Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: A theoretical and experimental study was performed in order to identify factors that influence the propensity of compounds containing anionic functional groups that are commonly found on pharmaceutical drug compounds to form hydrates. A Cambridge Structural Database (CSD) survey was initially undertaken to determine the propensity of different pharmaceutically acceptable anions to form hydrates. The results showed that hydrate formation will take place more regularly when the polarity of the functional group increases. Furthermore, if the charge distribution is very concentrated over the polar groups, hydrate formation will occur more readily. This observation was further investigated by performing a series of potential energy surface (PES) scans for the hydrogen bond (H-bond) in the structure of N-(aminoiminomethyl)-N-methylglycine monohydrate (creatine monohydrate) with various Density Functional Theory (DFT) and Wave Functional Theory (WFT) methods. WFT is often also referred to as ab initio, which refers to the construction of the wave function from first principles when this theory is applied. The scans revealed that several strong and directional H-bonds with different geometrical parameters between the carboxylate group and the water molecule are possible, which suggests that the H-bond plays an important role in driving the formation of pharmaceutical hydrates. A total of 44 hydrate structures were identified that have pharmaceutically acceptable functional groups. Optimisations in the gas phase and in an implicit solvent polarisable continuum solvent model with a variety of solvents showed that there is a significant dependence of the H-bond interaction energy on the anionic group as well as the steric density of surrounding substituents. It was found that the M06-2X method utilising the 6-311++G(d,p) basis set outperformed the other methods that were tested when compared to optimisations performed with the benchmark MP2/aug-cc-pVTZ level of theory. Furthermore, the strength of the H-bond was measured in the 44 experimentally determined structures by using a total of five generalized gradient approximation (GGA) methods, of which two methods contained the DFT-D3 correction. The results of these DFT methods were subsequently compared to results obtained at the benchmark MP2/aug-cc-pVTZ level of theory. The M06-2X method was identified as the most economical method to calculate H-bond energies. It was also found that the H-bond interaction energy shows a substantial dependence on the electrostatic environment. This was observed by a significant decrease in H-bond strength as the relative permittivity of the solvent increases. The effect of steric density on the H-bond interaction energy was investigated by performing hydrogen bond propensity calculations. These values were then compared to the interaction energies of each structure and the results showed that the presence of large bulky substituents can lead to an increase in bond energy by forcing the anionic functional group closer to the water molecule. Contrastingly, the bulky group can also push the anionic group away from the water molecule and result in a decrease in bond energy. Approximate values for the amount of stabilisation offered to the H-bonding system by the surrounding crystalline environment were calculated by optimising the H-bond geometrical parameters of selected compounds with a combination of the M06-2X and MP2 methods utilising the 6-311++G(d,p) basis set. The H-bond interaction energies were then calculated at the M06-2X/6-311++G(d,p) level of theory and compared to the H-bond interaction energies in geometries that have been fully optimised. After these energies were compared and the crystal packing of each structure was investigated, it was found that the packing of some structures within the crystalline environment limits the number of H-bonds that can be formed between the water and the compound of interest. Full optimisation calculations result in structures with cooperative stabilisation, such that more than one H-bond is found between the two fragments. The effect of substituents on H-bond interaction energy was investigated by the addition of six electron-donating and electron-withdrawing groups on four aromatic compounds with different anionic functional groups, namely carboxylate, nitrogen dioxide, sulfonate and phosphonate. It should also be mentioned that the nitrogen dioxide is not an anionic functional group, but it was included as it is a neutral radical that often forms hydrogen bonds. A total of 80 structures were optimised with a combination of the M06-2X and MP2 methods utilising the 6-311++G(d,p) basis set. This was followed by counterpoise corrected single point