PUMPS mimics natural geothermal vents as a conceptual model designed for the remediation of acid mine water (AMW) in voids of abandoned gold mines of the Witwatersrand Basin in South Africa. In this system, a reaction chamber containing Desulfotomaculum kuznetsovii sulfate reducing bacteria will be set at the bottom of a 3-4 km deep mine that will be flooded. A geothermal system with at least one (1) doublet will be drilled from the bottom of the mine to the depth of 8km, where the temperatures are sufficient for geothermal energy harvesting. AMW, used as a geothermal fluid, will be pumped down the injection well and circulate through hot rock. The hot water is then used to generate electricity and then channelled into the reaction chamber to undergo bio-remediation. Following treatment, the water flows back into the mine voids where it will improve the quality of untreated AMW through dilution. Eventually, the mine will be flooded with clean water that can be stored underground and/or pumped up to surface for social and ecosystem services. Following an introduction and proof of concept for the PUMPS, the research builds further on the technical and economic evaluation of the PUMPS in order to assert its viability and sustainability. The technical viability includes testing the ability for Desulfotomaculum kuznetsovii to survive in high pressure condition; quantifying the amount of energy that can be drawn from the geothermal reservoir; determining the placement and scheme of the geothermal wells; and, finally, developing a robust economic model of the system. Experiments show that Desulfotomaculum Kuznetsovii can tolerate high pressure conditions in of at least 100bar at their ideal sulfate reducing temperature of 63°C. Geochemical modelling shows that AMW can be used effectively as a geothermal fluid for PUMPS. To achieve highest efficiency and minimal fluid loss, the geothermal wells should be placed along the SSE-NNW direction, based on the known stress field across the Witwatersrand Basin. With a flow rate of 30l/s the energy drawn from the geothermal reservoir is sufficient to drive PUMPS and the surplus energy is determined by the volume of AMW treated per day. All results indicate that the PUMPS is technically and economically viable. The economic model shows that the value and viability of the PUMPS is best reflected with a comprehensive inclusion of potential revenue (for example from chemical solution mining of deep seated gold) and financial/environmental incentives.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Chemical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014 / Environmental legislation focusing on wastewater disposal in industries that utilise cyanide and/or cyanide-related compounds has become increasingly stringent worldwide, with many companies that utilise cyanide products required to abide by the Cyanide International Code associated with the approval of process certifications and management of industries which utilise cyanide. This code enforces the treatment or recycling of cyanide-contaminated wastewater. Industries such as those involved in mineral processing, photo finishing, metal plating, coal processing, synthetic fibre production, and extraction of precious metals, that is, gold and silver, contribute significantly to cyanide contamination in the environment through wastewater. As fresh water reserves throughout the world are low, cyanide contamination in water reserves threatens not only the economy, but also endangers the lives of living organisms that feed from these sources, including humans. In the mining industry, dilute cyanide solutions are utilised for the recovery of base (e.g. Cu, Zn, Ni, etc.) and precious metals (e.g. Au, Ag, etc.). However, for technical reasons, the water utilised for these processes cannot be recycled upstream of the mineral bioleaching circuit as the microorganisms employed in mineral bioleaching are sensitive to cyanide and its complexes, and thus the presence of such compounds would inhibit microbial activity, resulting in poor mineral oxidation. The inability to recycle the water has negative implications for water conservation and re-use, especially in arid regions. A number of treatment methods have been developed to remediate cyanide containing wastewaters. However, these chemical and physical methods are capital intensive and produce excess sludge which requires additional treatment. Furthermore, the by-products that are produced through these methods are hazardous. Therefore, there is a need for the development of alternative methods that are robust and economically viable for the bioremediation of cyanide-contaminated wastewater. Biological treatment of free cyanide in industrial wastewaters has been proved a viable and robust method for treatment of