Faculty of Applied Sciences

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Characterisation of biodiesel from Litsea glutinosa
(2014-08-08) Perumal, Alicia Ann; Odhav, Bharti
Global warming is a major concern to the world’s population. It is caused by greenhouse gases that result from the burning of fossil fuel. The fossil fuel reserves are rapidly depleting as the needs and wants of man in the world increases. Biodiesel is one of the solutions proposed to remedy this environmental crisis facing the world today. The aim of this study was to characterise the biodiesel that can be produced from the oil of Litsea glutinosa by transesterification. Biodiesel can be used in a diesel engine without modification and be produced from many different natural renewable oil sources such as algae, plants and kitchen waste material. Jatropha curcas has been identified as a potential producer of oil for biodiesel. The biodiesel properties of Jatropha curcas meet the required American Society for Testing and Materials (ASTM) standards. The fruit of Jatropha curcas contains 40.0% lipids. The oil has a saponification number of 202.6 and an iodine value of 93.0. However Jatropha curcas cannot be grown in South Africa because it is a highly invasive plant. Cetane number is the most important parameter of biodiesel. The higher the cetane value, the better the quality of the biodiesel. Oil from Jatropha curcas has a cetane number of 57.1. An alternative is the oil from Litsea glutinosa, which is found as a naturalised free forest along the South African coastline, and is also found in many Asian countries. It has many medicinal properties, however, it is not edible and hence its use for biodiesel does not add to the debate of fuel versus food production. The cetane number of oil from Litsea glutinosa is 64.79, which is ideal for ignition, and the fruit with 61.29% lipids can yield valuable quantities of biodiesel. Thus, the aim of the research was to determine the potential of Litsea glutinosa as a source of biodiesel. Furthermore, to maintain a sustainable source, Litsea glutinosa was micropropagated, and transformation of Litsea glutinosa was attempted for hairy root cultures. The Clevenger apparatus was used to extract fatty acids from dried crushed fruit of Litsea glutinosa. Fatty acids were converted to fatty acid methyl esters by transesterification. Transesterification was conducted in the presence of nitrogen and the reaction was catalysed with a mixture of methanol and sodium hydroxide (NaOH). The ratio 1 : 3 of oil to catalyst mixture was used for optimum transesterification to ensure a forward reaction and it was transferred to a separating funnel to allow the glycerol and fatty acid methyl esters to separate. GC-MS was used to determine the fatty acids. The iodine number, saponification number, acid value, viscosity, kinematic viscosity, density, specific gravity, thermostability, distillation point and sulphur content were determined. The seeds of Litsea glutinosa were germinated and tissue culture callus was produced from the seeds and leaves. The leaves and stems were used to produce hairy root cultures by inoculating them with Agrobacterium rhizogenes. Litsea glutinosa yielded 61% oil, which included 47 fatty acids in the fruit and 24 fatty acids in the seeds. The fatty acid profile of the oils indicated that the predominant fatty acids present were those that are essential for good quality biodiesel. The dominant fatty acids found in the fruit were 65.4% 9-octadecenoic acid and 13.6% hexadecanoic acid. The dominating fatty acids found in the seeds contained 36.3% 9-octadecenoic acid, 13.9%, hexadecanoic acid and 39.1%, dodecanoic acid. The iodine value was 6.3. The saponification value was 274. The acid value was 0.45 mg KOH. g-1. The viscosity was 22.48 mm2. s-1 and the kinematic viscosity was 23.84 mm2. s-1. The density was 942.69 kg. m-3 and the specific gravity was found to be 0.9 g. cm-3. The distillation temperature ranged between 52.2°C to 610.2°C. The sulphur content was found to be 383 µg. ml-1. These characteristics indicate that Litsea glutinosa can be used as a source of biodiesel, because the properties meet the required ASTM standards. However, the production of biodiesel from Litsea glutinosa has not been commercialised because the production of fuel is dependent on the fruit of the plant, which is seasonal. To overcome this, a part of this study investigated micropragation of Litsea glutinosa and transformation of Litsea glutinosa by Agrobacterium rhizogenes into hairy roots and attempts where made to determine whether fatty acid could be produced by these techniques. Callus cultures were grown on MS media and McCowns woody plant media supplemented with 1 ml BAP and 1 ml 2,4-D per 1 L of media. Callus cultures were obtained in the light. However, Litsea glutinosa resisted transformation by Agrobacterium rhizogenes.
Cyanobacteria-microalgae consortia as bio- inoculants for enhancing soil fertility and plant growth
(2024-05) Jose, Shisy; Bux, Faizal; Kumari, Sheena; Renuka, Nirmal; Ratha, Sachitra Kumar
Modern agriculture that heavily utilizes synthetic fertilizers has raised significant environmental concerns worldwide. Microalgae-based bio-inoculants have become a more viable and eco- friendly option to reduce the reliance on chemical fertilizers for improving soil fertility and plant growth in agronomic practices. Indigenous microalgal species can colonize and thrive well under local conditions, making them well-suited for use as bio-inoculants. Additionally, it appears that using microalgal consortia of green microalgae and nitrogen (N)-fixing cyanobacteria could be beneficial because the green microalgae can supply carbon (C), the cyanobacteria can fix C and N in the soil. They both can produce agriculturally beneficial metabolites and improve soil nutrient availability. This synergistic relationship could enhance the overall effectiveness of bio- inoculants and promote sustainable agriculture practices. In this study, thirteen microalgal strains were isolated from agricultural fields of Durban, KwaZulu Natal, South Africa. Two N-fixing cyanobacteria (Nostoc sp. and Calothrix sp.) and two green microalgae (Desmodesmus armatus and Chlorella sp.) strains were selected and analyzed for metabolites of agricultural significance for the development of suitable microalgal consortia under N-deficient conditions. The amount of indole acetic acid (IAA) in biomass extracts from cyanobacteria (Calothrix sp. (2.54 ng g−1) and Nostoc sp. (1.52 ng g−1)) was significantly higher than in extracts from green microalgae (Chlorella sp. (0.32 ng g−1) and Desmodesmus armatus (0.20 ng g−1)). A completely randomized design was used to develop and evaluate eight microalgal consortia on a N-deficient medium with the selected microalgal strains. A significant improvement in biomass productivity, indole acetic acid production, nutrients viz C, N, phosphorus (P), potassium (K), calcium (Ca), copper (Cu), iron (Fe), and manganese (Mn) was observed in the selected consortium compared to the individual isolates. The microalgal consortium was further analyzed for biostimulant properties using seed germination assay in chili seeds. A significant increase in seedling length and leaf number was observed in seeds treated with biomass extracts of consortium compared to the control. The pot culture study also supported the effect of microalgal bio-inoculant on soil fertility, chili plant growth and native soil microbiomes. Soil enzyme activity increased significantly (p < 0.05) with microalgal treatments, with soil dehydrogenase activity (DHA), organic carbon (OC), soil chlorophyll (Chl), total polysaccharides (TP) and nutrients such as C, N, P, K and Mn being more enriched at 100 % and 50 % treatment applications in comparison to control (Cnt). Growth responses in terms of shoot and root (fresh and dry weight), root length and leaf number were significantly high in 50 % microalgal treatments (Al(50 %)+CF(50 %)) when compared to Cnt. With different soil nutrient parameters and microbiome (bacterial and fungal) indicators, we could successfully predict higher soil fertility and plant growth responses to microalgal inoculations. Results using 16SrRNA and ITS amplicon sequencing suggested that microalgal bio-inoculation improved the diversity and composition of native soil microbiome, leading to an increase in soil fertility, plant growth and yield. Further, shotgun metagenomics has confirmed a higher enzymatic activity involved in C, N, and P metabolisms in 50 % and 100 % microalgal treatment compared to the control. Potential shifts in microbial taxa and functional genes indicated that microalgal bio-inoculant was a major driver of microbial metabolic change. The findings from the study suggested that microalgal bio-inoculation improved the diversity and composition of native soil microbiomes, leading to an increase in soil fertility, plant growth, and yield in chili plants.
