Theses and dissertations (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/10

Browse

Now showing 1 - 13 of 13

Assessing the feasibility and effectiveness of rooftop rainwater harvesting in Winnie Mandela Madikizela Local Municipality
(2023-05) Nakin, Abongile Ongezwa; Walker, Mark; Ikegwuoha, DC
South Africa's primary source of water is surface water. The potability of this water is doubtful especially in rural areas. Evaluation of rainwater quality from various roof materials is crucial. Additionally, there is a need to evaluate the quantity and the economic viability of Rooftop Rainwater Harvesting (RRWH). Winnie Madikizela Mandela Local Municipality (WMMLM) of Nomlacu currently has 73.6% municipal water supply backlog. With the current challenges, it is important not only to explore ways to save water but also to generate own sources of water. This makes RRWH systems as a viable water resource, an option for alleviating water scarcity. The study aims to assess the feasibility and effectiveness of RRWH for domestic use in WMMLM. The target is to determine the potential of rainwater harvesting as a potable water supply and conservation alternative. Hydrological data was obtained from the Weather SA to facilitate the calculation of the quantity of rainwater that can be harvested per household. Moreover, catchment areas were obtained through QGIS to determine size and materials of the roof types. Thus, to analyse the impact of roof materials on water quality for human consumption and irrigation. According to the results obtained in this study, Turbidity and E. coli produced noncompliant results of (0.8 – 2.8 NTU) and (0 - >2420 MPN /100mL) respectively. Although within limits, Aluminium, Colour, and Zinc concentrations present higher values on zinc metal roof compared to tiled roofing material. This is due to the high radiation and good heat conducting capacity of the metal. Results also showed higher pH levels on tiled roofs (7.05 – 7.39) compared to zinc roofs (6.27 – 7.19), which is in line with the nature of concrete. The most significant and immediate threat to health that roof collected water poses is bacterial contamination. Therefore, it is important to regularly clean the system, use disinfection solutions like chlorine tablets and boiling water before consumption. Overall, Nomlacu area receives relatively high amounts of rainfall which is greater than country’s annual rainfall. The study showed that RRWH can meet the annual demand of rainwater and have an overflow of roughly 7211L/year which is equivalent to an approximate potential annual harvest of 124% when utilized to its optimal potential and at worst case scenario can alleviate the pressure from the municipal water supply system by at least 81%. Results showed that optimal rainwater harvesting can be achieved by using more than two storage tanks per household. This then makes it possible for the system to alleviate pressure from the municipal water supply. On the economically aspect, installing a RRWH system is financially feasible, it would spare the municipalities approximately 48.8% of the municipal water supply spend to supply water to the municipality should this project be a government initiative.
Development of a flat sheet woven fabric membrane fermenter for xylanase production by Thermomyces lanuginosus
(2015) Thorulsley, Venessa; Rathilal, Sudesh; Pillay, Visvanathan Lingamurti; Ramsuroop, Suresh
Fermentation processes are vital for the production of numerous bioproducts. Fermentation being the mass culture of micro – organisms for the production of some desired product, is an extensive field, with immense prospects for study and improvement. Enzyme production is of significance as these proteins are biological catalysts, finding niches in numerous industries, xylanase for example is utilized in the pulp and paper, animal feed, biofuel and food production processes. During enzyme production, a critical step is biomass separation, whereby the valuable product, the enzyme, is removed from the broth or micro – biological culture before it is denatured. This is typically achieved via centrifugation. The aim of this study was to develop and evaluate a submerged membrane fermenter system with the specific outcome of increasing the rate of production of xylanase, from the thermophilic fungal species Thermomyces lanuginous DSM 5826. Preliminary shake flask experiments were performed to determine the optimal production conditions, followed by partial characterization of the enzyme. A bioreactor was then fabricated to include a flat sheet membrane module, with outlets for permeate and broth withdrawal and inlets for feed and sterile air input. Experiments were conducted to determine the optimal dilution rate for maximum volumetric productivity. Results from the shake flask experiments indicated that the best conditions for xylanase production, yielding xylanase activity of 5118.60 ± 42.76 U.mL-1 was using nutrient medium containing beechwood xylan (1.5 % w/v), yeast extract (1.5 % w/v), potassium dihydrogen phosphate (0.5 % w/v), adjusted to a pH of 6.5 and inoculated with 1.0 mL of spore solution, rotating in a shaking incubator set to 150 rpm at 50 °C. Apart from analysis of the effect of the carbon source on xylanase activity, coarse corn cobs were used in the shake flask experiments as a cost saving initiative. The pH optima was determined to be 6.5 while the temperature optima of the enzyme was 70 °C. SDS PAGE analysis revealed that the molecular weight of the enzyme was between 25 and 35 kDa and qualitative analysis via a zymogram revealed clear zones of hydrolysis on a xylan infused agarose gel. During short run membrane fermenter experiments the percentage increase in enzyme activity between the batch operation (610.58 ± 34.54 U.mL-1) and semi – continuous operation (981.73 ± 55.54 U.mL-1) with beechwood xylan nutrient replenishment was 60.78 %. The maximum volumetric productivity achieved with beechwood supplementation after 192 hours in semi – continuous operation (5.32 ± 0.30 U.mL-1.hr-1) was 2.1 times greater than that of batch operation (2.54 ± 0.14 U.mL-1.hr-1) which equates to an increase of 110.28 % in productivity measured at its peak. The increase in total activity between batch (610 576.92 U) and beechwood xylan medium supplemented semi – continuous mode (1 184 937.50 U) resulted in a 94.07 % increase. During long run experimental periods, the increase in production of xylanase between the batch (873.26 ± 61.78 U.mL-1) and the xylan medium membrane system (1522.41 ± 107.65 U.mL-1) was determined to be 74.34 % while an overall average increase in productivity between the batch and xylan fed membrane system was 43.25%. The total enzyme activity with in membrane mode with beechwood xylan nutrient medium feed was 160 % greater than the batch process offering a 2.6 – fold increase. Experiments where de – ionized water was alternated with beechwood xylan nutrient medium had no significant impact on the productivity or enzyme activity. The optimal dilution rate for maximum volumetric productivity as determined to be 0.0033 hr-1. The results are indicative of the potential viability of such a design, yielding the desired outcome of a membrane integrated system to significantly increase the production of enzymes during fermentation.
