Emission of odorous and gaseous compounds such as hydrogen sulphide (H2S) from livestock facilities can be a major impediment to its daily operations and potential expansion. Occupational and environmental concerns require the control of H2S emissions. A treatment approach used in the oil industry in which nitrite and/or molybdate are used as metabolic inhibitors to control the production of H2S in oil reservoirs was shown to be effective in controlling H2S emissions from swine manure.<p> The addition of nitrite and molybdate to swine manure was investigated in closed laboratory scale systems and then evaluated in semi-pilot scale open systems and in specifically designed chambers aiming to simulate an actual swine barn. The effect of manure age (extent of storage) on H2S emissions and the levels of nitrite and molybdate required for effective control of these emissions were assessed. Laboratory scale tests showed that emission of H2S was dependent on manure age. Fresh manure emitted the highest level of H2S and the level of emission decreased as manure age (1-6 months) increased. With fresh 1, 3, and 6-month old manures average H2S concentration in the headspace gas of the closed systems were 4856b460, 3431b208, 1037b98 ppm, and non-detectable (<0.4 ppm), respectively. This translated to lower levels of nitrite or molybdate required to control H2S emission with increase in manure age. When compared to molybdate, the addition of nitrite initially led to lower levels of H2S but its effect was only temporary and not as persistent as molybdate. In the semi-pilot and room scale tests H2S levels emitted from untreated fresh manure (831¡Ó26 ppm and 88.4 ppm, respectively), were significantly lower than those observed in the laboratory system (4856¡Ó460 ppm). Moreover, the levels of molybdate required to control the emission of H2S were much lower in both the semi-pilot system and in the room scale chamber than in the closed system (0.1-0.25 mM as opposed to 2 mM).<p> Small scale land application of manure treated with 0.1 mM molybdate did not raise the level of molybdenum in the soil that could cause potential toxicity to plants and animals. No major differences in the nutrient properties of the soils exposed to the treated and untreated manure were observed. Finally, a preliminary feasibility study of this treatment approach showed that the cost associated with this control approach was less than 1% of the total production cost.

Emission of odorous and gaseous compounds such as hydrogen sulphide (H2S) from livestock facilities can be a major impediment to its daily operations and potential expansion. Occupational and environmental concerns require the control of H2S emissions. A treatment approach used in the oil industry in which nitrite and/or molybdate are used as metabolic inhibitors to control the production of H2S in oil reservoirs was shown to be effective in controlling H2S emissions from swine manure.<p> The addition of nitrite and molybdate to swine manure was investigated in closed laboratory scale systems and then evaluated in semi-pilot scale open systems and in specifically designed chambers aiming to simulate an actual swine barn. The effect of manure age (extent of storage) on H2S emissions and the levels of nitrite and molybdate required for effective control of these emissions were assessed. Laboratory scale tests showed that emission of H2S was dependent on manure age. Fresh manure emitted the highest level of H2S and the level of emission decreased as manure age (1-6 months) increased. With fresh 1, 3, and 6-month old manures average H2S concentration in the headspace gas of the closed systems were 4856b460, 3431b208, 1037b98 ppm, and non-detectable (<0.4 ppm), respectively. This translated to lower levels of nitrite or molybdate required to control H2S emission with increase in manure age. When compared to molybdate, the addition of nitrite initially led to lower levels of H2S but its effect was only temporary and not as persistent as molybdate. In the semi-pilot and room scale tests H2S levels emitted from untreated fresh manure (831¡Ó26 ppm and 88.4 ppm, respectively), were significantly lower than those observed in the laboratory system (4856¡Ó460 ppm). Moreover, the levels of molybdate required to control the emission of H2S were much lower in both the semi-pilot system and in the room scale chamber than in the closed system (0.1-0.25 mM as opposed to 2 mM).<p> Small scale land application of manure treated with 0.1 mM molybdate did not raise the level of molybdenum in the soil that could cause potential toxicity to plants and animals. No major differences in the nutrient properties of the soils exposed to the treated and untreated manure were observed. Finally, a preliminary feasibility study of this treatment approach showed that the cost associated with this control approach was less than 1% of the total production cost.