Design and operation of a laboratory scale photobioreactor for the cultivation of microalgae
(2011) Bhola, Virthie; Bux, Faizal
Due to greenhouse gas emissions from fossil fuel usage, the impending threat of global climate change has increased. The need for an alternative energy feedstock that is not in direct competition to food production has drawn the focus to microalgae. Research suggests that future advances in microalgal mass culture will require closed systems as most microalgal species of interest thrive in highly selective environments. A high lipid producing microalga, identified as Chlorella vulgaris was isolated from a freshwater pond. To appraise the biofuel potential of the isolated strain, the growth kinetics, pyroletic characteristics and photosynthetic efficiency of the Chlorella sp was evaluated in vitro. The optimised preliminary conditions for higher biomass yield of the selected strain were at 4% CO2, 0.5 g l-1 NaNO3 and 0.04 g l-1 PO4, respectively. Pulse amplitude modulation results indicated that C. vulgaris could withstand a light intensity ranging from 150-350 μmol photons m-2s-1. The pyrolitic studies under inert atmosphere at different heating rates of 15, 30, 40 and 50 ºC min-1 from ambient temperature to 800 oC showed that the overall final weight loss recorded for the four different heating rates was in the range of 78.9 to 81%. A tubular photobioreactor was then designed and utilised for biomass and lipid optimisation. The suspension of microalgae was circulated by a pump and propelled to give a sufficiently turbulent flow periodically through the illuminated part and the dark part of the photobioreactor. Microalgal density was determined daily using a Spectrophotometer. Spectrophotometric determinations of biomass were periodically verified by dry cell weight measurements. Results suggest that the optimal NaNO3 concentration for cell growth in the reactor was around 7.5 g l-1, yielding maximum biomass of 2.09 g l-1 on day 16. This was a significant 2.2 fold increase in biomass (p < 0.005) when compared to results achieved at the lowest NaNO3 cycle (of 3.8 g l-1), which yielded a biomass value of 0.95 g l-1 at an OD of 1.178. Lipid accumulation experiments revealed that the microalga did not accumulate significant amounts of lipids when NaNO3 concentrations in the reactor were beyond 1.5 g l-1 (p > 0.005). The largest lipid fraction occurred when the NaNO3 concentration in the medium was 0.5 g l-1. Results suggest that the optimal trade-off between maximising biomass and lipid content occurs at 0.9 g l-1 NaNO3 among the tested conditions within the photobioreactor. Gas chromatograms showed that even though a greater number of known lipids were produced in Run 8, the total lipid percentage was much lower when compared to Runs 9-13. For maximal biomass and lipid from C. vulgaris, it is therefore crucial to optimise nutritional parameters such as NaNO3. However, suitable growth conditions for C. vulgaris in a tubular photobioreactor calls for innovative technological breakthroughs and therefore work is ongoing globally to address this.
Effect of internal woven roller shade and glazing on the energy and daylighting performances of an ofﬁce building in the cold climate of Shillong
(Elsevier, 2015) Singh, Ramkishore; Lazarus, Ian Joseph; Kishore, V.V.N.
The energy and visual performances of the façades are deﬁned by many parameters including façade size, properties of glazings and shadings, and their arrangements as well as control strategies. In this study, a number of combinations of internal woven roller shades and four double glazings have been proposed and assessed in integrated manner in order to improve the energy efﬁciency and visual comfort in new or existing ofﬁce buildings. Ofﬁce rooms facing south, east, north and west have been simulated for cold climate, by varying glazed areas and proposed glazing and shading alternatives. Results have been calculated, compared and analyzed in terms of the energy consumptions, energy saving potentials, daylight autonomy, useful daylight illuminance and discomfort glare free time, for each of the combina-tions. Simulation results show that the choice of glazing and shading alternatives can have substantial impact on energy and visual performances of the ofﬁce space. Regardless of façade orientation, the max-imum energy saving is achieved for a window-to-wall ratio (WWR) of 30%. Saving potential decreases signiﬁcantly for larger glazed area and for each façade orientation. For all façade orientations and glazed areas (except for 30% WWR in the north wall), a bare low-e coated double glazing (U = 1.616 W/m2 K, SHGC = 0.209, sv = 0.301) is found to be the most energy efﬁcient choice. For 30% north glazing, the energy efﬁciency can be maximized with a different bare low-e coated double glazing (U = 1.628 W/m2 K, SHGC = 0.370, sv = 0.581). Moreover, glare affected time, daylight autonomy and useful daylight illuminance in the ofﬁce spaces with these glazing choices are estimated P50%, between 46% and 99%and in the range of 53–88% respectively. Also, the visual comfort can further be improved just by deploy-ing even a highly transparent fabric (50% transmittance, 20% reﬂectance, 45% average openness) as an interior roller shade with these glazing choices.
Efficacy and mechanisms of antiretroviral drugs removal by algaefrom wastewater treatment plants
(2024-05) Reddy, Karen; Bux, Faizal; Kuttan Pillai, Sheena Kumari; Renuka, Nirmal; Moodley, Brenda
The presence, risks, and fate of pharmaceutical pollutants in the environment have raised concerns worldwide. South Africa, with the largest population consuming antiretroviral (ARV) drugs in Africa, faces challenges in efficiently removing these compounds from water bodies. This study's primary focus was to investigate the efficiency and mechanisms of nevirapine (NVP) removal by algae isolated from wastewater treatment processes. It included the isolation and screening of algal strains from wastewater treatment plants for their potential to remove ARV drugs, optimizing culture conditions to enhance removal efficiency, determining the potential mechanisms employed by selected algal strains for NVP remediation, and assessing the associated metabolic responses of algal cells to NVP using gene expression and metabolomics analyses. Eleven green indigenous fresh water microalgal isolates were screened from wastewater treatment plants (WWTPs) in KwaZulu-Natal, resulting in the selection of two strains, Coelastrella tenuitheca and Tetradesmus obliquus, based on their growth rates, biomass productivity and toxicity tolerance. In the ecotoxicity study, the calculated IC50 values of NVP (0–100 mg L−1) on selected algal strains after 96 h of exposure were 23.45 mg L−1 (C. tenuitheca) and 18.20 mg L−1 (T. obliquus), which far exceeds the concentration of NVP found in wastewater. Hence, T. obliquus and C. tenuitheca was selected for further NVP remediation studies using different cultivation conditions. A concentration range of 0-4000 ng L-1 of NVP was tested to assess the potential for NVP removal by both microalgae (autotrophic cultivation). Lower concentrations of NVP (up to 200 ng L−1) have shown to have a positive impact on microalgae growth. Specifically, in T. obliquus, the highest dry cell weight of 941.27 mg L−1 was obtained when exposed to a NVP concentration of 50 ng L−1. Both microalgae showed varying removal efficiencies (19.53–74.56%) when exposed to different NVP concentrations. During the late log phase on day 8, T. obliquus achieved the highest NVP removal efficiency, removing 74.56% of the NVP, while C. tenuitheca achieved a removal rate of 48% at an NVP concentration of 50 ng L−1. The photosynthetic efficiency (Fv/Fm and rETR) of both microalgal species was found to be unaffected by environmental concentrations of NVP (up to 4000 ng L−1) during the mid-log phase of growth. Furthermore, the scanning electron microscopy (SEM) analysis demonstrated that both algal species produced distinct ridges on their cell surfaces after NVP uptake. Additional evaluations were conducted on the microalga, T. obliquus, for the removal of NVP at 4000 ng L-1, as well as their cellular response (expression of antioxidant enzymes and metabolomics) and biomass production under different cultivation modes (autotrophic, heterotrophic, and mixotrophic). The highest NVP removal efficiency was observed under mixotrophic (80.13%) growth on day 8, whilst heterotrophic and autotrophic cultivation modes removed 70.30% and 64.40%, respectively. Mass balance calculations showed that the primary removal mechanism was identified as biodegradation, with a relatively low contribution from bioadsorption (2.39-3.36%) and bioaccumulation (0.55- 0.87%). Fourier-transform infrared (FTIR) spectroscopy results of harvested microalgal cells displayed bands in the region of 950-1000 cm-1, indicating the presence of aromatic C-H rings found in NVP. Additionally, 6 possible biotransformation products of NVP were identified by untargeted liquid chromatography-time of flight mass spectrometry. Additionally, under autotrophic conditions, the gene expression analysis revealed heightened activities of superoxide dismutase (sod1), glutathione peroxidase (gpx1) and catalase (cat2) in T. obliquus. The upregulation of antioxidant genes enhances the organism's ability to defend against oxidative stress induced by NVP. The expression levels of antioxidant genes were significantly reduced during heterotrophic and mixotrophic growth, suggesting microalgae can overcome oxidative stress with glucose supplementation. To further investigate the cellular level response of microalgal cells to NVP, metabolomic analysis was carried to out to identify and quantify key algal metabolites during mixotrophic cultivation. The increase in activity of the fatty acid biosynthesis pathway and carbohydrate synthesis was observed by T. obliquus in the presence of NVP under mixotrophic growth conditions. The findings from this study emphasize the significant potential of microalgae in the field of ARV drug remediation.
