Aerosol particle deposition rates on surfaces inside a clean room are predicted by a model developed to account for particle convection, diffusion and sedimentation. External forces acting on the particle also influence the rate of deposition. Both electrical charge build up on product surfaces and temperature gradients in the air near the product surface are known to effect the rate of deposition. A description of an electrostatic and thermophoretic force on the particle is thus included in the model. The equations governing the particle deposition process and the approach used in obtaining a solution to these equations are both described. A finite element numerical solution is detailed, followed by a description of the electrostatic force models. Finally, predictions of the model are presented with a comparison to data experimentally obtained by other researchers.

Master of Science / Department of Grain Science and Industry / Leland McKinney / Carryover of medicated feed additives between batches of feed can potentially result in harmful drug residues in the edible tissues of food-animals. Flushing the equipment with an ingredient, such as ground grain, is one method used to remove any residual medicated feed from the system. It is generally recommended that the quantity of flush used be between 5 and 10% of the mixer's capacity. However, there is little data that supports this recommendation. Therefore, two experiments were conducted to 1.)determine which manufacturing equipment is the major source of carryover, 2.)evaluate which flush size adequately prevents drug carryover, and 3.) quantify the interrelationship between flush size and drug concentration. In Experiment 1, feed medicated with nicarbazin (Nicarb 25%®; 0.0125%) was manufactured and conveyed from the mixer, through a drag conveyor and bucket elevator, and then into a finished product bin. The system was then flushed using ground corn in the amount of 2.5, 5, 10, 15, or 20% of the mixer's capacity (454.5 kg). Subsequently, a non-medicated diet was conveyed through the system and samples were collected and analyzed for nicarbazin. No significant (P > 0.05) differences were detected among the flush treatments, and all treatments were effective in preventing nicarbazin carryover to the non-medicated diet. In Experiment 2, feed medicated with three levels of monensin (Rumensin® 80; 100, 600, and 1,200 g/ton) was manufactured and handled in the same manner as in Experiment 1. The flushing treatments examined were: 1, 2.5, and 5% of the mixer's capacity. Samples of the non-medicated diet for each treatment were collected and analyzed for monensin. There was significant interaction (P < 0.05)between drug level and sampling location between treatments. As the drug level in the medicated diet increased, higher concentrations of monensin were detected in the non-medicated diet. Collectively, these studies demonstrate that a 2.5%, even a 1% flush size, is effective in preventing carryover of medicated feed additives. It was also demonstrated that the bucket elevator and finished product bin were the major sources of drug carryover in this particular feed manufacturing system.

Master of Science / Food Science Institute-- Animal Science & Industry / J. Scott Smith / Ammonia leaks in meat chilling/frozen storage or processing facilities are not uncommon. Often the meat products are packaged in polymer films that theoretically protect the product from contamination. Unfortunately, there is almost no data on whether ammonia can permeate packaging films. The objectives of this study were to evaluated meat contaminated by low levels of ammonia under frozen storage conditions (-17 ± 3[degree]C), and further evaluated the permeability of common meat packaging films including: low density polyethylene (LDPE), 3 mil Cryovac (E-2300), and 3 mil vacuum (V-PA/PE) at freezing (-17 ± 3 [degree]C) and room temperatures (21 ± 3 [degree]C). Fresh beef Semitendinosus muscles were fabricated to form 10 x 5 x 2.3 cm steaks. The packaging films were fabricated into 10 x 5 cm pouches and filled with 50 mL deionized water. The meat and the pouches were exposed in a plexiglass enclosure, contained in a freezer, to 50, 100, 250, and 500 ppm ammonia gas (85 mL/min) for exposure times of 6, 12, 24, and 48 hr. The ammonia levels in the meat samples were 34.2 (50 ppm exposure), 51.5 (100 ppm exp.), 81.1 (250 ppm exp.), and 116 ppm (500 ppm exp.), and the pH values ranged from 5.56 to 5.75 (control ranged from 5.31 to 5.43) at 48 hr. At freezing temperatures, ammonia residues remained undetected, and no differences in pH were found in the pouches. At room temperature, all pouches were slightly permeable to ammonia; the levels observed in the pouches were, 7.77 ppm (pH, 8.64) for E-2300, 5.94 ppm (pH, 8.38) for LDPE, and 0.89 ppm (pH, 7.23) for V-PA/PE at 500 ppm exposure for 48 hr (unexposed samples pH ranged from 5.49 to 6.44). The results showed that meat packaging materials have low ammonia permeability and thus protect meat products exposed to ammonia exposure during frozen storage. Moreover, meat content is low even with ammonia exposures as high as 500 ppm for up to 48 hr.