wastewaters containing cyanide. Several bacterial species, including Bacillus sp., can degrade cyanide to less toxic products, as these microorganisms are able to use the cyanide as a nitrogen source, producing ammonia and carbon dioxide. These bacterial species secrete enzymes that catalyse the degradation of cyanide into several end-products. The end-products of biodegradation can then be utilised by the microorganisms as nutrient sources. This study focused on the isolation and identification of bacterial species in wastewater containing elevated concentrations of cyanide, and the assessment of the cyanide biodegradation ability of the isolates. Thirteen bacterial isolates were isolated from electroplating wastewater by suppressing the growth of fungal organisms and these species were identified as species belonging to the Bacillus genus using the 16S rDNA gene. A mixed culture of the isolates was cultured in nutrient broth for 48 hours at 37°C, to which FCN as KCN was added to evaluate the species‟ ability to tolerate and biodegrade cyanide in batch bioreactors. Subsequently, cultures were supplemented solely with agro-waste extracts, that is, Ananas comosus extract (1% v/v), Beta vulgaris extract (1% v/v), Ipomea batatas extract (1% v/v), spent brewer‟s yeast (1% v/v) and whey (0.5% w/v), as the primary carbon sources. Owing to the formation of high ammonium concentration from the cyanide biodegradation process, the nitrification and aerobic denitrification ability of the isolates, classified as cyanide-degrading bacteria (CDB) was evaluated in a batch and pneumatic bioreactor in comparison with ammonia-oxidising bacteria (AOB). Furthermore, the effects of F-CN on the nitrification and aerobic denitrification was evaluated assess the impact of F-CN presence on nitrification. Additionally, optimisation of culture conditions with reference to temperature, pH and substrate concentration was evaluated using response surface methodology. Using the optimised data, a continuous biodegradation process was carried out in a dual-stage packed- bed reactor combined with a pneumatic bioreactor for the biodegradation of F-CN and subsequent nitrification and aerobic denitrification of the formed ammonium and nitrates. The isolated bacterial species were found to be gram positive and were able to produce endospores that were centrally located; using the 16S rDNA gene, the species were found to belong to the Bacillus genus. The species were able to degrade high cyanide concentration in nutrient broth with degradation efficiencies of 87.6%, 65.4%, 57.0% and 43.6% from 100 mg F-CN/L, 200 mg F-CN/L, 300 mg F-CN/L, 400 mg F-CN/L and 500 mg F-CN/L respectively over a period of 8 days. Additionally, the isolates were able to degrade cyanide in an agro-waste supported medium, especially in a medium that was supplemented with whey which achieved a degradation efficiency of 90% and 60% from 200 mg F-CN/L and 400 mg F-CN/L, respectively over a period of 5 days. The nitrification ability of the isolates was evaluated and the removal of NH4 +/NO3 - by the CDB and AOB in both shake flasks and pneumatic bioreactor was determined to be pH dependent. The maximum NH4 +/NO3 - removal evaluated over a period of 8 days for CDB and 15 days for AOB, observed at pH 7.7 in shake flasks, was 75% and 88%, respectively, in the absence of F-CN. Similarly, the removal of NH4 +/NO3 - in a pneumatic bioreactor was found to be 97.31% for CDB and 92% for AOB, thus demonstrating the importance of aeration in the designed process. The nitrification by CDB was not inhibited by cyanide loading up to a concentration of 8 mg FCN/ L, while the AOB were inhibited at cyanide loading concentration of 1 mg F-CN/L. The CDB removed the NH4 +/NO3 - in PBSs operated in a fed-batch mode, obtaining efficiencies >99% (NH4 +) and 76 to 98% (NO3 -) in repeated cycles (n = 3) under F-CN (≤8 mg F-CN/L). The input variables, that is, pH, temperature and whey-waste concentration, were optimised using a numerical optimisation technique where the optimum conditions were found to be: pH 9.88, temperature 33.60 °C and whey-waste concentration 14.27 g/L, under which 206.53 mg CN-/L in 96 h can be biodegraded by the microbial species from an initial cyanide concentration of 500 mg F-CN/L. Furthermore, using the optimised data, cyanide biodegradation in a continuous mode was evaluated in a dual-stage packed-bed bioreactor connected in series to a pneumatic bioreactor system used for simultaneous nitrification including aerobic denitrification. The whey-supported Bacillus sp. culture was not inhibited by the free cyanide concentration of up to 500 mg F-CN/L, with an overall degradation efficiency of ≥99% with subsequent nitrification and aerobic denitrification of the formed ammoniu and nitrates over a period of 80 days.