Extraction of caffeine from spent coffee grounds using ionic liquids
(2023-05) Singh, Nikita; Chetty, Manimagalay; Deenadayalu, Nirmala
Coffee is the most popular beverage consumed and the second-highest commodity in the world, after crude oil. In 2018, a total of 9,5 million metric tons of coffee were produced globally. This in turn generated 6 million tons of waste coffee grounds. In South Africa alone, it is estimated that approximately 100 million cups of coffee are brewed a year, resulting in 3000 tonnes of waste produced, of which 93% ends up in landfill sites (Lombard, 2021). This abundant waste source has shown promising potential for reusing, recycling, or converting the waste into valuable products like biofuels, fertilizers, animal feed, high-value chemicals, cosmetics and pharmaceutical products such as caffeine for medicinal purposes. Besides coffee being one of the most important agricultural commodities in the world, coffee is also one of the most valuable primary products in world trade. Coffee is also the central and popular activity of many cultures. The most popular reason for the consumption of coffee is its refreshing properties. Large quantities of this waste pose threats to the environment as it is a source of severe contamination and serious health problems. To avoid this catastrophe of the coffee waste, spent coffee grounds can be utilised to generate valuable products. The long-term usage of fossil fuels depletes the finite supply and contributes to greenhouse gas (GHG) and exhaust emissions. The global economic and environmental crisis related to the usage of fossil fuels and the fast depletion of natural resources has raised much awareness and need to find alternate strategies for cleaner and greener energy and chemical products needed for recycling waste has risen drastically. The use of biomass and other lignocellulosic material to produce bio-fuels and other high value products show promising results. Using lignocellulosic material has attracted considerable amounts of attention due its renewable nature and being abundantly available. Lignocellulosic material is used for sustainable development in the world. In this study caffeine extraction is a promising solution for sustainable development, where biomass is valorised. The characterisation of spent coffee grounds (SCGs) using Technical Association of the Pulp and Paper (TAPPI) methods was carried out. The effect of temperature, reaction time and solid-to-liquid loading ratio on the yield of caffeine extracted from spent coffee grounds was investigated. Simultaneously, the best extraction solvent between the (i) ionic liquid (IL) 1-ethyl-3-methylimidazodium chloride (98%), (ii) dichloromethane and (iii) water was determined. Variation of the parameters were established using the Box-Behnken design of experiment (DOE) methodology which varied the (i) temperature (88-120 degrees Celsius), (ii) reaction time (15-35 minutes) and (iii) solid-to-liquid loading ratio (20 g/10-25 mL). For the extraction process, both the conventional method and green method (IL and water) were investigated. The conventional method includes using dichloromethane as the extraction solvent, whereas the green method makes use of the ionic liquid 1-ethyl-3-methylimidazolim chloride and water as the extraction solvents. Extraction was carried out in a Parr pressure reactor where solid-liquid extraction occurs. High performance liquid chromatography (HPLC) was used to quantify the yield of extracted caffeine. Recrystallization of the highest caffeine yield was carried out and thereafter analysed using Scanning Electron Microscopy (SEM), Transition Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS) and Differential Scanning Calorimetry (DSC). The maximum yield of caffeine was obtained at the optimum conditions of 120 °C for 25 minutes using 25 mL volume of extracting solvent. The caffeine extracted from 1-ethyl-3-methylimidazolium, water and dichloromethane was 726.22mg/L, 646.33mg/L and 566.12mg/L respectively. Alternatively stated as 1-ethyl-3- methylimidazolium chloride, water and dichloromethane extracted 0.00363 g caffeine / 1 g SCG, 0.00323 g caffeine / 1 g SCG and 0.00283 g caffeine / 1 g SCG respectively. SEM images of the spent coffee grounds prior to extraction displayed a dense morphological chain-like structure, with large lumps present. The structure was tightly bonded together and appeared rough. After extraction using each solvent, the SEM micrographs were analysed. Extractions done with the IL demonstrated full degradation. The structure was loose, multiple open pores on the surface with a smooth and thin appearance. The water extractions appeared almost same to that of the IL, but slightly thicker. Lastly, extractions using DCM appeared to be unsuccessful as the SCG attempted to be broken but were still together. The surface had no open pores, rather an oil coated layer covering the spent coffee grounds. EDS results from 99% pure caffeine standard was compared against the caffeine extracted by all three extraction solvents. Pure caffeine appeared clean, properly formed, big separate particles and distinctive shapes. The caffeine extracted using IL was similar to the structure, crystallinity and appearance of the pure caffeine. Caffeine extracted by water were in long shards, but not fully individual/separated. The caffeine extracted by DCM appeared less crystalline, much smaller in size and more compact. DSC compared the melting points of the pure caffeine standard to those caffeine samples extracted by different solvents, thus providing the purity of the extracted caffeine. The standard caffeine sample had a melting point of 233. 55 ºC equalling 99 % pure. The melting points of 226. 52 ºC; 212. 28 ºC and 200 ºC were obtained for IL, water and DCM respectively. Purity obtained were 96 %, 90 % and 85 % per respective extraction solvent.