calculations at the M06-2X/6-311++G(d,p) level of theory. The results showed that the H-bond interaction energy bears no relationship to the inductive strength or the inductive ability of the substituents, but rather the ability of these substituents to rotate the anionic functional group and allow cooperative stabilisation of the H-bond. Furthermore, AIM analysis was performed for the substituted H-bonded aromatic structure. The results showed that electron-donating groups that are placed at the para position yield stronger H-bonds, which is once again accompanied by cooperative stabilisation. Electron-withdrawing groups with sufficient inductive effects can result in a weaker H-bond when placed at the meta position. The effect of water activity (aw) on the hydrate crystal formation was investigated experimentally by performing a series of crystallisations in various solvent mixtures. These mixtures consisted of water mixed with acetone, ethanol and ethyl acetate. A total of three organic acids were used in crystal formation, namely pyridine-4-carboxylic acid (isonicotinic acid), N-amino-iminomethyl-N-methylglycine (creatine) and benzene-1,3,5-tricarboxylic acid. It was found that water activity affects the formation of the hydrate as well as the anhydrous product. Additionally, nucleation and super saturation plays a large role in crystal formation and can serve as an effective technique when the formation of crystals of an appropriate shape and size is required for further analysis. / AFRIKAANSE OPSOMMING: 'n Teoretiese en eksperimentele studie was uitgevoer om faktore te identifiseer wat die geneigdheid van verbindings met anioniese funksionele groepe wat algemeen gevind word op farmaseutiese dwelm verbindings om die hidraat produk te vorm, affekteer. 'n Opname van strukture in die Cambridge Strukturele Databasis (CSD) is onderneem om die geneigdheid van verskillende farmaseutiese aanvaarbare anione om hidrate te vorm te bepaal. Die resultate het getoon dat hidraatvorming meer gereeld plaasvind indien die polariteit van die funksionele groepe toeneem. Verder is daar ook opgemerk dat 'n gekonsentreerde ladingsverspreiding op die polêre groepe ook tot 'n toename in hidraat vorming sal lei. Hierdie waarneming is verder ondersoek deur 'n reeks potensiële energie oppervlak (PES) skanderings van die waterstof binding (H-binding) vir die struktuur van N-amino-iminometiel-N-metielglisien monohidraat (kreatien monohidraat) met verskeie Digtheids-Funksionele Teorie (DFT) en Golffunksie Teorie (WFT) metodes uit te voer. Die skanderings het getoon dat verskeie sterk, gerigte H-bindings met verskillende geometriese parameters tussen die karboksilaatgroep en die watermolekule kan vorm. Hierdie bevindinge lê klem op die belangrike rol wat H-bindings in die vorming van farmaseutiese koolhidrate speel. 'n Totaal van 44 hidraat strukture met farmaseutiese aanvaarbare funksionele groepe was geïdentifiseer. Optimaliserings is in die gas fase asook in 'n implisiete kontinuum polariseerbare oplosmiddel model met 'n verskeidenheid oplosmiddels uitgevoer. Die resultate het 'n beduidende afhanklikheid van die H-binding interaksie-energie op die anioniese groep asook die steriese afkskerming van omringende groepe getoon. Daar is bepaal dat die M06-2X metode wat saam met die 6-311++G(d,p) basisstel die mees akkuraatste resultate gelewer het in vergelyking met die ander DFT metodes asook die MP2/aug-cc-pVTZ maatstaf. Die H-binding se sterkte is vir hierdie strukture bereken deur vyf GGA metodes te gebruik, waarvan twee metodes van die DFT-D3 korreksie gebruik maak. Die resultate van die berekeninge met hierdie DFT metodes is daarna vergelyk met resultate verkry met die MP2/aug-cc-pVTZ maatstaf. Daar is gevolglik bepaal dat die M06-2X metode die mees ekonomiese metode is om H-binding energië te bereken. Die H-binding interaksie energie toon 'n aansienlike afhanklikheid op die diëlektriese konstante van die oplosmiddel aan. Hierdie waarneming is op grond van 'n beduidende afname in die H-binding interaksie-energie indien die relatiewe permittiwiteit van die oplosmiddel verhoog word gemaak. Die effek van steriese digtheid is ondersoek deur waterstofbindinggeneigdheid waardes te bereken. Hierdie waardes is met die interaksie-energië van elke struktuur vergelyk. Die resultate dui daarop dat steries digte groepe tot 'n toename in interaksie energie kan lei wanneer die anioniese funksionele groep nader aan die water molekule gestoot word. Verder is dit ook moontlik vir hierdie steries digte groepe om die anioniese groep weg van die water molekule te stoot en gevolglik 'n afname in interaksie energie te veroorsaak. Benaderde waardes vir die hoeveelheid stabilisering wat die omringende kristallyne omgewing aan die H-binding bied is bereken deur die