The efficiency of phytoremediation using Panicum maximum and TiO2 nanoparticles
(2021) Cibane, Nozipho Sinenhlanhla; Mdluli, Phumlani Selby; Moodley, K.G.; Arthur, G.D.
This study focused on the application of Panicum maximum (guinea grass) for evaluating the phytoremediation of titanium dioxide nanoparticles (nTiO2). This study was done to explore the ability of Panicum maximum Jacq as a hyperaccumulator for phytoremediation of nTiO2. Titanium dioxide has steadily become more abundant in our environment over the years due to human activities, and this could potentially harm the environment. Panicum maximum (guinea grass) is a non-vascular plant with a short life cycle. It is well adapted to a wide variety of conditions. It originated from Africa but is presently found and cultivated in almost all parts of the world with tropical climates. It is loosely to densely tufted, with short rhizomous rooting at the lower nodes. Leaf blades are linear to narrowly lanceolate. Plant to metal oxide nanoparticle interaction was investigated by germination of seeds in the presence of titanium dioxide nanoparticles (nTiO2). The uptake of nTiO2 by Panicum maximum Jacq was evaluated after treatment of the seedlings with nTiO2. The synthesized nTiO2 was characterized, using Transmission Electron Microscope, Scanning Electron Microscope. Energy Dispersive Spectroscopy (EDX), and X-ray Diffraction (XRD). The average mean particle distribution was analyzed using Image J. The Image J analysis showed that the average particle distribution of nTiO2 was 9 nm. The TEM and SEM results revealed that the particles in the nTiO2 were spherical in shape. The XRD analysis revealed that the nTiO2 was predominantly 67.1% and 32.9% of anatase and rutile forms, respectively. Metal uptake was analyzed using the Inductively Coupled Plasma – Optical Emission Spectrometer method (ICP-OES) after the plants were digested using the wet digestion and microwave digestion methods. The ability of the plants to translocate the metals to the aerial parts of the plants (Translocation Factor - TF) was evaluated for the metal using concentration ranging from 5 ppm to 50 ppm. It was observed that the root had the highest concentration of nTiO2 while the lowest uptake was found in the leaf. The TF was highest for the 5 ppm sample. The roots with the shortest length, which indicated stress/toxicity were that of the plants which were treated with 50 ppm of nTiO2. These also had the highest accumulated nanoparticles which suggested that these plants were negatively impacted by a higher concentration of nTiO2. The standard with 5 ppm treatment showed the highest value of the translocation factor which suggested that at this concentration the nanomaterial aided and catalyzed the movement of nanoparticles to the aerial parts of the plant. The results suggested that seed treated with nanoparticles before planting for phytoremediation purposes could increase the metal uptake selectivity.
Extraction of aromatic solvents from reformates and paint solvent wastes during ionic liquids
(2016) Mabaso, Mbongeni Hezekia; Redhi, Gyanasivan Govindsamy; Moodley, K. G.
The work conducted in this study comprised three aspects: syntheses, characterizations, and multi-component liquid-liquid extractions. The main objectives of the project were: (1) to evaluate the efficacy and efficiency of ionic liquids to extract aromatic components from catalytic reformates and paint solvent wastes, and (2) to validate the method(s) used in this project to qualitatively and quantitatively analyze the aromatic molecules (BTEX) in multi-component mixtures. Therefore, this research critically investigated the major effects of the chosen ionic liquids as extractive solvents for the recovery of BTEX components from model and industrial organic mixtures. The project was concerned with the nature of solvents currently used in most industries for the separation by extraction of aromatic hydrocarbons from non-aqueous or organic mixtures. Most solvents currently employed for this purpose are highly volatile; hence they contribute significantly towards environment pollution. In addition, the extraction efficiency of these conventional solvents is limited only to mixtures containing aromatic hydrocarbons of 20% or more. Furthermore, conventional solvents are organic compounds which are generally toxic, flammable, and expensive to recover or regenerate from extract phases due to methods which involve several steps. In addition, they demand high energy input for the distillation steps. used in the analysis of aromatic components were evaluated for validity. According to the literature no such work was carried out by previous researchers. The study targeted four ionic liquids, namely, 1-ethyl-3-methylimidazolium ethyl sulphate [EMIM][ESO4], 1-ethyl-3-methylpyridinium ethyl sulphate [EMpy][ESO4], 1- Butyl-1-methyl-2-pyrrolidonium bromide [BNMP][Br], and 1,1-Dimethyl-2- pyrrolidonium iodide [MNMP][I] in an attempt to address this concern. These ionic liquids were synthesized and characterized in our laboratories using previously accepted methods. After synthesis and purification, they were characterized by techniques including FTIR, 1H-NMR, and 13C-NMR. The densities and moisture content of both the synthesized and standard ionic liquids were also determined using density meters and Karl-Fischer apparatus, respectively. The extractions were carried out on both the model and industrial mixtures using ionic liquids. Each ionic liquid was mixed with a target mixture in a water-jacketed vessel and then stirred vigorously at constant temperature achieved by a thermostatically controlled water-bath. After a selected period of time the operation was stopped and the resulting mixture was left to stand overnight to allow phase equilibration to be reached. The two phases were then separated and analyzed for the content of individual aromatic components in each phase using GC-FID calibrated with external standards of the components present in the mixtures being investigated. According to the results obtained from the synthesis and characterization methods the percentages yield of ionic liquids were reasonably high (> 95%). In addition, spectral studies showed high purity with fewer traces of impurities based on the observed relative intensities. Results from GC-FID indicated a relatively lower concentration of aliphatic hydrocarbons in the extract phase. On the other hand, the concentrations of aromatic II components in the extract phase were relatively higher than those of aliphatic hydrocarbons. The results obtained from the three extraction stages showed the total recovery of greater than 50% for the aromatic components. This suggests that at least six extraction stages would be required in order to achieve a total recovery of 100% aromatic components which is an indication of good efficiency. Also noticeable was that the first extraction stages for all ionic liquids recovery values were much higher than those values obtained from successive stages which showed approximately the same extraction results. In most experiments, 1-ethyl-3-methylpyridinium ethyl sulphate gave higher recovery values than the other three ionic liquids. It was also noted that the recovery values obtained from the extractions performed on model mixtures of the entire concentration range (0.5 – 25%) of individual aromatic components did not show any significant difference. Proportional difference in recoveries occurred across the entire concentration range of model mixtures. The results also indicated that the solubility of aromatic hydrocarbons in the ionic liquids decreases in the order: benzene > toluene > ethyl benzene >xylenes. This phenomenon is attributed to a decrease in π-π, cation- π, cation- anion interactions occurring between the ionic liquid and each of the aromatic molecules in this order. The recovery values for BTEX ranged from 80 to 120 % by volume for the three extraction stages. This is in line with results previous research studies carried out on liquid-liquid extractions involving ternary systems containing only one aromatic component in each mixture. Therefore this study shows that ionic liquids are capable extraction solvents for simultaneous recovery of the aromatic components from any organic mixtures containing low to high BTEX concentrations. In addition, the outcomes of this project have proved that ionic liquids are economically viable as potential extraction solvents since they can be easily recycled and reusable many times without any noticeable degradation. The results of this study are envisaged to make significant contributions to the current research efforts aimed at achieving greener environments and minimization of global warming. The findings of this project are also geared to boost the economy of our country through job creation using economically viable methods.
