Optimization of combined flotation and filtration at a large water treatment plant
- Authors: Van Beek, J.C.
- Date: 1994
- Subjects: Water - Purification , Water - Purification - Filtration , Water - Purification - South Africa
- Language: English
- Type: Masters Thesis
- Identifier: http://hdl.handle.net/10210/16883 , uj:15818
- Description: Abstract: The Rietvlei water treatment plant has recently (1988) been upgraded and redesigned to accommodate dissolved air flotation and filtration (DAFF) in the same process unit. The reason for this drastic change was the eutrophication of the raw water which made conventional sedimentation before filtration impossible due to the high algal content of the water. Rietvlei is the first treatment plant in South Africa that makes permanent use of DAFF at full-scale. After operating for a number of years it was possible to identify areas where the operation of this process could possibly be improved. This study was directed at these areas and it was shown that flocculation conditions in the baffled flocculation channel can be satisfactory predicted with the use of the Bratby reactor and the Argaman/Kaufman flocculation model, flocculation can be significantly improved with the aid of a nonionic polyelectrolyte... , M. Ing. (Civil Engineering)
- Full Text:
- Authors: Van Beek, J.C.
- Date: 1994
- Subjects: Water - Purification , Water - Purification - Filtration , Water - Purification - South Africa
- Language: English
- Type: Masters Thesis
- Identifier: http://hdl.handle.net/10210/16883 , uj:15818
- Description: Abstract: The Rietvlei water treatment plant has recently (1988) been upgraded and redesigned to accommodate dissolved air flotation and filtration (DAFF) in the same process unit. The reason for this drastic change was the eutrophication of the raw water which made conventional sedimentation before filtration impossible due to the high algal content of the water. Rietvlei is the first treatment plant in South Africa that makes permanent use of DAFF at full-scale. After operating for a number of years it was possible to identify areas where the operation of this process could possibly be improved. This study was directed at these areas and it was shown that flocculation conditions in the baffled flocculation channel can be satisfactory predicted with the use of the Bratby reactor and the Argaman/Kaufman flocculation model, flocculation can be significantly improved with the aid of a nonionic polyelectrolyte... , M. Ing. (Civil Engineering)
- Full Text:
Phosphorylated carbon nanotube-cyclodextrin/silver-doped titania nanobiocomposites for water purification
- Authors: Leudjo Taka, Anny
- Date: 2018
- Subjects: Water - Purification , Cyclodextrins , Titanium dioxide , Carbon nanotubes , Nanobiotechnology
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278734 , uj:29917
- Description: Ph.D. (Chemistry) , Abstract: Nowadays, the shortage of water resources is the major concern around the world and especially in Southern Africa. The challenge is to develop an effective method to recycle wastewater through adequate treatment. That is to design a water treatment material able to remove the pollutants from wastewater effectively and efficiently to the accepted levels. In this regard, the aim of this research project was to develop a new nanomaterial which was used as adsorbent and disinfectant to remove all the three classes of water pollutants (inorganic, organic and pathogenic microorganism) from wastewater. In this study, phosphorylated multiwalled carbon nanotube-cyclodextrin/silver doped titania (pMWCNT-βCD/TiO2-Ag) was synthesized, using a combined process of amidation reaction, cross-linking polymerization and the sol-gel method. For a better evaluation of the target material, the insoluble nanosponges β-cyclodextrin (βCD) polymer and pMWCNT-βCD composite polymer were also synthesized for comparison purposes. The prepared nanostructured materials were fully characterized using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET) method, electron microscopy, and spectroscopy techniques. Fourier-transform infrared (FTIR) spectroscopy was used to confirm the presence of functional groups on the surface of modified MWCNTs, and the polymerization reaction. X-ray photoelectron spectroscopy (XPS) was employed to further confirm the presence of functional groups on the surface of the nanomaterials synthesized and to provide the percentage elemental composition with binding energies. Laser Raman showed the presence of MWCNT, βCD, and TiO2 in the nanocomposite. The anatase crystalline form of TiO2 in the samples synthesized was confirmed by X-ray diffraction (XRD) spectroscopy analysis. Transmission electron microscopy (TEM) analysis confirmed the structural morphology of the new biopolymer nanocomposite (pMWCNT-βCD/TiO2-Ag) as a sponge-like structure which showed a good dispersion of Ag nanoparticles. The BET surface area of the newly developed pMWCNT-βCD/TiO2-Ag was very high (352.55 m2/g), and this favored the use of this new nanomaterial as an adsorbent for the effective removal of pollutants from synthetic i.e. model wastewater and mine effluent samples...
- Full Text:
- Authors: Leudjo Taka, Anny
- Date: 2018
- Subjects: Water - Purification , Cyclodextrins , Titanium dioxide , Carbon nanotubes , Nanobiotechnology
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278734 , uj:29917
- Description: Ph.D. (Chemistry) , Abstract: Nowadays, the shortage of water resources is the major concern around the world and especially in Southern Africa. The challenge is to develop an effective method to recycle wastewater through adequate treatment. That is to design a water treatment material able to remove the pollutants from wastewater effectively and efficiently to the accepted levels. In this regard, the aim of this research project was to develop a new nanomaterial which was used as adsorbent and disinfectant to remove all the three classes of water pollutants (inorganic, organic and pathogenic microorganism) from wastewater. In this study, phosphorylated multiwalled carbon nanotube-cyclodextrin/silver doped titania (pMWCNT-βCD/TiO2-Ag) was synthesized, using a combined process of amidation reaction, cross-linking polymerization and the sol-gel method. For a better evaluation of the target material, the insoluble nanosponges β-cyclodextrin (βCD) polymer and pMWCNT-βCD composite polymer were also synthesized for comparison purposes. The prepared nanostructured materials were fully characterized using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET) method, electron microscopy, and spectroscopy techniques. Fourier-transform infrared (FTIR) spectroscopy was used to confirm the presence of functional groups on the surface of modified MWCNTs, and the polymerization reaction. X-ray photoelectron spectroscopy (XPS) was employed to further confirm the presence of functional groups on the surface of the nanomaterials synthesized and to provide the percentage elemental composition with binding energies. Laser Raman showed the presence of MWCNT, βCD, and TiO2 in the nanocomposite. The anatase crystalline form of TiO2 in the samples synthesized was confirmed by X-ray diffraction (XRD) spectroscopy analysis. Transmission electron microscopy (TEM) analysis confirmed the structural morphology of the new biopolymer nanocomposite (pMWCNT-βCD/TiO2-Ag) as a sponge-like structure which showed a good dispersion of Ag nanoparticles. The BET surface area of the newly developed pMWCNT-βCD/TiO2-Ag was very high (352.55 m2/g), and this favored the use of this new nanomaterial as an adsorbent for the effective removal of pollutants from synthetic i.e. model wastewater and mine effluent samples...