Master of Science / Department of Biological & Agricultural Engineering / Naiqian Zhang / Four permittivity probes have been developed and tested to measure contaminants in water and in biodiesel fuel. An impedance meter was also used to measure the same contaminants. The pollutants measured in water were nitrate salts (potassium nitrate, calcium nitrate, and ammonium nitrate) and atrazine. The contaminants measured in biodiesel were water, glycerol, and glyceride. Each sensor measured the gain and phase of a sample with a known concentration of one of these pollutants. The resulting signals were analyzed using stepwise regression, partial least squares regression, artificial neural network, and wavelet transformation followed by stepwise regression to predict the concentration of the contaminant using changes in the gain and phase data measured by the sensor. The same methods were used to predict the molecular weight of the nitrate salts. The reliability of the probes and the regression methods were compared using the coefficient of determination and the root mean square error. The frequencies selected using stepwise regression were studied to determine if any frequencies were more useful than others in detecting the contaminants. The results showed that the probes were able to predict the concentration and the molecular weight of nitrates in water very accurately, with R2-values as high as 1.00 for the training data and 0.999 for the validation data for both concentration predictions and molecular weight predictions. The atrazine measurements were somewhat promising, the training R2-values were as high as 1.00 in some cases, but there were many low validation values, often below 0.400. The results for the biodiesel tests were also good; the highest training R2-value was 1.00 and the highest validation R2-value was 0.966.

Background : The sources and the epidemiology of Campylobacter jejuni (CJ) in environmental water are not well understood. We developed a spatial analysis methodology able to identify the main environmental factors predicting the presence and quantity of Campylobacter in river water. Methods : For two years, water samples were collected weekly and scanned for CJ and fecal coliforms at 32 sampling sites of Estrie hydrographic network, Québec. The quantity of CJ in water was estimated using the Most Probable Number method (MPN). The 32 sampling sites were linked to their catchment area; 10 of them were excluded from the analysis, because their hydrographic basin was not independent from the other sites. For each site, the following environmental variables were included: Water flow, slope, land-cover, land-use including type of farming, animal density, total precipitation in the 3 days prior to water sampling. A stepwise multivariate regression was realized across the different analysis windows to define the size of the area upstream from the sampling sites (from 1.5 to 24 km) which was the most closely associated with the mean quantity of CJ, and which environmental factors were associated with a higher mean quantity of CJ in water. Results : Preliminary results show that an area defined by a radius of 14 km upstream of the sample site was the most contributing zone for the bacteria (r2=0.38, p=0.002). Within this 14 km area, the only significant variable associated with a higher mean quantity of CJ was bovine density (p=0.002). When analyzing the data within a 120 m buffer zone across 14 km upstream of the sampling sites (r2=0.40, p=0.001), the only significant variable associated with a higher mean quantity of CJ was the percentage of agricultural surface (p=0.001). Conclusions : These results suggest a strong implication of bovine density in conjunction with crops and associated manure spreading on the quantity of CJ in environmental water.

It is common knowledge that water is one of the basic needs for human beings. However, the consumption of contaminated water can lead to waterborne diseases and fatalities. It is, therefore imperative to constantly monitor the quality of potable water. There are numerous technologies used for water quality monitoring. These technologies are relatively effective however these tests are expensive and complex to use, which then require experienced technicians to operate them. Other tests are not rapid, making consumers of water susceptible to waterborne diseases. In this study, dye-doped, surface functionalized silica nanoparticles (SiNPs) and surface-functionalized magnetic nanocomposites (MNCs) were proposed as materials that can be applied in order to reduce the time taken to get results as well as to make the processes less complex and portable. The aim of this study was to synthesize and characterize surface functionalized dye-doped SiNPs and surface functionalized MNCs for detection and preconcentration of in water. Additionally, proof of concept had to be shown using the synthesized materials. SiNPs were the materials of choice due to their easily functionalized surfaces and their strong optical properties. SiNPs are photostable and they do not leach in solution due to the inert nature of the silica matrix in aqueous media. MNCs were chosen as materials of choice for preconcentration of E. coli in water because they are easy to synthesize and they can be applied in various biological applications due to their functional groups. SiNPs were synthesized using the water-in-oil microemulsion. The SiNPs were further functionalized with amine and carboxyl groups and avidin. Thereafter, they were bioconjugated with biotinylated anti-E. coli antibodies. The pure and surface functionalized SiNPs were characterized using ATR-FTIR spectroscopy, FE-SEM, HR-TEM, Zeta Sizer, UV-vis spectroscopy and spectrofluorometry. The application of the dye—doped surface functionalized SiNPs in E. coli detection was characterized using the fluorescence plate reader. The SiNPs were spherical and uniform in size. They increased in size as they were being functionalized, ranging from 21.20 nm to 75.06 nm. The SiNPs were successfully functionalized with amine and carboxyl groups as well as with avidin and antibodies. Two methods were investigated for carboxyl group attachment (direct and indirect attachment) and the direct attachment method yielded the best results with a surface charge of -31.9 mV compared to -23.3 mV of the indirect method. The dye loading was found to be 1% after particle synthesis. The optical properties of the Ru(Bpy) dye were enhanced 3 fold when they were encapsulated in the Si matrix. The SiNPs were binding to the E. coli cells and enabled detection. MNCs were synthesized through in-situ polymerization. The MNCs were characterized using ATR-FTIR spectroscopy, SEM, TEM and XRD. The MNCs were successfully functionalized with carboxyl groups. The increase in size of the nanocomposites as seen in SEM images proved that the Fe3O4 was successfully encapsulated in the polymer matrix. The MNCs were proven to be magnetic by a simple magnetism test whereby they were separated in an aqueous solution using an external magnetic field. The antibody-labelled MNCs were binding to the E. coli cells as shown in TEM images. E. coli cells were removed from water at varying concentrations of 1x106 CFU/mL to 1x109 CFU/mL at 10 mL volumes. This study has demonstrated that dye-doped SiNPs amplify the signal of E. coli cells using fluorescence. The study has also demonstrated that the MNCs can be applied in sample preconcentration and enrichment for E. coli detection. However, further studies should investigate and optimize the combination of the two techniques in a point of use device for water quality testing of 100 mL-samples as per the requirement of the SANS 241 standard. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