Food consumption patterns and nutritional risks of women in low and middle income communities in KwaNdengenzi, KwaZulu-Natal
(2018) Gumede, Sthembile; Napier, Carin E.
Food consumption patterns have changed dramatically in the recent times, with traditional diets being replaced by so-called “westernised diets” and leading to nutritional risks such as malnutrition. Contributing factors are urbanisation, climate change, agricultural produce supply (food demand is greater than produce supply) and rising prices, to name but a few. The food security status is also in question as more and more South African households are said to be living in poverty and consequently undernourished even though the country was found to be nutritionally stable compared to previous years. Unemployment and lack of nutrition education also have an impact on communities, in terms of the food being purchased and consumed. The study was conducted to determine the socio-demographic status, food consumption patterns and nutritional risk of a low-income and middle-income community that resides in KwaNdengezi Township in KwaZulu-Natal. A sample of two hundred and fifty eight participants was required for the study. The households in both the north and south of KwaNdengezi Township were randomly selected by using the number of roads listed in the eThekwini municipality map. A sample of 130 households per area was targeted. The required number of households was selected by dividing the number of identified roads resulting in three households targeted in each of the 39 roads in the north section and five households in 26 roads in the south section being targeted. Upon the agreement by participants, the study was conducted where data was collected by means of an interview setting, where participants were interviewed by fieldworkers using pre- designed and tested questionnaires. The follow up was conducted on the days following. The participants answered a three set of questionnaires including, a Socio-demographic Questionnaire (Annexure D), a Food Frequency Questionnaire (Annexure F), 24-Hour Recall questionnaires (Annexure E). The anthropometric measurements were taken in order to determine the BMI status of the participants. The participants were weighed using a Physician Scale for weight, the Stadiometer for height and non- stretchable measuring tape for waist circumference. The north and the south sections of the township were both affected by unemployment, showing worrying rates that also corresponded with other studies illustrating that unemployment is a challenge in South Africa. The unemployment rate in the north section was very high, sitting at 78.5%, compared to the south section at 63.1%; even so both these communities are economically challenged. Food insecurity was more prevalent in the north section as 36.9% of the participants reported always not having enough money to purchase food whilst 0.8% of the participants in the south section reported the same, concluding that the north section is more vulnerable to hunger leading to malnutrition and poverty. The education status of the participants in the north section was a point of concern as only 3.1% of the participants had graduated while almost 29.2% in the south section had graduated; this illustrates a very clear difference, which might also be due to unemployed household caregivers who cannot afford further education. The mean Food Variety Scores (FVS) (±SD) for the north section for all food consumed from the various food groups during seven days was 34.44 (±8.419) and for the south section it was 33.87 (±10.670), indicating a medium food variety score where both sections had a good dietary diversity score ranging from 7-9 food groups, summarising the food group diversity as being in the majority in the north section at 63.85% (n=83) while in south section it was 60.77% (n=79). The results of the energy distribution of macronutrients from the average of the 24-hr recall results when compared to the WHO dietary factor goals showed that the participants’ diet was well balanced in terms of macronutrient intake for both sections while the diet for both sections was lacking in micronutrient intake. The results of the women caregivers for both the north and the south sections illustrated a high consumption of the following foods out of the top twenty foods consumed by the community. The foods mostly consumed included sugar, maize, bread and rice for both the 19-30 and 31- 50 years age groups ranging from 195.15-248.82g for maize, 17.61-18.90g for sugar, 82.73- 108.16g for bread and 127.14-131.69g for rice, meaning that the respondents’ diet was high in calorie intake, hence the doubled DRIs for carbohydrate. Overweight and obesity tests showed alarming results as the majority (56.15%) of women caregivers in the north section were found to be obese while 63.8% of the women in the south section fell into the obesity classification, showing that the women caregivers for both sections are at risk of obesity related illnesses (NCDs). The results for waist circumference showed that 71.53% and 78.46% of the women in the north and south sections respectively were above the waist circumference cut-off point (≥88cm). When the weight-for-height ratio was measured for the whole sample most of the women caregivers (69.23%) were found to be at risk of developing metabolic syndrome. The food consumption patterns illustrated in the study corresponded significantly with the results found. Both the communities consumed a diet high in caloric and fat intake but was low in fruit and vegetable intake. This leads to obesity, resulting in non-communicable diseases as well as micro-deficiencies, leading to malnutrition because of the lack of variety in the food consumed by the population. The lack of food variety is the result of not having enough money for food purchases, explaining the question why the community cannot meet the DRIs as a result of unemployment and poverty as well as a lack of nutrition education. With that said the two communities did not show much of a difference in lifestyle and food choices being made except for the education level that was low for the north section and a bit higher for the south section, as well as livelihoods that also showed that the north section was at a lower economic level than the south section but both the sections were at risk of malnutrition and poverty and needed the same intervention in terms of assistance. In the study it was recommended that policies drafted by the government and stakeholders should be focused and tailored more on women caregiver headed households. More nutrition knowledge should be geared towards educating the most vulnerable and poverty stricken communities. The micronutrient intake must be promoted at lower and middle income communities. The agricultural sector needs to recognise and promote women farmers as well as offer assistance in order to grow their standing as farmers. The government should devise and implement projects that empower women so that they not dependent on their male counterparts.