- Full Text:
Fabrication, characterisation and assessment of ultrafiltration membranes incorporating catalytic Metal Organic Frameworks (MOFs) for water treatment process
- Authors: Moima, Johannes Thapelo
- Date: 2019
- Subjects: Water quality management , Water - Purification
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/292601 , uj:31800
- Description: Abstract: The scarcity of water is a serious global problem. Due to contamination, clean water sources are threatened on daily basis and the provision of safe and affordable water to the needs of people is becoming an impossible. Major water pollutants can be divided into pathogens and chemicals. The scarce fresh water available in South Africa is declining in quality due to destruction of river catchments and increase in pollution caused by urbanisation, energy use, damming of rivers, mining, deforestation, agriculture, wetlands destruction, industrialisation, and accidental water pollution. About 2% of totally produced dyes are released into the water systems as effluents. These dyes are capable of causing allergic dermatitis, cancer, skin irritation, and mutation. They are also teratogenic and poisonous to fish species, people, and microorganisms. . The PVDF/GO(Cu-tpa) composite membranes of different MOF concentration and wt% were prepared via phase inversion and characterised with FTIR, AFM, and SEM including surface morphology, cross sectional view, EDS and elemental mapping and their performance were tested on WCA, water uptake, pure water flux and decolourisation of dye at different concentrations. The synthesis of GO was achieved by modified Hammer’s method and the GO was used with Cu-tpa to synthesise the composite. PVDF was used as the base polymer, PVP as a pore forming agent, and NMP as a solvent in preparation of membranes containing different fillers. The functional groups within the membrane were analysed by FTIR, AFM was used for topography and roughness, WCA was used to investigate the hydrophilicity, the information about the adsorption capacity of membranes was achieved via water uptake experiments, and membrane flux was utilised to obtain the information about the permeation of the membrane towards pure water. SEM was used for for the analyses of cross sectional area, surface morphology, EDS and EDS elemental analysis. Two membranes out of six were found to have morphological defects due to systematic and random errors. In WCA, pure water flux, and water uptake, the PVDF membrane was found to be hydrophobic and PVDF/[GO(Cu-tpa)0.1]0.25 membrane was found to be hydrophilic, and for decolourisation of the dye, hydrophobic membranes performed better than hydrophilic membranes. , M.Sc. (Nanoscience)
- Full Text:
- Authors: Moima, Johannes Thapelo
- Date: 2019
- Subjects: Water quality management , Water - Purification
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/292601 , uj:31800
- Description: Abstract: The scarcity of water is a serious global problem. Due to contamination, clean water sources are threatened on daily basis and the provision of safe and affordable water to the needs of people is becoming an impossible. Major water pollutants can be divided into pathogens and chemicals. The scarce fresh water available in South Africa is declining in quality due to destruction of river catchments and increase in pollution caused by urbanisation, energy use, damming of rivers, mining, deforestation, agriculture, wetlands destruction, industrialisation, and accidental water pollution. About 2% of totally produced dyes are released into the water systems as effluents. These dyes are capable of causing allergic dermatitis, cancer, skin irritation, and mutation. They are also teratogenic and poisonous to fish species, people, and microorganisms. . The PVDF/GO(Cu-tpa) composite membranes of different MOF concentration and wt% were prepared via phase inversion and characterised with FTIR, AFM, and SEM including surface morphology, cross sectional view, EDS and elemental mapping and their performance were tested on WCA, water uptake, pure water flux and decolourisation of dye at different concentrations. The synthesis of GO was achieved by modified Hammer’s method and the GO was used with Cu-tpa to synthesise the composite. PVDF was used as the base polymer, PVP as a pore forming agent, and NMP as a solvent in preparation of membranes containing different fillers. The functional groups within the membrane were analysed by FTIR, AFM was used for topography and roughness, WCA was used to investigate the hydrophilicity, the information about the adsorption capacity of membranes was achieved via water uptake experiments, and membrane flux was utilised to obtain the information about the permeation of the membrane towards pure water. SEM was used for for the analyses of cross sectional area, surface morphology, EDS and EDS elemental analysis. Two membranes out of six were found to have morphological defects due to systematic and random errors. In WCA, pure water flux, and water uptake, the PVDF membrane was found to be hydrophobic and PVDF/[GO(Cu-tpa)0.1]0.25 membrane was found to be hydrophilic, and for decolourisation of the dye, hydrophobic membranes performed better than hydrophilic membranes. , M.Sc. (Nanoscience)
- Full Text:
Measurement and expression of granular filter cleanliness
- Haarhoff, Johannes, van Staden, Samantha
- Authors: Haarhoff, Johannes , van Staden, Samantha
- Date: 2013
- Subjects: Water - Purification , Water treatment filters
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/24510 , uj:16224 , Citation: Haarhoff, J. and Van Staden, S.J. 2013. A proposal for the systematic classification of specific deposit on dirty filter media. Water SA, 39(5):701-706.
- Description: Abstract The problem of dirty filter media at water treatment plants, despite having good backwash systems, is a serious challenge that requires constant monitoring and maintenance. To aid the systematic analysis of filter media and the troubleshooting of problem filters, this paper firstly proposes a standard procedure for quantification of the specific deposit on filter media, including tentative guidelines for the interpretation of the results. Secondly, a standard procedure is proposed for the characterisation of the specific deposit, based on its volatility and its acid solubility. These fractions are helpful to trace the origin of excessively dirty filter media. Thirdly, the utility of the proposed procedures is demonstrated by the results of a South African treatment plant survey. This confirms some earlier observations that there often is a real problem with recalcitrant specific deposits that cannot be readily removed by backwashing, a fraction that correlates with the organic fraction in the specific deposit.
- Full Text:
- Authors: Haarhoff, Johannes , van Staden, Samantha
- Date: 2013
- Subjects: Water - Purification , Water treatment filters
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/24510 , uj:16224 , Citation: Haarhoff, J. and Van Staden, S.J. 2013. A proposal for the systematic classification of specific deposit on dirty filter media. Water SA, 39(5):701-706.
- Description: Abstract The problem of dirty filter media at water treatment plants, despite having good backwash systems, is a serious challenge that requires constant monitoring and maintenance. To aid the systematic analysis of filter media and the troubleshooting of problem filters, this paper firstly proposes a standard procedure for quantification of the specific deposit on filter media, including tentative guidelines for the interpretation of the results. Secondly, a standard procedure is proposed for the characterisation of the specific deposit, based on its volatility and its acid solubility. These fractions are helpful to trace the origin of excessively dirty filter media. Thirdly, the utility of the proposed procedures is demonstrated by the results of a South African treatment plant survey. This confirms some earlier observations that there often is a real problem with recalcitrant specific deposits that cannot be readily removed by backwashing, a fraction that correlates with the organic fraction in the specific deposit.
- Full Text:
Conducting nanocomposites for the removal of heavy metals from wastewater
- Authors: Kera, Nazia Hassan
- Date: 2018
- Subjects: Heavy metals - Absorption and adsorption , Sewage - Purification - Heavy metals removal , Water - Purification , Nanocomposites (Materials) , Water chemistry
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/366683 , http://hdl.handle.net/10210/278783 , uj:29923
- Description: Ph.D. (Chemistry) , Abstract: Hexavalent chromium, Cr(VI), is a toxic heavy metal pollutant that occurs in wastewater produced from mining and industrial activities such as leather tanning, chrome plating, wood preservation and alloy manufacture. Cr(VI) released into the environment is of concern due to its high mobility in water and soil and harmful effects on human health. The treatment of wastewater is necessary to prevent Cr(VI) contamination of water bodies in the environment. Conducting polymers, such as polypyrrole (PPy) and polyaniline (PANI), have the potential to be used as adsorbents for Cr(VI) in wastewater due to their abundant nitrogen-containing functional groups, anion-exchange sites and capacity to reduce Cr(VI) to the significantly less toxic, trivalent chromium, Cr(III). However, conducting polymers have shown low adsorption capacities for Cr(VI) due to agglomeration of particles and are also difficult to separate from treated water. The focus of this study was on the development of conducting polymer composites for the treatment of wastewater containing Cr(VI). In particular, the aim of the research carried out was the modification of conducting polymers to obtain adsorbents with high adsorption capacities for Cr(VI) that are well-suited towards water treatment applications. Three novel conducting polymer composites were prepared in this study, namely, polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, polypyrrole-polyaniline/iron oxide (PPy-PANI/Fe3O4) magnetic nanocomposite and polypyrrole-m-phenylenediamine (PPy-mPD) polymer for the desired application of removing Cr(VI) from industrial wastewater. The composites were synthesized easily and effectively by in situ chemical oxidative polymerization and their physicochemical properties characterized using various techniques including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch studies were carried out to investigate the effect of parameters such as initial solution pH, adsorbent dose, initial Cr(VI) concentration, temperature and co-existing ions in solution on Cr(VI) removal by the different composites...
- Full Text:
- Authors: Kera, Nazia Hassan
- Date: 2018
- Subjects: Heavy metals - Absorption and adsorption , Sewage - Purification - Heavy metals removal , Water - Purification , Nanocomposites (Materials) , Water chemistry
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/366683 , http://hdl.handle.net/10210/278783 , uj:29923
- Description: Ph.D. (Chemistry) , Abstract: Hexavalent chromium, Cr(VI), is a toxic heavy metal pollutant that occurs in wastewater produced from mining and industrial activities such as leather tanning, chrome plating, wood preservation and alloy manufacture. Cr(VI) released into the environment is of concern due to its high mobility in water and soil and harmful effects on human health. The treatment of wastewater is necessary to prevent Cr(VI) contamination of water bodies in the environment. Conducting polymers, such as polypyrrole (PPy) and polyaniline (PANI), have the potential to be used as adsorbents for Cr(VI) in wastewater due to their abundant nitrogen-containing functional groups, anion-exchange sites and capacity to reduce Cr(VI) to the significantly less toxic, trivalent chromium, Cr(III). However, conducting polymers have shown low adsorption capacities for Cr(VI) due to agglomeration of particles and are also difficult to separate from treated water. The focus of this study was on the development of conducting polymer composites for the treatment of wastewater containing Cr(VI). In particular, the aim of the research carried out was the modification of conducting polymers to obtain adsorbents with high adsorption capacities for Cr(VI) that are well-suited towards water treatment applications. Three novel conducting polymer composites were prepared in this study, namely, polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, polypyrrole-polyaniline/iron oxide (PPy-PANI/Fe3O4) magnetic nanocomposite and polypyrrole-m-phenylenediamine (PPy-mPD) polymer for the desired application of removing Cr(VI) from industrial wastewater. The composites were synthesized easily and effectively by in situ chemical oxidative polymerization and their physicochemical properties characterized using various techniques including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch studies were carried out to investigate the effect of parameters such as initial solution pH, adsorbent dose, initial Cr(VI) concentration, temperature and co-existing ions in solution on Cr(VI) removal by the different composites...
