Effects of diffuse effluents from Botshabelo on the microbiological quality of water in the Modder River

ThesisThe value of selected indicator micro-organisms for assessment of faecal pollution of water, as well as the distinction of faecal pollution of animal or human origin of pollution, has been investigated. The following indicators were included: faecal coliform bacteria, faecal streptococci, sorbitol-fermenting bifidobacteria, Rhodococcus coprophilus, somatic and male-specific coliphages and phages of Bacteroides tragilis. Comparative tests were carried out on water samples collected from a stream and river, and their respective catchments, exposed to predominantly faecal pollution of domestic animal origin. The same stream and river with catchments, were sampled after downstream exposure to run-off from a low socioeconomic developing settlement with restricted sanitation. Samples were collected from perennial flow in the stream and river during the dry season and from storm water run-off during general rain and immediately after thunder storms. Storm water run-off reached faecal coliform counts of up to 4 400 000 per . 100 ml, which is equivalent to that of many sewage effluents. Faecal pollution of the aquatic environment was less during the dry season. Sorbitol-fermenting bifidobacteria were identifiable with faecal pollution of human origin, and R coprophi/us with that of animal origin. Male specific coliphages were identifiable with sewage pollution as well as general faecal pollution of water. Certain selected ratios for the indicator organisms indicated possible distinction between faecal pollution of human origin and faecal pollution predominantly of animal origin under certain circumstances. Phages of B tragi/is were not detected in any of the samples, which implies that their application in this situation would require more sensitive techniques. The results show that the run-off from the developing settlement constituted a major source of pollution for a river catchment which downstream is used as a source of water for human consumption and that faecal pollution of human and animal origin can reliably be distinguished by means of combinations of appropriate indicators

Applying an abbreviated hazard analysis and critical control point programme to evaluate the effectiveness of two potable water treatment systems to remove health-related contaminants

ThesisThe abbreviated HACCP (Hazard Analysis and Critical Control Point) programme applied in this study comprised mostly of a health-related microbiological hazard analysis together with the use of critical performance limit targets (CPL Ts) to assess the effectiveness of treatment system components at two drinking water treatment facilities. The hazard analysis was based on the occurrence of total coliforms and faecal coliforms, both of which are health-related microbiological indicator organism groups. Turbidity was used to assess the effectiveness of the treatment components to produce quality of drinking water that would comply with national water quality guidelines. Turbidity testing was also included in this study to augment microbiological hazard analyses with the understanding that if turbidity levels were reduced to sufficient levels, microorganisms would also be reduced - an approach which could have offered the treatment facility manager a quick test option in lieu of microbiological testing. The raw river water used for drinking water treatment at both treatment facilities complied with the raw water extraction guidelines proposed for this study. The same was observed of the treated end-product, namely treated potable water. The end product complied with national health-related drinking water guidelines, which indicated that the designs of the selected treatment facilities were well planned and managed. To determine the effectiveness of the treatment components (known as critical control points (CCPs)), a set of critical performance limit targets (CPL Ts) was compiled for this study since such targets were not available at the treatment facilities. The premise was that if the CCP complied with the CPL T, the process was effective and thus functioning properly. Most of the health-related indicator results complied with the target CPL Ts. When comparing sedimentation from both treatment facilities, it appeared that this process within the Mazelspoort treatment faci lity functioned more effectively in reducing the health-related indicator levels than the sedimentation process at the Rustfontein treatment facility. The CPL T for sedimentation is 90% removal for the microbiological indicators and 85% removal for turbidity. Sedimentation at the Rustfontein treatment facility could not reduce any of the indicators used in this study to comply with the CPL Ts. It reduced only 87% of the total coliforms, 89% of the faecal coliforms and 45% of turbidity received from the raw water extraction point. The filters at the Rustfontein treatment facility under-achieved in the reduction of the indicator organisms, while the filters at Mazelspoort seemed to perform effectively with only occasional under-achievement in the reduction of faecal coliforms. The filters at the Rustfontein treatment facility failed to reduce the numbers of total coliforms to the required CPL T. They only reduced 41% (CPL T of 99%) of the total coliform load received from sedimentation, placing pressure on the chlorination stage to reduce the remaining organisms. Chlorination reduced the numbers of all the indicators to acceptable limits. Although some critical control points at these treatment facilities could face difficulties in controlling these healthrelated risks, these facilities could be perceived as effective in treating the raw river water to a high quality potable water to be distributed to the public. Weak correlations were found between the occurrence of the health-related indicator organisms and turbidity. The assumption could therefore be made that turbidity should not be used as a solitary indicator of process effectiveness. Additional microbiological and possibly additional chemical quality tests should be considered as monitoring procedures to manage a water treatment facility effectively