Fungal mycelium as leather alternative : a sustainable biogenic material for the fashion industry
(Elsevier BV, 2023-09) Amobonye, Ayodeji; Lalung, Japareng; Awasthi, Mukesh Kumar; Pillai, Santhosh
The global leather industry has been at the receiving end of various environmental and ethical backlash as it mainly relies on animal agriculture which contributes to deforestation, greenhouse gas emissions, and animal welfare concerns. In addition, the processing of animal hides into leather generates a huge amount of toxic chemicals, which ultimately get released into the environment. Thus, growing concern for environmental sustainability has led to the exploration of alternative materials to conventional animal- based leather. In this regard, the application of fungal leather alternatives in material technology is gaining traction because of its high biodegradability, biocompatibility, renewability, as well as its affordable and carbon-neutral growth processes. Fungal leather alternatives have been found to possess significant mechanical and physical properties, thanks to the interwoven hyphal network of the fungal mycelium, as well as antimicrobial activities which have been ascribed to their bioactive metabolites. Various fungal species, including those from the Agaricus, Fomes, Ganoderma, Phellinus, and Pleutorus genera, are currently being investigated for their potential in this area. This review, therefore, attempts to gain insights into the recent advances in scientific research and real-world applications of fungal-derived leather like materials. It makes a compelling case for this sustainable alternative and discusses the morphology-property relationship of the fungal mycelium driving this innovation. Additionally, the current processing methods and major players in the fungal leather substitute industry are presented. The paper also brings attention to the challenges facing the full deployment of fungal leather substitutes and proposes solutions with the aim of encouraging further research and resource mobilization for the acceptance of this renewable leather substitute.
Improving the feasibility of producing biofuels from microalgae using wastewater
(Taylor and Francis, 2013-10-08) Rawat, Ismail; Bhola, Virthie; Ranjith Kumar, R.
Biofuels have received much attention recently owing to energy consumption and environmental concerns. Despite many of the technologies being technically feasible, the processes are often too costly to be commercially viable. The major stumbling block to full-scale production of algal biofuels is the cost of upstream and downstream processes and environmental impacts such as water footprint and indirect greenhouse gas emissions from chemical nutrient production. The technoeconomics of biofuels production from microalgae is currently unfeasible due to the cost of inputs and productivities achieved. The use of a bioreﬁnery approach sees the production costs reduced greatly due to utilization of waste streams for cultivation and the generation of several potential energy sources and value-added products while oﬀering environmental protection. The use of wastewater as a production media, coupled with CO2 sequestration from ﬂue gas greatly reduces the microalgal cultivation costs. Conversion of residual biomass and by-products, such as glycerol, for fuel production using an integrated approach potentially holds the key to near future commercial implementation of biofuels production.
Mitigation of carbon dioxide from synthetic flue gas using indigenous microalgae
(2017) Bhola, Virthie Kemraj; Bux, Faizal; Swalaha, Feroz Mahomed
Fossil carbon dioxide emissions can be biologically fixed which could lead to the development of technologies that are both economically and environmentally friendly. Carbon dioxide, which is the basis for the formation of complex sugars by green plants and microalgae through photosynthesis, has been shown to significantly increase the growth rates of certain microalgal species. Microalgae possess a greater capacity to fix CO2 compared to terrestrial plants. Selection of appropriate microalgal strains is based on the CO2 fixation and tolerance capability, both of which are a function of biomass productivity. Microalgal biomass could thus represent a natural sink for carbon. Furthermore, such systems could minimise capital and operating costs, complexity, and energy required to transport CO2 to other places. Prior to the development of an effective CO2 mitigation process, an essential step should be to identify the most CO2-tolerant indigenous strains. The first phase of this study therefore focused on the isolation, identification and screening of carboxyphilic microalgal strains (indigenous to the KwaZulu-Natal province in South Africa). In order to identify a high carbon-sequestering microalgal strain, the physiological effect of different concentrations of carbon sources on microalgae growth was investigated. Five indigenous strains (I-1, I-2, I-3, I-4 and I-5) and a reference strain (I-0: Coccolithus pelagicus 913/3) were subjected to CO2 concentrations of 0.03 - 15% and NaHCO3 of 0.05 - 2 g/1. The logistic model was applied for data fitting, as well as for estimation of the maximum growth rate (µmax) and the biomass carrying capacity (Bmax). Amongst the five indigenous strains, I-3 was similar to the reference strain with regards to biomass production values. The Bmax of I-3 significantly increased from 0.214 to 0.828 g/l when the CO2 concentration was increased from 0.03 to 15% (r = 0.955, p = 0.012). Additionally, the Bmax of I-3 increased with increasing NaHCO3 concentrations (r = 0.885, p = 0.046) and was recorded at 0.153 g/l (at 0.05 g/l) and 0.774 g/l (at 2 g/l). Relative electron transport rate (rETR) and maximum quantum yield (Fv/Fm) were also applied to assess the impact of elevated carbon sources on the microalgal cells at the physiological level. Isolate I-3 displayed the highest rETR confirming its tolerance to higher quantities of carbon. Additionally, the decline in Fv/Fm with increasing carbon was similar for strains I-3 and the reference strain (I-0). Based on partial 28S ribosomal DNA gene sequencing, strain I-3 was found to be homologous to the ribosomal genes of Chlorella sp. The influence of abiotic parameters (light intensity and light:dark cycles) and varying nutrient concentrations on the growth of the highly CO2 tolerant Chlorella sp. was thereafter investigated. It was found that an increase in light intensity from 40 to 175 umol m2 s-1 resulted in an enhancement of Bmax from 0.594 to 1.762 g/l, respectively (r = 0.9921, p = 0.0079). Furthermore, the highest Bmax of 2.514 g/l was detected at a light:dark cycle of 16:8. Media components were optimised using fractional factorial experiments which eventually culminated in a central composite optimisation experiment. An eight-factor resolution IV fractional factorial had a biomass production of 2.99 g/l. The largest positive responses (favourable effects on biomass production) were observed for individual factors X2 (NaNO3), X3 (NaH2PO4) and X6 (Fe-EDTA). Thereafter, a three-factor (NaNO3, NaH2PO4 and Fe-EDTA) central composite experimental design predicted a maximum biomass production of 3.051 g/l, which was 134.65% higher when compared to cultivation using the original ASW medium (1.290 g/l). A pilot scale flat panel photobioreactor was designed and constructed to demonstrate the process viability of utilising a synthetic flue gas mixture for the growth of microalgae. The novelty of this aspect of the study lies in the fact that a very high CO2 concentration (30%) formed part of the synthetic flue gas mixture. Overall, results demonstrated that the Chlorella sp. was able to grow well in a closed flat panel reactor under conditions of flue gas aeration. Biomass yield, however, was greatly dependent on culture conditions and the mode of flue gas supply. In comparison to the other batch runs, run B yielded the highest biomass value (3.415 g/l) and CO2 uptake rate (0.7971 g/day). During this run, not only was the Chlorella strain grown under optimised nutrient and environmental conditions, but the culture was also intermittently exposed to the flue gas mixture. Results from this study demonstrate that flue gas from industrial sources could be directly introduced to the indigenous Chlorella strain to potentially produce algal biomass while efficiently capturing and utilising CO2 from the flue gas.