Whole Effluent Toxicity (WET) testing has been identified as one of the tools in the management of complex effluents in aquatic ecosystems. In South Africa, toxicity testing has not been required for regulatory purposes. Recently, the Department of Water Affairs and Forestry has adopted WET testing as a tool to evaluate the suitability of hazardous effluent for discharge into receiving environments. This has necessitated suitable procedures to be established for use in the South African situation. With the implementation of the new National Water Act (No 36 of 1998), industries have to comply with set standards to protect the aquatic environment. However, the South African Water Quality Guidelines for Aquatic Ecosystems have been set using international toxicity data, and it is not known if they are comparable with South African conditions. The aim of this study was to investigate the tolerances of selected indigenous riverine invertebrates to complex saline effluents. The study investigated the effects of kraft mill effluent to Tricorythus tinctus, a tricorythid mayfly from the Sabie River, Mpumalanga, and the effects of a textile effluent to baetid mayflies of the Buffalo River, Eastern Cape. Indigenous riverine invertebrates were chosen as test organisms, as there is no toxicity data in South Africa which could be used to evaluate the level of protection afforded by the South African Water Quality Guidelines for Aquatic Ecosystems. The use of indigenous riverine invertebrates added the challenge of variability of a wild population, and the use of a complex effluent as toxicant added the variability of effluent composition. In this study, WET testing was used to determine the dilution of whole effluents required for discharge. Hazard-based guidelines were developed for the disposal of kraft and textile effluents. The level of environmental hazard posed by different effluent concentrations was ranked, and was related to the River Health Class. This indicated effluent concentrations that may be allowed to enter the aquatic environment, e.g. 3% effluent concentration guideline for both general kraft effluent and general textile effluent for the protection of a Class A river. This approach could contribute to the use of an Environmental Risk Assessment, approach for the management of complex effluents. A number of acute 96 hour toxicity tests were conducted following an unreplicated regression design, using kraft and textile effluents as toxicants, mayfly nymphs as test organisms, and river water as diluent and control. Test organisms were sampled from unimpacted, flowing-water riffle areas, and were exposed in recirculating artificial streams (or channels) to a range of effluent concentrations. Mortality was selected as end-point and observed twice daily. The experimental results showed the variability and acute toxicity of both kraft and textile mill effluents. Baetids were more sensitive (mean LC50=16% effluent concentration) to General Textile Effluent (GTE), but less sensitive to Post Irrigation Textile Effluent (PITE). Textile effluent (PITE) held in a holding dam were therefore less variable and less toxic; suggesting that stabilization of the effluent could have contributed to reduced toxicity. Effluent composition, e.g. higher calcium levels, may also have contributed to lowering toxicity. T. tinctus was sensitive to kraft effluents, but showed less variable responses to Irrigation Kraft Effluent than General Kraft Effluent. Toxicity test data indicated that GKE, IKE and GTE should not enter the aquatic environment without treatment, as they can cause adverse effects to aquatic biota. Both kraft and textile effluents must therefore be treated before discharge. Different responses to different effluent batches were probably due to effluent variability. The use of indigenous organisms, and not a standard laboratory organism, could also have contributed to variability. A hazard-based approach could be useful, as it will provide a consistent basis for deciding on the acceptability of impacts, while allowing natural site-specific differences to be taken into account.

PhDENV (Hydrology) / Department of Hydrology and Water Resources / This study developed operating rules for groundwater supply from a probabilistic (risk-based) approach. Groundwater supply systems are often operated without relating groundwater yield/availability to demand which makes groundwater resource planning and management challenging and unpredictable. Risk-based approaches for developing groundwater operating rules comprehensively incorporate assurance of supply and also account for uncertainty due to model inputs, model structure and climate variability. A groundwater resource unit (GRU) was delineated and its hydrogeological conceptual model developed. Automatic curve matching was used to identify appropriate aquifer models and test solutions for estimating hydraulic characteristics (storativity, transmissivity and hydraulic conductivity) based on Aquifer Test Solver (AQTESOLV) Pro version 4.5. Limited groundwater levels and rainfall data were infilled and/or extended using Output Error-Nonlinear Hammerstein Weiner (OE-NLHW) and non-parametric regression (NPR), respectively. Performances of these models were based on relative error (RE), correlation coefficient (COR), root mean square error (RMSE), coefficient of determination (R2) and Nash Sutcliffe coefficient of efficiency (NSE). A program for generation of monthly groundwater levels for the GRU was coded in FORTRAN based on the revised version of the Pitman model (referred to as GW-PITMAN model). The model was calibrated using groundwater levels from a neighbouring borehole due to lack of observed representative data for the GRU. Validation was done by establishing the