Upset events due to the inflow of toxic chemicals are a critical issue for wastewater treatment facilities. Understanding the source-effect relationship of toxic chemicals can facilitate the prevention or improved reaction to upset events. Part one of this study was conducted to investigate the source of upset events at a regional industrial wastewater treatment plant (WWTP). Part two of this study determined the process performance effects of two chemical shocks, cyanide (zinc-cyanide complex) and pH, on nitrifying and non-nitrifying activated sludge. A modified respirometric assay protocol was developed to allow the industrial WWTP to screen industrial wastewaters for inhibitory properties. All five industrial wastewaters tested revealed inhibitory properties. Large day-to-day variations were found, illustrating the need for a large database of results for comparison over time. Additionally, a small volume contributor, that was thought by the utility to be an unlikely source of problems, contributed significantly to the wastewater oxygen demand and demonstrated inhibitory properties. The modified respirometric procedure enabled the WWTP to identify possible industrial sources that could cause an upset event. Lab-scale sequencing-batch reactors were used to determine the effects of cyanide and pH shock on activated sludge. Three reactors were shocked with increasing weak-acid complexed zinc cyanide or pHs of 5, 9, and 11. The resulting effects were compared to an un-shocked control reactor. It was found that respiration and nitrification were affected by the zinc cyanide complex, while COD removal, effluent TSS and dewaterability were not. Recovery was seen in less than 2 X solids residence time (SRT) for the nitrifying biomass and within 3 X SRT for the non-nitrifying biomass. The results of the pH experiment showed that the pH 11 shock affected the settleability, nitrification, COD removal, and effluent TSS levels of the reactors, while pH 5 and pH 9 shocks had no effect. Recovery was seen within 3 X SRT for both the nitrifying and non-nitrifying systems. / Master of Science

Improved technologies, increases in global demand for metals, and lax environmental policies and regulations are causing a shift of large-scale mining activities to the tropics. This shift of mining to the tropics has the potential to modify natural ecosystems and disrupt the social structures of rural and indigenous peoples in some of the most remote areas of the planet. This thesis encompasses research done in two villages of Guyana's Essequibo River basin after the 1995 Omai cyanide spill, and illustrates the local social consequences of a large-scale gold mining operation in the tropics. It documents not only the degradation of the local river ecology, but also the changes in local people's perceptions of their environment. That environment, once viewed as pristine, is now viewed as unsafe, leading to disrupted livelihoods and lifestyles. The finding of this study points to a direct link between international economic liberalization policies (which emphasize privatization, foreign direct investment, and economic growth) and the creation of disaster circumstances in developing countries. This thesis research is the result of a total of ten weeks of participant observer research in the area of the Essequibo River, Guyana. It utilizes the methodology of taped interviews of head-of-households. Interviews were conducted with approximately 85 percent of heads-of household of the villages of Rockstone and Riversview. Additionally, interviews were conducted with national and regional governmental officials, regional health officials, local and indigenous leaders, personnel of the Guyana Geology and Mines Commission, and the Environmental Protection Agency in Guyana. Interviews were supplemented with archival research. The findings of this thesis research closely mirror those of other researchers who contend that the social impacts of technological disasters are long-term and more severe than those related to natural disasters. Seven years after the cyanide spill, disruptions in livelihood activities, diet, and household behaviors continued to be evident in the two villages. There is little indication that the high negative perceptions of the villagers as a result of the disaster will change in the near future. The research found that macroeconomic policies, crafted by national governments and overseen by international financial institutions without the involvement of local citizenry, disproportionately affected the poor and rural populations through the degradation of local ecosystems. The thesis also illustrates the usefulness of ethnographic research-in particular, interviews in disaster studies of developing countries. / Master of Science

A double modulation microwave spectrometer is used to evaluate the linewidth parameters for some excited rotational components in the bending vibration v_8 of 13CH3 13C 15N and 13CH3C15N isotopomers of methyl cyanide. The linewidth parameters for self-broadening of the ΔJ=2←1 rotational components for the ground v_8 , 1v_8, and the 2v_8 vibrations were determined over a pressure range of 1 to 13 mtorr and at a temperature of 300 K. The double modulation technique is used to explore the high eighth derivative of the line shape profile of the spectral line. This technique proved to give good signal-to-noise ratios and enabled the recovery of weak signals. An experimental method is developed to correct for source modulation broadening. The tests of the ratios of the two inner peak's separation of the eighth derivative of the line showed that they were up to 95% similar to those for a Lorentzian line shape function. The line shapes were assumed to be Lorentzian for the theoretical analysis of the derivative profiles and comparisons were made between experiment and theory on this basis. Dipole moments for vibrationally excited states were calculated from linewidth parameters and show systematic decrease with the increase of excitation. Impact parameters were calculated using the "hard sphere" model of the kinetic theory of gases. The results were many times larger than the size of the molecule itself. This suggests that the dominant interaction is a long range dipole-dipole force interaction.

This study generated two cyanide dihydratase (CynD) mutants of Bacillus pumilus C1 with improved activity at higher pH by random mutagenesis. The purpose of this study was to create enzyme variants better suited to degrade cyanide under the harsh conditions of industrial applications. We employed error-prone PCR to construct a library of CynD mutants. A high throughput screening system was developed to screen the library for improved activity. Two mutants were identified that could degrade cyanide at pH10 whereas the wild-type enzyme was inactive at pH9 or higher. The mutants each had three amino acid substitutions compared to the wild-type enzyme. The mutants were also more stable than the wild-type enzyme at 42oC. E327G was identified as one of the key amino acids that are responsible for the improved activity. The goal of the second project was to convert substrate specificity of the Bacillus sp. OxB-1 nitrilase to that of a cyanidase by mutagenesis or construction of hybrid genes. The OxB-1 nitrilase of Bacillus sp. shows a high level of identity with the cyanide dihydratases from B. pumilus C1 and P. stutzeri AK61 but utilizes different substrate. This provides a valuable resource to study the substrate specificity determinants of cyanide degrading enzymes. One deletion mutant and four hybrid proteins were constructed based on the alignment information. The constructed proteins were all unable to degrade cyanide.

Measurement of the line width parameters of a molecule is of interest because collision diameters can be calculated from them. This gives an effective size of the molecule when it is involved in interactions with other molecules. Further, specific types of interactions can be inferred from detailed information about the dependence of the line width upon pressure. In this paper, an experiment for measuring line width parameters for methyl cyanide is described and the results of the experiment are analyzed. This investigation was successful in obtaining precise values for the line width parameter for the J-J' = 0-1, J-J'= 1-2, and J-J' = 2-3 transitions of methyl cyanide which agree with experimental values of other researchers where available. It was found that standing waves were the dominant effect in the measurement of center frequency shift.

The shape of collision-broadened microwave absorption lines is reviewed, along with a number of other broadening mechanisms. The Anderson and Murphy-Boggs linewidth theories are reviewed in detail. Several published modifications to these theories are reviewed. Computer programs which numerically evaluate linewidths and lineshifts are presented. Approximations are made to reduce the need for extensive use of the modified Bessel functions, thereby reducing computation time. Only dipole-dipole forces are considered.

Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017. / The high rate of industrialisation in most developing countries has brought about challenges of wastewater management especially in the mineral processing industry. Cyanide has been used in base metal extraction processes due to its lixiviant properties thus, its presence in wastewater generated is inevitable. Furthermore, partial and/or the use of unsuitable treatment methods for such wastewater is a potential hazard to both human and the environment. There are several reports on biotechnological treatments of cyanide containing wastewater but few mineral processing industries have adopted this approach. Hence, the thermodynamic study of biodegradation of cyanide containing wastewater was undertaken. The primary aim of this study was to explore the application of bioenergetic models and biological stoichiometry to determine the functionality and thermodynamic requirements for cyanide degrading isolate (Fusarium oxysporum EKT01/02), grown exclusively on Beta vulgaris, for a system designed for the bioremediation of cyanidation wastewater. Chapter 2 reviews some of the applicable thermodynamic parameters such as enthalpy, entropy, heat of combustion, heat capacity, Gibbs energy, including stoichiometry models in relation to their applicability for microbial proliferation in cyanidation wastewater. The chapter places emphasis on the application of agro-industrial waste as a suitable replacement for refined carbon sources for microbial proliferation in bioremediation systems because such systems are environmentally benign. The choice of using agro-industrial waste is due to organic waste properties, i.e. agro-industrial waste is rich in nutrients and is generated in large quantities. Chapter 3 presents the materials and various standardised methods used to address the research gaps identified in chapter 2. For an organism to degrade free cyanide in wastewater, it must be able to survive and perform its primary function in the presence of such a toxicant. Chapter 4 exemplifies both molecular and biochemical characteristics of Fusarium oxysporum EKT01/02 isolated from the rhizosphere of Zea mays contaminated with a cyanide based pesticide. The molecular analyses confirmed the fungal isolate to be Fusarium oxysporum EKT01/02 and the nucleotide sequence of the isolates were deposited with National Centre for Biotechnology Information (NCBI) with accession numbers KU985430 and KU985431. The biochemical analyses revealed a wide substrate utilisation mechanism of the isolate dominated by aminopeptidase including nitrate assimilation capabilities. A preliminary investigation showed free cyanide degradation efficiency of 77.6% (100 mg CN-/L) after 5 days by the isolate. The excess production of extracellular polymeric substance (EPS) was attributed to the isolates’ strive to protect itself from cyanide toxicity.

Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017. / Industrial wastewater management pertaining to the mining industry has become increasingly stringent, with companies being required to develop environmentally benign wastewater management practices worldwide. The industries that utilise cyanide compounds for the recovery of precious and base metals in a process known as the cyanidation process, have contributed substantially to environmental deterioration and potable water reserve contamination due to the discharge of poorly treated, or untreated, cyanide containing wastewater. Hence, a biotechnological approach was undertaken in this study to remediate free cyanide (CN-) and thiocyanate (SCN-), which are the major chemical contaminants which are normally found in cyanidation wastewaters. Furthermore, this biotechnological approach was investigated to understand the fundamental aspects of using this approach such that the information gathered can be utilized in pilot plant studies. Therefore, bioprospecting of potential CN- and SCN--degrading organisms was undertaken using two approaches; (i) culture-dependent approach and (ii) culture-independent approach. Using the culture-dependent approach, Pseudomonas aeruginosa STK 03, Exiguobacterium acetylicum and Bacillus marisflavi were isolated from an oil spill site and river sediment samples, respectively. STK 03 was evaluated for the biodegradation of CN- and SCN- under alkaline conditions. The organism had a CN- degradation efficiency of 80% and 32% from an initial concentration of 250 and 450 mg CN-/L, respectively. Additionally, the organism was able to degrade SCN-, achieving a degradation efficiency of 78% and 98% from non- and CN- spiked cultures, respectively. Furthermore, the organism was capable of heterotrophic nitrification but was unable to denitrify aerobically, with the autotrophic degradation of CN- by STK 03 being abortive.

Orientador: Rodnei Bertazzoli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-29T01:54:10Z (GMT). No. of bitstreams: 1 Lanza_MarcosRobertodeVasconcelos_D.pdf: 16742497 bytes, checksum: 9694de07ef18460a6c486a1664f9fafc (MD5) Previous issue date: 2001 / Resumo: Os cianetos inorgânicos são utilizados principalmente da indústria da galvanoplastia e da extração mineral, e os efluentes gerados nestas atividades industriais têm como característica a presença de metais pesados complexados. O uso intensivo deste composto gera grandes quantidades de efluentes e resíduos contendo altos teores de cianeto, representando um risco ecológico devido à sua alta toxicidade para a maioria das formas de vida. Este fato torna indispensável o tratamento adequado destes efluentes e resíduos antes do descarte final. Neste trabalho propõe-se um tratamento eletroquímico de efluentes cianídricos, atuando como tratamento principal ou coadjuvante ao processo químico convencional, com o objetivo de degradar anodicamente os cianetos e recuperar catodicamente os íons de metais pesados presentes, reduzindo a geração do lodo cianídrico. O objetivo é desenvolver e otimizar um reator eletroquímico em escala piloto para o tratamento de efluentes cianídricos contendo metais pesados. O processo de desenvolvimento e otimização do reator eletroquímico, utilizando eletrodos comerciais de óxidos de metais nobres (DSA®), foi executado em três etapas: I) a seleção do material do anodo comercial de óxidos de metais nobres, 2) o estudo do processo em um reator de bancada e 3) o estudo do processo em um reator piloto. Inicialmente foram avaliados dois eletrodos comerciais de óxidos de metais nobres, fabricados pela De Nora do Brasil Ltda: os eletrodos do tipo DSA®. As análises morfológica e elementar indicaram a composição aproximada para os eletrodos estudados: Ti/70TiO2-30RuO2 e Ti/55Ta205-45IrO2, para DSA® e DSA-Cl2 respectivamente. A voltametria hidrodinâmica com eletrodos disco rotatórios indicaram uma relação dos valores da constante cinética aparente (kapp) para os eletrodos DSA-Cl2 e DSA-02, respectivamente, na proporção de 1:1,2. Isto indica que o eletrodo Ti/55Ta205-45IrO2 apresenta um poder eletrocatalítico para a reação de evolução de oxigênio mais elevado e que, provavelmente, esse mesmo eletrodo apresente uma eficiência inferior ao eletrodo DSA-Cl2, para a destruição de cianetos. O uso da eletrólise a potencial constante confirmou este fato, pois mostrou que a constante cinética (kcN) do processo de oxidação de cianetos apresenta valores superiores sobre a superfície do eletrodo DSA- Cl2 em todos os potenciais estudados, tomando esse eletrodo o mais indicado para o uso nos reatores eletroquímicos. Na segunda etapa, o processo de destruição de cianetos foi estudado em um reator eletroquímico em escala de bancada, do tipo "flow-by", com um anodo comercial do tipo DSA Cl2. Neste reator, as concentrações de cianeto livre foram reduzidas a valores próximos a 0,1 mg L-1, a partir de soluções contendo 700, 500, 200, 100 e 50 mg L-1. Durante o tratamento em regime de recirculação, avaliou-se a influência da densidade de corrente anódica aplicada, da velocidade do fluido no interior do reator e da concentração inicial da espécie poluente sobre a constante cinética (kcN) do processo e o consumo de energia elétrica para oxidar cada kg de cianetos. O valor da constante cinética do processo, nas condições operacionais consideradas ótimas (1= 50 mA cm-2 e V= 0,22 m s-1), é de 2,2.10-4 m s-l. O custo aproximado do tratamento de um efluente contendo aproximadamente 700 mg L-1 de CN- livre, considerando-se uma taxa de remoção de -99%, é de R$ 1,70 kg-I de cianetos (-US$ 0.75 kg-1- valores de dezembro/2000). Na fase de estudo do processo de tratamento eletroquímico de efluentes cianídricos, utilizando um reator piloto com anodos comerciais do tipo DSA®- Cl2, determinou-se as condições operacionais (densidade de corrente aplicada e velocidade do fluxo no interior do reator) nas quais o processo de remoção de cianetos livres apresentou a melhor eficiência, e estas foram 41 mA cm-2 e 0,053 m s-l, respectivamente. O valor da constante cinética obtido para o efluente galvânico real foi de 1,99.1O-5 m s-1. No entanto, o consumo de energia elétrica por kg de cianeto oxidado ficou em 1.060 kWh kg-1, representando um custo financeiro de R$ 53,00 kg-1 de cianetos totais. O mesmo efluente tratado pelo método químico convencional, utilizou 2,5 L de NaClO a 12% e gerou um lodo de coloração preta e de difícil filtração, representando um custo nu de R$ 294,00 kg-I de cianetos totais (considerando-se o valor de R$ 1,00 L-I de NaClO a 12%). O tratamento eletroquímico apresentou um custo financeiro de aproximadamente 5,5 vezes menor do que o tratamento químico convencional, R$ 53,00 e R$ 294,00 respectivamente, para cada kg de cianetos totais oxidados / Abstract: Inorganic cyanide is still in use in the metal finishing industry and in the mining activities of noble metals extraction and refining. Gold and silver are extracted from its ores as cyanidric complexes. The intensive industrial use of cyanide complexes is responsible for the generation of high toxicity aqueous streams, which present high oxygen demand. The cyanide wastes must be adequately treated before being allowed to discharge from de process plant. The main goal of the present work is to propose an alternative electrochemical process for removal of cyanide from wastewater, using an electrolytic cell with a commercial dimensionally stable anode (DSA®). In the first step, we studied the performance of two commercial dimensionally stable anode (DSA®) oxide coatings. The coatings studied were 70TiO2/30RuO2 and 55Ta205/45IrO2, on Ti substrate. The efficiency of both materials in the electro-oxidation of free cyanide was compared using linear voltammetry and electrolysis at constant potential. Kinetic analysis has shown that the 70TiO2/30RuO2 electrode is less catalytic for oxygen evolution and shows a better performance in the electro-oxidation of free cyanide. In the second step, we used a flow reactor with a Ti/70TiO2/30RuO2 (w/w) DSA® type electrode for the electro-oxidation of cyanide in a batch recirculating mode. The device performance was evaluated considering concentration decay of cyanide concentration as a function of current density, flow rate and the initial pollutant concentration. The experiments have shown that cyanide electro-oxidation presents a first order kinetic relative to CN ions. For the operational conditions used in the experiments, rate constant for cyanide oxidation was in the range of 3.0 10-5 to 2.7 10-4 m s-1, with an optimum value of 2.2 10-4 m s-1 for current density of 50 mA cm-2 and linear velocity of 0.22 m s-1. Using these parameters with 700 mg L-1 cyanide containing solution 34 kWh is consumed for the oxidation of one kilogram of cyanide. An electrochemical pilot scale, with the Ti/70TiO2/30RuO2 (w/w) DSA® type electrode, was also used for the electro-oxidation of cyanide in a batch recirculating mode. The device performance was evaluated considering concentration decay of cyanide concentration as a function of current density and the flow rate. For the operational conditions used in the experiments, rate constant for cyanide oxidation was 2.0 10-4 m s-1 for current density of 41 mA cm-2 and linear velocity of O.053 m s-1. Cost estimation, based on electrical energy consumption, showed that electrochemical oxidation is 5.5 times less expensive when compared to the chemical treatment using a 12% sodium hipochloride solution for the oxidation of one kilogram of cyanide / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Utilization of cyanide as a nutritional nitrogen source in P. fluorescens NCIMB 11764 was shown to involve a novel metabolic mechanism involving nonenzymatic neutralization outside of cells prior to further enzymatic oxidation within. Several cyanide degrading enzymes were produced by NCIMB 11764 in response to growth or exposure to cyanide, but only one of these cyanide, oxygenase (CNO), was shown to be physiologically required for assimilation of cyanide as a growth substrate.