This master thesis project was carried out as a part of the chlorate research conducted at the Process RD&I department for bleaching chemicals at AkzoNobel Pulp and Performance Chemicals AB in Bohus. During the project already implemented filter cloths as well as new types of filters were studied and compared by experimental trials. The results were then examined in an attempt to evaluate existing filtration systems as well as investigate if there are other, better alternatives. The impurities found in a chlorate plant account for an efficiency loss in the process and a reduction of impurities would hence result in an energy reduction and a cleaner product. The trials were conducted at one of AkzoNobel’s chlorate plants. Six filters were studied and evaluated by measuring turbidity of the electrolyte and pressure over the filter during the experiments. Samples of the electrolyte were analyzed to obtain the metal content, and thereby the impurity content, of the electrolyte. The structures of the filters were studied by optical microscopy. The results from the trials show that all filter types except one, a needle felt filter, seem to be suitable for chlorate electrolyte filtration (including the filter types already used in the plants). The other filters all reach turbidity values below 0.1 FNU immediately or within 90 minutes of filtration, which is considered good enough. The results from the metal content analysis show a similar trend where the metal concentrations decrease to levels below the detection limits immediately or within 90 minutes of filtration. Apart from the lab trials performed some measurements were made on the existing filtration equipment in the chlorate plant. The measurements show varying results, partly similar to those achieved during the lab filter trials but also results showing a higher turbidity value and metal content, indicating that full scale operation are more complicated than lab scale operation. The lab trial results obtained with the filter types already used in the plants show that lower impurity content is possible to achieve. However, this would require closer monitoring of the filtration systems in the plants. Apart from the filtration trials, an attempt to determine the sizes of the particles present in the electrolyte using laser diffraction was performed. However, too little was known of the chlorate electrolyte’s optical data for the measurements to be reliable. Further work is needed before a method for size determination of the particles in a chlorate electrolyte can be achieved. Also, an Optical Filtration Test was tried on the electrolyte but was not sensitive enough for utilization on electrolyte with low (below 1 FNU) turbidity values.  The project concluded that a switch to another filtration system is unmotivated, unless a change in the product requirements would occur. Since the impurities have proven to affect the efficiency of the process, it is recommended to make an effort into utilizing the filtration system to its full extent.

Contamination of perchlorate and chlorate in nature is primarily the result of various industrial processes. The microbial respiration of these oxyanions of chlorine plays a major role in reducing the society’s impact on the environment. The focus with this thesis is to investigate the oxygen-dependent regulation of key components involved in the chlorate respiration in the gram‑negative bacterium Ideonella dechloratans. Chlorate metabolism is based on the action of the enzymes chlorate reductase and chlorite dismutase and results in the end products molecular oxygen and chloride ion. Up‑regulation of chlorite dismutase activity in the absence of oxygen is demonstrated to occur at the transcriptional level, with the participation of the transcriptional fumarate and nitrate reduction regulator (FNR). Also, the chlorate reductase enzyme was shown to be regulated at the transcriptional level with the possible involvement of additional regulating mechanisms as well. Interestingly, the corresponding chlorate reductase operon was found to be part of a polycistronic mRNA which also comprises the gene for a cytochrome c and a putative transcriptional regulator protein.

Previous reports have shown that some bacteria utilize a dissimilatory nitrate reductase enzyme (NR) in anaerobic environments. This enzyme reduces nitrate to nitrite and also has been shown to co-metabolize chlorate to cytotoxic chlorite. A commercially available competitive exclusion (CE) product was evaluated for its nitrate reductase activity and therefore its experimental chlorate product (ECP) sensitivity. Of the 29 constituent bacteria of the CE culture, 11 had slight utilization of NR, 3 had moderate utilization of NR; the remaining were NR negative (with slight and moderate utilization: >0.1 to < 1.0 mM and > 1.0 mM nitrate utilized within 6 h, respectively). In vivo studies utilizing CE and ECP showed significant reductions in Salmonella. Although some of the bacteria were affected by ECP, the combined effect of the CE culture and ECP were effective in reducing Salmonella. Clostridium perfringens (CP) is a pathogen in the commercial poultry industry, which is the etiologic agent of necrotic enteritis (NE). Day-of-hatch broilers were fed a wheat diet and assigned to the following groups: control, commercial coccidia vaccine, commercial bursal disease vaccine, or the combination of the two, and challenged with CP in order to develop a disease model. Broilers in each treatment group had significant increases (P≤ 0.05) in lesion scores, mortality, and CP incidence. As pressure mounts for discontinuing the use of antibiotics in the agriculture industry, it is important to develop new strategies to combat these costly enteric pathogens. In vitro investigations evaluated a mixed gut culture with CP and the ECP at 5 mM or a 10 mM concentrations, over time. By 3 h there was a reduction (P≤ 0.05) in the 5 mM ECP and 10 mM ECP treatment groups. In vivo studies showed significant reductions in the incidence of CP and populations of intrinsic E. coli in all of the chickens provided ECP in the drinking water. Birds administered ECP in the feed showed significant reductions in lesion scores, incidence of CP and also had reduced E. coli log10 values. These results show that an ECP could provide the industry with a new management tool for controlling NE.