Hydrological modelling under limited data availability : a case study of Umdloti River, South Africa
(2016) Mashiyane, Thulasizwe Innocent; Adeyemo, Josiah
Due to the water scarcity in South Africa, new strategies in management planning are needed in order to sustain water resources. The increase of population and economic growth in South Africa has a negative effect on the water resources. Therefore, it should be well managed. The main concerns of the sustainability of water resources are hydropower, irrigation for agriculture, domestic and industries. Hence, the use of integrated water resources management in a single system which is built up by a river basin will help in water resources. This study was focused on water management issues: some of the principal causes of water shortages in UMdloti River are discussed. The current situation of water supply and demand at present is discussed. It also addressed some essential elements of reasonable, cooperative and sustainable water resources management solutions. Many developing countries are characterized as there is limited data availability, water scarcity and decrease of water levels in the dams. The eThekwini municipality is also having similar problems. Water resources have been modelled under this limited data using the hydrological modelling techniques by assessing the streamflow and observed data. The aim of the study was to address the issue of water management how water supply sources can be sustained to be manageable to meet the population growth demand considering the capacity of Hazelmere Dam demand downstream of the dam. Hydrological models, simulation, and decision making support systems were used to achieve all the research objectives. Hazelmere Dam has been modelled so that it can be used efficiently for the benefit of all users downstream of the dam for their economic and ecological benefits. Monthly reservoir inflow data for Hazelmere Dam was obtained from the Department of Water Affairs, South Africa. The nature of data is streamflow volume in mega liter (Ml) recorded for every month of the year. This was converted to mega cubic meter (Mm3) for use in the analysis herein. A period spanning 19 years of data (1994 – 2013) was used for the analysis. Six parametric probability distribution models were developed for estimating the monthly streamflow at Hazelmere Dam. These probability distribution functions include; Normal, Log-Normal (LN), Pearson III, Log-Pearson type III (LP3), Gumbel extreme value type1 (EVI) and Log-Gumbel (LG). It was observed that UMdloti River is smaller when compared with other rivers within the KwaZulu-Natal Province which could make it difficult to implement integrated water resources management. The hydro-meteorological data collected also has some limitations. The meteorological stations are far away to one another and this would make it difficult to attach their readings with the corresponding water basin. The comparison between the observed and simulated streamflow indicated that there was a good agreement between the observed and simulated discharge. Even though, the performance of the model was satisfactory, yet, it should not be generalized equally for all purposes. The erosion on the study area must be addressed by the stakeholders. It must be minimized in order to sustain the water resources of the UMdloti River. Erosion has a bad impact on the environment because it causes environmental degradation as well. Further investigations are recommended that account for the geological characteristics and the source of the base flow to make sure the rate of groundwater is sufficient for any future developments. Harnessing more energy from existing water sources within the frontier of the country is important in capacitating the South African Government’s commitment to reduction of the country’s greenhouse gas emissions and transition to a low-carbon economy while meeting a national target of 3,725 megawatts by 2030. This study also aimed to determine the amount of energy that can be generated from Hazelmere Dam on the uMdloti River, South Africa. Behavioral analyses of the Hazelmere reservoir were performed using plausible scenarios. Feasible alternative reservoir operation models were formulated and investigated to determine the best operating policy and power system configuration. This study determines the amounts of monthly and total annual energy that can be generated from Hazelmere reservoir based on turbines efficiencies of 75%, 85% and 90%. Optimization models were formulated to maximize hydropower generation within the constraints of existing abstractions, hydrological and system constraints. Differential evolution (DE) optimization method was adopted to resolve the optimization models. The methodology was applied for an operating season. The optimization models were formulated to maximize hydropower generation while keeping within the limits of existing irrigation demands. Differential evolution algorithm was employed to search feasible solution space for the best policy. Reservoir behavioural analysis was conducted to inspect the feasibility of generating hydropower from the Hazelmere reservoir under normal flow conditions. Optimization models were formulated to maximize hydropower generation from the dam. DE was employed to resolve the formulated models within the confines of the system constraints. It was found that 527.51 MWH of annual energy may be generated from the dam without system failure. Storage was maintained above critical levels while the reservoir supplied the full demands on the dam throughout the operating period indicating that the system yield is sufficient and there is no immediate need to augment the system.
Integrated hydrological modelling for sustainable water allocation planning : Mkomazi Basin, South Africa case study
(2018) Amoo, Taiwo Oseni; Dzwairo, Bloodless; Allopi, Dhiren
Allocation of freshwater resources between societal needs and natural ecological systems is of great concern for water managers. This development has challenged decision-makers regarding how to reasonably allocate available water resources to meet the competing demands. Thus, turning these concerns into opportunities requires the need for both water technology innovation and water behavioural change, in order to manage fresh water in a sustainable manner. This study aimed at investigating the applicability of an integrated hydrological model in a Geographical Information Systems (GIS) environment for sustainable water allocation planning and management, using the Mkomazi Basin in KwaZulu-Natal Province, South Africa, as a case study. Specifically, the study identified ecosystems that depend on Mkomazi River for preservation of their environmental and public benefit values; developed a water allocation mechanism to achieve equitable water distribution and large benefits from water uses across the basin’s users; synthesised rules for sustainable development in sharing the limited water resources and maintaining environmental quality; and finally, established a framework for water trading in order to encourage water use efficiency and allow movement of water to new users. Historical 15-year (1990-2015) observed streamflows and daily meteorological variables (precipitation sums (mm), relative humidity (%), wind speed (m s_1), mean, minimum and maximum air temperature (oC), solar radiation (MJ/m2), sunshine duration (h) and evapotranspiration (mm)) were used for this study. The hydro-meteorological data collected from various sources were subjected to frequency trend analysis, correlation, regression and the double mass curve to test their accuracy, reliability, homogeneity, consistency and localisation gaps. The ombro-thermic diagram was used to classify the months into wet and dry periods. iii The identification of prominent ecosystems that depend on the Mkomazi River was achieved through a comprehensive desktop survey and documentation acquired from the Department of Water and Sanitation (DWS). Multivariate statistical methods; cluster, factor and principal component analysis, were applied to analyse the surface water quality data sets extracted from the repository of South Africa’s water resources website (WR2012), in other assess their impact on the aquatic net benefit values and environmental preservation. A semi-distributed event process and an integrated Soil and Water Assessment Tool (SWAT) model in a GIS environment, with