Investigation and evaluation of the aging behaviour of technical materials as a selection criterion for use in zinc-air flow batteries

Zinc-air secondary batteries have the potential to act as electrochemical energy storage devices in broad industrial applications. The main arguments for developing marketable systems are the good commercial availability and environmental compatibility of zinc [1]. A consortium of different companies and scientific institutions is engaged in the development of a scalable zinc-air secondary battery. For the establishment of the system, the concept and all components, such as the gas diffusion electrode as well as the zinc electrode, are being investigated and optimised. In order to achieve a certain marketability of the battery after the end of the project, the plastic-based housing, sealing and current-conducting components are also being examined for their long-term stability and suitability. The system concept has high demands on the chemical resistance of the components due to the alkaline electrolyte in use. The plastics in question are typical housing materials with good chemical resistance, soft sealing materials based on thermoplastic elastomers and compounds highly filled with graphite for current conduction within the battery. To evaluate the materials, comparative studies are carried out with regard to the material properties, such as mechanical stability and electrical conductivity, and the combustion behaviour to assess the aging between newly produced and aged parts. In particular, the compounds highly filled with graphite presumably exhibit side reactions in contact with the active materials used in the system due to unavoidable impurities. This behaviour is also integrated in the evaluation of the raw material selection

Microbial monitoring of surface water in South Africa: an overview

Infrastructural problems force South African households to supplement their drinking water consumption from water resources of inadequate microbial quality. Microbial water quality monitoring is currently based on the Colilert®18 system which leads to rapidly available results. Using Escherichia coli as the indicator microorganism limits the influence of environmental sources on the reported results. The current system allows for understanding of long-term trends of microbial surface water quality and the related public health risks. However, rates of false positive for the Colilert®18-derived concentrations have been reported to range from 7.4% to 36.4%. At the same time, rates of false negative results vary from 3.5% to 12.5%; and the Colilert medium has been reported to provide for cultivation of only 56.8% of relevant strains. Identification of unknown sources of faecal contamination is not currently feasible. Based on literature review, calibration of the antibiotic-resistance spectra of Escherichia coli or the bifidobacterial tracking ratio should be investigated locally for potential implementation into the existing monitoring system. The current system could be too costly to implement in certain areas of South Africa where the modified H2S strip test might be used as a surrogate for the Colilert®18

Estimating the burden of disease attributable to four selected environmental risk factors in South Africa

The first South African National Burden of Disease study quantified the underlying causes of premature mortality and morbidity experienced in South Africa in the year 2000. This was followed by a Comparative Risk Assessment to estimate the contributions of 17 selected risk factors to burden of disease in South Africa. This paper describes the health impact of exposure to four selected environmental risk factors: unsafe water, sanitation and hygiene; indoor air pollution from household use of solid fuels; urban outdoor air pollution and lead exposure.The study followed World Health Organization comparative risk assessment methodology. Population-attributable fractions were calculated and applied to revised burden of disease estimates (deaths and disability adjusted life years, [DALYs]) from the South African Burden of Disease study to obtain the attributable burden for each selected risk factor. The burden attributable to the joint effect of the four environmental risk factors was also estimated taking into account competing risks and common pathways. Monte Carlo simulation-modeling techniques were used to quantify sampling, uncertainty.Almost 24 000 deaths were attributable to the joint effect of these four environmental risk factors, accounting for 4.6% (95% uncertainty interval 3.8-5.3%) of all deaths in South Africa in 2000. Overall the burden due to these environmental risks was equivalent to 3.7% (95% uncertainty interval 3.4-4.0%) of the total disease burden for South Africa, with unsafe water sanitation and hygiene the main contributor to joint burden. The joint attributable burden was especially high in children under 5 years of age, accounting for 10.8% of total deaths in this age group and 9.7% of burden of disease.This study highlights the public health impact of exposure to environmental risks and the significant burden of preventable disease attributable to exposure to these four major environmental risk factors in South Africa. Evidence-based policies and programs must be developed and implemented to address these risk factors at individual, household, and community levels

Multi-residue method for the determination of selected veterinary pharmaceutical residues in surface water around Livestock Agricultural farms

A multi-residue method for the determination of the occurrence and prevalence levels of selected veterinary pharmaceutical residues in surface water was developed on a high performance liquid chromatography coupled to ultraviolet-visible (HPLC-UV) detector, and tested with the intent of profiling their distribution. The limit of detection (LOD) and limit of quantitation (LOQ) achieved for the selected pharmaceuticals; acetaminophen, diclofenac, salicylic acid, tetracycline, chloramphenicol, ciprofloxacin, bisphenol–A, 17β–estradiol, estriol, and ivermectin ranged between 0.06–3.45 μg L−1 and 0.17–10.35 μg L−1 respectively. Other International Conference on Harmonization (ICH) parameters for validation of analytical procedures were also evaluated and discussed. Pharmaceutical residues were recovered from surface water samples collected from around livestock farms in Cape Town, South Africa by solid phase extraction (SPE), and thereafter separated and quantified using a validated method on a HPLC-UV-detector. Most frequently detected residues were: acetaminophen (56%), diclofenac (53), tetracycline (72%), 17β–estradiol (73%); chloramphenicol (68%), and salicylic acid (67%), with significantly high (p > 0.05) spatial variability in the concentration distributions of the pharmaceuticals in the surface waters

Phthalate ester plasticizers in freshwater systems of Venda, South Africa and potential health effects

Phthalate ester plasticizers were determined in rivers and dams of the Venda region, South Africa. Liquid-liquid extraction, column chromatographic clean-up and capillary gas chromatography were the methods used for the quantitative analyses. Levels of phthalates in water samples from the rivers and dams ranged from 0.16 mg/ℓ to 10.17 mg/ℓ and varied between 0.02 mg/kg and 0.89 mg/kg in sediments. Generally, the highest concentrations of phthalates were found as DBP and DEHP, which is consistent with their common use in plastic materials and other industrial chemicals. The phthalate levels found in the water samples were much higher than the criterion of 3 μg/ℓ phthalates recommended by the United States Environmental Protection Agency (USEPA) for the protection of fish and other aquatic life, and higher than the Suggested No-Adverse Effect Levels (SNAEL) of 7.5 to 38.5 μg/ℓ for drinking water. The health risk-assessment studies on the phthalates found in the water systems suggested potential carcinogenic and other toxic effects they may pose to communities downstream which might be exposed either through drinking untreated water from the rivers, through dermal absorption or by using the freshwater sources to water their vegetable gardens. DEHP posed the highest risk potential of all the phthalates and the water use or exposure pathway that appeared to pose the highest potential health risk for carcinogenic as well as toxic effects was vegetable watering. The results for phthalates in the water samples give cause for environmental concern as people’s health downstream is at stake if rural populations use this water

Use of handheld computers for collecting water quality data in developing countries

A novel system is described for recording and storing details of water samples collected from rural African households and the water sources that they use. The system makes use of handheld computers for data entry instead of paper-based records. Bar codes are used to track water samples from the field to the laboratory, where total coliforms and Escherichia coli counts are enumerated for each sample. Participating household members and their water sources are documented using instamatic photography, enabling more rapid identification on subsequent visits. The system significantly reduces the lag-time between data collection and analysis. The use of bar codes and direct data entry reduces transcription errors that occur with paper-based recording

Technical Note: Use of hand-held computers for collecting water quality data in developing countries

A novel system is described for recording and storing details of water samples collected from rural African households and the water sources that they use. The system makes use of handheld computers for data entry instead of paper-based records. Bar codes are used to track water samples from the field to the laboratory, where total coliforms and Escherichia coli counts are enumerated for each sample. Participating household members and their water sources are documented using instamatic photography, enabling more rapid identification on subsequent visits. The system significantly reduces the lag-time between data collection and analysis. The use of bar codes and direct data entry reduces transcription errors that occur with paper-based recording

Organochlorine pesticide levels in Clarias gariepinus from polluted freshwater impoundments in South Africa and associated human health risks

There are increasing concerns regarding the safe human consumption of fish from polluted, freshwater impoundments. The aim of this study was to analyse the muscle tissue of the sharptooth catfish Clarias gariepinus for selected organo-chlorine pesticides (OCPs) and to perform a human health risk assessment using a standard protocol described by the United States Environmental Protection Agency (US EPA). Fish were collected from the polluted Roodeplaat-(RDPD), Rietvlei-(RVD) and Hartbeespoort (HBPD) Dam impoundments located in the north-eastern regions of South Africa. GC–MS analyses showed levels of various OCPs in fish muscle samples from all three impoundments. For fish collected from the RDPD, p,p0-DDE, endosulfan, lindane and band d-HCH were the most prevalent OCPs detected, while p,p0-DDE and endosulfan were the most predominant in fish from the RVD. Lindane and b- and d- HCH were the main OCPs detected in fish from the HBPD. Dieldrin was the only OCP detected at concentrations for which a cancer risk and a hazard index above the acceptable risk levels were estimated. This was the case for fish from both the RDPD and RVD impoundments. No toxic risk was estimated should fish from the HBPD be consumed.Water Research Commission of South Africa, the Universities of Pretoria and Johannesburg, National Research Foundation and DH Environmental Consulting.http://www.elsevier.com/locate/chemospherehb2016Urolog

Contamination of drinking water between source and point-of-use in rural households of South Africa and Zimbabwe: implications for monitoring the Millennium Development Goal for water

Aims: To assess contamination of drinking water in rural Zimbabwe and South AfricaMethods: We conducted a cohort study of 254 children aged 12-24 months in rural South Africa and Zimbabwe. In dry and wet seasons, we measured water quality, using the indicator organism E. coli, at improved and unimproved sources, in household storage and drinking cups. We also recorded hygiene and socio-economic factors for each household.Results: For improved sources, samples with E. coli counts less than 10 cfu/100ml were as follows: at source:165 (88%); in household storage 137 (59%); in drinking cups 91 (49%). The corresponding values for unimproved sources were: source 47 (29%); household storage 32 (19%); drinking cups 21 (18%). This significant deterioration in microbial quality of water from improved sources was seen in both countries and both survey rounds.Conclusion: Although improved sources generally delivered ‘safe’ water at the point-of-supply, 12% of source samples were contaminated and as such were ‘unsafe’. Furthermore, in household storage, more than 40% of samples were ‘unsafe’. For monitoring the Millennium Development Goal for water, UNICEF-WHO are assuming an equivalence between ‘improved’ sources and ‘safe’ water. Our findings suggest that this equivalence may be unsound