Thesis (doctoral)--Philipps Universität Marburg/Lahn. / Includes bibliographical references (p. 307-314).

The current research relates to a system driven by renewable energy and chemical energy contained in the feed, which will eliminate and reduce pathogens found in human excreta. A project in the form of an experiment for demonstration will be designed and built to operate in the local waste water treatment plant. Data will be analyzed and recorded, including fecal coliforms and E.coli levels, chemical oxygen demand (COD) and total solids removal (TS). The effectiveness of the system will depend upon results obtained and weather conditions. The principal objective of the research is to test and demonstrate that the "Small Decentralized ATAD" is successful in removing/eliminating enteric pathogens found in human excreta. Most importantly, the Bill and Melinda Gates Charity Foundation is providing financial support (Grants) for new sanitation ideas to help developing countries overcome diseases, specifically water borne diseases and also diseases related to hygiene and sanitation. Moreover, the "Water, Sanitation & Hygiene: Grand Challenges Explorations" granted a $100,000 Grant to Professor James Blackburn from Southern Illinois University at Carbondale in the Mechanical Engineering and Energy Processes Department. Consequently, the "Decentralized Next Generation for Diarrheal Pathogens" project will be tested using the ATAD (Autothermal Thermophilic Aerobic Digestion) to demonstrate its effectiveness in pathogen reduction and elimination.

Ozonation of drinking waters containing algae sometimes has a beneficial effect on the process of coagulation. It is hypothesized that the extracellular organic matter (EOM) from the algae affects the flocculation process. The effects on algal particle stability and flocculation due to ozonation and the role of EOM were investigated. Four species of algae were cultivated and EOM from the algae extracted. Scanning electron micrographs (SEMs) of the algae indicated little cell lysing for ozone doses of 3 mg/L or less. Extensive cell wall alteration was observed. Lysis of algae cells was prominent at 8 mg/L ozone. Ozonation decreased the algae volume concentrations and cell sizes. Cyclotella and Scenedesmus produced ten times as much EOM per unit cell number than Chlorella. The EOM of Cyclotella and Scenedesmus was also of higher molecular size than that of Chlorella. Increasing the ozone dose to extracted EOM and alginic acid, a model EOM compound, resulted in decreasing molecular size, colloid charge and increasing hydrophilicity and functional group charge. Bench scale jar tests and flocculation kinetic experiments were performed. Ozonation was not effective in decreasing the polymer dose required to coagulate the algae. However, ozonation improved overall removals of Scenedesmus, Cyclotella and Synura. Ozonation also increased the flocculation rate of Scenedesmus and Cyclotella, but had a detrimental effect on the rate for Chlorella. Increasing calcium (up to 30 mg/L as CaCO$\sb3$) and ozone dosage increased the flocculation rate of Scenedesmus. Natural waters spiked with Cyclotella and Synura showed an increased flocculation rate upon ozonation.

Disinfection may cause a dilemma for drinking water treatment plants using chlorine for the maintenance of a disinfectant residual in distribution systems. On one hand the chlorine residual should ensure microbially safe drinking water, but on the other hand harmful disinfection by-products (DBPs) can be formed from the reaction of natural organic matter (NOM) with chlorine. Many utilities are looking to the combined use of ozonation for primary disinfection, followed by chlorine or chloramines as a means of minimizing DBP formation while maintaining a stable disinfectant residual. However, these combinations may lead to a new spectrum of by-products that differs from that produced when a single disinfectant is used. The formation of mixed ozonation/chlorination and ozonation/chloramination by-products is the subject of this dissertation. A diverse collection of precursor compounds that produce a large amount of “unknown” total organic halides (TOX) was identified by performing bench scale tests to simulate chlorination of known ozonation by-products. Simple mono- and di-carboxylic acids were not found to react with chlorine. Di-aldehydes, α-keto-acids, and α-hydroxy-acids are oxidized by chlorine but do not show TOX formation. However, chlorine does become incorporated in β-diketones. Oxalacetic acid, 3-methyl-2,4-pentanedione, acetonedicarboxylic acid, and malic acid were found to form more “unknown TOX” than common chlorination by-products. Usually, the chlorine demand as well as the TOX increase with decreasing pH and increasing chlorination time. The identification of “unknown TOX” was the second major goal of this work. Quenched samples from the model compound studies were derivatized with pentafluorobenzylhydroxylamine (PFBHA), extracted with methyl-tert-butyl-ether (MtBE), and silylated with bis-(trimethylsilyl)-triflouroacetamine (BSTFA). Malic and acetonedicarboxylic acids were each found to produce a previously-unknown byproduct after reacting with chlorine. The identity of this and other new by-products was suggested based on the mass spectra. Surprisingly, mono-chlorinated species were found to be more abundant than di-chlorinated species in all cases. The third phase of this research showed that a substantial amount of “unknown TOX” is also formed in distribution systems where chlorine is used as final disinfectant. The “unknown TOX” ranged between 60% and 80% of the measured TOX.

Water utilities in the U.S. and Europe are investigating a wide range of treatment process improvements to meet more stringent water quality regulations (e.g., the U.S. D/DBP Rule). A relatively new process that has shown promise is catalytic ozonation, the use of a metal catalyst in conjunction with ozone. Laboratory-scale experiments were performed using a stirred batch and semi-continuous ozonation apparatus to study the catalytic ozonation process. Initial experiments were designed to evaluate dissolved metal ion assisted ozonation of oxalic acid at pH 6. The catalytic properties of dissolved cobalt (II) were subsequently studied in more detail. The results suggested that the first step in the catalytic ozonation reaction pathway is the formation of a cobalt (II) oxalate complex. Cobalt (II) oxalate is then oxidized by ozone. Further experiments showed that the rate of cobalt (II) assisted ozonation of oxalic acid increased with decreasing pH over the pH range of 5.3 to 6.7. The dissolved cobalt (II) studies provided the basis for understanding the catalytic properties of cobalt (II) oxide. It is anticipated that solid phase catalysts have more practical applications than dissolved catalysts in water treatment. The catalytic reactivity of two model di-carboxylic acids, oxalate and malonate, were compared in a series of laboratory experiments. In-situ attenuated total reflectance infrared spectroscopy indicated that oxalate formed an inner sphere complex and malonate formed an outer sphere complex with cobalt (II) oxide. Catalytic ozonation was evaluated for removal of pCBA, a non-adsorbing model micropollutant that does not react directly with molecular ozone. Cobalt (II) oxide and a mixed metal oxide (copper and zinc oxide with a calcium aluminate binder) either did not change the removal or they inhibited the removal of pCBA in deionized water compared to ozone alone. Alumina supported ruthenium also accelerated the removal of pCBA from a natural water, but it may follow a different catalytic reaction pathway. (Abstract shortened by UMI.)

This study investigated the influence of growth rate and glass slide preparation on bacterial attachment and biofilm development over time for methane-forming, anaerobic, mixed, microbial cultures. Photomicrographs and microscopic observations were also recorded. An anaerobic attachment vessel was designed, constructed, and used to quantify and visualize the initial attachment and biofilm development of chemostat grown bacterial cultures. The bacteria attached rapidly to washed/autoclaved glass slides. Within one to three hours, the number of irreversibly attached bacteria increased by approximately two orders of magnitude from 0 to 100-250 bacteria per 10,000 square micrometers. Only a slow increase in the number of attached bacteria was measured after the initial rapid increase. The counts of total bacteria after one week of inoculation were in a range of 250 to 450 bacteria per 10,000 square micrometers. No statistically significant difference was noted in the pattern of attachment for 8 days solids retention time (SRT) and 20 day SRT cultures. Two mathematical models were developed to describe the results. A significant percentage, usually 25%-75%, of the bacteria counted on the washed/autoclaved slides were methanogens. Final step autoclaving in the slide wash procedure had a statistically significant effect on attachment. Irreversibly attached bacteria counts on washed/unautoclaved slides over time were one half to one and one half orders of magnitude lower than the corresponding counts for washed/autoclaved slides. Scanning electron microscopy showed some cells do, and some do not, possess conspicuous appendages or extracellular fibers which appear to be used for attachment. At long inoculation times, more extensive development of extracellular fibers was observed sometimes and more amorphous, extracellular, gluelike material was present. Occasionally, extracellular fibers were observed to branch at longer inoculation times. Tip growth was proposed to account for this observation. At short and long inoculation times, cells attached as individuals and in clumps. The clumps were covered and/or interspersed with the gluelike material. Some clumps and individual cells appeared to have a ring around them, perhaps the secretion of extracellular polymers or enzymes. Higher concentrations of attached bacteria were sometimes observed on surface irregularities.

The development of high rate anaerobic processes has reached a point where there is a need for better monitoring and control strategies. The general objective of this research was to evaluate the potential of headspace gas monitoring and control of fixed-film anaerobic digesters. Laboratory-scale fixed-film anaerobic digesters treating a synthetic soluble carbohydrate waste were used. Trace gases, hydrogen and carbon monoxide, and final gases, methane and carbon dioxide, were monitored on-line. The effects of liquid recirculation on the rate of gas transfer from the generation site to the headspace of the reactor were evaluated. It was found that liquid recirculation rates do not affect mass transport rates significantly. Gas transport was primarily taking place by rising bubbles. Methane and carbon dioxide were transported from the bubbles to the surrounding liquid, whereas hydrogen was transported from the liquid to the bubbles. The rate of substrate uptake by the biofilm was significantly affected by liquid recirculation rates. The responses of trace gases to toxic stress by cadmium and formaldehyde were evaluated. Trace gases proved to be sensitive indicators of toxic stress. Comparison with previous studies revealed that fixed-film digesters were several times more resistant to toxicity than suspended-growth digesters. Adaptation to formaldehyde was fast and degradation of the compound was consistently observed. On-line control of effluent COD concentration using headspace parameters was possible when changes in influent strength were imposed to the system. A new parameter for digester monitoring was proposed in this study. The new parameter was named the methanogenic activity index, MAI. The MAI provides a simple criterion to determine when the reactor is reaching its maximum loading rate and also, provides a clear signal of the occurrence of toxicity events in the process.

Thesis (M. Dev.) --University of Limpopo, 2016 / The purpose of this study was to investigate the social factors that affect the acceptability of the Enviro Loo sanitation technology in schools. The study adopted the anti-positivism theory. Phenomenology school of thought was used as one of the three schools of thoughts as marked under Anti-positivism. The qualitative research method had its foothold in the fact that social factors, as a human activity, occurs in a particular natural and social environment. Utilising the qualitative research design, the researcher focused on describing and understanding the social factors that influence the acceptability of the Enviro Loo sanitation technology at schools. The study utilised an interview guide to collect data. The advantage of this is that it allowed the researcher to probe and ask for clarification of some answers as given by the respondents The population of this study comprised 35 secondary schools in Limpopo Province that benefited from the implementation of the Enviro Loo sanitation technology system during the 2010/11 financial years. Non-probability sampling was used. The method used to select the schools was convenience sampling as a non-probability sampling technique where subjects are selected because of their convenient accessibility and proximity to the researcher. This is because the researcher was bound by time, money and workforce and because of these limitations, it was almost impossible to randomly sample the entire population. Three sets of focus groups were used as sample, namely; the Provincial Sanitation Task Team (PSTT), School Governing Body (SGB) and Leaner’s Representative Council (LRC). All groups were gender balanced and members participated voluntarily. Nvivo was utilised to analyse data. The audio recordings from the digital voice recorder were transcribed, translated into English, typed into word and thematic analysis was used.

The effects of initial thermal processing, plant sanitation, and employee habits on the microbiological quality of blue crab (Callinectes sapidus) meat were determined in a commercial crab processing facility. Thermal processing was evaluated at 5, 7, and 8 minutes at 250ï °F for the destruction of microorganisms, including Listeria monocytogenes. F-values calculated indicated a sufficient reduction of L. monocytogenes at each processing time. Fresh picked crab meat was evaluated for microbial levels when exposed to ambient temperatures over a four hour period. It was found that time and temperature did not influence the microbial populations significantly except in the fourth hour. Plant sanitation was evaluated based on levels of adenosine triphosphate (ATP) and microbial counts. Areas found to have high levels of ATP typically had low microbial counts, thus suggesting that crab meat residual was the problem. The presence of Listeria species in the plant was determined using a commercial polyclonal antibody test. Listeria species were found under picking tables, on cooler doors, employees' aprons, and on several employees' hands. In a laboratory setting, an automated hand wash was compared with a manual hand wash for the removal of Listeria innocua, as a model for Listeria monocytogenes. It was found that a manual hand wash of 15 seconds was superior to an equal time automated wash. The microbial quality of crab meat was found to be affected by daily plant procedures, and could be changed by modifying procedures. / Master of Science

A dissertation Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Master of Science. 12 July 2017. / The mapping of mines, both operational and abandoned, is a long, di cult and occasionally dangerous task especially in the latter case. Recent developments in active and passive consumer grade sensors, as well as quadcopter drones present the opportunity to automate these challenging tasks providing cost and safety bene ts. The goal of this research is to develop an autonomous vision-based mapping system that employs quadrotor drones to explore and map sections of mine tunnels. The system is equipped with inexpensive, structured light, depth cameras in place of traditional laser scanners, making the quadrotor setup more viable to produce in bulk. A modi ed version of Microsoft's Kinect Fusion algorithm is used to construct 3D point clouds in real-time as the agents traverse the scene. Finally, the generated and merged point clouds from the system are compared with those produced by current Lidar scanners. / LG2018