Nitromethane is the simplest organic-nitro compound as well as the archetype of an important class of high explosive. Homogeneous nitromethane reactions have been the subject of extensive studies. Particularly the unimolecular isomerization of nitromethane to methyl nitrite is proven to be competitive with simple C-N bond (bond energy 60 kcal/mol) rupture. The activation energy for the rearrangement was measured to be 55.5 kcal/mol and methyl nitrite has a very weak CH3O-NO bond energy 42 kcal/mol lower than that for homolysis. The thermal chemistry of nitromethane on Cu(111) was studied by a combination of temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS) techniques. TPD spectra show that the desorption features include the physisorbed multilayer and monolayer of CH3NO2 at 150 and 190 K, respectively. The major decomposition pathway is via cleavage of O-N bond to yield a major product NO, which is characterized by m/z 30(NO+). A possible contribution from isomerization of nitromethane to methyl nitrite (CH3NO2 CH3ONO) on the surface cannot be ruled out at 278 K. In addition to isomerization, the dehydrogenation products CO and CO2 are also unveiled as part of the desorption features at 314 and 455 K, respectively. We can further prove the reactivity of nitromethane on Cu(111) at 367 K by using the deuterated form of nitromethane which reveals the corresponding desorption TPR/D signals of D2, D2O and CD4. However, we find that nitromethane also reacts by dissociating the C-H bond and the O-N bond, however, leaving the C-N bond intact. Along this reaction channel, HCN desorbs as a product above 360 K, as evidenced by a broad desorption feature of m/z 27. Dimerization of CN to C2N2 occurs at 815 K. The RAIR spectroscopy demonstrates that nitromethane is indeed adsorbed on Cu(111) at 100 K. The formation of methoxy and formyl are supported by the observation of desorption of NO at 278 K with the characteristic NO stretching mode found at 1535 cm-1. Moreover, we assign side-bonded CN and aminomethylene (HC-NH2) present on Cu(111). After the surface is annealed to 330 K, a signature band at 2173 cm-1 is assigned to terminal-bounded CN stretching mode. This band eventually fades out above 900 K consistent with the evolution of cyanogen at 815 K.

This study was to investigate the removal efficiency and the feasibility of containing-EDTA solutions by O3 and O3/UV, advanced oxidation processes (denoted by AOPs). The operation parameters conducted in semi-batch reactor were as follows: ozone dose, pH, temperature and initial concentration of EDTA. The best mineralization and COD removal was found at pH= 9 when the pH values in O3 process was controlled at 3, 5, 7, 9 and 11. Addition of UV in O3 process for treating solutions containing EDTA was found not increasing the reaction rate but raising the COD and mineralization efficiency. In O3 process, the reaction rate was proportional to the ozone dose, it caused a higher mineralization. The higher the initial concentration of EDTA, the lower reaction rate, and the decreasing the mineralization was. Changing the temperature in reaction process was not obviously affected the removal of EDTA due to the lower activated energy found in O3 process. In O3/UV process, EDTA was decomposed very fast, but it still could not be mineralized the intermediates completely. The concentration of nitrate formed in this process was low. It is probably for high energy NH-containing bonds which is not easy break down by O3/UV. Thus, the major reactions in this process are the break of C-N bond, and followed by the break of C-H bond.

This research focuses on anoxic ammonium oxidation (anammox). The anammox process for treating high ammonium and low organic carbon wastewater can reduce operational costs to a greater extent than the conventional autotrophic/heterotrophic treatment process can. The process has been widely researched because of its potential economic benefits. However, during long-term reactor operation, sudden reductions of nitrogen removal rates have been reported; maximum nitrogen removal rates in different reactor configurations could not approach values predicted based on mathematical modeling; and the crucial stability parameter, such as nitrite, did not have defined threshold concentration. It was hypothesised that free ammonia (FA) increase is the precursor of the instability of the anammox reactor. If it is true that nitrite up to about 200 mg N/L should stimulate nitrogen removal rate inside of the anammox reactor, when FA is kept below the inhibition threshold concentration. The research presented in the thesis argues that FA plays a larger role than has been previously considered in the instability of the anammox reactor. This study found FA inhibited nitrogen removal rates (NRR) at concentrations exceeding 2 mg N/L. In the pH range 7 to 8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 200 mg N/L did not negatively affect nitrogen removal rate. This study further found that low nitrite provided stable anammox reactor performance, but that high nitrite was not necessarily the cause for reactor destabilization. During the research high nitrogen removal rate was achieved when low FA was provided. During regular reactor operation at pH 6.5, the NRR at about 6.2 g N/Ld was archived. This value was never achieved before till this study was conducted. Conducted research showed controlling FA at low level is required to approach high rates in anammox reactors. Achieving high rates in anammox reactors allow significant reduction in reactor volume which saves resources. Further studies will be required to identify the FA effect on different microbial interactions, and that may provide more in-depth understanding of the nitrite and FA effect than observations based on NRR alone.