H-binding geometriese parameters van geselekteerde verbindings met die M06-2X en MP2 metodes en die 6-311++G (d,p) basisstel te optimaliseer. Die H-binding interaksie-energië is gevolglik by die M06-2X/6-311++G(d,p) vlak van teorie bereken en met die H-binding energië in strukture wat volledige optimaliseer is vergelyk. Nadat hierdie waardes vergelyk is, is daar gevind dat die pakking van strukture in the kristallyne omgewing verhoed dat sekere H-bindings tussen die water molekule en die verbinding van belang kan vorm. Strukture wat volledig optimaliseer is, lei tot strukture wat in staat is om koöperatiewe stabilisering te ondergaan. Koöperatiewe stabilisering word gekenmerk deur die vorming van meer as een H-binding tussen twee fragmente. Die effek van substituente op die H-binding interaksie energie is ondersoek deur die bevoeging van ses elektrondonor- en elektronontrekkendegroepe op vier aromatiese verbindings, naamlike die karboksilaatgroep , stikstofdioksied , sulfonaat en fosfonaat. Dit moet ook genoem word dat stikstofdioksied nie 'n anioniese funksionele groep is nie, maar dit was wel ingesluit omdat dit ‘n neutrale radikaal groep is wat dikwels waterstofbindings vorm. 'n Totaal van 80 strukture optimiserings was uitgevoer met 'n kombinasie van die M06-2X en MP2 metodes wat gebruik maak van die 6-311++G(d,p) basisstel. Dit is gevolg deur interaksie-energie berekeninge op die M06-2X/6-311++G(d,p) vlak van teorie. Die resultate het getoon dat daar geen verband tussen die induktiewe vermoë van die substituente en die sterkte van die H-binding is nie, dit is eerder die vermoë van hierdie substituente om die anioniese funksionele groep te laat roteer wat toelaat dat koöperatiewe stabilisering van die H-binding kan geskied. Die AIM analise is op 'n gesubstitueerde H-binding struktuur toegepas. Die resultate het getoon dat elektrondonorgroepe wat by die para posisie geplaas word tot sterker H-bindings sal lei, wat weereens met koöperatiewe stabilisering vergesel word. Elektrononttrekkendegroepe met sterk induktiewe effekte kan tot 'n swakker H-binding lei indien hulle by die meta posisie geplaas word. Die effek van water aktiwiteit (𝑎w) op hidraatkristalvorming is deur die uitvoering van 'n reeks kristallisasies in verskeie oplosmiddelmengsels ondersoek. Hierdie oplosmiddel mengsels bestaan uit water met asetoon, etanol of etielasetaat gemeng. Kristallisasies is vir drie organiese sure, naamlik piridien-4-karboksielsuur, N-amino-iminometiel-N-metielglisien monohidraat en 1,3,5-benseen tri-karboksielsuur uitgevoer. Daar is gevind dat water aktiwiteit 'n invloed op die vorming van die hidraat en watervrye produkte kan hê. Daarbenewens, speel water aktiwiteit 'n belangrike rol in die nukleasie fase van kristalvorming en kan as 'n effektiewe tegniek dien om kristalle van 'n toepaslike vorm en grootte vir verdere analise te verkry.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Polymer composites have been gaining more importance in our daily lives because of the favorable properties that can be provided by these types of material. A polymer composite consists of improved properties when compared to the individual polymers that it is compiled of. The reason that composites are better than the individual polymers is mainly because composites are a combination of all the bene cial properties from the individual materials that was used to make the polymer composite. High impact polypropylene (HiPP) is a complex copolymer that was developed to overcome the restrictions of polypropylene (PP). Although PP have excellent properties at lower temperatures, it loses these advantages at elevated temperatures. High impact polypropylene has a much better impact strength and is processable at high temperatures. High impact polypropylene has been studied in depth for its applications and its superior properties such as an improved impact strength. The tensile properties, after the incorporation of a nano ller, have however not been investigated to our knowledge. Nano llers have reinforcing abilities due to the nano-scale diameters. Particles that have sizes on a nanometer range are mostly devoid of defects. Nano llers that are biopolymers have additional advantages such that can consist of antimicrobial abilities, renewability, biocompatibility and biodegradability. Composites reinforced with chitin nanowhiskers (chnw) have shown to have valuable applications in the latest medical, industrial and environmental developments. Di erent loadings of chnw were incorporated into a HiPP matrix in order to investigate the e ects that this nano ller will have on the tensile properties of HiPP. There were two challenges that required attention during the incorporation of chnw into HiPP. The rst major challenge was the poor interaction that