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Item Open Access Effect of hysteresis on water flow in the vadose zone under natural boundary conditions, Siloam Village case study, South Africa(2017-10-17) Arrey, I. A.; Odiyo, J. O.; Makungo, R.; Kataka, M. O.A one-dimensional vadose zone model was used to simulate flow under natural boundary conditions. The effects of hysteresis and temporal variability of meteorological conditions were evaluated. Simulations were performed in HYDRUS-1D code for the period April 2013–January 2014 (6601 hours) at three different locations in a delineated portion of the sub-quaternary catchment A80A of Nzhelele with different soil textures. Soil hydraulic characteristics were estimated in a Rosetta library dynamically linked to the HYDRUS-1D model which is based on the numerical solution of a one-dimensional Richard’s equation. Analysis of the simulation results suggests that ignoring hysteresis for soils of similar textural class does not lead to any significant deviation of the model predicted soil moisture, unlike for soils with different textural classesItem Open Access Biosynthesis of Ultrasonically Modified Ag-MgO Nanocomposite and Its Potential for Antimicrobial Activity(Hindawi, 2018-08-29) Ayinde, Wasiu B; Gitari, Mugera W.; Muchindu, Munkombwe; Samie, AmidouThis study reports a green synthesis route for a bilayered Ag-MgO nanocomposite using aqueous peel extract of Citrus paradisi (grapefruit red) under an accelerated uniform heating technique and its antibacterial potency against Escherichia coli. Surface modifications and composition of the nanocomposite were examined using a UV-visible spectrophotometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray (EDX) analyzer. (e efficiencies of the as-synthesized Ag-MgO nanocomposite against Escherichia coli were examined. (e synthesized Ag-MgO nanocomposite showed characteristic synergetic bands at 290nm for MgO nanoparticle and at around 440nm for Ag nanoparticle which blue-shifted to 380nm in the composite. A spherically dispersed nanocomposite with cubical crystal lattice network with a diameter of about 20–100nm comprising Ag nanoparticle embedded within MgO nanoparticles was obtained. (e nanocomposite produced stronger antibacterial activity against Escherichia coli as compared to MgO nanoparticle, indicating a higher interaction between Ag and MgO ions. (e nanocomposite was successfully synthesized via an efficient modified method by bioreductive agents with an improved synergistic antibacterial property towards water purification.Item Open Access The Presence of Toxic and Non-Toxic Cyanobacteria in the Sediments of the Limpopo River Basin: Implications for Human Health(MDPI, 2018-07-03) Magonono, Murendeni; Oberholster, Paul Johan; Shonhai, Addmore; Makumire, Stanley; Gumbo, Jabulani RayThe presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analysis of the 16S rRNA gene. Bottom sediment samples were collected from selected rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand Rivers (South Africa); Notwane (Botswana); and Shashe River and Mzingwane River (Zimbabwe). A physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/L, in most of the river sediments, while alkalinity, pH and salinity were in excess of 500 mg/L. The FlowCam showed the dominant cyanobacteria species that were identified from the sediment samples, and these were the Microcystis species, followed by Raphidiopsis raciborskii, Phormidium and Planktothrix species. The latter species were also confirmed by molecular techniques. Nevertheless, two samples showed an amplification of the cylindrospermopsin polyketide synthetase gene (S3 and S9), while the other two samples showed an amplification for the microcystin/nodularin synthetase genes (S8 and S13). Thus, these findings may imply the presence of toxic cyanobacteria species in the studied river sediments. The presence of cyanobacteria may be hazardous to humans because rural communities and farmers abstract water from the Limpopo river catchment for human consumption, livestock and wildlife watering and irrigation.Item Open Access Mobility and Attenuation Dynamics of Potentially Toxic Chemical Species at an Abandoned Copper Mine Tailings Dump(MDPI, 2018-02-12) Gitari, Wilson Mugera; Thobakgale, Rendani; Akinyemi, Segun AjayiLarge volumes of disposed mine tailings abound in several regions of South Africa, as a