emissions of CS2 and DMDS together represent about 6% of the total. DMS emissions dominate during the summer season with 41% of the total. 

On a global scale, natural emissions of reduced sulfur compounds account for about 50% of the total sulfur flux into the atmosphere (1-3). Hence, it is important to understand the natural sulfur cycle in order to establish a "base line" for assessing the significance of anthropogenic perturbations (primarily SO2 emissions). Dimethylsul-fide (DMS) is the predominant reduced sulfur compound entering the atmosphere from the oceans (4-9), and DMS oxidation represents a major global source of S(VI). The atmospheric oxidation of DMS can be initiated by reaction with either OH or NO3. In marine environments, however, NO3 levels are typically very low and DMS is destroyed primarily by OH ... 

Communities near pulp mills Inhalation Mean annual total reduced sulfur concentrations 2-3 pg/ m 24-b average concentration 0-56 pg/ rtP, maximum 1-h concentration 155 pg/ m1 Daily Reported increased incidence of respiratory system symptoms (irritation, cough) and CNS symptoms (headache and migraine) significant increase only for headache and migraine. Communities exposed to relatively high concentrations of other malodorous sulfur compounds. Partti-Pellinin et al. 1996 (South Karelia Air Pollution Study)... 

Hoffmann, M. R., and A. P. Hong (1987), Catalytic Oxidation of Reduced Sulfur Compounds by Homogeneous and Heterogeneous Co(II) Phthalocyanine Complexes, Sci. Total Environ. 64, 99-115. 

The paper pulping industry is reportedly not, in total, a very large emitter of sulfur oxides, although individual plants may present local problems. Kraft mills emit more malodorous reduced sulfur compounds, whereas sulfite mills are more important as emitters of sulfur dioxide. The pulping processes (particularly sulfite) are most interesting because the chemical recovery cycles use basic chemistry that could well be applied to recovery of sulfur dioxide and sulfur from the flue and process waste gases of other types of sources. 

The proteins NodP (ATP sulfurylase) and NodQ (adenosine 5 -phosphosulfate (APS) kinase) are associated in a sulfate-activating complex that enables the synthesis of the sulfate donor (PAPS) for Nod factor sulfation [42]. PAPS is also the sulfate donor used for the synthesis of cysteine and it is produced in E. coli by the normal household proteins CysC, CysD, and CysN [43, 44]. The genes cysCDN are part of the cysteine regulon which is repressed in the presence of cysteine and other reduced sulfur compounds [45]. This means that the E. coli machinery of PAPS biosynthesis can be used for chitin oligosaccharide sulfation if the bacteria are cultivated with sulfate as the only sulfur source. The total PAPS demand for the synthesis of cysteine and methionine (87 and 146 pmol g dried cells, respectively) [46] largely exceeds the maximum demand that can be estimated for chitin oligosaccharide sulfation (around 20 pmol g dried cells). 

Among the measures which have successfully prevented metal dusting are the use of additives (steam, and compounds of S, As, Sb, and P) in the feed, reduction of pressure, reduction of temperature, and material change. The most common additives are sulfur compounds and steam. Susceptibility can be reduced by using a material in which the total percent of Cr plus two times the percent of Si is in excess of 22 percent. In some environments, a. small amount of a sulfur compound will stop the dusting. When sulfur compounds cannot be tolerated in the process stream, a combination of steam and an alloy with a Cr equivalent of over 22 percent may be most desirable. 

Early studies of reduced sulfur in the environment centered on the role of sulfate reducing bacteria in sediments and the measurement of hydrogen sulfide and other simple inorganic sulfur compounds in pore waters. Simple colorimetric assays are probably still the best for such studies. Typical methods include the methylene blue determination of sulfide (26.27) and the dithio-nitrobenzoic acid (DTNB) method for total thiols (28.29). 

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