Under iron (Fe3+)-reducing conditions where aqueous Fe2+ and unreduced solid Fe3+-oxides commonly coexist, soil Fe2+ oxidation has been shown to be coupled with nitrate (NO3-) reduction. One possible secondary reaction is the involvement of NO3- and nitrite (NO2-) with Fe-oxide minerals found in many natural environments. Yet, spectroscopic measurements and kinetic data on reactivity of NO3- and NO2- with Fe-containing oxide minerals such as goethite (a-FeOOH), and magnetite (Fe3O­4) are not found in the literature. The reactivity of goethite and magnetite with NO3- and NO2- was studied over a range of environmentally relevant pH conditions (5.5-7.5) with and without added Fe2+(aq) under anoxic conditions. Laboratory experiments were conducted using stirred batch experiments and reaction products were analyzed using ion chromatography (IC), gas chromatography (GC), ultraviolet visible near infrared spectroscopy (UV-VIS-NIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer, and Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Nitrate removal by goethite and magnetite was much slower when compared with NO2-. There was a pH-dependence in the reduction of NO2-, and the initial rate of NO2- removal was nearly 2 and 8 times faster at pH 5.5 than at pH 7.5 by magnetite and goethite, respectively. Nitric oxide (NO) and nitrous oxide (N2O) were identified as products when NO2- has reacted with magnetite, whereas N2O is the major reaction product in the experiment with goethite. In comparison to experiments containing magnetite or goethite alone, addition of Fe2+ greatly accelerated the NO2- removal rate. Wet chemical experiments combined with the Mössbauer study reveals that NO2- reduction to NO and subsequently to N2O by magnetite occurs via a heterogeneous electron transfer process. ATR-FTIR and diffuse reflectance spectroscopy (DRS) results from the studies with goethite indicate that NO2- was removed from solution by adsorption in a surface complex involving the oxygen atoms, and a portion of the nitrite is reduced to NO and N2O. This study suggests that under anaerobic conditions soil and sediments that contain goethite, magnetite, and other Fe3+-oxides can catalyze abiotic NO2- reduction and the kinetics data from this study can be used to predict the NO2- removal under such conditions.

This research focuses on anoxic ammonium oxidation (anammox). The anammox process for treating high ammonium and low organic carbon wastewater can reduce operational costs to a greater extent than the conventional autotrophic/heterotrophic treatment process can. The process has been widely researched because of its potential economic benefits. However, during long-term reactor operation, sudden reductions of nitrogen removal rates have been reported; maximum nitrogen removal rates in different reactor configurations could not approach values predicted based on mathematical modeling; and the crucial stability parameter, such as nitrite, did not have defined threshold concentration. It was hypothesised that free ammonia (FA) increase is the precursor of the instability of the anammox reactor. If it is true that nitrite up to about 200 mg N/L should stimulate nitrogen removal rate inside of the anammox reactor, when FA is kept below the inhibition threshold concentration. The research presented in the thesis argues that FA plays a larger role than has been previously considered in the instability of the anammox reactor. This study found FA inhibited nitrogen removal rates (NRR) at concentrations exceeding 2 mg N/L. In the pH range 7 to 8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 200 mg N/L did not negatively affect nitrogen removal rate. This study further found that low nitrite provided stable anammox reactor performance, but that high nitrite was not necessarily the cause for reactor destabilization. During the research high nitrogen removal rate was achieved when low FA was provided. During regular reactor operation at pH 6.5, the NRR at about 6.2 g N/Ld was archived. This value was never achieved before till this study was conducted. Conducted research showed controlling FA at low level is required to approach high rates in anammox reactors. Achieving high rates in anammox reactors allow significant reduction in reactor volume which saves resources. Further studies will be required to identify the FA effect on different microbial interactions, and that may provide more in-depth understanding of the nitrite and FA effect than observations based on NRR alone.