exist between chnw and HiPP due to the hydrophobic nature of the HiPP matrix and the hydrophilic nature of chnw. The second problem was the agglomeration that can occur because of the hydrogen bonding between the chnw that is caused by the structure of the chnw chains. In order to gain the best dispersion of chnw within the HiPP matrix it was necessary to use compatibilizers and di erent methods of incorporation. The two types of compatibilizers that were chosen to improve the compatibility between the HiPP matrix and chnw were polypropylenegraft- maleic anhydride (PPgMA) and poly(ethylene-co-vinyl alcohol)(EVOH). Injection molding is typically used to process HiPP and was chosen as one of the methods for incorporating chnw into the HiPP matrix. A second method of incorporation was used speci cally for the nancomposites containing EVOH known as electrospinning combined with meltpressing. Tensile testing, DSC, TGA and FTIR were used to investigate the changes in the mechanical and thermal properties of the nanocomposites. SEM and TEM were employed to investigate the morphology of the electrospun ber mats and to characterize the chnw. FTIR as well as TGA were used to characterize the chitin nanowhiskers and to identify the individual components within the nanocomposites after incorporation took place. The incorporation of chnw along with the compatibilizer did show improvement in some mechanical properties of the polymer matrix. However, the in uence that each type of compatiblizer had on this e ect varied depending on the content of the chnw and compatibilizer with regards to the polymer matrix.

Three plant species (Phylica paniculata Willd., Pergularia daemia Forssk. and Monsonia / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

In the first phase of the study, the effect of five Safol surfactants on the aqueous solubility of phenanthrene and acenaphthene was determined. The fixed variables were temperature and ionic strength, while surfactant concentration and pH were varied. Quantification of the polyaromatic hydrocarbons (PAHs) was conducted by UV-Visible spectrophotometry. The surfactants had little or no effect on analyte solubilisation below the critical micelle concentration (CMC) while a linear relationship between surfactant concentration and amount of solubilised phenanthrene was observed above CMC concentrations. Safol 45E5 had the highest phenanthrene molar solubilisation ratio (0.83) of the five surfactants tested. The solubilisation of phenanthrene increased marginally (4.1 % for Safol 45E12 and 15.2 % for Safol 45E7) by decreasing the pH from 8 to 5. The concentration of solubilised acenaphthene was 8.4 % higher than phenanthrene in a 1 mM solution of Safol 45E7. The aqueous solubility of phenanthrene was enhanced 11.0, 21.2, 19.6, 15.9 and 14.7 times in 1 mM solutions of Safol 45E3, 45E5, 45E7, 45E9 and 45E12 respectively. Seasand, Longlands sand, Longlands soil and a standard soil sample were spiked with the two PAHs and aged for two weeks. API sludge provided by Sasol and unspiked samples of the above mentioned sorbents were subjected to determinations of organic matter content, particle size distribution and moisture content. The spiked soils and sands and the sludge samples were then washed in various concentrations of Safol 45E7 (0.5, 1.0 and 2.0 mM) at the same temperature used in the solubility studies. A soil mass to solution volume of lg to 10 mL was used. Analyses of the soil and sand samples were conducted by High Pressure Liquid Chromatography (HPLC). Using a 2 mM Safol 45E7 surfactant solution, 100 % and 90 % of phenanthrene and acenaphthene were respectively extracted from Longlands sand and 88 % and 100 % of phenanthrene and acenaphthene were removed from seasand. 8.4 % phenanthrene and 8.17 % of acenaphthene was removed from Longlands soil, while 7.03 % phenanthrene and 6.64 % acenaphthene was removed from the standard soil sample. In the sand desorption studies, the amount of desorbed contaminants initially increased rapidly with increasing surfactant concentration, before levelling off at equilibrium. The amount of desorbed acenaphthene and phenanthrene increased exponentially with increasing surfactant concentration while contaminant concentrations decreased with increasing time in the Longlands soil and standard soil desorption experiments. Dry API sludge samples were also subjected to soil washing studies. The washed samples were Soxhlet extracted and analysed by gas chromatography. The 0.5 mM and 1 mM Safol 45E7 washed sludge samples showed respective phenanthrene peak area percent reductions representing a 44 % and 47 % extraction of phenanthrene from the API sludge. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