descriptive statistical of mean, median, mode, standard deviation, skewness, and kurtosis were employed to simulate the basin’s hydrological process in evaluating the basin’s water balance. The SWAT model was parameterised, calibrated and validated from corrected hydro-meteorological data from 2004 to 2013. Sequential Uncertainty Fitting Algorithm (SUFI2) was used for the model sensitivity analysis, calibration and validation of the model. Artificial Neural Networks (ANNs), Probability Distribution Functions (PDF), and a Flow Duration Curve (FDC) were used to project future available water. Based on the estimated available water, an estimation of allocable water was made based on percentage dependability of the river yield to the different users. The weilbul ranking was used for choosing the dependable flow; this was subsequently used for the different water riparian’s demand distribution. Large benefits derivation from water uses across the basin’s users was based on priority-driven sustainability. Extensive literature review work was used to synthesise rules for sharing limited water resources and maintaining environmental quality for sustainable development. These rules were all drawn from similar world experiences for efficient and gainful utilisation of water and other natural resources. The synthesised rules and principles were modified to suit iv KwaZulu-Natal Province (KZN) water allocation reform regulations. The established water rules were subsequently adapted to the present (Mkomazi) case study area. The proposed developed water trading framework leans on an inclusive simulation of ‘Hydrology, Environment, Life (aquatics), Policy and Sensitivity’ (HELPS) collective response of the basin in exploring the socio-economic and environmental consequences of water regulation. It uses a System Dynamic (SD) simulation technique to form a composite supply-side augmentation with demand-side improvement system to allow movement of water to new users and encourage water use efficiency. The results of the agglomerative hierarchical cluster analysis grouped the 10 sub-basin sites into three clusters of highly polluted (HP), medium polluted (MP) and relatively less polluted (LP) group basins with latent factors of 81.9, 3.14 and 0.858 (%) in the total water quality variance data sets. The water quality index analysis shows a mild effect on irrigation farming and aquatic species. The results of water balance simulation show that mean monthly values were 28.6 m3/s over the years with Nash-Sutcliffe Efficiency (NSE) values of 0.83 and a coefficient of determination (R²) of 0.77 at validation stage. The Curve Number (CN) is the most sensitive parameter for the estimation of both streamflow and water yield within the catchment. Other water balance simulation ratios include: Streamflow/precipitation (0.4 mm); Baseflow/Total flow (0.67 mm); Surface Runoff/Total flow (0.33 mm); Percolation/precipitation (0.20 mm); Deep recharge/precipitation (0.01 mm) with an Evapotranspiration/precipitation ratio of 0.58 mm respectively. The water allocation results in the different dependable flow rates of 60%, 70%, and 85% reliability revealed it to be 17465.56, 8068.04 and 6373.35 (m3/s) at U1H009 discharge station, respectively. The synthesised literature rules suggest water allocation reform acts should be catalysed v through the institutionalisation of capacity developmental platforms where climate change transformation experts and other stakeholders have input in legislating water reform acts, which should be supported by a strong political will. The invented SD framework confirms agricultural water use as the highest demand when compared with other users. Its sustainability index was evaluated as the ratio of aggregated possible water demand relative to the corresponding supply in the same period. The result shows an integrated scenario which combines rainfall variation with improved irrigation water use efficiency and gives the optimal sustainability performance index (0.25) of the system at 70% dependable flow. The simulated water balance results also reveal the use of scientific visualisation techniques in QSWAT to model spatially distributed and time-varying hydrologic-meteorological data sets in evaluating the water balance, while its calibration and validation in SWAT Calibration Uncertainty Procedure (SWAT-CUP) algorithm connotes a strong model efficiency performance. The developed SD framework provides comprehensive assessment methodology for the decision-maker in assessing water trading. The applied integrated model can be used in similar river basins sharing related attributes to the study area in resolving the current water – stressed challenges in South Africa as well as other regions of the globe. Considering the extent of the drought and the paucity of the uneven allocation of water resources at the study area, the needfulness of integrated hydrological models such as SWAT and ANNs cannot be overemphasised in ensuring the sustainability of Mkomazi Basin, while unlocking the untapped potential of water resources for the development of the agricultural and industrial sectors, and still meeting the requirements of the ecosystem.
A model review and proposed mechanistic tiller model for the canegro sugarcane crop model
(2000) Bezuidenhout, Carel Nicolaas; Bajic, Vladimir B.
The CANEGRO model is a mechanistic model that describes environmental, physiological and managerial features of the agricultural sugarcane production system. The model originated from many sources of crop, climatic and soil research work. This caused a fragmentation in the model's components. The objectives of this study was to give a detailed model overview after an investigation into the model's code, published and unpublished documentation and to propose a mechanistic approach in the modelling of tiller populations.
Modelling and optimization of competitive bio-sorption of copper and lead ions using fruit peels
(2022-09-29) Afolabi, Felicia Omolara; Musonge, Paul; Bakare, Babatunde F.
The application of various agricultural-based materials as adsorbents for the removal of heavy metal ions from aqueous solutions has attracted the interest of many researchers. Many studies have been conducted on the removal of heavy metals from wastewater using the bio-sorption process with a focus on wastewater containing single solutes. In addition, the existing column adsorption models were developed to describe the dynamic behaviour of single solute biosorption processes. However, the application of a linear driving force model which makes use of batch experimental results to describe the bio-sorption process in a fixed-bed has not been reported for binary solute systems. In this study, the performance of orange and banana peels was investigated for the removal of copper and lead ions from wastewater in both single and binary systems. These bio-sorbents were used in their natural form. The characterization of the bio-sorbents before and after adsorption was achieved using analytical techniques. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups present on the surface of the bio-sorbents. The results showed that the bio-sorbents contain various functional groups such as carboxyl, hydroxyl, carbonyl, aminyl, and alkyl groups that enhanced the adsorption process. After adsorption, there were significant shifts in the peaks representing hydroxyl and carboxyl groups which were common to both biosorbents. Therefore, it was concluded that ion exchange is the sorption mechanism responsible for the adsorption of metal ions. The Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) was used to determine the morphological structure and the elemental composition of the bio-sorbents. The surfaces of the bio-sorbents showed an irregular, and microporous structure while the elemental composition revealed the presence of carbon, oxygen, hydrogen, and potassium. The surfaces of the bio-sorbents became uniform, smooth, and covered after the adsorption and the EDS showed the presence of adsorbed metal ions. The X-ray diffractometer (XRD) which explained the crystallinity of the bio-sorbents showed that both bio-sorbents are amorphous. The values of the point of zero charge (pHpzc) for orange and banana peels obtained were 3.85 and 4.83 respectively. This revealed that the surfaces of both bio-sorbents were acidic and therefore suitable for the adsorption of cations. The design of experiments (DOE) was employed in the batch study to investigate the interactive effect of the operating parameters, and a 24 full factorial design was used to generate the experimental runs. The factors studied and their ranges are initial concentration (10 – 100 mg/L), solution pH (2 - 6), adsorbent dosage (0.1 – 1 g), and particle size (75 – 455 µm), for the single solute system. The interaction of the factors was studied using response surface methodology (RSM) with the central composite design (CCD). The highest removal of lead and copper for orange peels was 99.75% and 98.53% while 99.32% and 98.12% were obtained for lead and copper using banana peels. The results showed that both bio-sorbents have a high affinity for lead and copper while the order of influence of the factors gave adsorbent dosage > pH > initial concentration > particle size for the bio-sorption of copper and lead using both bio-sorbents. The optimum pH of 5.5 was obtained for both metals hence three factors (initial concentration, adsorbent dosage, and particle size) with the same parameter range specified for a single solute were considered for the binary solute interactive study using the same method. The initial concentration of the metal ions in the binary system was in the ratio of 1:1. In most of the experimental runs, the percentage yield of lead was higher than copper. The highest removal for lead and copper was 98.85 % and 87.32 % for orange peels, while for banana peels, lead was 97.85 % and copper was 97.6 %. The isotherm and kinetic studies of single and binary systems of copper and lead were carried out using both bio-sorbents. The Langmuir isotherm fitted the adsorption data signifying a monolayer adsorption mechanism while the pseudo-second-order model fitted the kinetic data which suggested the chemisorption process for both bio-sorbents in single and binary systems. The adsorption of lead was higher than copper in both single and binary systems and the adsorption of copper was sensitive to the co-existence of lead in binary systems. Orange peels bio-sorbent performed slightly better than banana peels hence, it was chosen for the dynamic column studies The fixed bed experiments were conducted to investigate the effect of column parameters such as flow rate (1 and 3 mL/min), initial concentration (10, 50, and 100 mg/L), and bed height (1 and 3 cm). The results showed that the performance of the bed was improved with an increase in the bed height while the volume of solution treated at breakthrough decreased with an increase in flow rate for both metals in a single solute system. The Thomas, Yoon Nelson, and Bohart Adams models were applied to the experimental data. The Thomas and Yoon Nelson models performed well with a high coefficient of correlation (R2 > 0.9) and the lowest mean absolute error value of less than 0.1. The breakthrough curves for the binary solution of copper and lead showed slightly different shapes than the single solute system. This can be ascribed to the influence of the co-existence of metal ions which led to competition for the limited binding sites on the bio-sorbent. The breakthrough time decreased with an increased initial concentration for both metal ions in the binary system. However, the breakthrough curves representing copper bio-sorption, reached the breakthrough point faster than lead suggesting a lower affinity of copper to bind to the active site. The bio-sorption capacity of lead was consistently higher than copper for all the initial concentrations considered. A mathematical model was developed for the binary solute system of copper and lead. The model was developed from the mass balance equation of the solid and liquid phases of an elemental section of the column. An assumption of axially dispersed plug flow was made, and a linear driving force (LDF) was used to describe the intraparticle mass transfer. The partial differential equation obtained from the mass conservation equation was discretized to form an ordinary differential equation (ODE) using the finite difference method. The resulting ODEs were solved using the ode15s solver in MATLAB. The mathematical model results followed a similar trend with the experimental results, such that the breakthrough curve of copper reached the breakthrough point faster than lead for all the initial concentrations considered. The model results showed that the mathematical model based on the linear driving force can be used to describe the dynamic behaviour of a bi-solute fixed-bed adsorption column. The mathematical model performed well at high initial concentrations. The Thomas model gave the lowest mean absolute error (MAE) value of 0.08 while the mathematical model gave an MAE value of 0.9 which explains the deviation of the models from the experimental results. In conclusion, the equilibrium isotherm studies carried out in the batch experiments were used to assess the adsorption capacity of the bio-sorbent which was used in the LDF expression of the model. Hence, this study has demonstrated that the mathematical model developed for the binary system is suitable for predicting the breakthrough curves using batch experimental results
Optimisation of biodiesel production from Croton Gratissimus oil
(2018) Jiyane, Phiwe Charles; Musonge, Paul; Tumba, Kaniki
Consumption of liquid energy products, primarily fossil-based fuels, by the transportation industry, is high and has caused an escalation of the energy crisis facing global communities. This protracted use of fossil fuels has inadvertently resulted in an increased concentration of CO2 and other greenhouse gases (GHG) in the atmosphere, leading to environmental degradation. An environmentally friendly alternative fuel source, in the form of biofuels, has been found. These biofuels are biodegradable, boasting reduced levels of particulate matter (PM), carbon monoxide (CO), obnoxious sulphur (SOx) and nitrogen compounds (NOx) in their combustion products. In African countries, particularly the Republic of South Africa (RSA), the urgency for the establishment of a viable biodiesel industry is driven by the vulnerability of crude oil prices, high unemployment, climate change concerns and the need for the continent’s growing economies to use their resources in a sustainable manner. In order to address these concerns, this investigation focused on the extraction of non-edible oil from the seeds of the indigenous Croton gratissimus plant, the catalytic synthesis of biodiesel and the optimisation of the developed biodiesel production process. In this optimisation study, biodiesel was produced from oil extracted from Croton gratissimus seeds using synthesised monoclinic sulphated zirconia (SO42–/ZrO2) and KOH as catalysts. Low oil extraction yields (29.35%) obtained for this crop were attributed to its low unsaturated fatty acid content of 25.4%. From the model developed for the esterification of Croton 2– gratissimus oil, the concentration of SO4 /ZrO2 catalyst had the most significant effect in the reduction of the Acid Value of oil. This was substantiated by flat response surfaces observed on the RSM surface plots when all other design factors were varied whilst keeping catalyst concentration constant. The operating conditions for the esterification process that could give an optimum Acid Value of 2.693 mg KOH/g of oil were therefore found to be; 10.96 mass % SO42–/ZrO2 catalyst concentration, 27.60 methanol-to-oil ratio and 64 0C reaction temperature. In the optimisation of the transesterification process, the model showed that catalyst concentration, methanol-to-oil ratio, reaction temperature, and their interactions were all significant model terms. But catalyst concentration and methanol-to-oil ratio, were the terms found to have the most influence on the percentage fatty acid methyl ester (FAME) yield and percentage FAME purity. It was established from the combined model that optimum responses of 84.51% FAME yield and 90.66% FAME purity could be achieved when operating the transesterification process at 1.439 mass % KOH catalyst concentration, 7.472 methanol-to-oil ratio and at a temperature of 63.50 0C. The two-step biodiesel process used in this work, produced biodiesel with a high FAME purity and a relatively high FAME yield. Improvement of the oil extraction process may be possible with polar co-solvent such as ethyl acetate, which may increase the FAME yield in the Croton gratissimus biodiesel production process.