realistic nature of simulated runoff, recharge and groundwater levels. A Variable Length Block (VLB) bootstrapping model was used for simultaneous generation of stochastic inputs (rainfall, evaporation and groundwater levels) of the groundwater operating rules model. Operating rules were developed from statistical analysis of 100 base yields for the GRU simulated from 5-year long stochastically generated sequences (with length of 34 years) of rainfall, evaporation and groundwater levels. The hydrogeological conceptual model indicated presence of faults and diabase dykes which influence preferential flow paths and storage of water in the aquifer. Identified aquifer test solutions were found to be suitable for estimation of hydraulic characteristics, since they had generally good model fits and low mean residual errors. Heterogeneous aquifer types were identified though leaky aquifer dominated. Storativity, transmissivity and hydraulic conductivity values ranged from 0.0003-0.060, 0.78-12.3 m2/day and 0.074-0.460 m/day, respectively, indicating limited storage with potential for local groundwater supply for private consumption. Graphical fits for observed and estimated rainfall and groundwater levels were mostly comparable, though scatter plots indicated cases of underestimation and overestimation of observed values. R2, COR, NSE, RMSE and RE values were 0.76 and 0.7, 0.87 and 0.84, 0.75 and 0.68, 3.67 and 3.03 mm and 30 and 29% for both calibration and validation runs, respectively, for NPR model. R2, COR, NSE, RMSE and RE were 0.99 and 0.86, 0.97 and 0.93, 0.99 and 0.84, 0.03 and 0.01 m and 0.08 and 0.11% for both calibration and validation runs, respectively, for OE-NLHW model. The models were therefore found to have efficient calibration and validation, and were thus, suitable for data extension. Estimated groundwater levels, streamflow and groundwater recharge for both calibration and validation runs of the GW-PITMAN model, generally fluctuated with changes in rainfall, indicating that they are realistic. Majority (9 out of 10) of the historical statistics were mostly well preserved by VLB, except for skewness. Historic highest groundwater levels were also not well preserved. Superimposing the cumulative demands on the base yield curves and analysis of percentages of water demands that can be supplied indicated that the groundwater system could not meet the water demands at all times. To promote sustainable multipurpose use of water that can enhance rural livelihoods, allocating water using priority classification was found to be essential. Operating rule curves for groundwater supply were derived using a risk-based approach. The operating rule curves indicated that if priority classification is used all water demands are met up to maximum groundwater level of 25 m. The developed operating rule curves are therefore expected to improve water supply to both domestic and productive water uses, if they are adequately implemented and hence improve livelihoods. The procedures followed in developing risk-based groundwater operating rules for Siloam Village were summarised to assist in their application in any delineated groundwater resource unit. Though minimal infrastructure is available to support implementation of the operating rules, additional monitoring boreholes are required to aid in estimation of average groundwater levels for further calibration and validation of the GW-PITMAN model. Detailed geological and geophysical investigation are required to improve on characterisation of the GRU and its hydrogeological conceptual model. Undertaking a study of this nature in other areas including those which are data-scarce could promote wide implementation of risk-based groundwater operating rules. / NRF

Thesis (M. Tech) - Central University of Technology, Free State, 2008 / Food and water are two basic human needs. International projections indicate that water shortages will be prevalent among poorer countries where resources are limited and population growth is rapid, such as the Middle East, parts of Asia and Africa. Provisional estimates are that South Africa will run out of surplus usable water by 2025, or soon thereafter. Urban and peri-urban areas will therefore require new infrastructure and inter-basin transfers to provide safe water and adequate sanitation. Due to the high cost of these developments, such water is seen as being used for industrial and public needs only and not for irrigation. Currently, the agricultural water users consume the majority of the water used by humans. Taking cognisance of the before mentioned it is a reality that in the future the irrigation sector will have to sacrifice some of its water for public and industrial usage. This suggests growing conflict between the different water users and the agricultural water users. An attempt by the Department of Water Affairs and Forestry (DWAF) to address this conflict has been the implementation of pilot studies to determine the steps Water User Associations (WUAs) could take to ensure more effective water use in the future by the agricultural sector. These steps include an increase in irrigation efficiency according to the benchmarks of crop irrigation requirements and more efficient dam and canal management. The Water Administration System (WAS) has been developed to fulfill this exact requirement as it ensures optimal delivery of irrigation water on demand. The program is designed as a management tool for irrigation schemes, WUAs and water management offices to manage their accounts, and also to manage water supply to clients more efficiently through canal networks, pipelines and rivers. The WAS program consists of four modules that are integrated into a single program. Three modules of the WAS program have already been