consequence of unregulated, unsustainable long years of mining activities. Tailings dumps occupy a large volume of valuable land, and present a potential risk for aquatic systems, through leaching of potentially toxic chemical species. This paper reports on the evaluation of the geochemical processes controlling the mobility of potentially toxic chemical species within the tailings profile, and their potential risk with regard to surface and groundwater systems. Combination of X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) techniques, show that the tailing profiles are uniform, weakly altered, and vary slightly with depth in both physical and geochemical properties, as well as mineralogical composition. Mineralogical analysis showed the following order of abundance: quartz > epidote > chlorite > muscovite > calcite > hematite within the tailings profiles. The neutralization of the dominant alumino-silicate minerals and the absence of sulfidic minerals, have produced medium alkaline pH conditions (7.97–8.37) at all depths and low concentrations of dissolved Cu (20.21–47.9 μg/L), Zn (0.88–1.80 μg/L), Pb (0.27–0.34 μg/L), and SO42− (15.71–55.94 mg/L) in the tailings profile leachates. The relative percentage leach for the potentially toxic chemical species was low in the aqueous phase (Ni 0.081%, Cu 0.006%, and Zn 0.05%). This indicates that the transport load of potentially toxic chemical species from tailings to the aqueous phase is very low. The precipitation of secondary hematite has an important known ability to trap and attenuate the mobility of potentially toxic chemical species (Cu, Zn, and Pb) by adsorption on the surface area. Geochemical modelling MINTEQA2 showed that the tailings leachates were below saturation regarding oxyhydroxide minerals, but oversaturated with Cu bearing mineral (i.e., cuprite). Most of the potentially toxic chemical species occur as free ions in the tailings leachates. The precipitation of secondary hematite and cuprite, and geochemical condition such as pH of the tailings were the main solubility and mobility controls for the potentially toxic chemical species, and their potential transfer from tailings to the aqueous phase.Item Open Access Treatment of Acid Mine Drainage with Coal Fly Ash: Exploring the Solution Chemistry and Product Water Quality(IntechOpen, 2018) Gitari, Wilson Mugera; Petrik, Leslie F.; Akinyeni, Segun A.A treatment process for Acid mine drainage (AMD) using coal fly ash (CFA) was developed. AMD was treated with CFA as the alkaline agent at different CFA: AMD ratios and pH, electrical conductivity (EC) evolution monitored over time. In a separate experiment two AMD sources with differing chemistry were treated with the same CFA to evaluate the impact of AMD chemistry on the treatment process and product water quality. Various CFA: AMD ratios were stirred in a beaker for a pre-set time and the process water chemistry determined. pH was observed to increase in a stepwise manner with buffer zones observed at 4-4.5, 4.5-7 and 6-8. AMD with low concentration of Al3+, Fe2+, Fe3+ and Mn2+ didn’t exhibit these buffer zones. Two competing processes were observed to control the evolving pH of process water: dissolution of basic oxides (CaO, MgO) from CFA led to pH increase and hydrolysis of AMD species such as Al3+, Fe2+, Fe3+ and Mn2+ led to pH decrease. These processes initiated mechanisms such as precipitation, adsorption and ion exchange that led to decrease in inorganic contaminants as the treatment progressed. Inorganic contaminants removal was directly related to amount of CFA in reaction media. Precipitation of insoluble hydroxides and Al, Fe-oxyhydroxysulphates contributed to removal of major and minor chemical species. Precipitation of gypsum contributed to removal of sulphate. Na, K and Mg remained largely in solution after initial decrease. Significant leaching of B, Sr, Ba, and Mo from CFA was observed and was directly linked to amount of CFA in the reaction media. This will be a shortcoming of the treatment process since other processes may be required to polish up the product water. The treatment of AMD with CFA was observed to depend on CFA, AMD chemistry, treatment time and might therefore be site specific.Item Open Access Mineralogical and Chemical Characteristics of Raw and Modified Clays and Their Application in Arsenic and Fluoride Removal: Review(IntechOpen, 2018-11-05) Gitari, Mugera W.; Mudzielwana, RabelaniClay and clay minerals have always been used since the ancient times for making ceramic materials and also as a building material. Over the past decades, there has been a growing trend in their applicability in different areas such as industries, environmental remediation and water treatment sectors. The growing trend is mainly associated with the fact that they are chemically and mechanically stable, have higher specific surface area and cation exchange capacity. Furthermore, clays can be modified to improve their functionalities in different sectors. In this chapter, we present a review of the structural, mineralogical and chemical properties of clay and the effect of surface modification in their structures. We further looked at their applicability in arsenic and fluoride removal in their raw and also in their modified form. Although the literature showed that modified clay minerals yields higher adsorption capacity as compared to raw clays little nothing has been reported yet in relation to the cost of modifying clays with chemical species. As such new studies should also elaborate on the cost effectiveness of modifying clay minerals with chemical species.Item Open Access Assessing environmental factors structuring populations and movement dynamics of the invasive snail Tarebia granifera in a subtropical Austral reservoir(2022-07-15) Makherana, Fhatuwani; Dalu. Tatenda; Cuthbert, Ross N.; Dondofema, FaraiInvasive alien species continue to spread and proliferate in waterways worldwide, but environmental drivers of invasion dynamics lack assessment. Understanding alien species ability to self-disperse via locomotion following arrival to new environments is also critical for prediction of invasion success. The study assessed: (i) the distribution and abundance of Tarebia granifera and the potential drivers of population structure in Nandoni reservoir; and (ii) compared movement traits between two widespread invasive alien snails, T. granifera and Physa acuta, to assess their net distance and velocity and determine dispersal potential. Tarebia granifera was widespread at sites invaded, with abundances exceeding 500 individuals m-2 at impacted areas. Tarebia granifera was significantly associated with sediment (i.e., chlorophyll-a, Mn, sediment organic carbon (SOC) and organic matter (SOM)) and water (i.e., pH, conductivity, total dissolved solids (TDS)) variables. Tarebia granifera seemed to exhibit two recruitment peaks in November and March, identified via size-based stock assessment. Tarebia granifera displayed a significantly greater velocity and covered a significantly larger net distance than Physa acuta. The exploratory behaviour (i.e., mean, or absolute turning angles and straightness index) did not differ significantly between the two alien species; both species showed a slight tendency to turn counter clockwise. Overall, the study shows that there was higher snail abundance during the summer season, furthermore, sediment and water variables were found to be important in structuring T. granifera populations. The present study suggests a more rapid capacity to self-disperse in T. granifera than P. acuta, but a similar level of exploratory behaviour between the two species. The study provided autecological information and insights on the distribution and extent of spread of T. granifera, given the often-overlooked role of animal behaviour in promoting invasion, this information can help inform and predict the invasion pattern of invasive alien freshwater snail. This information can also help in the development of invasive alien snail management action plans within the region and elsewhere.Item Open Access Impacts of Land Management on Water Resources in the Crocodile River Catchment, Mpumalanga(2022-07-15) Nkosi, Mary; Mathivha, F. I.; Odiyo, J. O.Land use/land cover (LULC) have a “cause and effect” relationship with the hydrology of catchment areas. The Crocodile River Catchment (CRC) has been reported to be fully utilised and at its limit. Due to its ecological and socio-economic importance, it is therefore imperative to quantify the changes in the river’s water resources. Using remote sensing (RS), QSWAT and Quantum GIS (QGIS) this study analysed and evaluated the long-term effects of LULC changes on the hydrology of the CRC between 1981 and 2020. LULC was classified into 8 major classes (cultivation land, forest plantation, water, grassland, built-up areas, bush/savannah and natural forest) for 1980/81, 2000/01 and 2020 to demonstrate the changes in land-use for the past 40 years. The study found that natural forests and grassland decreased by 12.8% and 1%, respectively. There was an increase in cultivated lands, forest plantations and built-up by 2.5%, 3.1% and 2.3%, respectively. Built-up areas, cultivated lands and forest plantations were identified as the major land-use activities and the hotspots for these were further mapped and analysed per quaternary catchment. The overall NDVI value for all LULC ranged between -0.3 and 0.9. The LULC maps were used as input data to the QSWAT model to evaluate LULC impacts on water resources. The model performance evaluation showed an NSE value between 0.41 to 0.79, PBIAS -4.44 to 44.7 and RSR 0.54 to 0.75 between simulated and the observed streamflow. For this study, these findings on model performance showed acceptable results. The results further showed a decreasing trend in streamflow from1981-2020. The decreasing trends were attributed to the increase in forest plantation and cultivation with built-up areas found to have minimum impacts on the catchment’s hydrological response because they occupied a small percentage of the catchment. The distribution of ET and surface runoff also varied with the LULC, however, climate was shown to have an influence on streamflow and the distribution of LULC in the catchment area, thus affecting the hydrological regime.Item Open Access International Conference on Sustainable Management of Natural Resources (ICSMNR) : Proceedings of the First International Conference in Sustainable Management of Natural Resources: 15th - 17th October 2018, Bolivia Lodge, Polokwane, South Africa(School of Environmental Sciences, 2018-10-17) Edokpayi, Joshua; Gitari, Wilson M.; Stam, Eduard M.; Mhlongo, Sphiwe E.Item Open Access Assessment of Microbial Quality of Surface Water Sources of Luvuvhu River Catchment, South Africa(2017-11-28) Mailula, M. A.; Gumbo, J. R.The majority of global rural communities, including South Africa, rely on untreated surface water for human consumption. The consumption arises partly from the local municipalities’ erratic supply of treated drinking water to its residents. Here we report on the microbial load of surface water sources and after simple water treatment using hand dug wells in Vhembe District, South Africa. The results of the pH were in the range 6.90 to 8.86 with the water temperature ranging from 16 to 25 ºC. The turbidity values were in the range 2.53 to 393.67 NTU which shows problem of soil erosion, rainfall runoff and wastewater discharge by upstream sewage works. The faecal coliform counts varied between 0 cfu/100 ml to > 300 cfu/100 ml, E. coli counts varied between 0 cfu/100ml and >300 cfu/100 ml, and faecal Streptococci counts between 1.5 cfu/100 ml to >300 cfu/100 ml. The microbial load in the hand dug wells was considerably lower than that of the Nandoni reservoir (due to soil filtering capacity). The existence of a high microbial load that exceeded acceptable regulatory guidelines render these water sources unsafe for human consumption. Physical conditions, such as water temperature, also enable bacterial propagation. Thus, the advent of climate change and especially the warming of surface waters may exacerbate the current condition of the use of untreated surface water sources.Item Open Access A Review: Spirulina a source of bioactive compounds and nutrition(2017-09) Gumbo, J. R.; Nesamvuni, C. N.The attainment of the nutrition related sustainable development goals (SDGs) is a challenge to South Africa. Part of the challenge is related to access to affordable nutrition by poor communities. Spirulina presents with nutritional benefits including 50 to 70% protein, and all essential amino acids in complete balance, 5 to 10% lipids and 10 to 20% carbohydrates, 10 vitamins especially vitamin B12 and pro-vitamin A (β-carotene), minerals such as iron and one of the few sources of dietary γ-linolenic acid (GLA). Health factors linked to Spirulina include anticarcinogenic, hypocholesterolemic and antioxidant properties. Spirulina is part of the cyanobacteria family of the Arthrospira species. The challenges that are there is to ensure that the isolates are pure and free from microbial, chemical and physical contamination during the cultivation phase. The cultivation is either in closed semi-continuous batch systems or open raceway that are prone to contamination from environmental elements. This paper highlights Spirulina use as a potential strategy to meet nutrition related Sustainable Development goals.Item Open Access Contamination of Soil due to Leakages of Polychlorinated Biphenyls (PCBs) at a Vandalized Electrical Transformer Site(2017) Nedzamba, R. M.; Gumbo, J. R.Worldwide and including in South Africa, the use of polychlorinated biphenyls (PCBs) has been banned as these have been implicated in the destruction of the ozone layer. The lack of the protective ozone layer has been widely blamed for increase in global warming. Here we report on impact of PCBs from a human vandalized electrical transformer on the soil environment at the Rietvlei farm in Louis Trichardt. The particle analysis showed that the soil was sandy followed by loam and then clay. The soil pH was in the range 6.79 to 10.15. The soil moisture content was on average below 6.8%. The analysis of Mg, Al, Ca and K for Cation Exchange Capacity (CEC) was carried out to determine the fertility of the soil. The average CEC of the soil sample was 7.48 meq/g and therefore the soil was fertile and but lacked organic nutrients. However at this site where the transformer oil was spilled it was observed that no grass was growing. The analysis of samples by the GC-MS and GCECD at Waterlab and SABS showed that there were ultra-traces of PCBs in the soil samples. Probably the absence of grass growing at the contaminated site was due to presence of the ultra-trace levels of PCBs. Thus there is a need to improve plant growth at the contaminated site in order to prevent easy water infiltration that might contaminate groundwater supplies. Makhado local municipality draws some of its water supplies from borehole just 1 m from the contaminated site.Item Open Access The Use of Ceramic Water Filters in Improving the Microbial Quality of Drinking Water(2017-11-28) Tshishonga, M.; Gumbo, J. R.Water borne infections are the number killer of children under five years in developing countries. The main reason is the consumption of untreated drinking water. Here we report on the use of ceramic water filters in reducing Escherichia coli, a surrogate for pathogens in drinking water and can be applied in a rural household. For microbiological analysis, the two ceramic water filters, one from Mukondeni and the other one from Sese in Zimbabwe reduced the high microbial load of the raw water. The result showed that the counts as colony form units, of coliform in the purified water was zero and in raw water was too many to count; these colonies were probably removed by the ceramic water filter. The microbial counts in the purified water were zero colony forming units per 100 ml and within the SANS 241 guidelines values. The ceramic water filters from Mukondeni and Sese were able to improve the microbial quality of the raw water. The Sese ceramic water filter was slow and thus further improvements are required in the composition of materials by increasing the saw dust component and reducing the clay component. Thus, ceramic water filters are suitable for use at household level.Item Open Access Impact of Tea Processing Water Wastes on Phytoplankton Composition of Tshinane River, Limpopo Province(2017-11-28) Sinthumule, H.; Mokgoebo, M. J.; Gumbo, J. R.The discharge of industrial waste water on freshwater resources is on the increase worldwide, including in South Africa. The study aimed at assessing the response of phytoplankton upon exposure to high levels of nutrients along the Tshinane River Limpopo Province. The study showed different phytoplankton assemblages with different changes in physico-chemical levels. Environmental factors do have a noticeable effect on phytoplankton abundance as it was shown by statistical analysis. Results computed by the Czekanowski coefficient showed that various environmental factors components contributed to the different composition and types of phytoplankton abundance (p<0.05). When environmental factors showed fluctuation (Increase or decrease) a different type of plankton was found to be tolerant to those levels. A total of 64 species were identified upstream and 103 species identified downstream. Phytoplankton spectrums were recorded from six taxonomic groups namely Chrysophyta, Dinophyta, Chlorophyta, Bacillariophyta, Cyanophyta and Dinophyta. The dominant taxonomic group was Chlorophyta (Downstream) and Bacillariophyta was the dominant phytoplankton upstream. The results supports the assumption that an increase in nutrients lead to a diverse phytoplankton species even if all the other parameters are within the South African Water Quality Range for Aquatic ecosystems. This shows that tea processing waste has a minimal impact on the ecosystem health of Tshinane River and the river is able to recover from the nutrient enrichment.Item Open Access Asessing the Quality of Traditionally Manufactured Ceramic Water Filters, Limpopo, South Africa(2017-11-28) Gumbo, Jabulani R.; Munarini, Asivhanzhi I.; Khangale NdishavhaThe traditional clay pot can be modernized by including sawdust to produce a ceramic water filter. Ceramic water filters are known to improve the quality of drinking water by inactivating waterborne pathogens. Here we report on the quality of traditionally manufactured ceramic water filter in improving the chemical and microbial quality of drinking water. The sources of drinking water were Mambedi dam and the Luvuvhu River. The water from Luvuvhu River was then filtered with ceramic water filter (CWF). The mean pH values of Luvuvhu River and purified water ranged from 6.20 to 6.56 and 7.79 to 7.91 respectfully. The electrical conductivity of Luvuvhu River and purified water ranged from 210 to 224 μS/cm and 229 to 284 μS/cm respectfully. The temperature of Luvuvhu River and purified water ranged from 21.3 to 23.5 °C and 23.1 to 25.5°C respectfully. The turbidity mean value of Luvuvhu River and purified water ranged from 1.67 to 4.38 NTU and 0.31 to 0.64 NTU respectfully. The CWF was effective in the removal of some metals Cr, Sr, and Ba and there was no leaching of metals As and Ni. The total coliforms and faecal coliforms in the purified water were 3 cfu/100 ml and 36 cfu/100 ml respectfully. Thus at household level, the ceramic water filter may be used to improve the chemical and microbial safety of the Luvuvhu river.Item Open Access Geochemical and Mineralogical Characterization of Gold Mine Tailings for the Potential of Acid Mine Darinage in the Sabie-Pilgrim's Rest Goldfields, South Africa(2017-11-28) Lusunzi, Rudzani; Gumbo, Jabulani Ray; Yibas, Bisrat; Novhe, ObedThe environmental hazards arising from active and abandoned mine tailings are a cause for concern. We report on the presence of mineral-related environmental hazards in both Glynn Lydenburg and Nestor mine tailings, approximately 6 km apart and located in the Mpumalanga Province of South Africa. Based on XRD, shows a wide range of minerals: pyritic sulphide, quartz and mica. The XRF results showed that quartz was the dominant oxide in both the mine tailings; followed by Fe2O3 and Al2O3. Furthermore, trace elements, such as As, Cr, Cu, Pb, V and Zn, were also found which are hazardous to the environment.Item Open Access The treatment of dye wastewater using natural South African magnesite(OMICS International, 2017-07-22) Ngulube, Tholiso; Gumbo, Jabulani Ray; Masindi, Vhahangwele; Maity, ArjunDischarging industrial colored wastewaters into aqueous environments can cause adverse effects on aquatic life due to the toxic nature of synthetic dyes. The present study aimed to evaluate the efficiency of using natural South African magnesite to remove an anionic dye from aqueous systems. The natural nanosorbent was characterized by Transmission Electron Microscopy, Fourier Transform Infra-Red and X-ray Diffraction analysis. Various important parameters namely contact time, initial concentration of dyes, magnesite dosage, solution temperature and solution pH were optimized to achieve maximum adsorption capacity. The XRD results revealed that raw magnesite contains magnesite, periclase, dolomite and quartz as the crystalline phases. Optimum conditions were observed to be 60 min of agitation, 0.1 g dosage of magnesite per 50 mL of aqueous solution, 40 mg/L initial dye concentration and room temperature. Removal of DR81 from aqueous solution was observed to be independent of initial pH of the aqueous solution. The adsorption ratio toward 40 mg/L of DR81 was 96.27%. The results indicate that natural South African magnesite is an efficient material for the removal of DR81. The magnesite, due to high accessibility, low cost and non-toxicity can be considered a good replacement option of other high cost materials used to treat colored wastewater especially in developing countries like South AfricaItem Open Access Approaches to the Evaluation of Teaching and Learning Methods at a University: Evidence from South Africa(2017) Gumbo, Jabulani R.An increasing number of students drop out of university in South Africa and throughout the world. The South African Council for Higher Education has introduced strategies to deal with high dropout rates, which include the improvement of teaching and learning through the Quality Enhancement Program. I hereby document and evaluate my teaching and learning methods. The data collection for this research involved student informal evaluation, formal evaluation and peer evaluation. The formative evaluation data was grouped in 14 themes with numbers in brackets representing the number of counts of student expression of [their free form]: good lecturer (51); stop pointing (12); request for softcopy of lecture notes (7); speak with a loud voice (5); time to write notes (4); field work/practicals (2);; do not understand lecture notes (2); lecturer coming late (2); lots of lectures notes and case studies are long (2); update notes (1); no double class on Friday (1); timetables are clashing (1); require a small tests (1); revision of lecture (1). The concerns for summative evaluation were: I was a good lecturer; issues on hard copies of lecture notes and feedback on assignments. With regard to peer evaluation, a fellow academic attended one of my lectures to make observations and review the teaching and learning procedures. I was able to observe that I ended my lectures too abruptly. As a result, the suggested approach was that gradually end the lectures with a series of questions that invoke a critical response from students and ask any student to summarize the lecture in three sentences. I have since implemented the student concerns.Item Open Access Effects of calcination temperature and solution pH on the defluoridation potential of Al/Fe oxide-modified diatomaceous earth: metal leaching and sorbent reuse(IWa Publishing, 2017) Izuagie, Anthony A.; Gitari, M.; Gumbo, Jabulani R.An evaluation of the effects of calcination temperature and solution pH on the fluoride removal capacity of Al/Fe oxide-modified diatomaceous earth was carried out. The sorbent was observed to be most effective and stable within the pH range 6.70–8.12, where the lowest concentrations of Al and Fe (<1 mg/L) in treated water were recorded. Thus, sorbent loss was minimal at that pH range. It was observed that the sorbent lost its efficiency and stability at calcination temperatures above 600 WC. Inductively coupled plasma-mass spectrometer analysis of metals in supernatants and thermogravimetric analysis of the sorbent showed that there was substantive loss of Al and Fe from the sorbent at temperatures above 600 WC because of evaporation. K2SO4 solution proved to be the best regenerant for spent sorbent compared to NaOH and Na2CO3, which caused sorbent loss owing to high solution pH. The CO2 3 from Na2CO3 bound to regenerated sorbent so much that it could not be displaced by fluoride during subsequent defluoridation experiments. Sorbent regenerated with 0.1 M K2SO4 solution could reduce 10 mg/L fluoride in artificial water at a dosage of 0.8 g/100 mL by 81.8% and 67.2% at the second and third cycles, respectively.Item Open Access Assessing the environmental context of hand washing among school children in Limpopo, South Africa(Tandonline, 2017) Bulled Nicola; Poppe Kara; Ramatsitsi Khuliso; Sitsula Londolani; Winegar Geoffrey; Gumbo Jabulani; Dellingham Rebecca; Smith JamesDespite its simplicity and efficacy, the promotion of hand washing for disease prevention remains a challenge, particularly in resourcelimited settings. This article reports on a quasi-experimental schoolbased study that aimed to improve habitual hand washing. Significant increases in hand washing occurred following improvements in hygiene and sanitation facilities (School A: t = 13.86, p = 0.0052). Smaller increases in hand washing occurred following education (School A: t = 2.63; p = 0.012; School B, no infrastructure improvements: t = 1.66, p = 0.239). Health policy and programming need to pay greater attention to the interplay of the structural, social and individual dimensions of unique contextual environments that influence habitual behaviours.