Owing to their non-selective nature, anti-cancer drugs affect both cancerous and non-cancerous cells and present a major health risk to healthcare staff working with them. This project was conducted at Derriford Hospital, Plymouth, to investigate the extent of contamination with anti-cancer drugs on work surfaces and the environmental emissions of these drugs. In the Isolator study, surface contamination arising from the preparation of five anticancer drug infusions (epirubicin, fluorouracil, cisplatin, oxaliplatin and carboplatin) in a pharmaceutical isolator and external surfaces of infusion bags and syringes using a conventional syringe and needle technique was investigated and compared with that obtained using a closed system drug transfer device (Tevadaptor). Wipe samples were taken for a period of one week from pre-defined areas in a pharmaceutical isolator and from the surface of prepared Intra-Venous (IV) infusion bags and pre-filled syringes to obtain baseline data. Gloves and preparation mats used during this period were also collected. Following a one-week operator familiarisation period, the Tevadaptor device was then introduced for cytotoxic preparation and wipe-sampling of surfaces and collection of consumables was continued for a further week (intervention period). The samples obtained were then analysed by HPLC and ICP-MS. The baseline contamination data from Tevadaptor isolator study was undetected to 0.9 ng cm-2 (epirubicin), undetected to 3.58 ng cm-2 (5-FU) and 0.05-0.92 ng cm-2 (Pt) in the wipe samples from the pharmaceutical isolator surfaces; amounts on glove samples were 1100-6100 ng/glove (epirubicin), 300-8100 ng/glove (5-FU) and 1-6 ng/glove (platinum). During the intervention phase isolator surface contamination was not detected in all samples for 5-FU and epirubicin and platinum was detected on the isolator surfaces in the range of 0.002-0.09 ng cm-2. The use of Tevadaptor resulted in a reduction of contamination on external surfaces by a factor of 10 or more for all marker drugs. A ward study investigated the surface contamination in the oncology out-patient department caused by cisplatin, oxaliplatin, carboplatin and gemcitabine. The study compared the effect of using the Tevadaptor to prepare and administer anticancer drugs infusions on ward surface contamination to the current UK standard practice. A questionnaire was also distributed to participating staff members to assess the user-friendliness of Tevadaptor. Wipe samples were taken from pre-defined areas from the oncology out-patients department and gloves used by nursing staff for assembly and administration of the above drugs were also collected. Sample collection followed a similar schedule to the Tevadaptor isolator study. The baseline ward surface contamination ranged from undetected to 4.97 ng cm-2 (gemcitabine) and 3.1 ng cm-2 (platinum). In the case of gloves used by nursing staff the levels of contamination ranged from undetected to 1251 ng/glove (gemcitabine) and 405.4 ng/glove (platinum). The contamination on ward surfaces during the intervention phase ranged from undetected to 3.21 ng cm-2 (gemcitabine) and 2.69 ng cm-2 (platinum) and contamination levels on gloves ranged from undetected to 9252 ng/glove (gemcitabine) and 1319 ng/glove (platinum). During the intervention phase there was a reduction in frequency of contamination, even though the total amount of surface contamination by anticancer drugs did not always decrease in comparison to baseline data, presumably due to unaccounted spillages. A drain study investigated the presence of platinum in hospital wastewater as a measure of contamination caused by the excretion of platinum-based anticancer drugs by patients. Platinum was measured over a three week period in one of the main drains and in the effluent of the oncology ward. The study showed the presence of measurable quantity of platinum which ranged from 0.02 to 140 μg L-1 in the oncology effluent and 0.03 to 100 μg L-1 in the main drain. Data from this study was coupled with published measurements on the removal of the drugs by conventional sewage treatment and then concentration of platinum arising from each drug was predicted in recipient surface waters as a function of water flow rate. Although predicted concentrations were below EMEA guidelines warranting further risk assessment, the presence of potentially carcinogenic, mutagenic and teratogenic substances in surface waters is cause for concern. The results showed that a closed system drug transfer device (CSTD) used in conjunction with an isolator is highly efficient in reducing surface contamination with anti-cancer drugs. However, despite current best practice contamination on ward surfaces remained even after the use of a CSTD. Nursing as well as healthcare staff should be educated of these results and the risks of occupational exposure to low levels of anti-cancer drugs and the use of PPE should be emphasised. Results of the drain study form the basis of preliminary estimates of the likely concentrations of platinum-based drugs in surface waters and their potential environmental impacts.

