Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. Additionally, increasing contamination of surface waters by wastewater effluents has made water treatment processes more challenging and expensive. The presence of these pollutants in the receiving water body may have negative effects on aquatic species and often pose potential human health risks through the reuse of treated wastewater for drinking purposes and other household use. In countries like South Africa, Namibia, USA, Singapore and Australia, water agencies are intensifying wastewater reclamation/wastewater reuse as part of their water resource agenda: in order to meet the demands of the growing populations. Nowadays, water reuse is generally considered as a viable method of water supply management. This study focused on the identification of the occurrence, quantification of emerging contaminants and evaluation of removal efficiency in wastewater treatment processes of three classes of emerging contaminants (ECs) in wastewater: 1) six types of perfluorinated compounds (PFCs), namely; perfluorooctanoic acid (PFOA), Perfluorooctane sulphonate (PFOS), perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUDA); 2) bisphenol A (BPA); and 3) Acetaminophen (ACP). These contaminants were identified and quantified in four wastewater treatment plants in the Western Cape. These treatment plants include three WWTPs in Cape Town, namely: Bellville WWTP, Scottsdene WWTP and Zandvliet WWTP and one WWTP in the central Karoo (Beaufort West wastewater reclamation plant).

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Having access to clean water is not a certainty for every human being. Today, there are major problems with polluted water that not just affect us humans, but also the ecosystem around us. In recent years, research into making aerogels from protein nanofibrils (PNF) has increased. What is interesting about these gels is their properties of adsorbing contaminants in the water, such as organic molecules and metal ions. In this report, hydrogels and non-dry aerogels (called “non-dry” due to there being one additional heat-treatment step that can be performed to “dry” the aerogel to make it sturdier and more water-proof), have been produced by whey protein isolate (WPI), which is extracted from the dairy industry. This is a sustainable, cheap, and renewable raw material. The goals are thus: (1) to examine if there is a difference in adsorption capacity between hydrogels and non-dry aerogels in a static setup and (2) to understand and examine which product parameters give the gels the best adsorption efficiency. To achieve these goals, eight different gels were synthesized with eight different contents. The parameters have varied from the following; dialyzed or non-dialyzed WPI solution, straight or curly seeds and whether or not salt had been added to the gels. The samples’ adsorption efficiency was analyzed by micro equilibrium dialysis (MED) and UV-VIS spectroscopy. For hydrogels, the dialyzed solution with salt and curly seeds was the variant with the highest binding capacity for ThT at 34% of the initial ThT concentration. For non-dry aerogels the dialyzed solution with curly seeds and no added salt was the best variant for binding ThT, at 84% of initial ThT content bound. It was also seen that the gels that have non-dialyzed WPI solution or that the solutions contained salt increased the adsorption capacity. The conclusions drawn were that salt has a positive effect on the adsorption capacity of the gels that have formed a matrix, and a negative effect on the adsorption of loose fibrils as well as that the solutions may not need to be dialyzed. The type of seeds or fibrils effect on adsorption capacity was inconclusive. The adsorption capacity for non-dry aerogels was three times higher compared to hydrogels. / Att ha tillgång till rent vatten är inte en självklarhet för varje människa. Idag är det stora problem med förorenat vatten som inte bara påverkar oss människor utan också ekosystemet. På senare år har forskning inom att tillverka aerogeler av protein nanofibriller (PNF) ökat. Det som är intressant med dessa geler är deras egenskaper att adsorbera föroreningar i vattnet, som till exempel organiska molekyler och metalljoner. I detta arbete har icke-torra aerogels (kallas "icke-torra" på grund av att det finns ytterligare ett värmebehandlingssteg som kan utföras för att "torka" aerogelen för att göra dem robustare och mer vattentålig) och hydrogels producerats av vassleproteinisolat WPI, som utvinns från mjölkindustrin. Detta protein är ett hållbart, billigt och förnybart råmaterial. Målet med denna rapport är att (1) undersöka om det finns skillnader i adsorptionskapaciteterna mellan hydrogels och icke-torra aerogels i ett statiskt medium (2) förstå och undersöka vilka produktionsparametrar som ger den bästa adsorptionskapaciteten. För att uppnå dessa mål har åtta olika geler syntetiserats med åtta olika innehåll. De varierande parametrarna var följande; dialyserad eller icke dialyserad WPI-lösning, raka eller krulliga frön och om salt har tillsatts eller inte. Proverna analyserades med mikro-jämvikts-dialys och UV-VIS spektroskopi. För hydrogeler var den dialyserade lösningen med salt och krulliga seeds den variant som hade högst bindningskapacitet för ThT, vilket låg på 34 % av den orginellaThT-koncentrationen. För icke-tora aerogels var lösningen som var dialyserad med krulliga frön och inget tillsatt salt den variant som var bäst på att binda ThT, med en kapacitet på 84% av den orginella koncentrationen. Vi såg även att gelerna som hade odialyserad WPI-lösning alternativt att lösningarna som innehöll salt ökade adsorptionskapaciteten. Slutsatserna som dragits är att salt har en positiv påverkan på gelernas adsorptionsförmåga när de format en fibermatris och en negativ påverkan när de bara består av fria fibriller, samt att lösningarna kanske inte behöver dialyseras. Typ av frön eller fibrillers påverkan på adsorptionsförmåga kunde inte påvisas. Icke-torra aerogels hade en adsorptionsförmåga på ThT som är tre gånger högre jämfört med hydrogels.

This work shows the results of modeling and optimizing pentahedron-shaped covers for application on a passive solar still. While modeling under the assumption of clear weather in Provo, Utah, United States of America, it was found that two main geometries resulted: A single slope still with fully vertical back and sidewalls and a south face tilted at 37.1°, absorbing a total of 8.98 megajoules of direct solar radiation. A half-pyramid shaped cover with vertical backwall, sidewalls tilted in at 60.6°, and a south face tilted in at 41.5°, absorbing 9.34 megajoules of direct solar radiation.With improved covers, solar radiation absorbed by the basin can be maximized. Maximum radiation absorbed will generally indicate maximum still output.In addition, the internal convection of a passive solar still was modeled in order to compare with existing correlations to find the best convection correlation. The convection was modeled using Fluent 12 (CFD software package) and simulations were run for various geometries and temperatures. It was found that Shruti's correlation agreed the best with the CFD results. However, another possible correlation is suggested here which accommodates a higher range of Grashof numbers. For a correlation of the form Nu=C•(Ra)^n, it was found that C = 1.02, 0.56, and 0.66, and n = 0.19, 0.24, and 0.24 for cover tilt angles of 15°, 30°, and 45° respectively. Also, Grashof number ranges are 4.0 x 10^3 < Gr < 1.9 x 10^7, 4.0 x 10^4 < Gr < 1.9 x 10^8, and 2.1 x 10^5 < Gr < 1.0 x 10^9 respectively.

M.S.

In this study, polypyrrole (PPy) prepared by chemical and electrochemical polymerization was investigated as the electrode of electrochemical supercapacitor (ES). New strategies were developed for the fabrication of nano-structured PPy and PPy based nano-composites, which included discovery of advanced anionic dopants and multi-functional nano-crystals, and development of co-dispersing agents. These methods improved the capacitive performance and cycle stability of PPy electrodes. The results indicated that high material loading and good capacitance retention of PPy was achieved using an electrochemical polymerization method and Ni plaque as the current collectors. Nano-crystalline (CTA)2S2O8 formed by a chemical precipitation method from solutions, containing anionic oxidant (S2O82-) and cationic surfactant (CTA+), could be used as the oxidant to synthesize PPy nano-fibers. We demonstrated that multi-wall carbon nanotubes (MWCNT) can be efficiently dispersed using such nano-crystals. Application of multi-functional nano-crystals is a conceptually new approach for the fabrication PPy coated MWCNT. Moreover, safranin and malachite green were found as universal dispersing and charging agents for cataphoretic deposition of graphene, MWCNT and PPy nano-fibers. It opens new strategies in colloidal and electrochemical processing of PPy nano-composites for ES electrodes. PPy coated MWCNT, prepared by the multi-functional nano-crystals (CTA)2S2O8, was employed for the fabrication of N-doped activated carbon-coated MWCNT (N-AC-MWCNT). The obtained N-AC-MWCNT was uniformly coated and possessed with high surface area. The use of N-AC-MWCNT enabled the fabrication of ES electrodes with high mass loading and high active material to current collector mass ratio. Symmetric and asymmetric ES cells, fabricated by N-AC-MWCNT and aqueous Na2SO4 electrolyte, showed high specific capacitance, good capacitance retention and large voltage window. The positive electrode of asymmetric ES, MnO2 coated MWCNT, was successfully prepared by the chemical reaction between KMnO4 and N-AC-MWCNT. The problem of degradation of MWCNT was avoided by the use of N-AC as the sacrificial carbon. Significant progress on ES technology has allowed for the development of capacitive dyes removal (CDR) methods using ES devices. In our study, porous carbon materials, N-doped activated carbon coated MWCNT (N-AC-MWCNT) and N-doped activated carbon nano-fibers (N-AC-NF), were developed as the electrodes for CDR applications. The experimental results indicated that capacitive performance of ES cells was influenced by the chemical structure, size, charge-to mass ratio, concentration and redox-active ligands of the dyes. CDR is a promising method for removal of various cationic and anionic dyes, which offers advantages of energy saving and simple electrode regeneration. / Thesis / Doctor of Philosophy (PhD)

Clean, drinkable water is nowadays taken for granted in most developed coun-tries. However, over two billion people in the world do not have access to drink-ing water. In an attempt to combat this, capacitive deionization (CDI) hasgained increased attention in recent years. CDI is an emergent method of de-salination through separation of ionic species in aqueous solutions. The perfor-mance of CDI is dependent on materials used and how the device is constructed.This paper investigates key metrics relating the efficiency and applicability oftwo different CDI materials, activated carbon (Zorflex FM10 Chemivron) andCobalt Prussian Blue Analogue (referred to as the active material), in regardsto the electrodes used. These metrics include energy consumption, energy re-covery and Faradaic efficiency. The results were gathered from building a circuitwith the CDI cell as the capacitor and switching the polarity of the cell when adefined threshold of the voltage (1.5 V) was reached. The energy consumptionof the activated carbon (0.450 kWh/m3) was found to be less than that of theactive material (1.45 kWh/m3). The energy recovery was found to be roughlyequal for both materials, 80.6 % for the activated carbon and 79.5 % for theactive material. Finally, the activated carbon had a Faradaic efficiency of 0.75while the active material had 1.8.

The USPHS limits color in water to 15 color units. However, it is desirable to remove all the color. Color in surface water is mainly due to humic substances and was found in concentrations varying up to 450 color units. Removal of color by coagulation and flocculation has been practiced over the years. The mechanisms involved have not yet been fully understood. During the course of this investigation, a literature survey, studying the nature of color, mechanisms or color removal, and optimum color removal conditions, has been conducted. Samples have been obtained from surface waters in Central Florida; namely Big Econ River and Lakes Pickett, Irma, Lee, and Florida. These samples have been examined for color intensity, based on tannic acid, alkalinity and pH. The color intensity varied from 3.25 to 35.5. The alkalinity varied from 2 to 26 ppm, whereas the pH's varied from 5.3 to 6.35. Aluminum sulfate and ferric sulfate were used to remove the color from the samples. Optimum conditions for color removal of dosages and ph's were made by jar tests. The optimum dosage of Fe₂(SO₄)3 • nH₂O and Al₂(SO₄)3 • 18H₂O varied from 33 to 55 mg/l, while the optimum pH's were found to vary from 6-10. Aluminum sulfate was found to be the better coagulant for removing color.

Properties and characteristics of colloidal systems are reviewed with a discussion of colloid systems to be found in natural and wastewaters. Current electric and magnetic field theory are reviewed and summarized to provide practical application of the theory to engineering problems in the environmental field. Literature of colloidal reactions to electrical and magnetic fields is discussed and reviewed to ascertain areas of potential application of electric and magnetic phenomena to natural and wastewater treatment systems having objectionable colloid suspensions. It is concluded that application of electrical fields (electrophoresis) does not currently hold much promise for practical applications in water treatment systems. However, and understanding of colloid systems and electrophoresis is strongly recommended for personnel involved in chemical treatment of waters. It is shown that there has been considerable research and many applications of magnetic field treatment of waters by the Russians, most analysis of which is performed in an empirical manner that tends to cloud the phenomena with an aura of mysticism. Practical applications of magnetic field phenomena to water treatment systems involving ferromagnetic colloidal suspensions appears promising and research into this area is recommended.

Radon dissolved in drinking-water can be transferred into the indoor air and is one of the main transfer pathways for radon. At water purification plants, large quantities of water are treated and there is a risk that radon degasses from the water and enters into the indoor air. Hence, there is a risk for elevated radon levels in the indoor air at these facilities. This study aims to investigate the general impact of water treatment processes on the radon concentration in water and its transfer into the indoor air. Moreover, the risk that radon exposure exceeds the regulatory limits at workplaces was investigated. In total, the results from 39 Swedish water purification plants are included in the study. The methodology includes long-term air measurements with alpha track detectors, and short-term air measurements with AlphaGUARDs. In addition, water samples were collected in order to analyze the radon concentration in the untreated and treated water. The results show that several plants experience elevated radon levels in the indoor air and in some cases the exposure could be problematic. Several connections were investigated without finding apparent connections for those cases. For example, the relation between radon concentration in the water and radon level in the indoor air was investigated and the connection between the volume of water treated and the radon level in the indoor air. Calculations with transfer coefficients indicate that the transfer of radon into the indoor air is relatively small. However, there can also be contribution from other radon transfer pathways, such as soil and buildings, which may have an impact on the radon levels in the indoor air.