Previous reports have shown that some bacteria utilize a dissimilatory nitrate reductase enzyme (NR) in anaerobic environments. This enzyme reduces nitrate to nitrite and also has been shown to co-metabolize chlorate to cytotoxic chlorite. A commercially available competitive exclusion (CE) product was evaluated for its nitrate reductase activity and therefore its experimental chlorate product (ECP) sensitivity. Of the 29 constituent bacteria of the CE culture, 11 had slight utilization of NR, 3 had moderate utilization of NR; the remaining were NR negative (with slight and moderate utilization: >0.1 to < 1.0 mM and > 1.0 mM nitrate utilized within 6 h, respectively). In vivo studies utilizing CE and ECP showed significant reductions in Salmonella. Although some of the bacteria were affected by ECP, the combined effect of the CE culture and ECP were effective in reducing Salmonella. Clostridium perfringens (CP) is a pathogen in the commercial poultry industry, which is the etiologic agent of necrotic enteritis (NE). Day-of-hatch broilers were fed a wheat diet and assigned to the following groups: control, commercial coccidia vaccine, commercial bursal disease vaccine, or the combination of the two, and challenged with CP in order to develop a disease model. Broilers in each treatment group had significant increases (P≤ 0.05) in lesion scores, mortality, and CP incidence. As pressure mounts for discontinuing the use of antibiotics in the agriculture industry, it is important to develop new strategies to combat these costly enteric pathogens. In vitro investigations evaluated a mixed gut culture with CP and the ECP at 5 mM or a 10 mM concentrations, over time. By 3 h there was a reduction (P≤ 0.05) in the 5 mM ECP and 10 mM ECP treatment groups. In vivo studies showed significant reductions in the incidence of CP and populations of intrinsic E. coli in all of the chickens provided ECP in the drinking water. Birds administered ECP in the feed showed significant reductions in lesion scores, incidence of CP and also had reduced E. coli log10 values. These results show that an ECP could provide the industry with a new management tool for controlling NE.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 74-78).

Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate in the same cell was investigated. The alkaline hydrogen peroxide was obtained by the electroreduction of oxygen in NaOH on a fixed carbon bed while the chlorate was obtained by the reaction of anodic electrogenerated hypochlorite and hypochlorous acid in an external reactor. An anion membrane, protected on the anode side with an asbestos diaphragm was used as the separator between the two chambers of the cell. The effects of superficial current density (1.2 - 2.4 kA m⁻²), sodium hydroxide concentration (0.5 - 2.0 M) and catholyte flow (0.1 x 10⁻⁶ - 0.5 x 10⁻⁶ m³ s⁻¹) on the chlorate and peroxide current efficiencies were measured. The effect of peroxy to hydroxy mole ratio on the chlorate current efficiency was measured too. The cell was operated at fixed anolyte flow of 2.0 x 10⁻⁶ m³ s⁻¹, inlet and outlet temperatures of 27/33°C (anode side), 20/29°C (cathode side), cell voltages of 3.0 - 4.2 V (current density of 1.2 - 2.4 kA -m⁻²) and a fixed temperature of 70°C in the anolyte tank. Depending on the conditions, alkaline peroxide solution and sodium chlorate were cogenerated at peroxide current efficiency between 20% and 86%, chlorate current efficiency between 51.0% and 80.6% and peroxide concentration ranging from 0.069 M to 0.80 M. The cogeneration of the two chemicals was carried out at both concentrated (2.4 - 2.8 M) and dilute (0 - 0.5 M) chlorate solutions. A relative improvement on the current efficiencies at concentrated chlorate was observed. A chloride balance indicated negligible chloride loss to the catholyte. The results are interpreted in terms of the electrochemical and chemical kinetics and the hydrodynamics of the cell . / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Four commercially available methods used for the analysis of low-level Chlorine Dioxide (ClO2) concentrations in drinking water were evaluated for accuracy and precision and ranked according to cost, efficiency and ease of the methods under several conditions that might be encountered at water treatment plants. The different analytical methods included: 1.The DPD (N, N-diethyl-p-phenylenediamine) method 2.Lissamine Green B (LGB) wet-chemical method 3.Palintest® kit LGB 4.Amperometric titration All these tests were performed with standard 1.0 mg/L ClO2 either alone or in the presence of different chlorine species, including chlorite ion (ClO2-, 0.5 mg/L), chlorate ion (ClO3-, 0.5 mg/L) and chlorine (Cl2, 1.0 mg/L). The tests were performed with four different matrices, with different concentrations of 0.1 mg/L ClO2, 0.5 mg/L ClO2 and 1.0 mg/L ClO2 at a constant temperature of 20oC and at different temperatures of 0oC, 10oC and 20oC at a fixed ClO2 concentration of 1.0 mg/L. None of the four methods produced the desired level of either accuracy or precision. For all four methods, interference to the measured ClO2 concentration from the addition of ClO2-, ClO3-, and Cl2 was minimal when the methods were performed according to specifications. The Palintest® was the best all-round method because it was easy to perform, performed well at all concentrations tested, and its colored product was stable. The HACH® DPD method was also easy to perform and gave the best results when measuring concentrations of 1.0 mg/L ClO2. The DPD method was less accurate than the Palintest® at lower concentrations. The DPD colored product that formed upon reaction of ClO2 and DPD was unstable, making it necessary to measure the intensity of the colored product at exactly 1 minute. The amperometric titration and lissamine green methods were more cumbersome and time-consuming to perform than either the DPD or Palintest® methods; for this reason they are less desirable for routine use. / Master of Science