Optimization of biomass and lipids production from microalgae using wastewater in a pilot scale raceway pond
(2021) Rawat, Ismail; Bux, Faizal
Microalgae provide a sustainable renewable solution for the production of commodity products such as liquid biofuels. There are numerous benefits to using algae for the production of biofuels, however, the cost of production is a major hurdle to commercial-scale development. Major factors influencing the production of algae are the cost of nutrients, availability of water, contamination, and grazers. Research into algal biomass for biofuels production at laboratory scale does not translate directly to cultivation at large scale due to the change in cultivation conditions and the constant flux of environmental factors. This study focuses on the upstream processes of cultivation of biomass in a ~ 1146 m2 raceway pond. It demonstrates biomass productivity under different climatic conditions and utilisation of post-chlorinated wastewater as a water and nutrient source. The study further elucidates the population dynamics of the system and provides insight into the challenges faced during the cultivation of algae at large scale. An indigenous Scenedesmus sp. gave biomass productivity of 31.23 g/m2 /d with lipid production of 29.6 % lipid/g DCW in a 10 m2 raceway pond in a greenhouse using BG11. Biomass productivity was reduced to 13.09 g/m2 /d with a lipid content of 22.9 % lipid/g DCW under 3-fold higher irradiance. Biomass productivity of circular 3000L ponds at the large scale site resulted in the highest biomass and acceptable lipid content using 250mg/L NaNO3 although significantly lower than the 10 m2 raceway ponds. Wastewater has shown potential to replace conventional media. Post-chlorinated wastewater was found to have low levels of nitrogen and phosphorus but contained metals that act as micronutrients for algae. Supplemented wastewater proved to be an effective growth. Six individual runs of a covered 1146 m2 raceway pond driven by paddlewheel were conducted over 15 months. The average water temperature ranged from 20.61±0.68°C during mid-winter to 31.03±2.22°C in late summer. Daylight ranges from 10.25 to 14 hours in winter and summer respectively. The highest average light intensity was 359.00±212.71 µmol/m2 /s from Mid-winter to early spring and 645.44±330.58 µmol/m2 /s in late summer. Biomass productivities were low ranging from 2.7 to 7.34 g/m2 /d for most runs of the raceway pond, mainly due to the long periods of cultivation. Average productivity at day 7 for all raceway runs was 7.25 g/m2 /d. Adaptive Neuro-Fuzzy Inference System (ANFIS) modelling of the system elicited that the major factors affecting biomass productivity in the raceway pond were light intensity, pH, and depth for the raceway pond. The model showed that maximum biomass productivity is possible at a depth between 20 and 22 cm at light intensities between 200 and 400 µmol/m2 /s. pH in the range of 9 to 9.5 correlated positively with light intensity ranging from 200 to 1000 µmol/m2 /s with maximum biomass expected in the region of 400 to 500 µmol/m2 /s. The main algal constituents for the raceway ponds were Scenedesmus obliquus, Scenedesmus dimorphus, Chlorella, Keratococcus, and species of unidentified cyanobacteria. Either Scenedesmus or Chlorella was dominant for extended periods. Bacteria in open systems can have a positive or negative effect on the growth of microalgae but is dependent on the strains of microalgae and bacteria as well as prevailing conditions making these systems highly complex. Rhodobacteraceae, Plactomycetaceae, Xanthomonadaceae, Flavobacteriaceae, Phycisphaeraceae, Comamonadaceae, and Cyclobacteriaceae were found to be the major families of bacteria that proliferate at different levels during the cultivation period in the circular ponds and the raceway pond. These families of bacteria have several beneficial traits to algae cultivation however further investigation is required. Modelling the system revealed that pH, depth, and light intensity were factors having a substantial effect on biomass productivity. As the system was carbon limited addition of CO2 (preferably a waste stream) could significantly enhance the overall biomass productivity. A major factor negatively affecting biomass productivity was the size of the pond. Inadequate mixing impacts biomass productivity in terms of access to nutrients and gaseous exchange. Shorter periods of cultivation resulted in higher productivities. For the scale of the system, semi-continuous harvesting would be required to achieve shorter residence time. This must be balanced against the energy utilization and cost of harvesting potentially lower culture densities
Optimization of the synthesis of levulinic acid and levulinic acid derivatives from sugarcane bagasse using ionic liquids
(2021) Mthembu, Lethiwe Debra; Deenadayalu, Nirmala; Lokhat, David
Globally, the effects of climate change due to natural sources and human activities that releases greenhouse gases has led to a greater need for a sustainable and renewable resource called biomass. In South Africa (KwaZulu-Natal) there is an excess of sugarcane bagasse (SB) therefore this study was undertaken using SB. SB was valorised to replace chemicals obtained from fossil fuel processing. Levulinic acid (LA) was identified by the National Renewable Energy Laboratory (NREL) as a chemical that can be produced from biomass. LA is a platform chemical therefore many compounds are produced from LA hence in this work three LA derivatives namely diphenolic acid (DPA), γ-valerolactone (GVL) and ethyl levulinate (EL) production were studied. The main purpose of this work was to optimize the production of LA from depithed sugarcane bagasse (DSB) using ionic liquids (ILs), which are environment benign compared to sulfuric acid which is currently used in commercial production of LA from biomass. Firstly, the optimal reaction conditions to produce LA from DSB using 1-ethyl-3- methylimidazolium hydrogen sulfate [EMim][HSO4] ionic liquid (IL) were investigated. The effect of temperature (100-220 oC), reaction time (2-12 h), and ionic liquid loading (1- 4 g) was assessed using response surface methodology (RSM) based on the Box-Behnken design (BBD). The optimum conditions were found to be 100 oC, 7 h, and 4 g of IL, which yielded 54.6 % of LA from DSB. The analysis of variance (ANOVA) indicated that the design model was significant at the 95 % confidence level. The pareto chart revealed that IL loading had the most significant effect on the production of LA, followed by temperature and reaction time. The P-values also showed that these were the significant model terms. There is a strong correlation between temperature and IL loading. Solvent optimization revealed that the type of solvent used in the LA production has a significant effect on LA yield. Water was used as the control solvent for this study. Methyl isobutyl ketone (MIBK) yielded the highest LA (62 %) from all the solvents that were used. Secondly, an environmentally friendly catalyst: 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BMMim][BF4]) was used to optimize the LA production from DSB. The Box-Behnken design (response surface methodology) was used to design the set of experiments with three variables, namely, time, temperature, and catalyst loading. The investigated conditions were temperature (100 - 220 oC), time (2 – 12 h), and catalyst loading (1 – 4 g). The optimum condition was found to be at 100 oC, 7 h and 4 g of a catalyst which yielded a maximum amount of 44.8 % of LA from DSB. This study also showed that the IL is capable of theoretically producing 62.1 % of LA. The reusability study showed that [BMMim][BF4] can be used for up to four times without losing it activity. Thirdly, an environmentally benign method to produce a LA derivative called ethyl levulinate (EL) was investigated. EL can be produced from LA using heterogeneous catalysts replacing the highly active, corrosive, and toxic homogeneous catalyst sulfuric acid. This work uses an environmentally friendly homogeneous catalyst: methanesulfonic acid (MsOH) as the control catalyst and ILs. The esterification of commercial LA into EL was first optimized using MsOH and response surface methodology. The optimum condition for the esterification of commercial LA into EL was 5.25 h, 90 oC, and 2.75 g of MsOH loading. The EL yield and selectivity obtained were 92.2 % and 94 %, respectively, at a LA conversion of 98 %. The optimized conditions were then utilized to produce EL from DSB derived LA with a EL yield of 75% using MsOH. Fourthly, gamma-valerolactone (GVL) production was optimized by a Box Behnken design from commercial LA with an environmentally friendly catalyst methanesulfonic acid. The optimum parameters were a temperature of 112.5 oC, reaction time of 6 h, and catalyst loading of 2.75 g yielding 78.6 % GVL with 97 % LA conversion and an 81 % selectivity. Thereafter the optimised conditions were used to produce GVL from LA derived from DSB. The hydrogen required for the reduction of LA to GVL was formed in-situ by formic acid and triethylamine in the presence of MsOH. Different solvents (including water and alcohols) were also tested to determine their effect on GVL yield, water yielded the highest GVL of 78.6 %. Different types of catalysts which included mineral acids and ionic liquids were used to determine their effect on GVL yield, and to provide a benchmark against MsOH. Sulfuric acid gave the highest GVL yield (80.9 %). Fifthly, the production of