Dewatered sludges and biosolids generated from wastewater treatment facilities are known to emit malodorous odors causing public inconvenience. The odors typically comprise of reduced organo sulfur based compounds and nitrogen containing compounds. Lime stabilization is a technique which is commonly used in the wastewater industry to produce biosolids having reduced odors that can be safely land disposed. In this research, odors produced from dewatered sludges and lime stabilized biosolids were investigated. Lime dosing and incorporation in sludge play an important role in generation of reduced sulfur and trimethylamine (TMA) odor compounds. Results revealed that poor lime dosing can lead to an increase in odors due to biological generation of volatile sulfur compounds (VSCs) during storage. In this study, a belt filter press gave a higher production of sulfur and TMA odors compared to a vacuum filter for the same sludge, which is attributed to the shear imparted to sludge during the dewatering process. Preliming studies suggested incomplete mixing of lime with sludge led to biological activity. The achievement of the correct pH and its maintenance during storage is considered critical for effective odor management from lime stabilized biosolids. A positive linear relation was obtained between sulfur based odor production and labile protein content in sludge. Furthermore, as the Al/Fe ratio increased, the labile proteins was observed to decrease. Trivalent metals are found to play an important role in binding of labile proteins thus effecting odor potential contained in sludge/biosolids. This was found true for most sludge irrespective of their liming status and independent of upstream process conditions. Further work in this area is needed to be able to provide a better understanding of odor production to aid in development of odor control techniques. Trimethylamine odors, having a characteristic fishy odor, are commonly found in lime stabilized biosolids. Cationic polymers used as dewatering aids are the primary precursors for TMA production. Proteins present in sludge are also associated with odor forming compounds but they produce much lower levels than polymers. These two components under the action of shear present in dewatering devices such as centrifuge are more likely to cause an increase in odor production from lime stabilized biosolids. It was also determined that abiotic polymer degradation to produce TMA either does not occur, or the rate is so slow that TMA production in this way is insignificant for actual field situations. / Master of Science

Call number: LD2668 .T4 1979 P63 / Master of Science

A nitrogen-cooled and an argon-cooled hydrogen flame have been used for the determination of sulfur containing species in solids by molecular emission cavity analysis (MECA). The argon-cooled flame is much more sensitive for the determination of SO₄²⁻. In a solid mixture containing S₈, S²⁻, SO₃²⁻, and SO₄²⁻, the presence of one or more of these sulfur containing species can be determined with the argon-cooled flame. The nitrogen-cooled flame can be useful, for example, in the determination of a mixture of S₈ and SO₃²⁻ in a solid matrix. All these sulfur containing species can be quantitatively determined in the argon-cooled flame in the concentration range from about 10 ppm to 5000 ppm. The variation from 10 percent to 30 percent in the reproducibility of these measurements has been attributed to the non-homogeneity of the solid materials and the small sizes required. Sulfur dioxide has been used for the reduction of ammoniacal copper(II) solutions to solutions containing various copper(I) compounds. These copper(I) compounds can be reduced further to copper metal by varying the solution conditions. The mechanisms of the reactions involved must be understood before they can be successfully used for the large scale production of copper. Porth et al.'s method was followed for the synthesis of Cu(I) intermediates. Several compounds were isolated and their compositions determined. The changes in the relative concentrations of Cu(I) and Cu(II) are also important for unraveling the kinetics and mechanisms of these reactions. A simple spectrophotometric method using 2,9-dimethyl-1,10-phenanthroline was developed to monitor the Cu(I) concentration in solution. The sensitivity of the method is sufficient to determine 10⁻⁵ M Cu(I) in the presence of Cu(II); SO₂, however, interferes with the method. Other possible methods including the use of a mixture of EDTA and 2,9-dimethyl-1,10-phenanthroline were also examined. Evidence is presented for the formation of a ternary complex of copper(I), 2-9-dimethyl-1,10-phenanthroline, and EDTA. The possibility of using a mixture of Cu(II) and 2,9-dimethyl-1,10-phenanthroline to determine SO₂ was tested. Oxygen was found to interfere with this method.

No description available.

No description available.

Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / Atmospheric deposition of sulfur (S) and nitrogen (N) as a result of fossil fuel combustion is known to impact ecosystem structure and function. Potential impact includes acidification of soil and surface water and mobilisation of metal ions, with the resultant loss of plant productivity, changes in plant species diversity and changes in biotic communities in aquatic ecosystems. Rates of S (~8 kg S ha-1 year-1) and N (>6 kg S ha-1 year-1) deposition to the grasslands of the South African Highveld are comparable to other industrialised areas where ecosystem impacts have been observed. As part of a larger project, this work investigated four aspects of ecosystem impact: changes in soil and river water chemistry as well as S and N mineralisation rates. Reassessment of the soil chemistry at 18 sites on the South African Highveld after a 16-year period showed increases in both acidic and basic ion concentrations for individual sites and when the values for these sites were averaged to represent the study region. Grouping the soils by clay content showed that all sites with less than 25% clay (16 of 18 sites) showed significantly reduced pH(H2O) values. Sites with less than 4% clay showed increased exchangeable acidity and decreased acid neutralising capacity. Spatial scaling and mapping from site to soil form and land type, showed that across 92% of the study area the pH(H2O) values had been reduced. This method identified the sandier soils, near the southern and eastern boundaries of the study area where rainfall is higher, as sensitive to additional acidic inputs via atmospheric deposition. Clay-rich soils occur in the drier central part of the study area, close to emission sources. It is suggested that this proximity to emission sources results in the co-deposition of basic and acidic ions, adding to the buffering capacity of the soils, resulting in small but significant increases in soil acidity status over the 16 years. Sulfur and N mineralisation rates, using the in situ incubation method at 11 sites, were found to range between -0.66 and 1.09 μg SO42- g-1 soil day-1 and -0.97 and 1.21 μg N g-1 soil day-1. This translated into an annual flux of between -40 and 9.9 kg S ha-1 and between 27 and 81 kg N ha-1 from the soil organic pools. The use of the in situ incubation technique to determine S mineralisation is a new Theresa Bird 9505067D development and is proposed for in-field studies where S and N cycling are of interest as the method allows for concurrent mineralisation rate determination. It was found that from a biogeochemical perspective the Highveld grasslands are under researched with respect to S and N and complete assessments of the S and N cycles are proposed. The S budget proposes accretion of S in the soil organic pool due to continued inputs via deposition and low losses to the atmosphere or deeper soil horizons. Nitrogen, however, appears to limit productivity in these grasslands because atmospheric inputs and mineralisation rates are approximately equal to plant uptake. In the assessment of river water quality it was hypothesised that between 1991 and 2008 concentrations of dissolved salts, sulfate, nitrate and ammonium would increase in surface waters at five sites draining the Highveld grasslands. The Department of Water Affairs water quality monitoring database was accessed to assess for spatial and temporal differences in water quality. Significant spatial differences were found; however, over time few significant increases were found to support the hypothesis: sulfate, nitrate-plus-nitrite, and ammonium were observed to increase at one site each. In addition, the export of nitrogen, as mass load, from natural grasslands was found to be negligible at <2 kg N ha-1year-1. A conceptual framework proposes that soil texture, distance from emissions and land use are key drivers in the response of the grassland soils and surface waters to atmospheric S and N deposition. Although the study identified the soils most sensitive to deposition, it is proposed that processes in the Highveld grasslands are not yet negatively affected by the additional sulfur and nitrogen inputs. Continued monitoring for impacts on ecosystem structure and function is advocated.

Production of volatile sulfur compounds in cheese is associated with desirable flavors. The direct source of these compounds has been assumed to arise from the metabolism of methionine and cysteine. However, the methionine concentration in cheese rises above the amount found in casein during aging, suggesting that alternative sulfur sources are present in milk. This led us to hypothesize that lactococci may acquire sulfur from the inorganic sulfur pool of milk, in addition to methionine and cysteine, to generate volatile sulfur compounds during cheese ripening. A turbidimetric method to determine total sulfate content in milk samples was developed. The average sulfate content of milk was determined to be ~49 mg/L ± 2.0 mg/L. The limit of detection of the test was ~2.5 mg/L in Tris buffer and ~10 mg/L in milk. Skim milk samples had significantly higher total sulfate content as compared to whole milk samples. Transport of sulfate by three strains of Lactococcus sp. was studied after we determined that milk had small, but measurable amounts of inorganic sulfate. A decrease in the environmental pH increased sulfate transport. The maximum transport occurred during exponential cellular growth phase. All strains tested had the ability to transport much more sulfate than is native in milk. The last phase of study was to determine the metabolic fate of sulfate. Incorporation of radio-labeled sulfate into cellular protein was studied by two-dimensional gel-electrophoresis of crude cellular lysate followed by auto-radiography. Production of volatile sulfur compounds from inorganic sulfur was determined with analysis of the head space gas with gas chromatography and scintillation counting. The incorporation of radio-labeled sulfur from sulfate was not detected in proteins on two-dimensional gels. Detectable volatile sulfur compounds were found only in the case of gas chromatographic analysis of ML3 head space. However, radio-labeled volatile sulfur was detected in the head space of all the three strains with scintillation counting. This study defined that lactococci can fix inorganic sulfur into volatile sulfur compounds in small amounts.

Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 110-113). Also available for download via the World Wide Web; free to University of Oregon users.

The primary objective of this study is to investigate the suitability of utilizing dune sand as a paving construction material in hot desert-like areas of the world, where regions of sand dunes exist. The high availability, low cost, and excellent physical properties of the current surplus of elemental sulfur and the benefits given to asphaltic binders by sulfur raises the possibility of using sulfur in asphalt mixes to produce stable mixtures with locally obtainable dune sand. Characterization of various sulfur-asphalt-dune sand mixtures for highway construction were made. The materials used in this investigation were elemental sulfur, AR-4000 (60-70 pen.) asphalt, and dune sand from Yuma, Arizona. The main variables include (a)proportion of sulfur and asphalt in the binder, (b)amount of binder in the mixture, (c)curing temperature, (d)test temperature, and (e)mixing techniques. The various mixtures were prepared by the one-wet mixing cycle technique. Similar dune sand mixtures with asphalt only were evaluated for comparison purposes. The different mixes were evaluated by the Marshall method, tensile strength tests (double punch), compression tests (standard and immersion), flexural tests (standard), dynamic modulus tests (double punch), and microscopic examinations of sulfur-asphalt binders and sulfur-asphalt-dune sand mixtures (thin sections). Preliminary characterizations of the various mixes were made on the basis of their Marshall stability, flow, density, and air void contents. Other engineering properties such as tensile strength, compressive strength, modulus of rupture, dynamic modulus, and microscopic studies were determined for selected mixes. The results consistently indicated that the sulfur-asphalt-dune sand mixes exhibited superior engineering characteristics and performance as compared to similar mixes without sulfur. The overall conclusion drawn from this study is that the dune sand which is not normally accepted for use as aggregate in asphaltic mixtures, can be used with the utilization of sulfur-asphalt binder systems to produce paving mixtures with compatible or better engineering properties in comparison to conventional asphaltic concretes.