- Full Text:
Multi-synthetic routes towards polyethersulfone-based microfiltration membranes with hydrophilic, pH responsive, low fouling, and degradative properties against persistent organic pollutants in water
- Authors: Ndlwana, Lwazi
- Date: 2018
- Subjects: Water - Purification
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278775 , uj:29922
- Description: Ph.D. (Chemistry) , Abstract: The main focus of this work was to develop new synthetic routes towards membranes with the following properties: enhanced hydrophilicity, high protein rejection, pH responsivity, low-fouling, and catalytic action for degradation of persistent organic pollutants such as PCB 77 and methyl orange azo dye (MO). In the first section, a bulk heterogeneous functionalization of polyethersulfone (PES) with polymethacrylic acid (PMAA) as performed by graft polymerization of methacrylic acid (MAA) using 2,2‘-azo-bis-isobutyronitrile (AIBN) as an initiator is reported. The effect of grafting temperature and monomer concentration on the degree of grafting, were investigated. The grafting was confirmed by Fourier transform infra-red (FTIR), and X-ray photoelectron spectroscopy (XPS). The membranes were subsequently prepared from the functionalized polymer using the phase inversion method. Contact angle measurements showed an increase in membrane hydrophilicity to about 40% as a result of grafting of the PMAA chains. Water uptake (swelling), water permeation fluxes, recyclability, protein rejection (up to 97%) and a low propensity to fouling was recorded upon grafting where pure water flux recoveries recorded were up to 86%. In addition, the membranes indicated a dependence on pH stimulus due to the opening and closing of the pores at low and elevated pH respectively. In the second part of this work, grafted polyethersulfone (PES) powders were prepared via microwave (MW) assisted synthesis. This new method works by virtue of the polar and MW active nature of monomers such as MAA. These properties are reported for grafting to PES powder in this manner for the first time. Successful grafting was achieved in 7 minutes as compared to conventional heating methods with reaction times of a minimum of 4.5 hours having been reported. Furthermore, this method eliminates the use of solvents and catalysts, which can be toxic and expensive, requiring extensive washing steps that may be costly. This grafting was investigated by FTIR and XPS. Further characterization followed where scanning electron microscopy (SEM) showed reduced pore size after grafting. Contact angle measurements showed improved hydrophilicity as compared to the pristine PES membranes. Water uptake and permeation fluxes presented improvements with increasing DG. Enhanced protein rejection (up to...
- Full Text:
- Authors: Ndlwana, Lwazi
- Date: 2018
- Subjects: Water - Purification
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278775 , uj:29922
- Description: Ph.D. (Chemistry) , Abstract: The main focus of this work was to develop new synthetic routes towards membranes with the following properties: enhanced hydrophilicity, high protein rejection, pH responsivity, low-fouling, and catalytic action for degradation of persistent organic pollutants such as PCB 77 and methyl orange azo dye (MO). In the first section, a bulk heterogeneous functionalization of polyethersulfone (PES) with polymethacrylic acid (PMAA) as performed by graft polymerization of methacrylic acid (MAA) using 2,2‘-azo-bis-isobutyronitrile (AIBN) as an initiator is reported. The effect of grafting temperature and monomer concentration on the degree of grafting, were investigated. The grafting was confirmed by Fourier transform infra-red (FTIR), and X-ray photoelectron spectroscopy (XPS). The membranes were subsequently prepared from the functionalized polymer using the phase inversion method. Contact angle measurements showed an increase in membrane hydrophilicity to about 40% as a result of grafting of the PMAA chains. Water uptake (swelling), water permeation fluxes, recyclability, protein rejection (up to 97%) and a low propensity to fouling was recorded upon grafting where pure water flux recoveries recorded were up to 86%. In addition, the membranes indicated a dependence on pH stimulus due to the opening and closing of the pores at low and elevated pH respectively. In the second part of this work, grafted polyethersulfone (PES) powders were prepared via microwave (MW) assisted synthesis. This new method works by virtue of the polar and MW active nature of monomers such as MAA. These properties are reported for grafting to PES powder in this manner for the first time. Successful grafting was achieved in 7 minutes as compared to conventional heating methods with reaction times of a minimum of 4.5 hours having been reported. Furthermore, this method eliminates the use of solvents and catalysts, which can be toxic and expensive, requiring extensive washing steps that may be costly. This grafting was investigated by FTIR and XPS. Further characterization followed where scanning electron microscopy (SEM) showed reduced pore size after grafting. Contact angle measurements showed improved hydrophilicity as compared to the pristine PES membranes. Water uptake and permeation fluxes presented improvements with increasing DG. Enhanced protein rejection (up to...
- Full Text:
Permeable reactive barriers for acid mine drainage treatment : a review
- Shabalala, Ayanda N., Ekolu, Stephen O., Diop, Souleymane
- Authors: Shabalala, Ayanda N. , Ekolu, Stephen O. , Diop, Souleymane
- Date: 2014
- Subjects: Acid mine drainage - Environmental aspects - South Africa , Acid mine drainage - Purification , Permeable reactive barriers , Water - Purification
- Type: Article
- Identifier: uj:5072 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13643
- Description: Contaminated water flowing from abandoned mines is one of the most significant contributors to water pollution. Acid mine drainage (AMD) can have severe impacts on aquatic resources, can stunt terrestrial plant growth and harm wetlands, contaminate groundwater, raise water treatment costs, and damage concrete and metal structures. Permeable reactive barriers (PRBs) are one of the passive treatment technologies widely accepted for sustainable in situ remediation of contaminated groundwater and may be used in the management of localised seepage plumes from mine residues that contaminate shallow groundwater. These barriers provide chemical interactions with AMD as the polluted water flows through it. The ability of PRBs to remediate contaminants is dependent on the type of reactive material used. Some of the reactive media remove contaminants through physical contact while others work by altering the biogeochemical processes in the treatment zone, thus providing conditions conducive for contaminant immobilization or (bio) degradation. A variety of materials has been employed to remove contaminants including heavy metals, chlorinated solvents, aromatic hydrocarbons, and pesticides. This paper gives an overview of the PRB technology, which includes the advantages and limitations of the PRB, the types of reactive materials used, laboratory treatability tests used to evaluate suitable reactive materials and to aid in the designing and the implementation of the PRB and the installations schemes used in PRB field application.
- Full Text:
- Authors: Shabalala, Ayanda N. , Ekolu, Stephen O. , Diop, Souleymane
- Date: 2014
- Subjects: Acid mine drainage - Environmental aspects - South Africa , Acid mine drainage - Purification , Permeable reactive barriers , Water - Purification
- Type: Article
- Identifier: uj:5072 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13643
- Description: Contaminated water flowing from abandoned mines is one of the most significant contributors to water pollution. Acid mine drainage (AMD) can have severe impacts on aquatic resources, can stunt terrestrial plant growth and harm wetlands, contaminate groundwater, raise water treatment costs, and damage concrete and metal structures. Permeable reactive barriers (PRBs) are one of the passive treatment technologies widely accepted for sustainable in situ remediation of contaminated groundwater and may be used in the management of localised seepage plumes from mine residues that contaminate shallow groundwater. These barriers provide chemical interactions with AMD as the polluted water flows through it. The ability of PRBs to remediate contaminants is dependent on the type of reactive material used. Some of the reactive media remove contaminants through physical contact while others work by altering the biogeochemical processes in the treatment zone, thus providing conditions conducive for contaminant immobilization or (bio) degradation. A variety of materials has been employed to remove contaminants including heavy metals, chlorinated solvents, aromatic hydrocarbons, and pesticides. This paper gives an overview of the PRB technology, which includes the advantages and limitations of the PRB, the types of reactive materials used, laboratory treatability tests used to evaluate suitable reactive materials and to aid in the designing and the implementation of the PRB and the installations schemes used in PRB field application.
- Full Text:
A critical evaluation of physical water treatment for the prevention of scale
- Authors: Howell, Sanja Steyn
- Date: 2012-08-15
- Subjects: Calcium carbonate , Incrustations , Descaling , Water - Purification
- Type: Thesis
- Identifier: uj:9343 , http://hdl.handle.net/10210/5782
- Description: M.Sc. , Calcium carbonate scale formation is a major problem in industrial water and cooling systems as well as in household systems. The resulting reduction in heat transfer and the removal of the scale are very costly processes. One of the methods used in the past 50 years and investigated for nearly a century, is the use of physical fields to reduce, remove and / or inhibit scale formation. These physical fields are usually magnetic fields, but RF electric and electrostatic fields are also used. These fields are claimed to reduce the cost involved in the removal of scale to a minimum. To investigate these claimed effects on scale formation, a pure calcium bicarbonate solution was exposed to some of the commercial available units: The exposed solution was then forced to precipitate by elevating the temperature. The pH was monitored against time, to investigate the nucleation process of CaCO 3 and the resulting precipitate analysed for changes in crystal morphology. The principle conclusions made from the results were, firstly that the nucleation of CaCO 3 was significantly delayed in one of the units tested and that the preferred morphology was changed from the thermodynamically more stable calcite to the more unstable aragonite in that unit. Secondly, that a direct correlation existed between the release of trace amounts of metals from the unit and the observed effects.