Optimization of irrigation water in South Africa for sustainable and beneficial use
(2017) Ikudayisi, Akinola Mayowa; Adeyemo, Josiah
Water is an essential natural resource for human existence and survival on the earth. South Africa, a water stressed country, allocates a high percentage of its available consumptive water use to irrigation. Therefore, it is necessary that we optimize water use in order to enhance food security. This study presents the development of mathematical models for irrigation scheduling of crops, optimal irrigation water release and crop yields in Vaal Harts irrigation scheme (VIS) of South Africa. For efficient irrigation water management, an accurate estimation of reference evapotranspiration (ETₒ) should be carried out. However, due to non-availability of enough historical data for the study area, mathematical models were developed to estimate ETₒ. A 20-year monthly meteorological data was collected and analysed using two data–driven modeling techniques namely principal component analysis (PCA) and adaptive neuro-fuzzy inference systems (ANFIS). Furthermore, an artificial neural network (ANN) model was developed for real time prediction of future ETₒ for the study area. The real time irrigation scheduling of potatoes was developed using a crop growth simulation model called CROPWAT. It was used to determine the crop water productivity (CWP), which is a determinant of the relationship between water applied and crop yield. Finally, a new and novel evolutionary multi-objective optimization algorithm called combined Pareto multi-objective differential evolution (CPMDE) was applied to optimize irrigation water use and crop yield on the VIS farmland. The net irrigation benefit, land area and irrigation water use of maize, potatoes and groundnut were optimized. Results obtained show that ETₒ increases with temperature and windspeed. Other variables such as rainfall and relative humidity have less significance on the value of ETₒ. Also, ANN models with one hidden layer showed better predictive performance compared with other considered configurations. A 5-day time step irrigation schedule data and graphs showing the crop water requirements and irrigation water requirements was generated. This would enable farmers know when, where, and how much water to apply to a given farmland. Finally, the employed CPMDE optimization algorithm produced a set of non-dominated Pareto optimal solutions. The best solution suggests that maize, groundnut and potatoes should be planted on 403543.44 m2, 181542.00 m2 and 352876.05 m2areas of land respectively. This solution generates a total net benefit of ZAR 767,961.49, total planting area of 937961.49 m2 and irrigation water volume of 391,061.52 m3. Among the three crops optimized, maize has the greatest land area, followed by potatoes and groundnut. This shows that maize is more profitable than potatoes and groundnut with respect to crop yield and water use in the study area.
Performance of a horizontal roughing filtration system for the pretreatment of greywater
(2016) Mtsweni, Sphesihle; Rathilal, Sudesh; Bakare, Babatunde F.
A large fraction of the world's population, around 1.1 billion people, do not have access to acceptable sources of water. In South Africa there is a growing pressure on the available freshwater resources. New sources of freshwater supply are becoming increasingly scarce, expensive or politically controversial. This has led to large scale interest in the application of water reclamation and reuse of domestic, mining and industrial wastewater as an alternative water supply sources. This is becoming critical to sustain development and economic growth in the Southern African region. This research aims at providing both social and scientific information on the importance of greywater reuse and recycling as an alternate source to aid water demand management under South African conditions. The approach to this research work was divided into two main thrusts: the first was to gain an understanding of the public attitudes towards the idea of reusing greywater that is usually perceived as wastewater which pose health concerns. The second was to provide an understanding of typical greywater quality in a peri-urban community in Durban, South Africa as well as investigate the suitability of a horizontal roughing filtration system in reducing pollutant strength of contaminants found in greywater for non-potable reuse applications. In order to achieve the central aim of this research study, the following objectives were considered: • Investigation of public perception and attitudes towards the reuse of greywater. • Determination of greywater quality in a peri-urban community in Durban South Africa. • Investigation of the performance of a horizontal roughing filtration system for the treatment of greywater collected from a peri-urban community in Durban, South Africa. It was important to have an understanding of public perception and attitudes towards the reuse of greywater because of the fact that the success of any reuse application depends on the acceptance of the public. The methodological approach for this aspect of the research work involved administering of structured questionnaires to residents within the community through field visits. The questionnaire addressed issues related to attitudes towards the reuse of greywater, perceived advantages related to the reuse of greywater and concerns related to public health issues regarding the reuse of greywater. The successful implementation of any greywater treatment process depends largely on its characteristics in terms of the pollutant strength. The methodological approach for this aspect of the research work involved physico- chemical characterization of the greywater collected from different sources within the households in the peri-urban community. Greywater samples were collected from the kitchen, shower and laundry within each of the households. This aspect of the research work was undertaken to gain an understanding of greywater quality from different sources within and between households. In order to achieve the third objective of this research work, a pilot plant horizontal roughing filtration system was designed and fabricated for the treatment of greywater. The system consisted of three compartments containing different sizes of gravel that served as the filter media. This was done in order to investigate the effect of varying filter media size on the performance of the horizontal roughing filtration system in treating greywater. The system had an adjustable manual valve used in varying the filtration rate. The impact of varying filtration rate on the performance of the horizontal roughing filtration system in treating greywater was also investigated. The main findings of this research were: • From the survey conducted, the percentage of the public willing to accept the reuse of greywater within the community was far higher than the percentage opposing its reuse. Concerns have often been expressed by the public that the reuse of greywater could pose possible adverse effects to public health. However, in this pilot study it was found that a higher percentage of respondents (>60%) disagree that the reuse of greywater could negatively impact on public health compared to less than 20% of the respondents that agree. An interesting finding of this study was that a greater percentage of the respondents were willing to have a dual water distribution system installed in their current place of residence. • The physico-chemical characterization of greywater from different sources within the households investigated indicated that, the quality of greywater varies considerably between all sources and from household to household. None of the households investigated produced the same quality of greywater. It was also found that greywater generated from the kitchen contains the most significant pollutants in terms of the physico-chemical parameters considered in this study compared to the other sources within the household. • The pilot plant horizontal roughing filtration system demonstrated its suitability for the treatment of greywater for non-potable reuse applications. It was observed that 90% turbidity and 63% Chemical Oxygen Demand reduction was achieved over the entire duration of operation of the horizontal roughing filter. It was also observed that the removal efficiency was significantly higher in the compartment with the smallest filter media size and the removal efficiency was significantly higher at lower filtration rates. It is therefore concluded from the investigation conducted in this research that the role of the public is a vital component in the development and implementation of any reuse system / application. It was found that there was a relatively high level of acceptance for the reuse of greywater among the respondents within the community where the study was conducted. The greywater characteristics results obtained from this investigation indicated the necessity of treatment prior to disposal in the environment. Also, a low BOD5/COD ratio of 0.24, which is significantly lower than 0.5, is an indication that the greywater generated from the community cannot be easily treated using biological treatment processes and/or technologies. The pilot horizontal roughing filtration system used for the treatment of greywater in this study demonstrated its suitability for the treatment of greywater for non-potable reuse applications such as irrigation, toilet flushing and washing activities.