A total of 34 sewage sludge samples were collected from South African provinces: KwaZulu- Natal, Gauteng, North West and Western Cape province. The samples were analysed for mineral ions and polynuclear aromatic hydrocarbons (PAH). The methods used for sample preparation were US-EPA 3050B and 3540C for mineral ions and PAHs respectively. The moisture content was also analysed. A minimum of 4.5 % and maximum of 99.5 % moisture were detected in the samples. The sludge that had stayed longer in their sampling points had low moisture contents than those that were sampled immediately after production. A total of 22-minaral ions were detected in the samples. When these were quantified an abundance trend that was found to be most common was: P>Ca>Fe>Al>Mg>K>Zn>Na>Mn>Cu>Ba>Cr>Pb>Si>Se>Sr>B>Ni>Mo>Co>Cd>Be. Phosphorous was the most abundant mineral ion in most of the samples apart from calcium, which was found to be abundant in a few cases. Comparing these results to the South African guideline limits, it emerges that most of the sewage works are compliant with the guidelines. The mineral ion that was found to be above the set limit in most occasions was selenium. The current South African guidelines were found to compare favourably to those of other countries. In the study 16 PAHs were also analysed, based on frequency of occurrence these were found to be: benzo(b)fluorathene ~ benzo(k fIuoranthene> phenanthrene> acenaphthylene> fluorine> naphthalene> benzo(a)anthracene> chrysene> acenaphthene> benzo(a)pyrene> fluoranthene> anthracene ~ pyrene> benzo(g,h,i)perylene> indeno(l ,2,3-cd)pyrene> dibenzo(a,h)anthracene Dibenzo(a,h)pyrene was below the detection limit in all the samples analysed while benzo(b)fluoranthene and benzo(k)fluoranthene were the most abundant compounds. All the samples analysed had concentration of benzo(a)pyrene below the South African limit of 2.53 mg kg"1. Comparing these guidelines with other international countries, South Africa specifies a single compound for monitoring while in other countries more than one compound is monitored. Thus South African guidelines need to be put in line with those of major EU countries such as Germany and Denmark with respect to PAH limits. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

This project is focused on the synthesis and biological activity of aloin and derivatives. Aloin is a C-glucoside anthrone that is found in Aloe marlothii, a common Southern African plant used in traditional medicine. Aloin was isolated from A. marlothii, employing a selective chelation isolation procedure. This compound is known to have numerous biologically active properties, and can be used as a laxative, an anti-bacterial agent, an anti-oxidant, and as a cytotoxic drug against breast and ovarian tumour cell lines. More relevant to this research investigation, was the reported anti-inflammatory activity of aloin. Specifically, the inhibitory activity of aloin on matrix metalloproteinases, which when excessively secreted, can lead to the development of osteoarthritis and cancer metastasis. Aloin has also been reported to have antiplasmodial activity, which was also investigated. Aloin was synthetically transformed into several derivatives, which could be potentially useful medicinal compounds. The choice of derivatives to be made was based upon (i) known biologically active compounds (e.g. aloe-emodin) and (ii) interesting biologically active functional groups (e.g. amines). These aloin derivatives include aloe-emodin, rheinal, rhein and three amine derivatives. Homonataloin, an aloin-analogue, which was also isolated from A. marlothii, was synthetically transformed into nataloe-emodin. These two compounds serve as aloin structural analogues for the biological testing. Aloin and derivatives were characterised using NMR, HR-MS, UV and IR, which allowed for their unambiguous structural elucidation. Aloin and derivatives were all tested for (i) possible inhibition towards MMP-2 and MMP-9, which are the two most common MMPs in the blood, and (ii) antiplasmodial activity against chloroquine sensitive Plasmodium falciparum parasites. Doxycycline, a clinical tetracycline drug, was used as a reference compound for the biological assays, since it shares many common structural features with aloin and derivatives. 11-(Piperidin-1-yl)chrysophanol and 11-(morpholin-1-yl)chrysophanol proved to be the most potent selective MMP-2 inhibitors. 11-(Piperidin-1-yl)chrysophanol was also found to be the most potent against P. falciparum parasite, along with 11-(pyrrolidin-1-yl)chrysophanol. Aloin has been shown to be a cheap, easily obtainable lead compound that could facilitate the production of a range of powerful medicinal drugs. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