Neisseria meningitidis is the causative agent of potentially life-threatening meningitis and septicaemia. According to W.H.O., meningococcal disease causes at least 500,000 cases and results in 50,000 deaths worldwide each year (W.H.O., 2008). Neisseria gonorrhoeae is causing the second most common sexually transmitted bacterial infection, with a global incidence of 62 million cases per year. Previous studies have shown surface expressed proteins like pilin, the subunit protein that forms pili (Type IV Fimbriae), in N. meningitidis and N. gonorrhoeae are post-translationally modified by O-glycosylation. This modification has been proposed to be of importance in the pathogenesis of these species. Although the exact function of these post-translational modifications are not fully understood, it is suggested that these modification have a role for immune evasion in the host. In this thesis, an additional outer membrane glycoprotein was identified in pathogenic Neisseria, the nitrite reductase AniA. Mass spectrometry analysis showed that AniA is glycosylated in its C-terminal imperfect (AASAP) repeat region by the pilin glycosylation pathway. This is the first report of a general O-glycosylation pathway in a prokaryote. It was shown AniA is surface exposed. To investigate whether AniA is subject to immune selection, a large collection of N. meningitidis and N. meningitidis clinical isolates were sequence analysed and evaluated. Analysis of published AniA 3D structure revealed that AniA displayed polymorphisms in residues that map to the surface of the protein. This suggests that AniA is under immune selection, and that glycosylation may facilitate immune evasion. Sequencing analyses revealed a frame shift mutation that abolished AniA expression in 34% of N. meningitidis strains surveyed. However, all N. gonorrhoeae strains examined are predicted to express AniA, implying a crucial role for AniA in gonococcal biology. In summary, the data presented here suggested that the protein may be under immune selective pressure. The addition of a phase variable glycan to this surface protein may serve as an additional immune evasion strategy. Immune selection on surface proteins in these host-adapted pathogens may have been the driving force for the evolution of this general O-glycosylation pathway. Therefore, the discovery that AniA is a glycoprotein has given insights into the pathogenesis and the host-pathogen interactions of these organisms.

Mainz, Univ., Diss., 2002.

Humans have dramatically increased the amount of reactive nitrogen cycling through the biosphere. In coastal systems, excess nitrogen can lead to negative impacts. Thus, it is crucial to understand how nitrogen is cycled within, and eventually removed from, marine systems and the variables that regulate these processes. Sediment denitrification (the microbial conversion of nitrate (NO3^-) to dinitrogen (N2) gas) and water column nitrification (the two step oxidation of ammonium (NH4^+) to nitrite (NO2^-) and then nitrate (NO3^-)) rates were quantified along an in situ gradient of environmental conditions from an estuary to the continental shelf off Rhode Island, USA. Sediment net denitrification rates were directly measured over multiple seasonal cycles using the N2/Ar technique. Denitrification rates ranged from 20-75 μmol m^-2 hr^-1 (mean 44±4), indicating that this process removes ~5% of total reactive nitrogen entering the North Atlantic shelf region per year. Based on model results, these rates also represented a three-fold decrease in sediment nitrogen removal in New England continental shelf sediments over the past century. A literature review of marine water column nitrification observations were compiled to evaluate how ammonium, nitrite, and total oxidation rates vary worldwide. Rates of ammonium, nitrite, and total oxidation differed among estuary, continental shelf, and open ocean environments (p<0.05). This review highlights that as we continue to study marine "nitrification," it is necessary to consider both individual oxidation processes and environment type. Water column ammonium and nitrite oxidation rates were measured using stable isotope tracers off Rhode Island. At all study sites, nitrite oxidation rates (0-99 nM d^-1) outpaced ammonium oxidation rates (0-20 nM d^-1). These oxidation processes responded in dissimilar ways to in situ water column conditions (depth, salinity, dissolved oxygen, and pH), and these relationships varied with location. Nitrous oxide (N2O) production rates up to 10 times higher than ammonium oxidation indicated that ammonium oxidation may be underestimated if this byproduct is not measured. For the first time, the link between sediment metabolism and water column nitrification was also examined, and the results highlight the importance of benthic-pelagic coupling as controlling factor of water column ammonium and nitrite oxidation. / 2019-04-30T00:00:00Z