The pervious pavement system has been identified as an effective source control device capable of removing urban stormwater pollution by trapping pollutants within the system and biodegradation. Recent studies have further demonstrated that the pervious pavement system could be used as a source of renewable energy capable of reducing household energy bill by about 80%. In view of ever increasing demand for water and the continued reduction in available fresh water resources in the world, stormwater has been recognized as a potential valuable source of water which could be harnessed. The overall aim of this multi disciplinary research was to evaluate the suitability of a modified pervious pavement system (PPS) for water harvesting and re-use, particularly focussing on potential third world applications and taking advantage of the latest developments in materials that are available for such applications. The aim was a holistic one in which water re-use was examined in terms of both the potential advantages from an irrigation point of view without ignoring the very important public health concerns that are often of concern when water is stored in circumstances which do not fit the normally used criteria for potable supplies. The results of this study confirmed the pollution control capability of the porous pavement system as earlier determined by previous studies. Also, a novel experimental rig was designed to reproducibly create very high and realistic rainfall events over model pavement structures. Furthermore, the performance of a new geotextile, Inbitex Composite® in the pervious pavement system was determined for the first time. Furthermore, this study also tested for the first time, the performance of a pervious pavement system modified by the incorporation of Inbitex Composite® geotextile with slits and made prescriptions as to how this new geotextile could be best installed in a modified pervious pavement system in order to achieve high infiltration without compromising pollution control. This study tested the practical use of the pervious pavement system for water harvesting and storage for reuse in irrigation. In order to achieve this, the author took what could be considered as a holistic approach to water quality issues and determined the chemical, electrochemical and microbiological quality of water stored in the system as well as investigated the public health concern of the potential of pathogenic organisms in waters stored in unconventional water storage system as the pervious pavement system. It also determined that the pervious pavement system have the capability to recycle water with physical, chemical and microbiological qualities that will meet international standards for irrigation and that the system does not offer a conducive environment for potential pathogenic organisms if contamination incident occurs from adjoining areas. This study also became the first to practically relate Sustainable Urban Drainage System (SUDS) to agricultural benefit by demonstrating how a SUDS device (pervious pavement system) could be used in addition to its urban drainage control role, as a source of supply of high quality irrigation water to cultivate crops fit for human and animal consumption despite high application of pollutants. This study determined contrary to the observation of earlier studies that the use of slow-release iv fertilizer could lead to eutrophication problems in cases where the water is channeled to natural water courses. Furthermore, active response of potential pathogenic bacteria to the presence of slow-release fertilizer was observed in this study. This raises a huge question on the need to add fertilizer to the pervious pavement system. Coupe, (2004) had demonstrated that oil degrading microbes would respond positively to food sources in the system and hence, there was no significant need for simulation by nutrient addition, the author concluded in the study presented here that fertilizer addition should only be conducted if the waters are to be used for irrigation where the nutrients would be beneficial to the plants and that even in this case, the microbiological water quality should be constantly monitored and the addition suspended if the risk of contamination from adjoining areas is high.

Dirt ingress in hydraulic cylinders is one of the sources that leads to pollution of hydraulic systems. There are already several test rigs to investigate external contamination mechanisms. However, until now only the behavior of the whole sealing system was analyzed. A new testing method to understand the dirt particle transport between a reciprocating motioned rod and a wiper is presented. The new approach aims to avoid known issues such as limited reproducibility and long duration. The paper describes the test rig design and operating principle. First measurement results are shown.

Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming