Polychlorinated Biphenyls (PCBs) are hazardous and toxic chemicals to both humans and animals. In the late 1960’s PCBs were discovered to be a harmful pollutant which could cause environmental contamination due to its slow degradation and even trace amounts of PCBs were regarded as toxic to both human and animals. Oil spills are a frequent occurrence at Eskom substations which could contain PCBs. The contaminated sediments which are easily carried away by rain and wind can further contaminate the environment and aquatic bodies. Eskom currently disposes of soil and ballast stones contaminated with PCBs by thermal destruction. This is a costly process as PCBs are regarded as hazardous materials and needs to be safely transported and disposed of at a licensed disposal facility. Based on literature, ozone has been used on a laboratory scale to treat soil contaminated with PCBs with the addition of chemicals such as hexane and acetone which assist in breaking down PCBs. The objective of this study was to evaluate whether ozone without the addition of chemicals could reduce the levels of PCBs present in contaminated soil. In this study, two soil samples and one ballast stone sample were contaminated with 50 ppm, 200 ppm and 600 ppm of PCBs and then exposed to 0.4, 0.5 and 0.6 l/min of ozone for a period of 60 minutes to examine the effects of increasing ozone flow rates on PCB destruction in soil. The results of the experimental tests showed that ozone gas reduced the concentration of PCBs in the soil and ballast stone samples for the different total gas flow rates. The literature study identified that the final products of the ozonation of PCBs are carbon dioxide and water and that any products formed after this process could possibly be degraded by the soil natural microorganisms. Calculations based on the Shin et al. (2004) model proved that ozone was in excess after the ozonation process. The results of the experiments also confirmed this, as the PCB residuals were similar for all three total gas flows, which showed that there was no dependence on the gas flow rates hence, ozone was in excess. The experimental data was then trended with zero, first and second order reaction equations, which showed that the best fit was obtained with the firstorder reaction equation. It is recommended that ozone be used for the treatment of PCB contaminated soil at Eskom substations. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

No description available.

Although the kinetics and mechanism of monochloramine decay in organic-free waters are relatively well understood, those in natural waters are not, due to exceedingly complex and poorly defined interactions of monochloramine with natural organic matter (NOM) and particles. Ozonation followed by a biologically activated carbon (BAC) filtration is a commonly practiced process option that affects the characteristics of both dissolved and particulate constituents in the water. However, how these changes in water constituents affect stability of the residual disinfectant, or monochloramine in particular, are currently unknown. Kinetics of monochloramine decay in water samples obtained before and after ozonation and BAC treatments were performed under varying operating conditions were determined by bench-scale batch experiments. Stability of monochloramine in the BAC filter effluent samples obtained at different times after backwashing was determined. It was found that in most cases monochloramine stability was greatly decreased after BAC filtration. Further filtering the BAC effluents with 1.2 and #61549;m polycarbonate membrane resulted in a substantial increase in monochloramine stability. A further increase was observed after filtering the samples using a 0.4 m membrane. This finding suggested that particulate matter generated from the filters could be the major cause of monochloramine instability. The fines from the activated carbon, possible components of the particulate matter eluting from the BAC filters, were found to exert an insignificant monochloramine demand both in the presence and absence of NOM, which is contrary to previous speculation in the literature about their demand for monochloramine. While there appears to exist a relationship between chloramine demand and HPC count of the filter effluent, more research will be needed to determine the effect of nature and type of microorganisms and their byproducts have on chloramine demand. Effect of ozonation on monochloramine stability is also under investigation using both the water sampled from full-scale plant and the synthetic water prepared with Suwannee River NOM.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

A bench scale laboratory ozonator was constructed and determined to produce 27 mg O3/hr. A contacting system and experimental procedure was developed to approximate a mass balance of 0, 1, 2, 4, 8 and 16 ppm were applied to raw and magnesium treated water from Lake Washington which is the potable water source for Melbourne, Florida. The effect of ozone on trihalomethane precursors was studied by comparing THM formation at 1, 24, 48, 72, and 96 hours following chlorination. The concentrations of each specie, chloroform, bromodichloromethane, dibromochlormethane and bromoform are reported. The highest 96 hour TTHM concentrations reported were 2773 ppb for the raw and 1205 ppb for the treated water. Chloroform was found to be the major specie of the THM's, averaging 80%. Ozone was found to reduce color of the raw and treated Lake Washington water. Ozone was shown to neither increase nor decrease TTHM concentrations with utilized ozone dosed up to 10.6 ppm. Increasing utilization of ozone was found to increase CHClBr2 concentrations in the raw and coagulated water. Regression equations at the 0.01 level of significance were developed for CHClBr2 formation and utilized ozone, color reduction and utilized ozone, TTHM formation and reaction time, and finally ozone production and time.

