The effect of nitrite and nitrate concentrations on low F/M filament bulking in nitrogen removal activated sludge systems

Includes bibliography.Filamentous bulking and its associated poor sludge settleability is a considerable problem in South African activated sludge plants, as indicated by the two surveys undertaken on these plants in 1985 and 1988 (Blackbeard et al., 1986, 1988). Amelioration of this problem would enable a greater daily flow and load of wastewater to be treated by these plants. From the surveys it is apparent that bulking in long sludge age activated sludge plants is mainly due to the proliferation of the group of so-called low F/M filaments (as classified by Jenkins et al., 1984). In the course of a 4-year research program investigating specific bulking control methods, Gabb et al. (1989) concluded that the selector effect, which was proposed as a method for controlling low F/M filament bulking, was ineffective. This research also indicated that in fully aerobic systems low F/M bulking was ameliorated, but in intermittently aerated anoxic-aerobic systems low F/M filament bulking was promoted. The research presented in this thesis forms part of a follow-up bulking research program into low F/M bulking which led to the formulation of a bulking hypothesis by Casey et al. (1992b) and focuses on the effect of different anoxic-aerobic conditions and their effect on the concentration of nitrate and nitrite entering the aerobic zone/reactor in single intermittently aerated and multi-reactor nitrification-denitrification systems

Stroke in the young

CITATION: De Villiers, R. V. P., February, E. & De Villiers, M. L. 2003. Stroke in the young. South African Medical Journal, 93(11):836-837.The original publication is available at http://www.samj.org.za[No abstract available]Publisher’s versio

The Socio-Economic Benefit of the Livestock Traceability System on Communal Beef Farmers in Swaziland

In this article, Swaziland is placed in the forefront as a small African country that implemented a livestock traceability system to benefit both communal and commercial farmers. The communal farmers are also able to export beef to European countries, markers that were previously unavailable to them, due to the successful implementation of the Swaziland Livestock Information and Traceability System (SLITS).  Livestock traceability is briefly explained to align it with the importance of safe food production for human consumption and a few aspects are highlighted. The traceability systems is further explained in terms of its benefit to the rural economy, its role in growing the GDP and the realization of its aims as was initially expected by the Swazi Government. The data collection methods used were a document review, a case study and five interviews. It is concluded that livestock traceability systems should be adopted wider by other developing countries as it has a direct effect on the improvement of the socio-economic conditions of the rural poor. Its development and implementation remains very expensive, but Swaziland can be used as an example of a country that is able to reap the rewards from a commodity that is ample in their country, but scarce globally, leading to wider food sustainability

Occupational exposure to bloodborne viruses amongst medical practitioners in Bloemfontein, South Africa

Background The possibility of occupational exposure to bloodborne viruses such as HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) is an everyday reality to health care workers. This study reports on doctors' extent and outcome of exposure to bloodborne viruses in Bloemfontein. Methods A descriptive study was done. Doctors (n=441) actively involved in public and/or private medical practice were requested to anonymously complete a questionnaire regarding occupational exposure to bloodborne viruses (HIV, HBV, and HCV). Results A response rate of 51.7% was obtained. More than half (54.2%, 95% CI [ 47.7% ; 60.5% ]) of respondents were exposed to bloodborne viruses; 48.3% occurring with HIV positive patients and 4.3% with known HBV positive patients, and no positive HCV patients. After exposure occurred, 68.9% of patients were tested for HIV, 10.9% for HBV and only 4.2% for HCV infection. The frequency of serological testing for doctors immediately after exposure was 65.3% for HIV, 21.7% for HBV and 8.2% for HCV. No seroconversion to HIV or HCV was reported, while two seroconversions to HBV were reported. Most exposures occurred as a result of needle stick injury (85%) and occurred in the operating theatre during procedures 59.3%. The majority (59.8%) of exposed doctors did not take any prophylactic treatment and those who did, did not always complete the treatment Conclusions The risk of seroconversion to HIV after occupational exposure was as expected, while seroconversion to HBV was less than expected. The lack of adequate follow up serological testing after occupational exposure is alarming. It is the responsibility of the occupationally exposed doctor to adequately comply with prophylactic measures and undergo serological testing to ensure the least possible risk of contracting infection from a bloodborne virus. South African Family Practice Vol. 49 (3) 2007: pp. 1

Human papilloma virus and breast cancer

PubMe

Persistent pain following ankle sprain: Bilateral accessory soleus muscles

Persistent pain following ankle sprain remains a difficult diagnostic and management dilemma. We report a 22 year old rugby player who presented with a persistent painful left ankle following a minor ankle sprain. After examination and imaging investigations, a symptomatic accessory soleus muscle was diagnosed on the left ankle, and an asymptomatic accessory soleus muscle on the right

Inhibiting the Thermal Gelation of Copolymer Stabilized Nonaqueous Dispersions and the Synthesis of Full Color PMMA Particles

Polymeric particle dispersions have numerous potential applications; currently one of the most relevant is their use as inks in electrophoretic displays. These colloidal particles are synthesized from the appropriate monomer using nonaqueous dispersion (NAD) polymerization in a nonpolar solvent, which requires a stabilizer to control particle size and morphology. We have previously reported the facile synthesis of poly(methyl methacrylate)-block-poly(octadecyl acrylate) (PMMA-b-PODA) by atom transfer radical polymerization (ATRP), and its use in the NAD polymerization of MMA in hexane/dodecane solvent mixtures. Here we report the synthesis of monodisperse PMMA particles in dodecane following a standard “industrial” procedure using these PMMA-b-PODA stabilizers. However, it was observed that the particle suspensions solidified when they were left at temperatures below ?18 °C yet redispersed upon being heated. Differential scanning calorimetry, dynamic light scattering, and rheological studies demonstrated that this thermoresponsive behavior was due to a liquid–gel transition occurring at 17.5 °C as a consequence of the upper critical solution temperature of PODA in dodecane being traversed. Consequently, new copolymers were synthesized by ATRP with an ethylhexyl acrylate (EHA) co-monomer incorporated into the lyophilic (dodecane compatible) block. Dispersions stabilized by these PMMA-b-P(ODA-co-EHA) polymers with high EHA contents exhibited lower gelation temperatures because of the greater solvent compatibility with dodecane. The use of a PMMA65-b-(ODA10-co-EHA45) copolymer stabilizer (with the highest EHA content) gave PMMA dispersions that showed no gelation down to 4 °C and monodisperse cross-linked PMMA particles containing organic dyes (cyan, magenta, red, and black) giving colored particles across the size range of approximately 100–1300 nm

Experiments on sedimentation in wide reservoirs and erosion following dam removal

River morphodynamics and sediment transportSedimentation in reservoir