- Full Text:
- Authors: Howell, Sanja Steyn
- Date: 2012-08-15
- Subjects: Calcium carbonate , Incrustations , Descaling , Water - Purification
- Type: Thesis
- Identifier: uj:9343 , http://hdl.handle.net/10210/5782
- Description: M.Sc. , Calcium carbonate scale formation is a major problem in industrial water and cooling systems as well as in household systems. The resulting reduction in heat transfer and the removal of the scale are very costly processes. One of the methods used in the past 50 years and investigated for nearly a century, is the use of physical fields to reduce, remove and / or inhibit scale formation. These physical fields are usually magnetic fields, but RF electric and electrostatic fields are also used. These fields are claimed to reduce the cost involved in the removal of scale to a minimum. To investigate these claimed effects on scale formation, a pure calcium bicarbonate solution was exposed to some of the commercial available units: The exposed solution was then forced to precipitate by elevating the temperature. The pH was monitored against time, to investigate the nucleation process of CaCO 3 and the resulting precipitate analysed for changes in crystal morphology. The principle conclusions made from the results were, firstly that the nucleation of CaCO 3 was significantly delayed in one of the units tested and that the preferred morphology was changed from the thermodynamically more stable calcite to the more unstable aragonite in that unit. Secondly, that a direct correlation existed between the release of trace amounts of metals from the unit and the observed effects.
- Full Text:
Synthesis, characterisation and application of ethylene diamine functionalised carbon nanoparticles for the removal of cadmium (II) and lead (II) from water
- Authors: Tshwenya, Luthando
- Date: 2017
- Subjects: Water - Purification , Cadmium , Nanostructured materials , Nanotubes , Carbon
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/235777 , uj:24118
- Description: M.Tech. (Chemistry) , Abstract: This work explores the synthesis, characterisation and application of carbon nanoparticles derived from glucose (GCNPs) and functionalised with ethylene diamine (EDA), towards the removal of Cd(II) and Pb(II) in water samples. Glucose is a simple sugar that is readily available in nature, since it is organic, it can be easily converted to carbon through dehydration. GCNPs were successfully modified to form EDA-GCNPs and characterised by electron microscopy (TEM and SEM), CHNS elemental analysis, Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Modification of GCNPs with EDA was confirmed from an increase in C-H stretch. Disappearance of carboxyl in the GCNPs and appearance of an amide linkage in the infrared spectra. Based on the particle size results obtained from TEM studies, it was also confirmed that indeed carbon nanoparticles were formed (as the particle sizes were in the nanorange). The adsorption behavior of the two materials for Cd(II) and Pb(II) was investigated by batch adsorption and the effect of several conditions such as contact time, pH, initial metal concentration and competing ions on cadmium and lead uptake were investigated. The adsorption results show that both adsorbents could effectively remove Cd2+ and Pb2+, with lead adsorption being more favoured as compared to that of cadmium. Equilibrium results best fitted the Langmuir model, and the maximum adsorption capacities for Pb(II) were found to be 15.15 and 28.99 mg g-1 for GCNPs and EDA-GCNPs, respectively, whilst Cd(II) adsorption resulted in lower sorption capacities (GCNPs = 10.31 mg g-1 and EDA-GCNPs=18.71 mg g-1). The adsorption processes were found to favour chemisorption, given that the pseudo-second-order kinetic model and Langmuir isotherms best fitted the adsorption results, implying that the functional groups present on the adsorbent surfaces are behind the uptake of these metal ions. The adsorbents showed applicability in real water samples and multi-elemental systems, with competing ions not affecting adsorption processes, moreover, regeneration studies show that both adsorbents are fully recyclable, indicating possible industrial applicability.
- Full Text:
- Authors: Tshwenya, Luthando
- Date: 2017
- Subjects: Water - Purification , Cadmium , Nanostructured materials , Nanotubes , Carbon
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/235777 , uj:24118
- Description: M.Tech. (Chemistry) , Abstract: This work explores the synthesis, characterisation and application of carbon nanoparticles derived from glucose (GCNPs) and functionalised with ethylene diamine (EDA), towards the removal of Cd(II) and Pb(II) in water samples. Glucose is a simple sugar that is readily available in nature, since it is organic, it can be easily converted to carbon through dehydration. GCNPs were successfully modified to form EDA-GCNPs and characterised by electron microscopy (TEM and SEM), CHNS elemental analysis, Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Modification of GCNPs with EDA was confirmed from an increase in C-H stretch. Disappearance of carboxyl in the GCNPs and appearance of an amide linkage in the infrared spectra. Based on the particle size results obtained from TEM studies, it was also confirmed that indeed carbon nanoparticles were formed (as the particle sizes were in the nanorange). The adsorption behavior of the two materials for Cd(II) and Pb(II) was investigated by batch adsorption and the effect of several conditions such as contact time, pH, initial metal concentration and competing ions on cadmium and lead uptake were investigated. The adsorption results show that both adsorbents could effectively remove Cd2+ and Pb2+, with lead adsorption being more favoured as compared to that of cadmium. Equilibrium results best fitted the Langmuir model, and the maximum adsorption capacities for Pb(II) were found to be 15.15 and 28.99 mg g-1 for GCNPs and EDA-GCNPs, respectively, whilst Cd(II) adsorption resulted in lower sorption capacities (GCNPs = 10.31 mg g-1 and EDA-GCNPs=18.71 mg g-1). The adsorption processes were found to favour chemisorption, given that the pseudo-second-order kinetic model and Langmuir isotherms best fitted the adsorption results, implying that the functional groups present on the adsorbent surfaces are behind the uptake of these metal ions. The adsorbents showed applicability in real water samples and multi-elemental systems, with competing ions not affecting adsorption processes, moreover, regeneration studies show that both adsorbents are fully recyclable, indicating possible industrial applicability.
- Full Text:
Monitoring of selected contaminants (physico-chemical and bacteriological parameters) in wetland filters: A case study of a 10- year old Johannesburg zoo constructed wetland
- Authors: Mabhena, Bhekisipho
- Date: 2015-11-12
- Subjects: Oraganic water pollutants , Pollution - Environmental aspects , Water - Purification
- Type: Thesis
- Identifier: uj:14562 , http://hdl.handle.net/10210/15095
- Description: M.Tech. (Biotechnology) , Please refer to full text to view abstract
- Full Text:
- Authors: Mabhena, Bhekisipho
- Date: 2015-11-12
- Subjects: Oraganic water pollutants , Pollution - Environmental aspects , Water - Purification
- Type: Thesis
- Identifier: uj:14562 , http://hdl.handle.net/10210/15095
- Description: M.Tech. (Biotechnology) , Please refer to full text to view abstract
- Full Text:
The use of filter media to determine filter cleanliness
- Van Staden, S.J., Haarhoff, J.
- Authors: Van Staden, S.J. , Haarhoff, J.
- Date: 2011
- Subjects: Water treatment plants - Design and construction - Data processing , Water - Purification - Membrane filtration , Water - Purification
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/16727 , uj:15805 , ISSN: 14747065 , DOI: 10.1016/j.pce.2011.07.067 , Van Staden, S.J., & Haarhoff, J. (2011) The use of filter media to determine filter cleanlines. Journal Physics and Chemistry of the Earth 36 (14-15) 1135-1140. DOI:10.1016/j.pce.2011.07.067
- Description: Abstract It is general believed that a sand filter starts its life with new, perfectly clean media, which becomes gradually clogged with each filtration cycle, eventually getting to a point where either head loss or filtrate quality starts to deteriorate. At this point the backwash cycle is initiated and, through the combined action of air and water, returns the media to its original perfectly clean state. Reality, however, dictates otherwise. Many treatment plants visited a decade or more after commissioning are found to have unacceptably dirty filter sand and backwash systems incapable of returning the filter media to a desired state of cleanliness. In some cases, these problems are common ones encountered in filtration plants but many reasons for media deterioration remain elusive, falling outside of these common problems. The South African conditions of highly eutrophic surface waters at high temperatures, however, exacerbate the problems with dirty filter media. Such conditions often lead to the formation of biofilm in the filter media, which is shown to inhibit the effective backwashing of sand and carbon filters. A systematic investigation into filter media cleanliness was therefore started in 2002, ending in 2005, at the University of Johannesburg (the then Rand Afrikaans University). This involved media from eight South African Water Treatment Plants, varying between sand and sand-anthracite combinations and raw water types from eutrophic through turbid to low-turbidity waters. Five states of cleanliness and four fractions of specific deposit were identified relating to in situ washing, column washing, cylinder inversion and acid-immersion techniques. These were measured and the results compared to acceptable limits for specific deposit, as determined in previous studies, though expressed in kg/m3. These values were used to determine the state of the filters. In order to gain greater insight into the composition of the specific deposits stripped from the media, a four-point characterisation step was introduced for the resultant suspensions based on acid-solubility and volatility. Results showed that a reasonably effective backwash removed a median specific deposit of 0.89 kg/m3. Further washing in a laboratory column removed a median specific deposit of 1.34 kg/m3. Media subjected to a standardised cylinder inversion procedure removed a median specific deposit of 2.41 kg/m3. Immersion in a strong acid removed a median specific deposit of 35.2 kg/m3. The four-point characterisation step showed that the soluble-volatile fraction was consistently small in relation to the other fractions. The organic fraction was quite high at the RG treatment plant and the soluble- non-volatile fraction was particularly high at the BK treatment plant
- Full Text:
- Authors: Van Staden, S.J. , Haarhoff, J.
- Date: 2011
- Subjects: Water treatment plants - Design and construction - Data processing , Water - Purification - Membrane filtration , Water - Purification
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/16727 , uj:15805 , ISSN: 14747065 , DOI: 10.1016/j.pce.2011.07.067 , Van Staden, S.J., & Haarhoff, J. (2011) The use of filter media to determine filter cleanlines. Journal Physics and Chemistry of the Earth 36 (14-15) 1135-1140. DOI:10.1016/j.pce.2011.07.067
- Description: Abstract It is general believed that a sand filter starts its life with new, perfectly clean media, which becomes gradually clogged with each filtration cycle, eventually getting to a point where either head loss or filtrate quality starts to deteriorate. At this point the backwash cycle is initiated and, through the combined action of air and water, returns the media to its original perfectly clean state. Reality, however, dictates otherwise. Many treatment plants visited a decade or more after commissioning are found to have unacceptably dirty filter sand and backwash systems incapable of returning the filter media to a desired state of cleanliness. In some cases, these problems are common ones encountered in filtration plants but many reasons for media deterioration remain elusive, falling outside of these common problems. The South African conditions of highly eutrophic surface waters at high temperatures, however, exacerbate the problems with dirty filter media. Such conditions often lead to the formation of biofilm in the filter media, which is shown to inhibit the effective backwashing of sand and carbon filters. A systematic investigation into filter media cleanliness was therefore started in 2002, ending in 2005, at the University of Johannesburg (the then Rand Afrikaans University). This involved media from eight South African Water Treatment Plants, varying between sand and sand-anthracite combinations and raw water types from eutrophic through turbid to low-turbidity waters. Five states of cleanliness and four fractions of specific deposit were identified relating to in situ washing, column washing, cylinder inversion and acid-immersion techniques. These were measured and the results compared to acceptable limits for specific deposit, as determined in previous studies, though expressed in kg/m3. These values were used to determine the state of the filters. In order to gain greater insight into the composition of the specific deposits stripped from the media, a four-point characterisation step was introduced for the resultant suspensions based on acid-solubility and volatility. Results showed that a reasonably effective backwash removed a median specific deposit of 0.89 kg/m3. Further washing in a laboratory column removed a median specific deposit of 1.34 kg/m3. Media subjected to a standardised cylinder inversion procedure removed a median specific deposit of 2.41 kg/m3. Immersion in a strong acid removed a median specific deposit of 35.2 kg/m3. The four-point characterisation step showed that the soluble-volatile fraction was consistently small in relation to the other fractions. The organic fraction was quite high at the RG treatment plant and the soluble- non-volatile fraction was particularly high at the BK treatment plant
- Full Text:
Polymer-zeolite nanocomposites : preparation, characterization and application in heavy-metal removal
- Authors: Mthombo, Sydney Thabo
- Date: 2013-09-11
- Subjects: Nanocomposites (Materials) , Polymers , Zeolites , Heavy metals - Absorption and adsorption , Water - Purification
- Type: Thesis
- Identifier: uj:7734 , http://hdl.handle.net/10210/8603
- Description: M.Sc. (Chemistry) , Polymer nanocomposites are a new class of composites in which at least one dimension of the particles dispersed in the polymer matrix is in the nanometer range. Recently, different types of zeolite minerals, either natural (Clinoptilolite, chabazite, modernite) or synthetic (A-type, X-type, Y-type) are being employed as particulate fillers into the polymer matrix. Owing to their unique ion exchange phenomenon, zeolites have been widely studied as heavy metal adsorbents, but very few researchers have focused on the sorption of heavy metal ions on zeolite-filled polymer nanocomposites...
- Full Text:
- Authors: Mthombo, Sydney Thabo
- Date: 2013-09-11
- Subjects: Nanocomposites (Materials) , Polymers , Zeolites , Heavy metals - Absorption and adsorption , Water - Purification
- Type: Thesis
- Identifier: uj:7734 , http://hdl.handle.net/10210/8603
- Description: M.Sc. (Chemistry) , Polymer nanocomposites are a new class of composites in which at least one dimension of the particles dispersed in the polymer matrix is in the nanometer range. Recently, different types of zeolite minerals, either natural (Clinoptilolite, chabazite, modernite) or synthetic (A-type, X-type, Y-type) are being employed as particulate fillers into the polymer matrix. Owing to their unique ion exchange phenomenon, zeolites have been widely studied as heavy metal adsorbents, but very few researchers have focused on the sorption of heavy metal ions on zeolite-filled polymer nanocomposites...
- Full Text:
How can filter cleanliness be determined?
- Van Staden, S. J., Haarhoff, J.
- Authors: Van Staden, S. J. , Haarhoff, J.
- Date: 2010
- Subjects: Water - Purification , Water treatment plants
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16461 , uj:15775 , Van Staden, S.J. & Haarhoff, J. 2010. How can filter cleanliness be determined? In: Proceedings of the 11th WaterNet/WARFSA/GWP-SA Symposium, 27-29 October 2010, Victoria Falls, Zimbabwe:676-690
- Description: Abstract: It is general believed that a sand filter starts its life with new, perfectly clean media, which becomes gradually clogged with each filtration cycle, eventually getting to a point where either head loss or filtrate quality starts to deteriorate. At this point the backwash cycle is initiated and, through the combined action of air and water, returns the media to its original perfectly clean state. Reality, however, dictates otherwise. Many treatment plants visited a decade or more after commissioning are found to have unacceptably dirty filter sand and backwash systems incapable of returning the filter media to a desired state of cleanliness. In some cases, these problems are common ones encountered in filtration plants but many reasons for media deterioration remain elusive, falling outside of these common problems. The South African conditions of highly eutrophic surface waters at high temperatures exacerbate the problems with dirty filter media as such conditions lead to the formation of biofilm in the filter media, shown to inhibit the effective backwashing of sand and carbon filters A systematic investigation into filter media cleanliness was therefore started in 2002 at the University of Johannesburg (the then Rand Afrikaans University), involving media from eight South African Water Treatment Plants, varying between sand and sand-anthracite combinations and raw water types from eutrophic through turbid to low-turbidity waters. Five states of cleanliness and four fractions of specific deposit were identified relating to in-situ washing, column washing, cylinder inversion and acid-immersion techniques. These were measured and the results compared to acceptable limits for specific deposit, as determined in previous studies, though expressed in kg/m3. These values were used to determine the state of the filters. In order to gain greater insight into the composition of the specific deposits stripped from the media, a four-point characterisation step was introduced for the resultant suspensions based on acid-solubility and volatility. Results showed that a reasonably effective backwash removed a median specific deposit of 0.89 kg/m3. Further washing in a laboratory column removed a median specific deposit of 1.34 kg/m3. Media subjected to a standardised cylinder inversion procedure removed a median specific deposit of 2.41 kg/m3. Immersion in a strong acid removed a median specific deposit of 35.2 kg/m3. The four-point characterization step showed that the soluble-volatile fraction was consistently small in relation to the other fractions. The organic fraction was quite high at the RG treatment plant and the soluble-non-volatile fraction was particularly high at the BK treatment plant.
- Full Text:
- Authors: Van Staden, S. J. , Haarhoff, J.
- Date: 2010
- Subjects: Water - Purification , Water treatment plants
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16461 , uj:15775 , Van Staden, S.J. & Haarhoff, J. 2010. How can filter cleanliness be determined? In: Proceedings of the 11th WaterNet/WARFSA/GWP-SA Symposium, 27-29 October 2010, Victoria Falls, Zimbabwe:676-690
- Description: Abstract: It is general believed that a sand filter starts its life with new, perfectly clean media, which becomes gradually clogged with each filtration cycle, eventually getting to a point where either head loss or filtrate quality starts to deteriorate. At this point the backwash cycle is initiated and, through the combined action of air and water, returns the media to its original perfectly clean state. Reality, however, dictates otherwise. Many treatment plants visited a decade or more after commissioning are found to have unacceptably dirty filter sand and backwash systems incapable of returning the filter media to a desired state of cleanliness. In some cases, these problems are common ones encountered in filtration plants but many reasons for media deterioration remain elusive, falling outside of these common problems. The South African conditions of highly eutrophic surface waters at high temperatures exacerbate the problems with dirty filter media as such conditions lead to the formation of biofilm in the filter media, shown to inhibit the effective backwashing of sand and carbon filters A systematic investigation into filter media cleanliness was therefore started in 2002 at the University of Johannesburg (the then Rand Afrikaans University), involving media from eight South African Water Treatment Plants, varying between sand and sand-anthracite combinations and raw water types from eutrophic through turbid to low-turbidity waters. Five states of cleanliness and four fractions of specific deposit were identified relating to in-situ washing, column washing, cylinder inversion and acid-immersion techniques. These were measured and the results compared to acceptable limits for specific deposit, as determined in previous studies, though expressed in kg/m3. These values were used to determine the state of the filters. In order to gain greater insight into the composition of the specific deposits stripped from the media, a four-point characterisation step was introduced for the resultant suspensions based on acid-solubility and volatility. Results showed that a reasonably effective backwash removed a median specific deposit of 0.89 kg/m3. Further washing in a laboratory column removed a median specific deposit of 1.34 kg/m3. Media subjected to a standardised cylinder inversion procedure removed a median specific deposit of 2.41 kg/m3. Immersion in a strong acid removed a median specific deposit of 35.2 kg/m3. The four-point characterization step showed that the soluble-volatile fraction was consistently small in relation to the other fractions. The organic fraction was quite high at the RG treatment plant and the soluble-non-volatile fraction was particularly high at the BK treatment plant.
- Full Text:
Separation of solid-liquid suspensions with acoustic energy
- Authors: Bekker, M. C.
- Date: 2014-02-05
- Subjects: Separation (Technology) , Electro-acoustics. , Water - Purification
- Type: Thesis
- Identifier: uj:3642 , http://hdl.handle.net/10210/9027
- Description: M.Ing. , Fouling of suspended solids on piping and equipment causes severe operating and maintenance problems in process, water treatment and miningrelated plants. In the SASOL environment fouling related problems are mainly experienced on equipment operating in process cooling water services. Suspended solids appear in the form of activated sludge in the cooling water system and the solid particle sizes are usually submicron in size. Conventional solid liquid separation techniques like centrifuging, sedimentation, filtration, etc. could up to this stage not be applied successfully to remove the finest solids from the process cooling water system. The possibility to separate solid liquid suspensions by means of acoustic energy was investigated. The theoretical principles of acoustic waves, especially standing waves, were studied and explained. A theoretical model indicates that separation of solid/liquid suspensions can be obtained virtually immediately after acoustic energy is applied. Theoretically the size and frequency of a tipical acoustic transducer can be calculated for a specific application. Based on theoretical calculations and findings, an experimental setup was prepared to carryout experiments on different suspensions. A control suspension made-up of water and powder, of Yttlich the particle sizes were approximately 10 pm, was prepared and exposed to a standing acoustic wave. Separation was achieved successfully. Follow-up experiments were carried out to establish the optimum conditions to which separation could be achieved. Different flow velocities were tested as well as different power inputs. The best separation was achieved with the lowest flow rate of 2.5 mils and the highest available voltage of 12 Volt. These conditions were not only used to separate a control suspension but also in a real situation where it was attempted to separate suspended solids from the cooling water system. The attempts were unsuccessful. Additional experiments were also done on ash water and cooling water blowdown which also failed. The failure of effective separation of the process cooling water suspensions is due to the extremely small sizes of the solid partides in suspension. Greater energy input than was available for this project, is required as the particle sizes decreases. Provision needs to be made for all particle sizes to achieve effective results. The separation of solid liquid suspensions is achievable with the aid of acoustic energy. The physical properties of the suspension however determines the size and magnitude of the separating equipment. A proposal for the implementation of a full scale acoustic separation system is given. The proposal comprises of a parallel system to ensure continuity of the cooling process.
- Full Text:
- Authors: Bekker, M. C.
- Date: 2014-02-05
- Subjects: Separation (Technology) , Electro-acoustics. , Water - Purification
- Type: Thesis
- Identifier: uj:3642 , http://hdl.handle.net/10210/9027
- Description: M.Ing. , Fouling of suspended solids on piping and equipment causes severe operating and maintenance problems in process, water treatment and miningrelated plants. In the SASOL environment fouling related problems are mainly experienced on equipment operating in process cooling water services. Suspended solids appear in the form of activated sludge in the cooling water system and the solid particle sizes are usually submicron in size. Conventional solid liquid separation techniques like centrifuging, sedimentation, filtration, etc. could up to this stage not be applied successfully to remove the finest solids from the process cooling water system. The possibility to separate solid liquid suspensions by means of acoustic energy was investigated. The theoretical principles of acoustic waves, especially standing waves, were studied and explained. A theoretical model indicates that separation of solid/liquid suspensions can be obtained virtually immediately after acoustic energy is applied. Theoretically the size and frequency of a tipical acoustic transducer can be calculated for a specific application. Based on theoretical calculations and findings, an experimental setup was prepared to carryout experiments on different suspensions. A control suspension made-up of water and powder, of Yttlich the particle sizes were approximately 10 pm, was prepared and exposed to a standing acoustic wave. Separation was achieved successfully. Follow-up experiments were carried out to establish the optimum conditions to which separation could be achieved. Different flow velocities were tested as well as different power inputs. The best separation was achieved with the lowest flow rate of 2.5 mils and the highest available voltage of 12 Volt. These conditions were not only used to separate a control suspension but also in a real situation where it was attempted to separate suspended solids from the cooling water system. The attempts were unsuccessful. Additional experiments were also done on ash water and cooling water blowdown which also failed. The failure of effective separation of the process cooling water suspensions is due to the extremely small sizes of the solid partides in suspension. Greater energy input than was available for this project, is required as the particle sizes decreases. Provision needs to be made for all particle sizes to achieve effective results. The separation of solid liquid suspensions is achievable with the aid of acoustic energy. The physical properties of the suspension however determines the size and magnitude of the separating equipment. A proposal for the implementation of a full scale acoustic separation system is given. The proposal comprises of a parallel system to ensure continuity of the cooling process.
- Full Text:
Greener synthesis of biopolymer-inorganic nanocomposite beads and membranes for use in water purification
- Authors: Masheane, Monaheng Leonard
- Date: 2016
- Subjects: Water - Purification - Membrane filtration , Water - Purification , Nanocomposites (Materials) , Nanotechnology , Biopolymers
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84682 , uj:19251
- Description: Abstract: In South Africa, the unavailability of clean drinking water is a life-threatening problem, especially in the rural areas. Millions of people living in rural areas rely on water directly from the source (surface and groundwater) for drinking, cooking and other domestic purposes without any prior treatment. These sources of water are known to be affected by contaminants from untreated wastewater, industrial effluent, agricultural runoffs and domestic waste. The exposure of humans to these polluted water bodies results in infection and waterborne diseases which sometimes result in death. This has a direct consequence to the productivity of the people living in these communities and has cost implications to the government. This study was aimed at determining the potential pollutants present in drinking water sources in Lochiel, a small community in the Mpumalanga province, eastern part of South Africa, and to develop efficient and cost effective materials (beads and membranes) that could be used in the rural communities to provide safe and clean water for consumption. The application of adsorption materials (e.g. in the form of beads) and filtration materials (e.g. membranes) has attracted great interest in water purification. This is because they have several advantages over the conventional methods. These advantages include but are not limited to low capital and operations costs, low energy requirements (especially when chemically modified) and ease of operation. In this study chitosan (CTs) was chosen to prepare novel and environmentally benign nanocomposite materials either in the form of beads or flat sheet using greener solvents. In an attempt to prepare biopolymer-ceramic nanofiltration composite membranes, small amounts of multiwalled carbon nanotubes (MWCNTs) (5 wt%) and alumina (Al) (20 wt%) were added to CTs in pH controlled aqueous media near room temperature. The resulting nanocomposite was found to readily form insoluble beads... , M.Sc. (Chemistry)
- Full Text:
- Authors: Masheane, Monaheng Leonard
- Date: 2016
- Subjects: Water - Purification - Membrane filtration , Water - Purification , Nanocomposites (Materials) , Nanotechnology , Biopolymers
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84682 , uj:19251
- Description: Abstract: In South Africa, the unavailability of clean drinking water is a life-threatening problem, especially in the rural areas. Millions of people living in rural areas rely on water directly from the source (surface and groundwater) for drinking, cooking and other domestic purposes without any prior treatment. These sources of water are known to be affected by contaminants from untreated wastewater, industrial effluent, agricultural runoffs and domestic waste. The exposure of humans to these polluted water bodies results in infection and waterborne diseases which sometimes result in death. This has a direct consequence to the productivity of the people living in these communities and has cost implications to the government. This study was aimed at determining the potential pollutants present in drinking water sources in Lochiel, a small community in the Mpumalanga province, eastern part of South Africa, and to develop efficient and cost effective materials (beads and membranes) that could be used in the rural communities to provide safe and clean water for consumption. The application of adsorption materials (e.g. in the form of beads) and filtration materials (e.g. membranes) has attracted great interest in water purification. This is because they have several advantages over the conventional methods. These advantages include but are not limited to low capital and operations costs, low energy requirements (especially when chemically modified) and ease of operation. In this study chitosan (CTs) was chosen to prepare novel and environmentally benign nanocomposite materials either in the form of beads or flat sheet using greener solvents. In an attempt to prepare biopolymer-ceramic nanofiltration composite membranes, small amounts of multiwalled carbon nanotubes (MWCNTs) (5 wt%) and alumina (Al) (20 wt%) were added to CTs in pH controlled aqueous media near room temperature. The resulting nanocomposite was found to readily form insoluble beads... , M.Sc. (Chemistry)
- Full Text:
Synthesis of polyethersulfone and polyvinylidene fluoride based nanostructured membranes supported on non-woven fabrics for water purification
- Tshabalala, Tumelo Gladstone
- Authors: Tshabalala, Tumelo Gladstone
- Date: 2014-07-15
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Water - Fluoridation , Nanotechnology
- Type: Thesis
- Identifier: uj:11678 , http://hdl.handle.net/10210/11400
- Description: M.Sc. (Chemistry) , Water purification technologies based on membranes are prone to fouling by natural organic matter (NOM) and other biological species in water. This leads to the short lifespan of the membranes and high demand in energy than normal due to high pressure needed to pump water across the fouled membrane. In a quest to address these challenges, polyethersulfone (PES) and polyvinylidene flouride (PVDF) membranes supported on 3 different types of non-woven fabrics NWF1(polyester), NWF2 (polyphenylene sulphide) and NWF3( thicker polyester) were fabricated using the phase inversion method. This enabled the modification the active top layer of PES and PVDF thin film while maintaining the high mechanical strength offered by the NWFs. FTIR spectroscopy, sessile drop contact angle measurements, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the membranes. The membrane flux and rejection were studied using the cross-flow membrane unit. The contact angle results revealed that the hydrophilicity of PES and PVDF membranes increased as the polyvinyl pyrrolidone (PVP) concentration was increased. TGA revealed that the PES and PVDF membranes were thermally stable up to 580ºC and 530ºC respectively. The cross-sectional SEM revealed that membrane pores become enlarged when PVP has been added. AFM showed that membrane roughness improved when PVP was added. A rejection of 98% humic acid was obtained for PES membranes supported on NWF1, compared to 94 % and 96 % for membranes supported on NWF2 and NWF3 respectively. The highest rejection of humic acid (HA) recorded for PVDF membranes supported on NWF1 was found to be 97 % compared to the 95% for membranes supported on NWF2 and NWF3 fabrics respectively. PES membranes supported on NWF2 exhibited low but best As(III) metal ions rejections whilst PVDF membranes supported on NWF3 exhibited low but best rejections for Cr(III) metal ions.
- Full Text:
- Authors: Tshabalala, Tumelo Gladstone
- Date: 2014-07-15
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Water - Fluoridation , Nanotechnology
- Type: Thesis
- Identifier: uj:11678 , http://hdl.handle.net/10210/11400
- Description: M.Sc. (Chemistry) , Water purification technologies based on membranes are prone to fouling by natural organic matter (NOM) and other biological species in water. This leads to the short lifespan of the membranes and high demand in energy than normal due to high pressure needed to pump water across the fouled membrane. In a quest to address these challenges, polyethersulfone (PES) and polyvinylidene flouride (PVDF) membranes supported on 3 different types of non-woven fabrics NWF1(polyester), NWF2 (polyphenylene sulphide) and NWF3( thicker polyester) were fabricated using the phase inversion method. This enabled the modification the active top layer of PES and PVDF thin film while maintaining the high mechanical strength offered by the NWFs. FTIR spectroscopy, sessile drop contact angle measurements, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the membranes. The membrane flux and rejection were studied using the cross-flow membrane unit. The contact angle results revealed that the hydrophilicity of PES and PVDF membranes increased as the polyvinyl pyrrolidone (PVP) concentration was increased. TGA revealed that the PES and PVDF membranes were thermally stable up to 580ºC and 530ºC respectively. The cross-sectional SEM revealed that membrane pores become enlarged when PVP has been added. AFM showed that membrane roughness improved when PVP was added. A rejection of 98% humic acid was obtained for PES membranes supported on NWF1, compared to 94 % and 96 % for membranes supported on NWF2 and NWF3 respectively. The highest rejection of humic acid (HA) recorded for PVDF membranes supported on NWF1 was found to be 97 % compared to the 95% for membranes supported on NWF2 and NWF3 fabrics respectively. PES membranes supported on NWF2 exhibited low but best As(III) metal ions rejections whilst PVDF membranes supported on NWF3 exhibited low but best rejections for Cr(III) metal ions.
- Full Text:
Organic-inorganic based nanocomposite for wastewater treatment
- Authors: Nduka, Peter Chijioke
- Date: 2017
- Subjects: Water - Purification , Nanocomposites (Materials) , Nanotechnology , Materials science , Environmental chemistry
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/279331 , uj:29997
- Description: M.Sc. (Chemistry) , Abstract: Improper treatment of wastewater from industries before disposal poses severe environmental and health hazards to the surrounding communities. Several treatment techniques have been developed and applied in making sure that these wastewaters are properly treated before being discharged into the environment. Photocatalysis is the most promising of all the techniques that have been employed. This is because its operation is simple and involves the use of readily available semiconductors and sunlight. However, the disadvantage of using these semiconductors as photocatalysts for photocatalytic degradation of organic pollutants are among others their wide band gap and the rate at which photogenerated electrons and holes recombine. These demerits make it difficult for the photocatalytic activities of these semiconductors to be extended into the more abundant visible light region of the solar spectrum. This research work focused on the synthesis of visible light active ZnO photocatalyst through its modification with nitrogen and graphene oxide followed by its application towards the degradation of Brilliant green (BG) dye. The GO and ZnO were synthesized using Hummers and co-precipitation methods respectively while N-ZnO and NZnO-GO composites were synthesized using solvent free method. The characterization of the synthesized photocatalysts was done using optical approaches such as X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR), Transmission Electron Microscopy (TEM) and UV–Vis Absorption and Diffuse Reflectance Spectra (UV-Vis DRS). ZnO modified with nitrogen and graphene oxide (N-ZnO-GO) having different weight percentages of GO (0.1% wt-GO, 0.5% wt-GO, and 1% wt-GO) showed a higher photocatalytic activity in degrading BG dye in water compared to the bare ZnO and nitrogen-doped ZnO (N-ZnO) nanoparticles. The composite with 0.1% wt GO achieved 100% degradation and 80% mineralization of BG within 90 mins of irradiation. The results also showed that the degradation of BG using 0.1% wt-GO occurred faster in basic medium (pH 9) compared to acidic medium. Photostability test of 0.1% wt-GO analyzed after three cycles of exposure gave 94% degradation of BG which implied that the composite is also highly stable and can be recovered and reused. The results obtained highlighted that the modifications made on ZnO increased its light absorption capability into the visible region and thus drastically improved its photocatalytic activity under visible light...
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- Authors: Nduka, Peter Chijioke
- Date: 2017
- Subjects: Water - Purification , Nanocomposites (Materials) , Nanotechnology , Materials science , Environmental chemistry
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/279331 , uj:29997
- Description: M.Sc. (Chemistry) , Abstract: Improper treatment of wastewater from industries before disposal poses severe environmental and health hazards to the surrounding communities. Several treatment techniques have been developed and applied in making sure that these wastewaters are properly treated before being discharged into the environment. Photocatalysis is the most promising of all the techniques that have been employed. This is because its operation is simple and involves the use of readily available semiconductors and sunlight. However, the disadvantage of using these semiconductors as photocatalysts for photocatalytic degradation of organic pollutants are among others their wide band gap and the rate at which photogenerated electrons and holes recombine. These demerits make it difficult for the photocatalytic activities of these semiconductors to be extended into the more abundant visible light region of the solar spectrum. This research work focused on the synthesis of visible light active ZnO photocatalyst through its modification with nitrogen and graphene oxide followed by its application towards the degradation of Brilliant green (BG) dye. The GO and ZnO were synthesized using Hummers and co-precipitation methods respectively while N-ZnO and NZnO-GO composites were synthesized using solvent free method. The characterization of the synthesized photocatalysts was done using optical approaches such as X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR), Transmission Electron Microscopy (TEM) and UV–Vis Absorption and Diffuse Reflectance Spectra (UV-Vis DRS). ZnO modified with nitrogen and graphene oxide (N-ZnO-GO) having different weight percentages of GO (0.1% wt-GO, 0.5% wt-GO, and 1% wt-GO) showed a higher photocatalytic activity in degrading BG dye in water compared to the bare ZnO and nitrogen-doped ZnO (N-ZnO) nanoparticles. The composite with 0.1% wt GO achieved 100% degradation and 80% mineralization of BG within 90 mins of irradiation. The results also showed that the degradation of BG using 0.1% wt-GO occurred faster in basic medium (pH 9) compared to acidic medium. Photostability test of 0.1% wt-GO analyzed after three cycles of exposure gave 94% degradation of BG which implied that the composite is also highly stable and can be recovered and reused. The results obtained highlighted that the modifications made on ZnO increased its light absorption capability into the visible region and thus drastically improved its photocatalytic activity under visible light...