diphenolic acid (DPA) which is one of the LA derivatives was studied. DPA has a potential to replace bisphenol A, a plasticizer. To determine the optimum conditions for DPA production, commercial LA was used with a mild environmentally benign acid namely, methanesulfonic acid. The optimized reaction parameters were time (6 h), temperature (75 oC), and catalyst loading (5.5 g) yielding 65.8 % DPA at 90 % LA conversion. The response surface methodology study indicated that the temperature had the most significant effect on DPA yield followed by time and catalyst loading. The analysis of variance (ANOVA) revealed that the model was able to satisfactorily predict the DPA yield. To determine the effect of catalyst on DPA production from commercial LA, ionic liquids (ILs), MsOH, and sulfuric acid were used. IL catalysts produced 59-68 % of DPA, MsOH produced 65.6 % of DPA, and sulfuric acid produced the maximum DPA of 74 %. The study also investigated the effect of the LA: phenol ratio using the optimised reaction conditions. The LA: phenol ratio of 2:5 yielded the most DPA (86.35%). The optimized reaction conditions were then used to produce DPA from LA derived from depithed sugarcane bagasse (DSB), which yielded 64.5 % of DPA. This indicates that the DSB derived LA is a good starting material for DPA production. The LA production from depithed sugarcane bagasse was successfully optimized by using two ionic liquids namely 1-ethyl-3-methylimidazolium hydrogen sulfate and 1-butyl-2,3- dimethylimidazolium tetrafluoroborate, where for both ILs the same conditions yielded a maximum LA yield. MIBK was found to be the optimum solvent for both ILs, giving a higher LA yield compared to when water is used as a solvent. This study also revealed that at the optimum conditions there was no formation of humins, but humins were observed at maximum reaction conditions. Both ILs showed that they can be reused up to four times, which is very important for any catalysts especially for the ILs because they are known to be expensive. This study also illustrates the first-time optimization of three LA derivatives namely EL, GVL, and DPA using methanesulfonic acid.
Removal of organic and inorganic nutrients in a constructed rhizofiltration system using macrophytes and microbial biofilms
(2016) Mthembu, Mathews Simon; Swalaha, Feroz Mahomed; Bux, Faizal
Many households in developing countries are still without proper sanitation systems. The problems are even more prevalent in rural communities where there are no septic systems in place for the treatment of wastewater. This has resulted in the urgent need for the development and implementation of innovative wastewater treatment systems that are inexpensive, environmental friendly and are able to reduce contaminants to levels that pose no harm to the communities. Constructed rhizofiltration systems have been explored for this purpose. They have been used for many decades in many countries with varying degrees of success at the primary, secondary and tertiary levels of wastewater treatment. Poor optimization of this technology has been due to limited information available about the roles played by the whole system as well as by each component involved in the treatment technology. The current work elucidates the role played by macrophytes and microbial biofilms in the removal of nutrients in the rhizofiltration system. Factors affecting waste removal as well as environmental friendliness of the system were also investigated. The rhizofiltration system was constructed in Durban and was divided into planted (planted with Phragmites australis and Kyllinga nemoralis) and unplanted (reference) section. Dissolved oxygen (DO), pH, water temperature, total dissolved solids (TDS), electrical conductivity (EC) and salinity were monitored. The removal efficiency of nutrients was measured using spectrophotometric methods by measuring the concentration of ammonia, nitrate, nitrite, phosphate and orthophosphate in the wastewater pre- and post-treatment. The total organic carbon, chemical oxygen demand (COD), total Kehldjahl nitrogen, biological oxygen demand (BOD), ammonia, nitrate and the flow rate of wastewater into the system from the settling tank were used for the estimation of carbon dioxide, methane and nitrous oxide emitted from the rhizofilter using the 2009 EPA formulae. Both the planted and reference sections of the system removed nutrients with varying efficiencies. The reduction of nutrients in the rhizofilter was found to be seasonal, with most nutrients removed during the warm seasons. The system also retained more nutrients when wastewater containing low levels of nutrients was used. The unpaired t-test was used to determine the differences between nutrient removals between planted and reference sections. Higher reduction efficiencies of nutrients were obtained in the planted section. Up to 65% nitrite and 99% nitrate were removed while up to 86% total phosphorus was removed in a form of orthophosphate (86%). Removal of total nitrogen was shown to increase under high temperature conditions, while the same conditions decreased the total phosphorus removal. High temperatures also increased the performance of the system. The reduction of nutrients in the system corresponded to reduction of the chemical oxygen demand which also positively correlated to the dissolved oxygen concentration. Considering the discharge limits for all nutrients, the discharges in the effluent of the planted section were within the allowable limits as per South Africa’s Department of Water affairs and Forestry in 2012 but not in 2013. The results obtained in 2013 were due to increased nutrient loading introduced into the system. Diverse microbial communities occurred in the treatment system, with more diversity in the planted section. These organisms were supported by macrophytes in the planted section, and were responsible for nitrogen and phosphorus transformation. This explains why total nitrogen and phosphorus reduction was higher in the planted compared to the reference section. Both the planted and the reference sections of the rhizofiltration system produced the greenhouse gases. When the two sections were compared, the planted section produced more gases. Gases emitted by both sections were lower when compared to emission from sludge treatment reed beds and other conventional systems of wastewater treatments. These findings indicated that constructed rhizofiltration is a cleaner form of waste treatment, producing significantly less greenhouse gases and affecting less of a climate change. Findings of this work have revealed that rhizofiltration technology can be used as a low-cost alternative technology for the treatment of wastewater, using the combination of macrophytes and microbial biofilms. Macrophytes accumulated nitrogen and phosphorus as well as supported diverse microorganisms that metabolized and reduced nutrients in the rhizofiltration unit.
Screening for indigenous algae and optimisation of algal lipid yields for biodiesel production
(2011) Rawat, Ismail; Bux, Faizal
The depletion of global energy supplies coupled with an ever increasing need for energy and the effects of global warming have warranted the search for alternate renewable sources of fuel such as biodiesel. First generation biofuels are not sustainable enough to meet long term global energy requirements and more recently there has been concern expressed as to the potential negative implication of crop based biofuels in the form of negative energy balances and potentially no greenhouse gas benefit due to land utilisation not being taken into account. Microalgae have shown great promise as a sustainable alternative to first generation biofuels. They have faster growth rates, have greater photosynthetic efficiencies, require minimal nutrients and are capable of growth in saline waters which are unsuitable for agriculture. Microalgae utilise a large fraction of solar energy and have the potential to produce 45 to 220 times higher amounts of triglycerides than terrestrial plants. The use of microalgae for biodiesel production requires strain selection, optimisation and viability testing to ascertain the most appropriate organism for large scale cultivation. This study focuses on bioprospecting for indigenous lipid producing microalgae, screening, selection and optimisation of growth and lipid yields with respect to nutrient limitation. Further we have ascertained the sustainability of a selected species of microalgae in open pond system. Chlorella sp. and Scenedesmus sp. were found to be dominant amongst the isolates. Strains we selected and underwent media selection and growth and lipid optimisation trials. BG11 media was selected as the most appropriate media for the growth of the selected Chlorella and Scenedesmus strains. Little variation in growth was observed for both cultures ten days into cultivation under varying nitrate concentrations. Phosphate optimum was shown to be 0.032g/l for Scenedesmus sp and 0.04g/l for Chlorella sp. Best lipid yield determined during exponential growth was achieved in cultures with 0.3g/L to 0.6g/L nitrate and phosphate as per BG11 medium. pH optimisation showed that cultures may be adapted to growth at higher pH over time. The optimum pH range for growth was determined to be narrow and was found to be between pH 10 and pH 11. Chlorella sp. was shown to be sustainable as a dominant culture in open pond system. Open pond systems however are prone to contamination by other species of microalgae within weeks of inoculation.
Selective extraction of lignin from lignocellulosic biomas using ionic liquids
(2016) Mkhize, Thandeka, Y.; Deenadayalu, Nirmala; Reddy, P.
Globally there is a drive for the use of renewable materials for the production of biofuels or high-end value chemicals. The current production of chemicals from crude oil refining is unsustainable and leads to global warming effects. Biomass is the most attractive renewable energy source for biofuel or fine chemical production. Sugarcane bagasse is a by-product of the sugar milling industry and is abundantly available. In this study lignin was sequentially extracted using ionic liquids. The ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and triethylammonium hydrogen sulfate ([HNEt3][HSO4]) were used to fractionate the sugarcane bagasse. The pre-treatment of sugarcane bagasse was carried out at different temperatures ranging from 90 - 150 0C and reaction times ranging from 1 - 24 h in a convection oven at a 10 % biomass loading. Both ILs were able to dissolve the raw bagasse samples at 120 0C with [Emim][OAc] giving a lignin maxima of 28.8 % and a low pulp yield of 57 % after 12 h; [HNEt3][HSO4] gave a lignin recovery of 17.2 % and low pulp yield of 58.5 % after 6 h. Regenerated lignin was obtained by adding ethanol/ water to the mixture followed by vacuum filtration. The regenerated pulp materials were characterized by Scanning Electron Microscope (SEM) to study the morphology; Fourier Transform Infrared Spectroscopy (FTIR) to study the characteristic bands and thermal analysis to study the thermal stability.
Synthesis and characterization of a biocomposite derived from banana plants (Musa cavendish)
(2015) Paul, Vimla; Kanny, Krishnan; Redhi, Gyanasivan Govindsamy
Over decades synthetic composites have become an indispensable part of our lives with their various applications such as packaging, sporting equipment, agriculture, consumer products, medical applications, building materials, automotive industry, and aerospace materials among others. Although these polymers have the desired properties for the above applications, they are invariably costly. Furthermore, they cannot be easily disposed of at the end of their useful lives and simply pile up and cause significant damage to the environment. However, the dwindling supply of fossil fuel, increased oil prices, together with the growing public concern of greenhouse gas emissions and global warming, has forced scientists to search for new development of sustainable materials from renewable resources. Hence in recent years, there is an increased interest in biocomposite manufacturing with natural resources as environmental issues are addressed. The research work presented in this dissertation is to the best of the author’s knowledge a world-first overall investigation pertaining to the concept of synthesizing a banana sap based bio-resin (BSM) reinforced with banana fibres. In this work the chemical composition of banana sap was determined to investigate the chemical reactions taking place in the resin formulation. BSM was synthesized, characterized and proposed as a potential bio-resin to be used in the biocomposite manufacture for non-functional motor vehicle components. BSM, a hybrid bio-resin was synthesized with equimolar quantities of maleic anhydride and propylene glycol and 50% banana sap. A control resin without the banana sap was also synthesized for comparison purposes. It was proposed that the presence of sugars, esters and pthalates from the sap, determined by HPLC and GC-MS, contributed to the cross-linking of the polymer chain. The acid value and viscosity of BSM were determined and found to be within specification of an industry resin. The molecular weights of the BSM and control resins were 2179 and 2114 units respectively. These were within the required molecular weight of unsaturated polyester resins. The gel and cures times of the BSM were 60% lower than the control resin suggesting that the banana sap behaved as an accelerator for the curing process. The lower cure time meant that using the banana sap in the formulation was cost effective and time saving. The thermal properties of BSM showed improved degradation temperatures and degree of crystallinity compared to the control resin. A parametric study showed that increasing banana sap concentration in the resin formulation led to increased tensile and flexural properties with 50% being the optimum amount of sap to be added to the formulation. The synthesized bio-resin and control resin were applied to biocomposites and characterized in terms of physical, thermal, mechanical, morphological, chemical and biodegradable properties. Mechanical tests indicated a 15 % increase in tensile strength, 12 % improvement in tensile modulus and a 25 % improvement in the flexural modulus, when compared to structures produced without banana sap. Natural fibres present the challenge of poor adhesion to the matrix. Chemical treatment of the banana fibre was done to improve on the compatibility of resin to fibre. Fibre pull-out showed that treated fibres had a better bond than the untreated fibre. Parametric studies were also done to evaluate the effect of fortifying the BSM resin with nanoclay. A 5% clay loading resulted in a 24% increase in tensile strength and 28% increase in flexural properties. Finally biodegradation studies of the BSM bio-resin, BSM biocomposite, control resin and control composite were investigated and compared to a positive reference, cellulose. Results showed that over a period of 55 days the BSM biocomposite showed 17.6% biodegradation compared to 8% with the control composite. No difference in biodegradation between the BSM bio-resin and the control resin was recorded. BSM biocomposite was proposed as a potential replacement to synthetic composites that contribute to the environmental landfill problems. The main contribution of this research is the use of the reinforcement and matrix from the same natural source. An enriched understanding of the synthesis, characterization and performance of the banana sap based bio-resin and biocomposite for the use of non-functional motor vehicle components is the key outcome of this investigation.
Uncertainty and sensitivity analyses of energy and visual performances of ofﬁce building with external venetian blind shading in hot-dry climate
(Eslevier, 2016) Singh, Ramkishore; Lazarus, Ian Joseph; Kishore, V. V. N.
Fenestration has become an integral part of the buildings and has a signiﬁcant impact on the energy and indoor visual performances. Inappropriate design of the fenestration component may lead to low energy efﬁciency and visual discomfort as a result of high solar and thermal heat gains, excessive daylight and direct sunlight. External venetian blind has been identiﬁed as one of the effective shading devices for con-trolling the heat gains and daylight through fenestration. This study explores uncertainty and sensitivity analyses to identify and prioritize the most inﬂuencing parameters for designing glazed components that include external shading devices for ofﬁce buildings. The study was performed for hot-dry climate of Jodhpur (Latitude 26 1800N, longitude 73 0100E) using EnergyPlus, a whole building energy simulation tool providing a large number of inputs for eight façade orientations. A total 150 and 845 data points (for each orientation) for input variables were generated using Hyper Cubic Sampling and extended FAST methods for uncertainty and sensitivity analyses respectively. Results indicated a large uncertainty in the lighting, HVAC, source energy consumptions and useful daylight illuminance (UDI). The estimated coefﬁcients of variation were highest (up to 106%) for UDI, followed by lighting energy (up to 45%) and HVAC energy use (around 33%). The sensitivity analysis identiﬁed window to wall ratio, glazing type, blind type (orientation of slats) and slat angle as highly inﬂuencing factors for energy and visual perfor-mances regardless of façade orientation. The other inﬂuencing parameters are interior surface absorp-tance of wall and front surface solar reﬂectance of blind slat; however, the magnitude of inﬂuence varied with façade orientation.