A framework for assessing and predicting the environmental health impact of infectious diseases: a case study of leptospirosis

This article demonstrates the practical application of an integrated environmental health impact assessment (IEHIA) methodology to investigate an infectious disease (leptospirosis) and the value of using such an approach to estimate future health impact. The assessment described the current health impact (using leptospirosis seroprevalence as a proxy measure) and estimated the future health impact based on scenarios that included indicators of different risk factors. The application of an IEHIA methodology to assess the health impact of an infectious disease was shown to enhance the ability to quantify associations between a disease agent and its health impact by taking into account the environmental drivers of transmission, human behaviour, socioeconomic factors, and the multiple pathways through which exposure and infection could occur

Exploiting Metacognitive Networks Embedded in Narrative Focus Group Interviews Using NodeXL

Development of metacognitive theory for changing pedagogy remains an essential research activity. A lack of sufficient clear-cut qualitative analysis procedures extracting embedded metacognitive constructs from qualitative data (e.g., narrative focus group interviews) can hinder development of theory. An approach is therefore needed to analyse qualitative metacognitive data exploiting embedded metacognitive constructs for theory development. In an undergraduate fourth-year mathematics education module, two groups of students (Group A: n = 6; Group B: n = 5) participated in a series of focus group interviews. Participants designed and refined mathematics lessons about the concept of place value. We identified metacognitive networks as an embedded construct in students’ metacognitive processes. Findings indicate that metacognitive networks of an individual, social and socially shared metacognitive nature are embedded in qualitative data, and can be exploited to develop new metacognitive theory. We offer a novel three-step process in this methodology paper to extract metacognitive networks using Microsoft Office, ATLAS.ti and NodeXL

Exposure of rural households to toxic cyanobacteria in container-stored water

Cyanobacteria are potent producers of cyanotoxins that may present a health risk to people. This is especially important in rural areas where people use untreated surface water, containing cyanobacteria, for household purposes including cooking and drinking. Water is collected from these sources mainly in plastic containers, transported home and stored during use. This study investigated the occurrence of cyanobacteria and their associated toxins in these containers as well as in the associated surface water sources. The results suggest that cyanobacteria are transferred from the water sources to the containers and then survive and possibly grow in biofilm forming inside the vessels. Their associated cyanotoxins were not found in any health-significant quantities in containers. However, the occurrence of cyanobacteria in the water used by the households collected in containers clearly indicates that it can be an important route of exposure especially if toxic cyanobacteria are present in the source water. In several cases a risk of cyano-intoxication might exist unless the households undertake preventative measures.Keywords: cyanobacteria, cyanotoxin, microcystin, surface water sources, drinking water containers, biofil

A rapid and low-cost DNA extraction method for isolating Escherichia coli DNA from animal stools

The price of commercial DNA extraction methods makes the routine use of polymerase chain reaction amplification (PCR) based methods rather costly for scientists in developing countries. A guanidium thiocayante-based DNA extraction method was investigated in this study for the isolation of Escherichia coli (E. coli) DNA from goat, chicken, pig, cow and human stool samples. Two versions of the lysis buffer, with and without α-casein, were tested to alleviate PCR inhibition associated with DNA isolated from stool samples. Results obtained show that, this method using the lysis buffer containing α-casein, produces PCR ready DNA at a fraction of the cost of commercial DNA extraction kits.Key words: DNA extraction, Escherichia coli, polymerase chain reaction amplification (PCR), stool samples