The use of ozone in a recirculating aquacultural production system on a commercial scale was investigated. ozonation was responsible for statistically significant differences in all test parameters, including: heterotrophic plate count, total coliforms, fecal coliforms, total solids, and total volatile solids. Results indicated ozone had a significantly positive effect in the recirculating aquacultural production system. Further study is recommended, however, to better understand the effects of ozone and to justify economically the use of ozone in commercial systems. / Master of Science

Orientador: Marco Aurélio Cremasco / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T13:54:46Z (GMT). No. of bitstreams: 1 Pacheco_JoseRicardo_M.pdf: 2421854 bytes, checksum: 0892102a47f0322520b05c0bad2a79d9 (MD5) Previous issue date: 2012 / Resumo: A gestão dos recursos hídricos, englobando uso de água para fins potáveis e processos industriais, tornou-se de vital importância e ganhou visibilidade na última década do século vinte. Dentre as tecnologias e processos de tratamento de água potável e residuária destaca-se a ozonização. Diante deste contexto a presente dissertação de mestrado visou construir e avaliar um sistema de ozonização baseado em coluna de borbulhamento. Foi construída uma célula de geração de ozônio para se estudar a eficiência de geração, com três gases de alimentação: ar úmido; ar seco e oxigênio. O ar úmido foi captado diretamente da atmosfera, o ar seco e oxigênio foram fornecidos através de um secador de ar e um concentrador de oxigênio respectivamente. O processo de fornecimento de ar seco e oxigênio foi o de "PSA" (pressure swing adsorption) no qual o ar atmosférico passou por uma coluna recheada com zeólita capaz de reter a umidade e moléculas de nitrogênio. A célula geradora de ozônio teve então as condições de descarga elétrica fixas e os três gases de alimentação foram passados pela mesma. A eficiência de geração de ozônio foi então comparada entre os três gases de alimentação. Os valores obtidos apresentaram consistência em relação aos valores de outros autores. Para avaliação da ozonização em fase líquida foi construída uma coluna de borbulhamento onde o ozônio foi borbulhado na parte inferior da coluna usando-se água destilada. Foram realizados experimentos: a) com recirculação da água da parte inferior da coluna até o topo; b) sentido contra-corrente água/gás; c) sentido co-corrente água/gás...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The management of water resources embracing the use of water for potable and industrial processes, has become of vital importance and has gained visibility in the last decade of the twentieth century. Among the technologies and processes for treatment of drinking water and wastewater, ozonation plays an important role. Considering this context the dissertation work aimed to construct and evaluate a system based on bubble column ozonation. An ozone generation cell was built to study the generation yield with three feed gases: humid air; dry air and oxygen. The humid air was captured directly from the atmosphere, dry air and oxygen were supplied by an air dryer and one oxygen concentrator respectively. The feed gas preparation process to supply dry air and oxygen is called "pressure swing adsorption", which the atmospheric air is passed through a column filled with a zeolite compound which retains moisture and nitrogen molecules. Ozone generation cell discharge electrical conditions were fixed, after the three feed gases were passed through the cell. Then ozone generation efficiency was measured and compared between the three feed gases. The values obtained were consistent with those obtained by other authors. To evaluate ozonation in the liquid phase a bubble column was constructed, where gaseous ozone was bubbled into the column bottom. Distilled water was chosen as the liquid medium. Experiments were carried out in the following conditions: a) recirculating water from the bottom to the top of the column; b) countercurrent flow directions between gas/liquid; c) concurrent flow directions between gas/liquid...Note: The complete abstract is available with the full electronic document / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

No description available.

Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

The aim of the investigation described in this work is to gain a better understanding of the processes involved in the oxidation of organic compounds by photolytic ozonation in a laboratory scale reactor. The results and discussions are presented in Chapter III. This chapter contains four parts. In the first part, mass transfer efficiency and the calculation of the mass transfer coefficient, KLa, as well as the ozone decomposition rate constant, KD, are presented and compared with those obtained by other investigators. The second part deals with the kinetics of the photolysis of 2,2',4,4',6,6'-hexachlorobiphenyl both in purified and natural lake water. Mathematical expressions and a discussion of the possible reaction processes involved are given. Kinetic models of ozonation and photolytic ozonation in purified and natural lake water are developed and discussed in part three. Rate constants are calculated from experimental data and used to predict values of substrate destruction with a mathematical model. The fourth part of this chapter deals with the identification of products from the photolysis, ozonation and photolytic ozonation of 2,2'4,4',6,6'-hexachlorobiphenyl. The products are isolated and identified using combined gas chromatography and mass spectroscopy, and reaction mechanisms are suggested.