A comprehensive literature survey looking at different aspects of organic contaminants in sewage sludge is incorporated in the thesis. It is clear from the data available that plants do not take up most of the organic pollutants. However, a risk of contamination of the food chain exists when sludge is spread directly onto crops that are to be consumed raw or semi-cooked. The major source of human exposure to sludge-borne organic pollutants is through the consumption of animal products such as meat and milk through the bioaccumulation of compounds such as polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs) or polynuclear aromatic hydrocarbons (PAHs). This is due to the ingestion of soil and sludge by livestock due to the spreading of sludge on the land used for grazing. Currently little is known about the plant uptake of phthalates and nonylphenols, which are present in relatively high levels in sludge. Included in the literature survey is a list of the most common methods normally used for extraction of organic compounds and the possible methods of analysis. What is noted is that there is no universally accepted and validated analytical method for analysing most of the organic compounds. In addition, data concerning levels of organic pollutants is scarce worldwide. The methods selected for this project were EPA Methods 35IOC (Liquid-liquid extraction) and 3540C (Soxhlet extraction) for the aqueous and solid sewage sludge respectively. These two methods were chosen because they are simple, inexpensive and effective. The chosen purification method was the sulfur clean-up process (EPA Method 3660B). This is because sulfur precipitates were observed in most of the concentrated extracts, especially from the solid samples. A total of 109 samples from 78 sewage works were extracted, using Soxhlet extraction for solids and liquid-liquid extraction for liquid samples. All the extracts were analysed using GC-MS. The identification of the organic compounds was made possible by the use of GC-MS Wiley library. A total of 712 organic compounds were identified in the South African sewage sludge. These included Phenols, Pesticides, PAHs, Phthalates, PCBs, Furans, Amines, Aldehydes, Esters, Acids, Chlorinated Hydrocarbons, Alcohols, Hydrocarbons and Others (all sorts of organic compounds that did not belong to the named categories). The extraction efficiency and reproducibility using a "clean" sludge matrix was carried out. The results showed that the method chosen for extraction i.e. Soxhlet method had an efficiency of over 80% and the results were reproducible. A total of 14 samples were selected for the quantification of p-cresol, nonylphenol and pesticides listed in the current legislation. The results showed negative results for pesticides, confirming that the pesticides listed in the legislation are not the compounds that need to be regulated as far as organic pollutants are concerned. The reasons for this are most likely due to the fact that most of the pesticides listed are banned or their use is severely restricted. The results for the quantification of p-cresol and nonylphenol, when comparing the liquid and the solid extracts of the liquid sludge, show that 99% of p-cresol is concentrated in the liquid phase. The opposite is true when looking at nonylphenol where 90% of it is trapped in the solid matrix leaving 10% in the liquid phase. It is also noted that liquid sludge contains high concentrations of both p-cresol and nonylphenol when compared to the solid sludge. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

A local company instituted a new chemical procedure in their spray phosphating system used in the pretreatment of large components for industrial racking systems. An inorganic conversion coating is deposited on the workpiece surface during phosphating and this prepares the surface to receive an organic top-coat. The organic coating is applied to the workpiece surface in the form of a powder and cured to form a continuous film about 80 u.m thick. The solution chemistry of the phosphating system was monitored by sampling and chemical analysis and taking direct reading instrumental measurements on the process and rinse solutions. The process was also evaluated using the results of a waste minimisation audit. This involved gathering data on composition, flow rates and costs of inputs and outputs of the process. Two types of information were collected and used during the audit, namely chemical monitoring (concentration levels of Na, Fe, Zn, Mo, Mn and Cr and measurements of conductivity, TDS, SS and pH) and water usage data on the Phosphating Line and existing data (raw materials, workpieces and utility inputs as well as domestic waste, factory waste and scrap metal outputs). The data were analysed using four established waste minimisation techniques. The Scoping Audit and the Water Economy Assessment results were determined using empirically derived models. The Mass Balance and the True Cost of Waste findings were obtained through more detailed calculations using the results of the chemical analysis. The results of the audit showed that the most important area for waste minimsation in the Phosphating Line was the (dragged-out phosphating chemicals present in) wastewater stream. According to the scoping audit, water usage had the third highest waste minimisation potential behind powder and steel consumption for the entire powder coating process. While the scoping audit and the specific water intake value showed that water consumption for the process was not excessive, it did not indicate that the pollution level in the rinse waters was high. Further, drag-out calculations showed that drag-out volumes were typical of those found in the metal finishing industry. However the presence of high levels of metal species in the rinse waters was highlighted through the chemical monitoring of the Phosphating Line. The True Cost of Waste Analysis estimated potential financial savings for the effluent stream at about R8000 for a period of 105 days. However this does not take into consideration the cost of the liability associated with this stream when exceeding effluent discharge limits (given in the Trade Effluent Bylaws) or of the chemical treatment necessary to render this stream suitable for discharge to sewer. Intervention using only "low-cost-no-cost" waste minimisation measures was recommended as a first step before contemplating further areas for technical or economic feasibility studies. However, a further study involving monitoring the sludge was recommended in order to establish the potential financial savings offered by this waste stream. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

No abstract available. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004

A total of 78 sludge samples originating from 69 sewage works of South Africa were used in this investigation. Seven of the sludge samples were liquid and the rest were solid. Moisture content, pH and mineral ion determination using ICP-OES were carried out. The methods used to digest the samples were EPA 3050B and 301OA for solid sludge and effluent (liquid sludge) respectively. The moisture content determination showed that fresh wet sludge was composed of water between 40 to 90 %. The minimum moisture content was found to be 2.70 % while the maximum was 88.50 % with a mean value of41 %. The pH results showed that the majority sludges produced had pH values between 4.8 - 6.5. The ICP-OES results which involved analysis and quantification of 22 mineral ions showed that the order ofabundance that was most common to the majority ofthe samples was P, Ca, Fe, AI, Mg, K, Zn, Na, Si, Mn, Cu, Cr, Ba, Pb, Sr, Se, B, Ni, Co, Mo and Cd. Even though phosphorus was the most abundant, 11 of the samples had calcium as the highest element. Looking at the heavy metals, zinc was the highest with cadmium being the least. The order of abundance in majority of the solid samples (64 in total) was Zn> Pb > Ni> Cd with the relative metal concentrations of Cu, Se, B, Cr, Co & Mo varying among the sewage works. The liquid samples also had phosphorus as one of the most abundant elements but was 102 times smaller comparing to solid sludges. In addition, most of the transition elements were found to be below the detection limit. Beryllium was exceptionally found to be below detection limit in all sludge samples. The results have pointed out that industrial effluent have 3 times the level of pollutants when compared to the domestic effluents. However, the methods of preparing sludge have no influence on the content or quantity of mineral ions. The results have been compared with 1989 data. The outcome shows that concentrations of the major nutrients namely calcium, magnesium and potassium remained relatively constant whereas phosphorus increased by more than 3 fold. On heavy metals, the data shows that the mean concentration level of Zn, Cu, Cr, Pb, Ni and Cd declined whereas that of Se, B and Mo showed an increase in 2002, all to a varying degree. The current results were also compared with the current maximum limits as stipulated in the permissible utilization and disposal of sewage sludge government guideline. The amount of Cu, Se, Pb and Zn were found to be above the limit in more than 90 % of the samples. There was no sewage works that met the required limits for all the elements of interest. When these results are compared with the intenational limits, all the elements fall within the acceptable range. It is therefore clear that the current South African guideline limit is too restrictive. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.