Chlorine dioxide (ClO₂) was included in the Spring Hollow Water Treatment Plant (Roanoke County, Virginia) to oxidize manganese and iron, prevent tastes and odors, and avoid the formation of excessive halogenated disinfection by-products. A state-of-the-art, gas:solid ClO₂ generation system manufactured by CDG Technology, Inc. was installed at the plant and is the first full-scale use of this technology in the world. The ClO₂ generator produces a feed stream free of chlorine, chlorite ion (ClO₂⁻), and chlorate ion (ClO₃⁻), resulting in lower by-product concentrations in the treatment system The objectives of this project were to study ClO₂ persistence and by-product concentrations throughout the treatment plant and distribution system and to evaluate granular activated carbon (GAC) columns for removing ClO₂⁻ from the finished water. The ClO₂ dosages applied during this study were relatively low (<0.75 mg/L), and, as a result, ClO₂⁻ concentrations never approached the maximum contaminant level (MCL) (1.0 mg/L). Likewise, the plant effluent ClO₂ concentration never approached the maximum residual disinfectant level (MRDL) (0.80 mg/L), but concentrations as high as 0.15 mg/L reformed in the distribution system by ClO₂⁻ reaction with chlorine. Chlorate ion was monitored despite the fact that no ClO₃⁻ MCL has been proposed, and concentrations were quite low (never greater than 0.10 mg/L) throughout the treatment plant and in the distribution system. The reasons for the low concentrations are that ClO₃⁻ is not produced by the gas-solid generator used at the facility and ClO₂⁻ concentrations in the clearwell prior to chlorination were uniformly low. The average ClO₂⁻ reduction upon passage of treated water through the GAC contactor was approximately 64 percent, but the GAC effectiveness was declining over the six-month study period. Apparently, GAC effectiveness, as shown by others, is short-lived, and if higher ClO₂ dosages are ever applied at the Roanoke County facility, the ClO₂⁻ concentrations will have to be reduced by either ferrous coagulants or reduced-sulfur compounds. Regenerated ClO₂ concentrations in the distribution system were below 0.2 mg/L, but concentrations as low as 0.03 mg/L were found at homes of customers who complained of odors. During this study, twelve complaints were received from eight customers, and each complainant had recently installed new carpeting, which has been shown to contribute volatile organics that react with ClO₂ to produce odors similar to kerosene and cat urine. While meeting the Cl₂ MCL likely will be no problem if the ClO₂ dose at the plant remains below 1.0 mg/L, the problem of offensive odors in the distribution system will likely continue as long as any ClO₂ is in the finished water when chlorine is present. / Master of Science

Microbial respiration of oxochlorates is important for the biotreatment of effluents from industries where oxochlorates are produced or handled. Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase, in the gram-negative bacterium Ideonella dechloratans. Both chlorate reductase and the terminal oxidase of I. dechloratans were found to utilize soluble c cytochromes as electron donors. For further investigation, two major heme-containing components were purified and characterized. The most abundant was a 9 kDa c-type cytochrome (class I), denoted cytochrome c-Id1. This protein was shown to serve as electron donor for both chlorate reductase, and for a terminal oxidase. The other major component was a 55 kDa homotetrameric cytochrome c', (class II). A function for this cytochrome could not be demonstrated but it does not appear to serve as electron donor to chlorate reductase. A gene predicted to encode a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. The predicted sequence did not match any of the cytochromes discussed above. The gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.