Real time optimal water allocation in the Orange River catchment in South Africa
(2015) Olofintoye, Oluwatosin Onaopemipo; Adeyemo, Josiah; Otieno, Fredrick Alfred O.
The planning and management of water resources systems often involve formulation and establishment of optimal operating policies and the study of trade-off between different objectives. Due to the intricate nature of water resources management tasks, several models with varying degrees of complexities have been developed and applied for resolving water resources optimisation and allocation problems. Nevertheless, there still exist uncertainties about finding a generally consistent and trustworthy method that can find solutions which are very close to the global optimum in all scenarios. This study presents the development and application of a new evolutionary multi-objective optimisation algorithm, combined Pareto multi-objective differential evolution (CPMDE). The algorithm combines methods of Pareto ranking and Pareto dominance selections to implement a novel generational selection scheme. The new scheme provides a systematic approach for controlling elitism of the population which results in the simultaneous creation of short solution vectors that are suitable for local search and long vectors suitable for global search. By incorporating combined Pareto procedures, CPMDE is able to adaptively balance exploitation of non-dominated solutions found with exploration of the search space. Thus, it is able to escape all local optima and converge to the global Pareto-optimal front. The performance of CPMDE was compared with 14 state-of-the-art evolutionary multi-objective optimisation algorithms. A total of ten test problems and three real world problems were considered in the benchmark of the algorithm. Findings suggest that the new algorithm presents an improvement in convergence to global Pareto-optimal fronts especially on deceptive multi-modal functions where CPMDE clearly outperformed all other algorithms in convergence and diversity. The convergence metric on this problem was several orders of magnitude better than those of the other algorithms. Competitive results obtained from the benchmark of CPMDE suggest that it is a good alternative for solving real multi-objective optimisation problems. Also, values of a variance statistics further indicate that CPMDE is reliable and stable in finding solutions and converging to Pareto-optimal fronts in multi-objective optimisation problems. CPMDE was applied to resolve water allocation problems in the Orange River catchment in South Africa. Results obtained from the applications of CPMDE suggest it represents an improvement over some existing methods. CPMDE was applied to resolve water allocation problems in the agricultural and power sectors in South Africa. These sectors are strategic in forging economic growth, sustaining technological developments and contributing further to the overall development of the nation. They are also germane in capacitating the South African government’s commitment towards equity and poverty eradication and ensuring food security. Harnessing more hydropower from existing water sources within the frontier of the country is germane in capacitating the South African Government’s commitment to reduction of the countries’ greenhouse gas emissions and transition to a low-carbon economy while meeting a national target of 3 725 megawatts by 2030. Application of CPMDE algorithm in the behavioural analysis of the Vanderkloof reservoir showed an increase of 20 310 MWH in energy generation corresponding to a 3.2 percent increase. On analysis of storage trajectories over the operating period, it was found that the real time analysis incorporating a hybrid between CPMDE and ANN offers a procedure with a high ability to minimize deviation from target storage under the prevailing water stress condition. Overall, the real time analysis provides an improvement of 49.32 percent over the current practice. Further analysis involving starting the simulation with a proposed higher storage volume suggests that 728.53 GWH of annual energy may be generated from the reservoir under medium flow condition without system failure as opposed to 629 GWH produced from current practice. This corresponds to a 13.66 percent increase in energy generation. It was however noted that the water resources of the dam is not in excess. The water in the dam is just enough to meet all current demands. This calls for proper management policies for future operation of the reservoir to guard against excessive storage depletions. The study herein also involved the development of a decision support system for the daily operation of the Vanderkloof reservoir. This provides a low cost solution methodology suitable for the sustainable operation of the Vanderkloof dam in South Africa. Adopting real time optimisation strategies may be beneficial to the operation of reservoirs. Findings from the study herein indicate that the new algorithm represents an improvement over existing methods. Therefore, CPMDE presents a new tool that nations can adapt for the proper management of water resources towards the overall prosperity of their populace.