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Nanostructured membranes embedded with hyperbranched polyethyleneimine (HPEI) hosts and titanium dioxide (TiO2) nanoparticles for water purification
- Authors: Mathumba, Penny
- Date: 2016
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Titanium dioxide , Nanotechnology
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84654 , uj:19247
- Description: Abstract: Water scarcity is a huge challenge throughout the world. The capacity of water in South African water systems will decrease dramatically in the next 10 years. Moreover the removal of pollutants from industrial and municipal water has become a challenge for water treatment industries. In particular, the textile industry consumes large volumes of water during dyeing processes. Thus textile industries are regarded as major polluters in the world. Azo dyes (e.g. Methyl Orange and Methyl Blue) constitute about 70% of the dyes used in the textile industry. The water discharged from textile industries is highly coloured and contains compounds that are complex in nature. Coloured water prevents the penetration of light into rivers and lakes thus affecting the process of photosynthesis and this affects the natural flora and fauna. Moreover, the improper discharge of untreated coloured dye effluent into the environment has resulted in numerous public protests. Methyl orange has been reported to be toxic and mutagenic to animals. Moreover, most of these dyes are also not effectively removed by the use of conventional biological treatment processes since they are non-biodegradable... , M.Sc.
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- Authors: Mathumba, Penny
- Date: 2016
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Titanium dioxide , Nanotechnology
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84654 , uj:19247
- Description: Abstract: Water scarcity is a huge challenge throughout the world. The capacity of water in South African water systems will decrease dramatically in the next 10 years. Moreover the removal of pollutants from industrial and municipal water has become a challenge for water treatment industries. In particular, the textile industry consumes large volumes of water during dyeing processes. Thus textile industries are regarded as major polluters in the world. Azo dyes (e.g. Methyl Orange and Methyl Blue) constitute about 70% of the dyes used in the textile industry. The water discharged from textile industries is highly coloured and contains compounds that are complex in nature. Coloured water prevents the penetration of light into rivers and lakes thus affecting the process of photosynthesis and this affects the natural flora and fauna. Moreover, the improper discharge of untreated coloured dye effluent into the environment has resulted in numerous public protests. Methyl orange has been reported to be toxic and mutagenic to animals. Moreover, most of these dyes are also not effectively removed by the use of conventional biological treatment processes since they are non-biodegradable... , M.Sc.
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Functionalized electrospun nanofibers impregnated with nanoparticles for degradation of chlorinated compounds
- Authors: Mapazi, Odwa
- Date: 2014-07-01
- Subjects: Dechlorination , Electrospinning , Nanofibers , Water - Purification
- Type: Thesis
- Identifier: uj:11634 , http://hdl.handle.net/10210/11347
- Description: M.Sc. (Nanoscience) , Supported bimetallic Fe/Ni nanoparticles have been used for years as catalysts for the dechlorination of organochlorine compounds in ground water remediation. However, their fate and potential harm to the environment is of concern, hence, ways of reducing these negative aspects are being explored. As a way to solve this problem, catalytic nanoparticles are immobilised on a variety of substrates ranging from membranes, clays, silica, etc. In the current effort, the immobilisation of Fe/Ni bimetallic nanoparticles on electospun cellulose-based nanofibers was examined with the ultimate view to apply the materials for dechlorination studies. Fe/Ni bimetallic nanoparticles were anchored on ligand-functionalised cellulose nanofibers by the successive reduction of Fe(II) and Ni(II) ions from their respective solutions using NaBH₄...
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- Authors: Mapazi, Odwa
- Date: 2014-07-01
- Subjects: Dechlorination , Electrospinning , Nanofibers , Water - Purification
- Type: Thesis
- Identifier: uj:11634 , http://hdl.handle.net/10210/11347
- Description: M.Sc. (Nanoscience) , Supported bimetallic Fe/Ni nanoparticles have been used for years as catalysts for the dechlorination of organochlorine compounds in ground water remediation. However, their fate and potential harm to the environment is of concern, hence, ways of reducing these negative aspects are being explored. As a way to solve this problem, catalytic nanoparticles are immobilised on a variety of substrates ranging from membranes, clays, silica, etc. In the current effort, the immobilisation of Fe/Ni bimetallic nanoparticles on electospun cellulose-based nanofibers was examined with the ultimate view to apply the materials for dechlorination studies. Fe/Ni bimetallic nanoparticles were anchored on ligand-functionalised cellulose nanofibers by the successive reduction of Fe(II) and Ni(II) ions from their respective solutions using NaBH₄...
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Hyperbranched polymer membranes for the removal of organic and inorganic pollutants from water
- Authors: Vlotman, David E.
- Date: 2017
- Subjects: Water - Purification
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/279242 , uj:29984
- Description: M.Sc. (Chemistry) , Abstract: The scarcity of clean and accessible water has become a global obstacle. This is specifically alarming for a dry country like South Africa where, for example, the average level of major dams in the Western Cape was only 36.1% on 27 November 2017. Since 10% of a dam’s water cannot be extracted, thus, about 10% of the actual dam level non-usable. Another growing concern in South African water systems is the presence of numerous inorganic pollutants and organic pollutants, including persistent organic pollutants (POPs). Of all the water users, agriculture consumes about 70% of all freshwater thus water shortages and the presence of various pollutants may greatly affect the food production process. Inorganic pollutants are usually of mineral origin and include heavy metals like lead, cadmium, chromium and arsenic. Arsenic, one of the most toxic heavy metal pollutants found in water originates from both natural sources and human activities. Prolonged exposure to arsenic can cause various health problems including different forms of cancer. Arsenic often concurs with several POPs in water as well. Persistent organic pollutants are synthetic organic pollutants which have low solubility in water and due to their lipophilic nature, they tend to have a great affinity for fat-rich tissues. One of the most problematic POPs is polychlorinated biphenyls (PCBs). Health effects caused by PCBs include endocrine disruption, defects in the immune, reproductive and nervous systems as well as cancer. Conventional water and wastewater treatment methods such as coagulation-flocculation and biological methods have shown certain limitations towards complete removal of arsenic (more specifically As(III)) and PCBs, especially at trace levels. This has urged researchers to formulate superior methods that can successfully remove arsenic and PCBs from water. This study therefore employed membrane technology modified with a hyperbranched polyethyleneimine (HPEI) to firstly remove arsenic(III) from synthetic and spiked tap water. The incorporation of HPEI in membranes assists in the encapsulation of heavy metal during water treatment. Characteristic amine and amide bands in the FTIR-ATR spectra confirmed the successful incorporation of HPEI on the...
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- Authors: Vlotman, David E.
- Date: 2017
- Subjects: Water - Purification
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/279242 , uj:29984
- Description: M.Sc. (Chemistry) , Abstract: The scarcity of clean and accessible water has become a global obstacle. This is specifically alarming for a dry country like South Africa where, for example, the average level of major dams in the Western Cape was only 36.1% on 27 November 2017. Since 10% of a dam’s water cannot be extracted, thus, about 10% of the actual dam level non-usable. Another growing concern in South African water systems is the presence of numerous inorganic pollutants and organic pollutants, including persistent organic pollutants (POPs). Of all the water users, agriculture consumes about 70% of all freshwater thus water shortages and the presence of various pollutants may greatly affect the food production process. Inorganic pollutants are usually of mineral origin and include heavy metals like lead, cadmium, chromium and arsenic. Arsenic, one of the most toxic heavy metal pollutants found in water originates from both natural sources and human activities. Prolonged exposure to arsenic can cause various health problems including different forms of cancer. Arsenic often concurs with several POPs in water as well. Persistent organic pollutants are synthetic organic pollutants which have low solubility in water and due to their lipophilic nature, they tend to have a great affinity for fat-rich tissues. One of the most problematic POPs is polychlorinated biphenyls (PCBs). Health effects caused by PCBs include endocrine disruption, defects in the immune, reproductive and nervous systems as well as cancer. Conventional water and wastewater treatment methods such as coagulation-flocculation and biological methods have shown certain limitations towards complete removal of arsenic (more specifically As(III)) and PCBs, especially at trace levels. This has urged researchers to formulate superior methods that can successfully remove arsenic and PCBs from water. This study therefore employed membrane technology modified with a hyperbranched polyethyleneimine (HPEI) to firstly remove arsenic(III) from synthetic and spiked tap water. The incorporation of HPEI in membranes assists in the encapsulation of heavy metal during water treatment. Characteristic amine and amide bands in the FTIR-ATR spectra confirmed the successful incorporation of HPEI on the...
- Full Text: