An increase in anthropogenic activity has led to the heightened levels of pollution entering aquatic systems. These excessive concentrations of heavy metals, nitrogen (N), and phosphorus (P) in water bodies can lead to several adverse impacts, such as eutrophication and human health risks. Therefore, the removal of pollutants from wastewaters, prior to their discharge into the natural environment, is of paramount importance. However, conventional wastewater treatment (WWT) technologies have their limitations; for instance, large capital/operational costs, and incomplete removal of contaminants. Therefore, innovative and more effective treatment technologies are required. Macro-algae typically have high growth and solar energy conversion rates, and are able to sequester nutrients, utilise CO2, and adsorb metals from aquatic environments. Therefore, algae may have potential applications in WWT. Furthermore, costs could be negated by the production of renewable algal biomass which may have a variety of commercially exploitable applications. However, issues such as poor selection of species or cultivation systems, and a lack of understanding of the influence of biological, chemical and physical factors, particularly in a highly dynamic wastewater environments, has led to varied results and prevented algal WWT becoming a widespread reality. In this thesis the algae Cladophora coelothrix and Cladophora parriaudii were studied as potential organisms for implementation into WWT. In addition to the features mentioned above, Cladophora was selected due to its ubiquity, filamentous morphology, which minimises harvesting costs, as well as their natural dominance and bloom forming behaviour in nutrient-rich environments. The influence of dewatering techniques, environmental factors, and nutrient regime upon the growth, nutrient/metal removal, and biochemical composition of the biomass were assessed. The first aspect of the thesis was an abiotic screening process, in order to investigate the robustness of Cladophora and its suitability for WWT applications on a fundamental level. Good rates of growth (4-13.3% d-1) and nutrient removal (45.2-99.9%) were observed throughout the screening process, except under the most extreme of conditions, e.g. pH 3. This indicated that Cladophora are potentially suitable for treating a broad range of wastewaters and merit further research to improve its potential applicability for WWT applications and commercial realisation. For instance, developing a reliable and accurate method for fresh weight (FW) assessment and hence productivity estimation. The determination of growth rate via FW measurement is one of the most basic aspects of algal biology, yet no standardised method exists for filamentous macro-algae. A variety of FW methods were systematically assessed in terms of accuracy and physiological impact. Methods involving mechanical pressing to dewater the biomass resulted in >25% reduction in the final biomass yield, compared to control cultures. The best method for FW determination employed a reticulated spinner, which was rapid, reliable, and easily standardised. Furthermore, this approach ensured accurate growth estimation with minimal physiological impact, measured as growth, maintenance of structural integrity and nutrient removal. This indicates that the method developed has the potential for widespread application in macro-algal cultivation, as such the method was employed throughout this thesis. The influence of nutrient regime on growth, biochemical composition, and bioremediation capacity was studied for both species of Cladophora. The nutrient regimes tested, representative of a broad variety of wastewaters, included four different N/P ratios, four N sources (ammonium, nitrate, nitrite and urea), and six different equimolar N source combinations provided at two N/P ratios. There were clear differences in performance between the two species, with higher rates of growth observed in all instances by C. parriaudii (4.75-11.2% d-1 vs. 3.98-7.37% d-1). Furthermore, ammonium was removed preferentially, whereas urea was removed secondarily. However, the presence of urea in the medium enhanced growth and uptake of the other co-existing N-forms, and yielded a carbohydrate-rich biomass (37.6-54% DW). These findings demonstrate that algal strain selection is important for treating wastewaters with specific nutrient profiles. In addition, results from this study suggest that nutrient regimes can be tailored to produce biomass with certain properties or characteristics, which make it suitable for further, potentially commercially viable, applications, such as metal biosorption. Since the biochemical characteristics of algal biomass were shown to be affected by nutrient regime, the final chapter describes research investigating the influence of nutritional history on metal biosorption. C. parriaudii was cultivated under different nutrient regimes to produce biomass of varying biochemical composition. This biomass was then used for metal removal, with maximum removal rates ranging from 1.08-2.35 mmol g1, 0.3-0.62 mmol g-1, 0.22-0.48 mmol g-1, and 0.43-0.61 mmol g-1 for Al2+, Cu2+, Mn2+, and Pb2+, respectively. Observations from this work indicate that metal removal is achieved by various mechanisms including adsorption, ion exchange, complexation and micro-precipitation, and that the biosorption efficacy is dependent upon the number and type of functional groups present, which are in turn influenced by the cultures nutrient regime. Overall, this study demonstrates the inter-relatedness of biological, chemical, and physical factors on algal growth, nutrient removal, biochemical composition, and metal biosorption. Results from this work have highlighted the need for standardisation in protocols, increased understanding of the influence of algal selection and nutrient characteristics in bioremediation, and highlighted the importance of considering biological aspects, specifically nutritional history, in biosorption studies.

<p>Waste-derived organic products are nutrient-rich materials often applied to agricultural land as a fertilizer to enhance agricultural production and soil quality. Commercially available biosolid-based products, which are sold and distributed in bags or bulk, are rapidly gaining popularity for urban and suburban use. Although biosolid-derived products have many benefits, they may contain trace organic contaminants such as per- and polyfluoroalkyl acids (PFAAs) and pharmaceutical and personal care products (PPCPs), in varying levels, depending on waste source composition. These organic compounds have been used in a variety of consumer and industrial products and are known to accumulate in biosolids due to their recalcitrance in conventional wastewater treatment processes. Thus, the application of commercially available biosolids-based products on urban and suburban gardens may lead to transfer and accumulation of organic contaminants into food crops, raising food safety concerns. Most studies to date have focused on municipal biosolids application on agricultural lands with very few studies focused on commercial products available for home and urban gardens. For the latter, the evaluations of bioavailability and subsequent plant uptake of organic contaminants from biosolids have also often been conducted by adding organic contaminants to the growing media (e.g., soil or hydroponic) at a concentration that greatly exceed environmentally relevant concentrations. Moreover, there are currently no studies evaluating leaching and plant uptake potential of contaminants from commercially available (e.g., local stores) biosolids. The research described in this dissertation 1) assessed the occurrence of PFAAs and representative PPCPs in commercially available biosolid-based products and their porewater concentrations in saturated media as a measure of bioavailability and leachability; 2) investigated how heat-treatment, composting, blending and thermal hydrolysis processes on biosolids to convert them to commercial biosolid-based products affect PFAA concentrations in the production of commercial biosolid-based product; and 3) assessed the bioavailability and plant uptake of PFAAs and targeted PPCPs by kale and turnips grown in soil-less potting media amended with Milorganite (a commercially available biosolids-based fertilizer product) at the recommended rate and four times the recommended rate.</p><p>The biosolid-based products displayed varying levels of organic contaminants. Higher PFAA concentrations were detected in biosolid-based products compared to nonbiosolid-based products. The common treatment processes used in taking biosolids to commercially available products were ineffective in reducing PFAA levels in the products except for blending with other essentially PFAA-free materials, thus served as a simple dilution. Porewater concentrations of PFAAs and PPCPs as an indicator of leachability and bioavailability were higher for the less hydrophobic compounds (e.g., short-chain PFAAs and diphenhydramine and carbamazepine with lower octanol-water partition coefficient). Leachability alone did not explain the observed plant uptake potential of PFAAs and PPCPs. With similar leachability and molecular weight/size between diphenhydramine and carbamazepine, higher uptake was observed with a positively charged compound (diphenhydramine compared to a neutral compound (carbamazepine). However, not all positively charged compounds were taken up by the plant. Azithromycin, a positively charged compound, had lower uptake than other contaminants which may be due to its large molecular size compared to diphenhydramine. Higher concentrations of miconazole, triclosan, and triclocarban were found in the biosolids-fertilizer; however, these compounds had low leachabilities and limited uptake by plants. Also, for PPCPs, the application rates of biosolid-based products did not necessarily correlate with the higher uptake and translocation of contaminants to the above-ground portion of plants. </p><p>This study provides an evaluation of commercially available waste-derived organic products under condition comparable to home and urban garden setting. Although biosolids-based products can serve as alternatives to synthetic fertilizers, they contain higher levels of trace organic contaminants than nonbiosolid-organic products. Common biosolids treatment processes are ineffective for reducing the levels of trace organic contaminants in biosolids, particularly for PFAAs. Thus, it is critical to control the sources contributing to the higher level of these contaminants in biosolids-based products. Also, regulations (e.g., triclosan and triclocarban) and replacements (e.g., longer-chain PFAAs to short-chain PFAAs) of persistent trace organic chemicals have led to a reduction in their levels in biosolids-based products. Although longer chain PFAAs are more likely to bioaccumulate and persistent than the replacement short-chain alternatives, the current study has shown that the short-chain PFAAs are more readily taken up to edible parts of plants than longer-chain PFAAs even when applying at the recommended fertilizer rate. Thus, the current movement to replace longer chain PFAAs with short chains has the potential to result in higher total PFAA concentrations being bioavailable for plant uptake, thus increasing the risk of food contamination by PFAAs. </p>

Um dos desafios na elaboração de projetos de aterros sanitários é o equacionamento do destino/tratamento dos líquidos percolados em função das elevadas concentrações de poluentes, associadas a grandes variações, e seu abrandamento natural ao longo do tempo. Nesse sentido, o trabalho avalia, a partir da montagem de unidade piloto, a viabilidade do lançamento dos líquidos percolados gerados no aterro de sanitário, localizado no município de Piracicaba-SP, na Estação de Tratamento de Esgoto que dispõe de sistema australiano de lagoas. A unidade foi montada na própria estação e operada durante 18 meses, sendo avaliado o comportamento da eficiência para vazões crescentes de líquidos percolados. No trabalho foi investigado também a adequação dos métodos Suíço, Racional e do Balanço Hídrico na previsão da taxa de geração de líquidos percolados, a partir da comparação das estimativas obtidas pela aplicação dos métodos com a observada na prática. De maneira geral, pode-se dizer que é viável o lançamento de chorume em estações de tratamento de esgoto, sem prejuízo na eficiência do sistema. Com relação às estimativas das vazões de chorume pela aplicação dos métodos, os erros variaram desde menos 22% até mais 20% da vazão obtida na prática. / One of the challenges in the project of sanitary landfills is the solution of the destination/treatment of leachates due to the high concentration of pollutants, which is also associated to large variations and a natural reduction with time. This work evaluates, based on a pilot unit, the feasibility of the treatment of leachates, produced in sanitary landfills, in a wastewater treatment plant that uses a system of stabilization lagoons. The pilot unit was mounted in the wastewater treatment site and operated for 18 months, in which the performance was monitored for crescent flowrates of leachates. It was also investigated the prediction of leachate flowrates by different methods (Swiss, Rational and Hydric Balance) based on the comparison of predicted leachate generation rates with observed data. In general, it is possible to perform the treatment of leachates in wastewater treatment plants because there was no reduction of efficiency. Related to the prediction of leachate volumes, the errors of the tested methods range from -22% to + 20% of the observed flowrates.

This work investigates the elimination of new and emerging microcontaminants (EMs) from water by means of photochemical oxidation processes, namely heterogeneous and homogeneous photocatalysis. Representative compounds of artificial sweeteners (saccharin, SAC), endocrine disruptors (bisphenol-A, BPA), and pharmaceutica ls (antipyrine, AP) of high environmental persistence and widespread occurrence in the water cycle are used as case studies. Novel concepts that can make photochemica l oxidation a more cost-effective and environmentally benign technology are tested. In Chapter 4, the photocatalytic treatment of SAC and BPA is investigated. Novel submicronic anatase-rutile nanocomposite particles with tuned phase ratio are used as catalysts to increase the photocatalytic performance under UVA irradiation. At the best-assayed conditions (C0 = 3 mg/L, catalyst = 400 mg/L), SAC and BPA are completely degraded within 90 and 150 min of photocatalytic treatment, respectively. [variables: anatase-rutile ratio; initial substrate concentration; catalyst concentration; catalyst reuse; sonication during catalyst recovery] In Chapter 5, a UVA light-emitting diode (UVA-LED) and sunlight are used as irradiation sources to reduce energy requirements and environmental impacts of photocatalytic processes. The photocatalytic degradation of SAC and BPA is studied under UVA irradiation provided by either a UVA-LED or a conventional fluoresce nt blacklight UVA lamp (UVA-BL) and solar irradiation. At the best-assayed conditions (C0 = 2.5 mg/L, TiO2 = 250 mg/L), BPA is completely degraded within 20, 30, and 120 min under UVA-LED, solar, and UVA-BL irradiation, respectively. The treatment time required for the complete elimination of SAC is 20 min under UVA-LED and 90 min under UVA-BL irradiation. [variables: initial substrate concentration; catalyst concentration; water matrix; light source; reactor configuration] In Chapter 6, a comparative study is carried out among the photocatalytic systems of Chapters 4 and 5 in terms of EMs removal, photonic and energy efficiencies. Technica l and economic aspects of all the processes are assessed. LED-driven photocatalysis achieves the highest efficiency in terms of organic removal with the minimum energy consumption, rendering it the most sustainable technology for the treatment of EMs. In Chapter 7, olive mill wastewater (OMW) is used as an iron-chelating agent in the photo-Fenton reaction to obviate the need for water acidification at pH 2.8. Conventional, OMW- and EDDS-assisted photo-Fenton treatment is applied for SAC degradation in a solar compound parabolic collector (CPC). It was found that OMW forms iron complexes able to catalyse H2O2 decomposition and generate hydroxyl radicals. At the optimal OMW dilution (1:800), 90% of SAC is degraded within 75 min. [variables: pH; iron-chelating agent; initial SAC concentration; OMW dilution] In Chapter 8, other complexing and oxidising agents, namely oxalate and persulfate, are used for the intensification of AP degradation during UVA-LED photo-Fenton treatment. Neural networks are applied for process modelling and optimisation. At the optimal conditions (hydrogen peroxide = 100 mg/L, ferrous iron = 20 mg/L, oxalic acid = 100 mg/L), complete degradation of AP and 93% mineralisation is achieved within 2.5 and 60 min, respectively. [variables: initial concentration of hydrogen peroxide, ferrous iron, oxalic acid, persulfate] It is concluded that LED-driven photocatalysis is a sustainable technology for the elimination of EMs from water. Results from this work highlight the need for development and optimisation of engineering proper LED reactors. Furthermore, this work introduces a new concept towards the sustainable operation of photo-Fenton that is based on the use of wastewaters rich in polyphenols instead of pricey and hazardous chemicals for iron chelation. The addition of ferrioxalate complexes is proposed for the intensification of EMs mineralisation during UVA-LED photo-Fenton treatment. Finally, the findings of this work encourage the use of chemometric tools as predictive and optimisation tools.

Um dos desafios na elaboração de projetos de aterros sanitários é o equacionamento do destino/tratamento dos líquidos percolados em função das elevadas concentrações de poluentes, associadas a grandes variações, e seu abrandamento natural ao longo do tempo. Nesse sentido, o trabalho avalia, a partir da montagem de unidade piloto, a viabilidade do lançamento dos líquidos percolados gerados no aterro de sanitário, localizado no município de Piracicaba-SP, na Estação de Tratamento de Esgoto que dispõe de sistema australiano de lagoas. A unidade foi montada na própria estação e operada durante 18 meses, sendo avaliado o comportamento da eficiência para vazões crescentes de líquidos percolados. No trabalho foi investigado também a adequação dos métodos Suíço, Racional e do Balanço Hídrico na previsão da taxa de geração de líquidos percolados, a partir da comparação das estimativas obtidas pela aplicação dos métodos com a observada na prática. De maneira geral, pode-se dizer que é viável o lançamento de chorume em estações de tratamento de esgoto, sem prejuízo na eficiência do sistema. Com relação às estimativas das vazões de chorume pela aplicação dos métodos, os erros variaram desde menos 22% até mais 20% da vazão obtida na prática. / One of the challenges in the project of sanitary landfills is the solution of the destination/treatment of leachates due to the high concentration of pollutants, which is also associated to large variations and a natural reduction with time. This work evaluates, based on a pilot unit, the feasibility of the treatment of leachates, produced in sanitary landfills, in a wastewater treatment plant that uses a system of stabilization lagoons. The pilot unit was mounted in the wastewater treatment site and operated for 18 months, in which the performance was monitored for crescent flowrates of leachates. It was also investigated the prediction of leachate flowrates by different methods (Swiss, Rational and Hydric Balance) based on the comparison of predicted leachate generation rates with observed data. In general, it is possible to perform the treatment of leachates in wastewater treatment plants because there was no reduction of efficiency. Related to the prediction of leachate volumes, the errors of the tested methods range from -22% to + 20% of the observed flowrates.

MESHWR / Department of Hydrology and Water Resources / Water borne diseases due to inadequate and unsafe drinking water is a global challenge that has led to a significant number of deaths and illnesses reported annually. These diseases are prevalent in less-developed countries, especially in rural areas where there is shortage of basic infrastructure and inadequate funds for piped water systems in individual households. Community members are forced to resort to collecting water from communal water points and later storing the water in containers for daily use. Recontamination of microbiologically safe drinking water during and after collection from the water source has been recognised as a problem; hence treating water at household level is one way to provide potable water for affected communities. The microbiological quality of household water may be improved by using point-of-use treatment technologies such as chemical disinfection, solar disinfection and ceramic water filters. Some of these technologies are expensive, less effective and difficult to implement in rural communities. This research thus focused on ceramic water filters and finding an appropriate method for silver application so as to produce filters that are effective in both the provision of clean drinking water and the release of silver levels that are safe for human consumption. An assessment of the efficiency of ceramic water filters made with silver nitrate as point-of -use water treatment device in Dertig Village, North West Province, South Africa was carried out. During production of filters made with silver nitrate, the filters undergo firing in an electric kiln and ionic silver is reduced to metallic nanopatches dispersed throughout the porous ceramic media. Both filters made with silver nitrate and conventional silver nanoparticles impregnated ceramic water filters were manufactured at the PureMadi Dertig Ceramic Filter Facility, South Africa. Resulting filters were evaluated and quantified for total coliform and E. coli removal as well as silver concentration in the effluent. Ceramic water filters made with silver nitrate had a high removal efficiency for total coliforms (94.7%) and E. coli (99.3%). A comparison of the performance of filters made with silver nitrate and silver nanoparticles in the provision of potable water was carried out and results showed that the different filters had similar levels of total coliform and E. coli removal, although the silver nitrate filters produced the highest average removal of 97.23% while silver nanoparticles filters produced the lowest average removal of 85.43%. Reasonable silver levels were obtained in effluent from all filters. Average effluent silver levels were 0.07±0.04mg/L, 0.6±1.10 mg/L and 0.8±1.0mg/L for 1 g, 2 g and silver nanoparticle filters, respectively (below the EPA and WHO standard of 100 mg/L). Because silver nitrate filters resulted in the lowest effluent silver concentrations, this could potentially increase the effective life span of the filter. A cost analysis of the process proved that it was cheaper to produce ceramic water filters using silver nitrate as the chemical can be purchased locally and also eliminates labour related costs. Thus, filters made using silver nitrate could potentially improve performance, reduce production costs, and increase safety of production for workers. The results obtained from this study will be applied to improve the ceramic filtration technology as point-of-use water treatment device in an effort to reduce health problems associated with microbial contamination of water stored at household level. / NRF

No description available.

Traditionally, energy capture by non-concentrating solar collectors is calculated using the Hottel-Whillier Equation (HW): Q(u)=A(c)*F(r)*S-A(c)*F(r)*U(l)*(T(fi)-Tₐ), or its derivative: Q(u)=A(c)*F(r)*S-A(c)*F(r)*U(l)*((T(fi)-T(fo))/2-Tₐ). In these models, the rate of energy capture is based on the collector's aperture area (A(c)), collector heat removal factor (F(r)), absorbed solar radiation (S), collector overall heat loss coefficient (U(l)), inlet fluid temperature (T(fi)) and ambient air temperature (Tₐ). However real-world testing showed that these equations could potentially show significant errors during non-ideal solar and environmental conditions. It also predicts that when T(fi)-Tₐ equals zero, the energy lost convectively is zero. An improved model was tested: Q(u)=A(c)F(r)S-A(c)U(l)((T(fo)-T(fi))/(ln(T(fo)/T(fi)))-Tₐ) where T(fo) is the exit fluid temperature. Individual variables and coefficients were analyzed for all versions of the equation using linear analysis methods, statistical stepwise linear regression, F-Test, and Variance analysis, to determine their importance in the equation, as well as identify alternate methods of calculated collector coefficient modeling.

This thesis is an investigation on water reuse in the fresh-cut fruits and vegetable industry. Fresh water is used intensively in washing, cutting/peeling processes and disinfecting fruits and vegetables, as a result washwater with heavy solids is generated. Effective removal of solids is needed to allow for water reuse. Thus dissolved air flotation (DAF) and centrifuge with coagulation and flocculation process were explored for solid removal capabilities; some settling analysis was also conducted. Bench scale studies show DAF and centrifuge produce waters of similar quality (Turbidity). DAF is able to produce waters with higher UV transmittance and can work better with membrane filtration and UV disinfection. While centrifuge showed higher reduction in pathogen levels, it can be cost effective and compact in design. Membrane filtration feasibility showed that high quality waters (low turbidity) can be produced, but were unable to remove pathogens. Collimated beam results show UV disinfection can further be used to completely eliminate pathogens and allow for water reuse. This allows the processors to reduce their water foot-print, increase sustainability of their operations, and meet the increasing demand for fresh-cut fruits and vegetables.

Wastewater treatment is traditionally considered a separate part of an industrial activity, hardly connected to the production units themselves. It is nowadays essential to ensure that the quality of water is not degraded and that water that has been polluted is purified to acceptable levels, especially in a country with scarce water resources such as South Africa. Where water quality is concerned, Zero Effluent Discharge (ZED) is the ultimate goal, in order to avoid any releases of contaminants to the water environment. The push towards ZED in South Africa is also promoted further by the South African Government’s plan to reduce freshwater usage and the pollution of water sources due to the water scarcity in a semi-arid South Africa. Future legislation will see a marked increase in the cost of freshwater usage and/or a possible limitation of the quantity of freshwater available. There is a need in the South African Industry for a framework of Best Management Practices (BMPs) in order to provide interested stakeholders, which include not only industry, but also academia, environmental interest groups and members of the public, with a procedure to meet the ZED statutory requirements. This dissertation explores the regulatory requirements and current environmental management practices implemented. A framework of BMPs to successfully attain ZED status in South African industries is developed from the literature study and the researcher’s own experience. The BMP framework embodies practices for one integrated strategy within three dimensions. The three dimensions of the BMP framework were selected to differentiate between BMPs for management (Governance BMPs), the project management team responsible for ZED projects (Project Management BMPs) and the implementation of preventative and operational measures to obtain and sustain ZED compliance for South African industries. The BMP framework was validated against the practices applied by Mittal Steel. The Mittal Steel plant in Vanderbijlpark implemented various projects, reduced the intake of water and eliminated the discharge of effluent and by doing this successfully realised their ZED status. The BMP framework will enable South African industries to develop their own BMPs Manual which should be specific to their operational and environmental requirements. The implementation of these BMPs should be tailored and used accordingly to demonstrate compliance to ZED requirements in South African industries. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2009.