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Now showing 1 - 7 of 7
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    Remote water quality diagnostic system
    (2019) Gulzar, Iqra
    Water is the basic necessity for all living organisms. About, five million people specifically children are dying each year due to dehydration or use of toxin infected water around the world. In South Africa approximately seventeen percent of the population do not have access to safe drinking water. Considering all of these challenges it is evident that monitoring the quality of water is important for providing safe and clean water. Several researchers have shown that the parameters related to the quality of drinking water can be monitored effectively in the field. To accurately determine the quality of water it needs to be tested for many parameters. Measuring all possible parameters can be a daunting task. It is very costly and time consuming at the same time. There is also research available in which researchers have proposed remote monitoring of water quality based on fewer parameters in a given water sample to conclude whether or not the given sample was safe for drinking. This has met with limited success. There is however very limited or no scientific evidence available to validate the effectiveness of the selected fewer parameters to determine the quality of drinking water. The research presented in this dissertation proposes a list of fewer parameters that are monitored to determine the quality of water. The effectiveness of those parameters in determining the quality of drinking water has been verified by conducting a detailed analysis on a number of water samples in a laboratory environment. The research has also proposed a system that is capable of monitoring those parameters remotely. This enables the water supplying authorities to determine the basic quality of water without testing it in the laboratory environment resulting in a decreased time and lower cost.
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    Impacts of a defunct colliery on water quality of the Wasbank river, UMzinyathi Municipality, KwaZulu-Natal
    (2019) Nyath, Linah Thobekile
    The inefficiency of South Africa’s previous legislation that regulated the operation and closure of mining activities, has resulted in too many mines being abandoned without adequate rehabilitation (Naidoo, 2017). Therefore, currently, the State has taken a responsibility to identify all these abandoned mines, assess and rehabilitate them in order to mitigate their environmental impacts, mainly the acid mine drainage (AMD) impacts. A defunct colliery in Glencoe, which ceased its operation in 1973, is one of the mines that was identified as an abandoned mine. This mine is located on the upper Wasbank catchment area in KwaZulu-Natal and study was conducted in order to determine whether this defunct colliery has any negative effects on the water quality of this catchment area. A zone above the mine shaft of the defunct colliery was identified and considered as a pristine zone, which was then used as a reference zone, and three more zones were identified, adjacent and below the mine shaft, named sampling zone B, C and D in order to assess the trend of water quality indicators and therefore to determine whether the defunct colliery is contaminating this catchment area or not. Each zone had distinct sampling points within the zone, ranging from one to four sample points per zone. Water quality of this catchment area was tested on a monthly basis during the wet season (December 2017 to March 2018) and the dry season (April 2018 to July 2018). The parameters that were tested in the field were pH, electrical conductivity, and temperature. Furthermore, once a season, water samples were collected from each sampling point in order to determine the concentration of dissolved ions. All results were analyzed against the results of the reference zone and furthermore, against the South African Water Quality Guidelines for livestock farming and domestic use. The conclusion drawn from these results is that this catchment area is altered by mine drainage from the defunct colliery. However, it seems that mitigation measures designed by previous miners are effectively treating the AMD generated which has resulted in the neutralization of this acidity such that any decant from old mine works into the Wasbank River is slightly alkaline. Furthermore, based on SAWQG, the study concluded that this catchment is within the water quality standards for livestock farming and domestic use. However, there are minor restrictions to certain specific uses because of its salty state. Subsequent to the findings of this study, the defunct colliery can be considered as low priority of future rehabilitation efforts due to the state of water quality of the surrounding drainage
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    Experimental assessment of emulsification stability during enhanced oil recovery in the presence of polymer (PMMA) and nanoparticles (ZnO)
    (2018) Muzang, Emmaual Ndakwe
    Among several methods proposed as secondary or tertiary recovery techniques, water flooding has proven to be less costly in terms of operating costs but often results in lower recovery value and sweep efficiency. Water flooding may be preferred when limited economic resources exist and/or for the displacement of oils with similar mobility to water. In heavy oil reservoirs the low mobility of the oil makes this method inefficient as water mobility is much greater than the oil leading to unfavorable mobility ratio, large viscosity difference which may cause channeling or fingering in the reservoir sweep and an early water breakthrough. Surfactant injection has been considered as an attractive alternative in order to attain higher oil recovery volumes. For instance when a stable oil-in-water emulsion is injected in a reservoir after a secondary recovery with water flooding, it tend to flow through the same high permeable water-wet zone previously covered by water flooding and the oil droplets get trapped in the pore throats changing the wettability of the rock surface and decreasing the permeability of the invaded zone. As a result water injected afterwards is forced to flow through less permeable zones that were not swept previously and lead to an oil recovery increase. Often surfactant injection is useful for improving the sweep in the reservoir. It has been found that polymer injection may decrease further water mobility, thus contributing to a favorable mobility ratio and optimized volumetric sweep efficiency. Though injection of polymer may not reduce the residual oil saturation in the reservoir, it results in an improvement of displacing front stability and better oil recovery compared to other techniques such as water flooding. Polyacrylamide copolymers or hydrolyzed polyacrylamide (HPAM) polymers are by viii far the most widely used polymer for EOR but they are still expensive. Poly (methyl methacrylate) or PMMA was considered for this work since it’s relatively cheaper and readily available. On the other hand emulsions can be typically stabilized by the use of emulsifiers that are usually added in volumes (up to less than 1%wt) in order to lower the operational cost of the recovery process. In particular, emulsions stabilized by solid particles (nanoparticles) have become recently an attractive alternative that provides stabilization in oil-in-water and water-in oil emulsions by reducing the interfacial tension and the capillary pressure, but are still relatively less covered in open literature. Therefore this dissertation considers oil-in-water/water-in-oil emulsions stabilized by nanoparticles and polymers to extent knowledge in this area. Therefore; this study investigates the stability of crude oil/water emulsions in the presence and absence of polymer and nanoparticles using crude oil blend received from NATREF with average API gravity of 35 and in particular assess the influences of the temperatures, brine concentration, polymer/nanoparticle concentration, oil/water ratio and stirring mechanism. It further investigates whether or not the combination of polymers and nanoparticle can provide a more stable emulsion than polymers only. Poly (methyl methacrylate) or PMMA polymer and zinc oxide (ZnO) nanoparticle were used. Furthermore droplet size distribution was analyzed using a microscope to see how tight the emulsions are and the droplets distribution.
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    A framework to determine the true cost of centralised waste water systems on the economies of South African Cities
    (2017) Forster, Cleo
    Green Drop data indicates that South African metropolitan areas are particularly poor at ensuring that the effluent quality released by their wastewater treatment plants meets the required national standards. The impact of the poor performance of wastewater plants, although known, is not quantified in terms of real impact on the South African economy. This research report identifies the health, environmental and economic externalities associated with the pollution of water bodies by untreated or partially treated wastewater, and determines economic methods through which these externalities can be monetised. As these methodologies should ideally be incorporated into existing wastewater evaluation approaches, the feasibility and method in which to incorporate externality evaluation into the existing Green Drop system is investigated and through key informant interviews the resulting recommendations contextualised. The research report concludes with recommendations as to how the approach to South African wastewater treatment evaluations can be improved through the incorporation of economic externalities Key words: Ineffective wastewater treatment, water pollution, externalities, economic impact, Green Drop SA
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    Assessment of the potential of selected adsorbents for use in small-scale systems for the removal of uranium from mine-impacted water
    (2017) Mabape, Kgaugelo Ishmael Smiley
    The tailoring of zeolites surface properties using organic functionalising agents displaying higher binding affinity for metal ions is a widely explored approach for water treatment. In this study, amine functionalised zeolites and phosphate functionalised zeolites were separately synthesised from similar natural zeolite precursors using reflux methods. The surface composition and morphological elucidations were achieved by characterising the adsorbents using Fourier Transform Infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), Zeta potential, Point of zero charge (pHPZC), and the Brunauer, Emmett and Teller analysis (BET). In case study 5.1, the sorption mechanisms of the uranyl ion onto amine functionalised zeolites (AMZ), activated carbon (AC) and natural zeolite (NZ) were studied as function of various environmental batch parameters. There was effective adsorption when uranium existed as uranyl ions: UO22+ and UO2OH+. The data fitted numerous kinetic and isotherm models suggesting that the equilibrium mechanisms were characteristic of a combination of chemisorption and physisorption for these three adsorbents. The Dubinin-Radushkevich (DR) model did not fit the data and therefore the energy values derived from it were not used to predict the mechanisms involved. However, the thermodynamic evaluations of parameters ∆H, ΔG and ∆S° showed that equilibrium mechanisms were exothermically, randomly and spontaneously favoured for all adsorbents at temperatures ranging between 22 and 40oC. The adsorption capacity of 0.452 mg g-1 was achieved at pH 3 by 500 mg AC dosage using 20 mL volume of 10 mg L-1 uranyl ion solution after equilibrating for 6 h within the temperature ranges of 22 to 30oC. Under the same conditions of sorbent dosage of 500 mg, uranyl solution volume of 20 mL and 10 mg L-1 U(VI) solution concentration, the maximum adsorption capacity of 0.506 mg g-1 for NZ and 0.480 mg g-1 for AMZ were both achieved at pH 4 after equilibration time of 21 h and 6 h with the optimum temperature range of 22 to 30oC, respectively. The model results predict that intraparticle diffusion thorough pores decreased in the order AC ˃ NZ ˃ AMZ while estimating that chemisorption occurred in a reverse order. On the basis of the modelled data, it was deduced that amine functionalisation of natural zeolites improves their chemisorption capability for uranyl ion and can therefore be used as a cost efficient adsorbent for small-scale remediation of contaminated aquatic systems. In another case study 5.2, the surface properties of successfully prepared aminomethyl phosphonic acid functionalised natural zeolite (APZ) were compared to those of commercial silica polyamine composites (SPC) for uranium uptake in batch aqueous solutions. The FTIR spectrum revealed that (3-aminotrimethyl) phosphonic acid functional groups were successfully grafted onto natural zeolite. The TGA analysis showed that the APZ had higher thermal stability and fewer active sites compared to SPC. The optimum adsorption capacity (qe) of 49 mg g-1 and 44 mg g-1 uranium was achieved using 25 mg SPC and 100 mg APZ, respectively at pH 4, 25oC after 1 and 6 h equilibrating time. The data best fitted the pseudo second-order kinetic model and Freundlich isotherm model. The thermodynamic studies showed that adsorption occurred chemically and exothermically for both APZ and SPC. The overall selectivity order for APZ was; Na ˃ Mn ≥ U ˃ Ca ˃ Fe and for SPC was; Fe ˃ Mn ≥ Ca ˃ U˃ Na. The findings showed that phosphate- and amine-functionalised zeolite bind strongly to uranium compared to the unmodified natural zeolite and other conventional adsorbents such as activated carbon. Their selectivity for this element was commendable. With further improvements in the synthetic protocols e.g. by using microwave-based methods, it should be possible to obtain functionalised zeolite that has superior properties to SPC.
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    The use of impulse response tracer experiments in horizontal subsurface flow constructed wetland development
    (2016) Pieters, Werner
    In the past three decades there has been an increased interest in constructed wetlands (CW) and their effectiveness in treating water. The hydraulic efficiency of a CW can be determined by using chemical reactor theory to develop residence time distribution (RTD) parameters such as effective volume (Veff), normalized variance (σ2) and mean residence time (τm). Five experiments were conducted to study the effects on these RTD parameters in a CW by using a glass pilot-scale laboratory rig and varying the inlet-outlet positions. The rig made use of a glass tank 250x250x500mm filled with clear superabsorbent polymer balls as a packing. The clear tank and balls made it possible for the flow to be observed when a FWT red impulse tracer dye was inserted into the system. The flow was photographed at specific time intervals for visual analysis and comparison. . The visual results showed the formation of a hull-shaped velocity profile in all the experiments. The RTD was obtained by collecting tracer samples at specific outlet positions during the course of each experiment. The five inlet-outlet configurations RTD parameters results showed; a straight flow path from a single inlet to outlet yielded the lease desirable hydraulic performance with dead volumes contributing to up to 67% of the CW. An increase in the number of outlets and changing the direction of flow diagonally showed up to a 96% improvement to the effective volume of the system could be achieved when compared with single inline inlet-outlet flow. The best result was achieved by combining the visual and RTD data to make changes to the rigs geometry in order to eliminate dead zones and yielded up to a 148% improvement in the effective volume of the system when compared with single inline inlet-outlet flow. A well designed CW with respect to inlet-outlet position can result in reduced land requirements and construction costs by minimizing the dead volume and improving hydraulic efficiency.
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    Passive treatment of acid mine drainage through permeable concrete and organic filtration
    (2016) Zaal, Steven Michael
    The aim of this research was to reduce heavy metal and sulfate content of acid mine drainage (AMD) through the methods of passive filtration by combining permeable concrete and organic materials. This was to achieve a low cost, yet effective temporary treatment method for rural/poor communities who are affected by AMD. The acids are filtered through layers of alternating pervious concrete and biological composting layers. The concrete layers target removal of heavy metals such as iron, manganese, potassium, and magnesium, etc. through precipitation as well as reduce sulfate content to a small degree along with total dissolved solids. The concrete layers also aid in raising the pH of the AMD to more acceptable levels. The biological layers achieve sulfate remediation through the metabolism of sulfatereducing- bacteria (SRB). This process however required time and the organic layers were thus thicker and less permeable than the concrete layers in order to allow seepage to take place at a reduced rate. A wide variation of composting layers were tested, including cow manure, chicken manure, sawdust, straw, zoo manure, and leaf compost to find an optimum mix of materials which allows for the greatest sulfate reduction through sulfate reducing bacteria in the shortest possible time. Short as well as Long-term testing of rigs was undertaken to establish effectiveness, limitations and lifespan of the filtration systems. AMD from a mine in the Mpumalanga coal fields with exceptionally high sulfate content was used to test effectiveness of the organic materials over a short period of time. With long term testing conducted with a synthetic AMD, due to limited supply from the mine. The short term testing yielded removal of sulfates in the order of 56% when using kraal manure as the biological reagent mixed with sawdust for added organic carbon. The mix percentages by volume were 80%Sawdust to 20%manure and this setup was able to achieve the 56% removal of sulfates within 14 days. The filter also successfully raised the pH to 8 while removing a significant portion of heavy metals. The long term tests showed complete (100%) remediation of sulfates after a period of approximately sixty days. The tests are continuing to determine their finite lifespan and limitations. The results show promise for using the technology as a low cost, temporary measure to protect locally impacted groundwater, especially for isolated and/or rural communities while a permanent long term solution is sought.