implemented at the Vaalharts irrigation scheme. This scheme has been transformed from a government controlled scheme to a privately owned scheme, and is now known as the Vaalharts Water User’s Association (VHWUA). The main purpose of this study was to implement the fourth module of the WAS program at the VHWUA as only full functionality of the complete program will ensure effective water use at the scheme. The fourth module calculates the volume of water to be released for all the canals (main canal and all its branches), allowing for lag times, water losses and accruals in order to minimise waste and thus save water. The methodology followed in this study was to first of all develop an understanding of the distribution cycle and the current calculation procedure of the VHWUA. The fourth module was then applied on a typical feeder canal and used to calculate the release volumes in order to compare these results with the current values. The next step was then to verify all data abstracted from the database used by the WAS program to calculate the release volumes. The database consists of information like cross-sectional properties, positioning of the sluices, canal slope, as well as canal capacities. The verification of data was done by field work, by studying existing engineering design drawings, through meetings and consultations with all parties involved in the VHWUA as well as by mathematical calculations. Cross-checking and verification, if necessary, of all above mentioned data were done. After the verification process, the database was updated and another cycle of calculations were run to do the final calibrations. Accurate calibrations were done to the seepage and the lag time coefficient. Some final adjustments were also made to the canal geometry in the database. This was an important part of the study as only a trusted and verified database will deliver correct results, irrespective of the software program used. After calibration of the database, the fourth module was again applied, but this time water losses were included in the calculations and the results revealed trustworthy and accurate real-time release volumes. The study therefore succeeded in the implementation of the fourth module on a typical feeder canal at the VHWUA. The study was concluded by the compilation of a checklist, which the VHWUA can use to implement the module on the whole scheme. This would enable the VHWUA to implement and apply the complete WAS program, which offers all the benefits and answers in every need of any water management office. Sustainable water resource utilisation can only be achieved through proper management. Applying this most effective management program will ensure a cost effective and optimised process at the VHWUA.

MENVSC / Department of Hydrology and Water Resources / ABSTRACT Siloam and Tshipise Springs are scalding geothermal springs geologically located within the Soutpansberg Group in the Limpopo Province of South Africa. These geothermal springs are associated with faults and impermeable dykes and are assumed to be of meteoric origin. The optimal use of a geothermal spring largely depends upon its physical and chemical properties as well as the geological controls at source and surrounding pathway to the surface. This study aimed at investigating trace element concentrations in these geothermal springs in order to quantify their impacts on neighbouring soil and vegetation. Impact on vegetation was assessed by incorporating seasonal variations of the trace element mobility from the geothermal springs to the vegetation (Mangifera indica at Siloam and Acacia robusta at Tshipise) via soil. The geothermal spring water, soil and vegetation samples at both sites were collected from May – July (winter) and September – November (summer), 2014. The soil samples were collected at 5 m intervals up to 20 m away from the geothermal spring in each of the sites. The bark and leaf parts of the vegetation were sampled. The control samples for water, soil and vegetation were obtained from Riverside residence at University of Venda, Thohoyandou, Limpopo Province, where there is non-geothermal source of water. The temperature, electrical conductivity (EC), pH and total dissolved solid (TDS) of the geothermal spring water and control samples were determined in situ and in the laboratory. The water samples were acidified for major cations and trace elements determination. There were also non-acidified water samples for major anion analyses. The soil and vegetation samples were digested using microwave and hot block methods, respectively. Concentrations of arsenic (As), antimony (Sb), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), mercury (Hg), lanthanum (La), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), tin (Sn), strontium (Sr), tellurium (Te), thallium (Tl), titanium (Ti), tungsten (W), vanadium (V), and zinc (Zn) were determined by inductively coupled plasma – mass spectrometry (ICP-MS) (Agilent 7700 series). Concentrations of calcium (Ca), magnesium (Mg), sodium (Na) and potassium (K) were analysed using inductively coupled plasma – optical emission spectrometry (ICP-OES) (X – Series 2) whereas the concentrations of chloride (Cl-), fluoride (F-), nitrate (NO3-), phosphate (PO42-), bicarbonate (HCO3-) and sulphate (SO42-) were determined by ion chromatography (IC) (Dionex Model DX 500). Results from this study revealed that the geothermal springs were rich in trace elements compared to that from non-geothermal source of water. The mineral elements present were vii mainly due to rock-water interaction in the deep aquifer at both sites. The geothermal spring water is not fit for drinking because it is particularly high in fluoride (F) having 6.66 and 5.97 mg/L at Siloam ; 6.72 and 7.28 mg/L at Tshipise for winter and summer, respectively. Also, high Nickel (Ni) with 462 µg/L and 868 µg/L: Lead (Pb) with 652 µg/L and 211 µg/L at Siloam and Tshipise respectively, for summer season. In addition, it is not suitable for irrigation owing to high sodium absorption ratio (SAR) values which were above the standard guidelines (˂1) by South African Bureau of Standards (SABS) and World Health Organization (WHO) at both sites. In summer season, there were higher trace elements concentrations than in the winter season. The higher concentration values could be attributed to rainfall, which aids in the dissociation of rock particles, resulting in higher concentrations of these elements. Siloam spring water was more mineralised than Tshipise spring water, hence its neighbouring soils and vegetation possess more trace elements concentrations than the latter. Owing to their high mineral elements content, the geothermal spring water flows across the soil, making it vulnerable to sorption of the trace elements. The trace elements present in the surrounding soil of the geothermal spring were as a result of geothermal water and soil pedogenesis. The geothermal water contaminates the surrounding soil with substantial quantity of trace elements, which decreases with the distance from the geothermal spring, making far distanced soil less-contaminated. High levels of Cr, Co, Ni, Cu, Zn and Pb at Siloam soil can be attributed to more minerals present in the spring, therefore making absorption by Mangifera indica inevitable. Soils at Tshipise are moderately concentrated owing to moderate trace elements concentrations from the geothermal spring water. Generally, seasonal variations were observed in the parameters analysed in the geothermal spring water, surrounding soil and vegetation to ascertain the most favourable season in terms of the trace elements concentrations. There were higher concentrations of trace elements in the geothermal spring, particularly during the summer season, compared to the winter season; this leads to more contamination of the surrounding soils and vegetation. This study showed that geothermal spring has potential to enrich the neighbouring soils and vegetation with trace elements, which could result in contamination. It can be concluded that geothermal spring, despite its benefits to humans, also contaminates the surrounding surface soils with toxic trace elements. Soils are a platform for vegetation. Therefore, if the soil is contaminated by toxic elements, there are high possibilities that these trace elements are absorbed by the neighbouring vegetation, which is likely to affect human beings adversely.

MESHWR / Department of Hydrology and Water Resources / Irrigation uses the largest amount of water, estimating to 60 % of the total consumption in South Africa. For this reason, the efficient and reasonable use of water by irrigators is of paramount importance. Thus, this study was carried out to assess the suitability of Wetting Front Detectors (WFDs) in improving water management. The study involved an on-farm survey; field installations; testing of WFD technology on selected plots within the scheme; identification of the crops grown; documentation of the current water supply and documentation of the challenges faced by farmers in relation to irrigation. These were carried out to identify the ideal situations in the scheme. Irrigation scheduling helps farmers to know when to irrigate and amount of water required supplying for crop need. The study presented WFD, as a means of improving irrigation efficiency. The WFD is a simple tool that helps farmers to identify what is occurring around the root zone. Four plots with a representative farmer in each of the plot were identified in four Blocks (Block 1 farmer 1, Block 1 farmer 2; Block 2 farmer 1; Block 3 farmer 1 and Block 4 farmer 1). On-farm experiment of the WFD was carried out. However, with Block 4 farmer 1, insufficient data was collected due to absence of LongStop equipment. This also involved field installation, observation and measurements of the LongStops (LSs) and FullStops (FSs) WFDs at placement depth of 30 cm, 45 cm and 60 cm. The efficiency of an irrigation system depends on different performance indicators including Irrigation Efficiency (IE), Conveyance Efficiency (CE), Application Efficiency (AE), Storage Efficiency (SE), Distribution Uniformity (DU) and Coefficient uniformity (CU). In this study, attention was focused only on DU; CU and SE, as represented by water moisture availability. All the DU for all plots in blocks were below the standard DU of furrow, which is 65%. Farmer 2, in Block 1, had a higher DU and CU, which were 60% and 68%, respectively- considered closer to the standard DU value. For the other farmers, their DU and CU prior to irrigation were very low, which indicated that there was uneven distribution of water in these plots. The poor DU in Block 1 farmer 1, indicated by the uneven infiltrated water, resulted in excessive watering. Analysing the WFD showed that farmers were performed well in all the Blocks, except for farmer 1 in Block 1. Average soil moisture content result indicated high water loss through deep percolation. The highest volumes of water recorded before and after irrigation were 131 ml and 159 ml, respectively, for LS90 placed at a depth of 90 cm in Block 2 farmer 1. High volumes of water were collected in Block 1 farmer 2, Block 2 farmer 1 and Block 3 farmer 1 before and after irrigation. The result showed that, the more placement depth down the soil profile, the more accumulation of water in the LSs. Therefore, it was recommended that farmers continue to use the WFD as a tool for irrigation efficiency. However, there is need for improvement and capacity building in using the tool.

MENVSC / Department of Ecology and Resource Management / Some boreholes in South Africa which serve as a source of drinking water for rural communities are reported to have high fluoride concentration, much above the WHO guideline of 1.5 mg/L. This study aimed at activating aluminosilicate clay soil mechanochemically, modifying aluminosilicate clay soil with Al-oxide and fabricating porous ceramic granules using Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch and evaluating their performances in defluoridation of groundwater. The raw clay materials were mechanochemically activated for 5, 10, 15 and 30 minutes for physicochemical transformation of the solid aggregate. The morphology of the samples showed the honeycomb structure. The surface area analyses of samples using Brunauer–Emmett–Teller (BET) gave the highest surface area of 50.5228 m2/g at 30 min activation time. Hence, the optimum activation time was 30 min. The Fourier Transform Infrared (FT-IR) analysis showed increase in the absorbance of FT-IR by Si-O-H groups at 510 cm-1 with increasing milling time. This is evidence that more surface Si-O-H groups were available at higher particle surface area that would be necessary to interact with fluoride. X-ray diffraction (XRD) analyses revealed that, at 30 minutes milling time, the peak broadening is intensified whereas the reflection peak intensities decreased. The X-ray fluorescence spectrometry (XRF) results for 30 minutes milling time showed that silica and alumina were the highest components in the clay soil. Using the activated clay in batch defluoridation of fluoride-spiked water, a maximum fluoride removal of 41% was achieved at a pHe of 2.41. The initial fluoride concentration was 9 mg/L while the sorbent dosage was 0.6 g/100 mL and the contact time being 30 minutes. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Optimization of Al3+ concentration for modification was carried out by modifying the mechanochemical activated aluminosilicate clay soil with different concentrations of Al3+ from which the optimum modification was achieved with 1.5 M. Characterisation studies on the Al-oxide modified mechanochemically activated aluminosilicate clay soil by SEM, BET, FT-IR, XRD and XRF, analyses were carried out to determine the resultant changes in physicochemical properties of the adsorbent owing to modification. The SEM image of Al-oxide modified mechanochemically activated clay soil showed many small pores and honey-comb structure on the surface of different images. The BET surface area and the BDH adsorption cumulative area of the Al-oxide modified mechanochemically activated v aluminosilicate clay soil were more than double those for the raw clay soil. There was also an increase in pore volume of the Al-oxide modified mechanochemically activated aluminosilicate clay soil. The FT-IR spectra showed that there was increase in the absorbance by the Si-OH, H-O-H, Al-O-H and Si-O-Al. The equilibrium pH of solution was higher than the point-of-zero charge (pHpzc) implying that fluoride removal occurred at solution pH > pHpzc where the net surface charge of the mechanochemically activated clay aluminosilicate soil was negative.The efficiency of 1.5 M Al-oxide modified aluminosilicate clay soil to remove fluoride from water was studied and found to be 96.5 % at pHe 6.86, contact time of 30 minutes and dosage of 0.3 g/100 mL for 10 mg/L fluoride solution at 200 rpm shaking speed. The result shows that Al-oxide modified mechanochemically activated aluminosilicate clay soil is effective for defluoridation. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Al-oxide modified mechanochemically activated aluminosilicate clay soil was tested for fluoride removal on field water and the percentage fluoride removal was 96.5 % at the dosage of 0.6 g/100 mL with the pHe of 6.48. The optimum Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch mixing ratio for fabrication of porous ceramic granules was determined by varying ratios and temperature. The optimum ratio found was 20:5:1.The porous ceramic granules were characterised using SEM, BET, FT-IR, XRD and XRF. SEM analysis showed that the porous ceramic granules have the porous structure of the organic foam template. The porous ceramic granule showed an increase in pore surface area and volume as compared to mechanochemically activated aluminosilicate clay soil. The FT-IR showed the presence of a strong broad bending and stretching vibrations band at about 993 cm-1 which shows the presence of Si–O–Si bonds. Mineralogical characterisation showed the presence of quartz, albite, horneblende and microcline as the main minerals of the calcined porous ceramic granules. The major oxides of the porous ceramic granules as shown by XRF analysis were SiO2, Al2O3, MnO and Na2O. The porous ceramic granules reduced the concentrations of fluoride in the water from 10 to 3.31 mg/L. The optimum adsorption capacity was 0.6648 mg/g at a pHe of 6.32 and the percentage fluoride removal was 66.9 % at an adsorbent dosage of 1.0063 g/100 mL and a temperature of 600 ⁰C. The porous ceramic granules were tested for fluoride removal on field water and the percentage fluoride removal was 45.4 % at the dosage of 1.0009 g/100 mL with the pHe of 7.87. Mechanochemically activated aluminosilicate clay soil showed higher adsorption capacity at acidic pH, therefore it is recommended that future work should focus on improving their adsorption capacity at wider range of pH. The porous ceramic granules can also be evaluated in column dynamic flow experiments.

MENVSC / Department of Geography and Geo-Information Sciences / Agricultural abandonment is a challenge in areas of South Africa more especially in rural areas. The study employs both qualitative and quantitative methods of in sampling and collection and analysis. It adopted a case cross-sectional study design. This design is a case study in nature, hence this study compared the active and none active farmers in identifying the causes and effects of the phenomenon studied. Comparatively, the study sought to find out if there are factors influencing farm abandonment and its consequences in Tshiombo village. The study was based on field surveys allowing for observation and with respect to agricultural abandonment. In addition to observation open ended questions together with questionnaires were administered to extension officers. The data collected from open ended questions and questionnaires was recorded and subjected to descriptive analysis. Several factors have been identified influencing farm abandonment. The challenges ranges from needs prioritization, infrastructure and capacity. It was recommended that government should reinstate its support to small scale farmers prioritize the maintenance of irrigation canals. The prioritisation of agriculture will attract many into agricultural practice with the aim of reducing poverty and starvation in rural communities. / NRF

MENVSC / Department of Ecology and Resource Management / Fluoride is one of the anionic contaminants which is found in excess in groundwater because of geochemical reaction or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as precipitation, ion-exchange processes, membrane processes, the adsorptions process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. In this work, the preparation of clay polymer nanocomposites (CPNCs) used in defluoridation began by modifying the original natural Mukondeni clay to render the layered silicate miscible with the chosen polymer, microcrystalline cellulose. Clay polymer nanocomposites (CPNCs) were synthesized using the melt intercalation method. Mukondeni black clay with microcrystalline cellulose as polymers was melt mixed at 220 °C for 10 minutes in an extruder for exfoliation of the resulting composite. Physicochemical characteristics and mineralogical characteristics of the CPNC was determined using XRD, XRF, BET, FTIR and SEM. Batch adsorption experiments were conducted to determine the efficiency of CPNCs in defluoridation of groundwater. The pH, EC, TDS and fluoride concentration of field water was determined using the CRISON MM40 multimeter probe and the Orion versastar fluoride selective electrode for fluoride concentration. Elemental analysis revealed that CPNC 1:1 is mainly characterized of cellulose, Quartz and Albatite as the major minerals with traces of Montmorillonite, Ednite and Magnesium as minor minerals constituting CPNC 1:1. The structure of 1:4 CPNC was partially crystalline and partially amorphous showing increased cellulose quantity (1:4 clay to cellulose) as compared 1:1 CPNC, 1:2 CPNC and 1:3 CPNC. Maximum adsorption of fluoride was attained in 10 minutes using 0.5g of 1:4 CPNC removed 22.3% of fluoride. The initial fluoride concentration for the collected field groundwater was 5.4 mg/L, EC 436 μS/cm, and TDS 282 mg/L. The regeneration potential of CPNCs was evaluated through 3 successive adsorption desorption cycles. Fluoride removal decreased after the first cycle for all ratios of CPNCs, a continued decreased can be observed following the second cycle. CPNC 1:2 decreased from 9.32 % at the 1st cycle to 2.84 % and 0.56 % on the 2nd and 3rd cycle respectively. CPNC 1:4 decreased from 8.22 % at the 1st cycle to 4.80 % and 0.72 % on the 2nd and 3rd cycle respectively. The fluoride-rich Siloam groundwater had a slightly alkaline pH of 9.6. iv The low adsorptive characteristic displayed by all 4 CPNCs can be deduced from the BET analysis that revealed low surface area, pore volume, and pore size, it is evident from the BET analysis that less fluoride will be absorb as adsorption sites will be limited. Based on the findings of this study, recommendations are designing of correct preparation techniques to obtain nanocomposites with desirable properties, polymer melting points and evaporation point of the binder should be taken into consideration. / NRF