The role of cadastral surveying and GIS in the management of restitution and land rights claims, a case study of Lady Selborne
(2023-05) Ngidi, Lungileyo Nontobeko; Allopi, Dhiren; Singh, C
Twenty six years into democracy, the issue of land redistribution as promised by the government of South Africa is still far from being resolved. The government promised to correct the injustices of the past which left many black people stripped of their land and poor. The state passed the Restitution of Land Rights Act 22 of 1994 to bring back the land to the rightful owners, but to date some claimants who lodged their claims before 1998 have not seen the ‘promised land’ yet. The time that has passed since independence clearly indicates that there are challenges that are hindering the process. The Commission on Restitution of Land Rights (CRLR) is facing challenges with regard to the shortage of skilled staff to collect evidence because project officers, who are supposed to assist the claimants, seem confused by the maps. In addition, some of the rural land for expropriation has not been surveyed yet. The aim of the study was to discuss and show the importance of the involvement of Cadastral Surveying and Geographical Information Systems (GIS) in the processing of restitution of land rights claims in improving the turnaround time of claims and to show how that can be done. The case study was conducted at lot 408 Lady Selborne township situated in Pretoria North (25˚41ʹ27ʹʹS and 28˚07ʹ42ʹʹE) City of Tshwane Metropolitan Municipality (CTMM), Gauteng Province (GP). Qualitative research methodology was used to discuss the role of cadastral surveying and GIS. Articles, journals, books, reports and legislation documents were used to gather the required information. Another methodology used was overlay methodology which superimposes different data (cadastral documents, historical images and shape files) with common coordinates reference systems. Geomatics is regarded as a scarce skill specialising in measuring the earth size, boundary positioning, analysing structure and physical features. In this study a combination of cadastral surveying and Geographical Information System (GIS) technology was used. The focus was to investigate and locate the actual piece of land that was claimed. The role of cadastral surveying and GIS in the restitution and land claims is to paint a clear picture to those who were not there during dispossession, by giving historical background data in terms of size, historical images and maps. Another role is to serve as a mediator to resolve boundary disputes, encroachment disputes, overlapping claims and multiple claims on one piece of land, and by locating of the correct boundary beacons. This process provides an objective truth regarding land details, thereby providing clarity regarding the claimed land. Open-source software Quantum GIS (QGIS), Microsoft excel and Base Map Google satellite were used for the analysis of data. In this study, the land reform process of the Republic of South Africa (RSA) was compared with Australia, New Zealand and the Canada. These countries were chosen because they are rectifying past discriminatory injustices by allowing black citizens to claim back their land. The focus was to compare their structure in terms of specialists involved in collecting data for the purpose of compensation to the claimants. The findings revealed that competent and experienced skilled personnel can extract, analyse and manipulate data in order to collect data on claimed land. A combination of cadastral surveying and GIS can be used for research on un-surveyed land, complex overlapping claims, and to manage change detections on claimed land. Recalculation of old coordinates (points), conversions of coordinates, sides, reconstruction of parcels and other related data can be accomplished. The Department of Agriculture, Land Reform and Rural Development (DALRRD) has land specialists but they are not involved in the process. The DALRRD hires external experts to resolve complex claims, while they have experts within the department. The DALRRD has resources, equipment and employees who are being underutilised. Recommendations are that research and investigations based on locating the claimed land must be conducted by professional people with the relevant experience and skills to perform the job. This will prevent disputes with landowners and help in shortening the period taken to complete research, as claimants tend to lose patience and take the Commission to court. The DALRRD also needs to understand that the most important part of a land claim is the piece of land that is being claimed, hence there should be no mistakes regarding finding enough information about each piece of land.
Water supply challenges in urban and rural areas of Eastern Cape
(2020-05-05) Dolo, Mpumelelo; Allopi, Dhiren
Water is regarded as the most important substance found on earth. There is no substitute for it. The daily running of production businesses, industrial firms and agricultural production that help sustain the economy of countries are largely dependent on the availability of water for them to function. The importance of water cannot be over emphasised. The food which is consumed daily depends on water; it can therefore be safely concluded that without water there would be no food, and without food there would be no life. Despite the importance of water in relation to human life, animals and plants, research studies show that the its availability becoming increasingly deficient around the globe. Water levels of major dams and rivers around the world are dropping, limiting the supply of potable water to those dependent on them. Global warming is one factor that is influencing the dropping of water levels, through evaporation. Other factors include climate change, drought and population growth. In South Africa, the government has been fighting a continuous battle of trying to address the backlog of water infrastructure, particularly in the areas which were disadvantaged by the apartheid government. These areas include rural areas, small towns (semi-urban) and townships. The Eastern Cape province in South Africa is top of the list from a backlog point of view. Rural dwellers migrate to urban areas for various reasons such as better education, better health care, job opportunities and more efficient services. Water supply is one of the services which is more adequately supplied in the cities compared to the rural areas. Even though the supplied water in the urban areas of the Eastern Cape is not the best standard when compared to other cities around the country or the world, it is still at an acceptable standard. Thus, this study was conducted to seek ways of improving the supply of water in the urban and rural areas of the Eastern Cape. The availability and the quality of water differs between the urban and rural areas. The purpose of this study was to seek ways of bridging the gap between these areas while improving the standard of water supply in both rural and urban areas. While working towards improving the lives of the Eastern Cape people, the study also seeks to promote water preservation and awareness to the people of the province. In order to find better alternatives which have been tested in various places around the world, an in-depth literature review was conducted in the study. This functioned as an effective comparison of what is obtained in different places around the world and the context of this study, which is the Eastern Cape. A survey method was used to gather data regarding the problems surrounding water supply and options that could be adopted to remedy those problems. The survey was conducted in the form of a self-observation assessment, questionnaire for households in urban and rural areas and interview sessions with prominent government entities and local technical service providers. The survey covered the whole spectrum of individuals and groups that play a major role in the supply and usage of water. The study was conducted within three municipalities of the Eastern Cape. These municipalities cover approximately two-third of the Eastern Cape considering the size of population in those areas. The municipalities covered by the study were: Amathole District Municipality (ADM), Buffalo City Metropolitan Municipality (BCMM) and OR Tambo District Municipality (ORTDM). The findings from the study showed that indeed the standard of water supply between urban and rural areas was not equal. This relates to the purification methods, the convenience of collecting water by users, the quality of infrastructure being constructed (due to good or poor monitoring during construction) and the quality of the water as well as operation and maintenance response from the various service providers. Moreover, it was found that there was an acceptable level of awareness by citizens when it comes to using water, and precautions to save it were being taken by some. However, some dominant factors such as poor management, poor infrastructure resulting in leaks, climate change, run-offs and population growth were putting a strain on the existing water resources which is not coping with the increasing demand by people. Recommendations made in the study to balance the supply of water in rural areas and urban areas include: improving the purification of water so as to achieve a standard quality within the Eastern Cape; that rural areas be allowed to have an option of having yard or house connections, particularly those who are willing to pay rates at a scale suiting their class or standard; and that water service providers make it their responsibility to extend reticulation networks if there is expansion or development of more houses in rural areas in order to keep the distance minimal to standpipes