How to measure specific deposit washout and backwash efficiency of granular filters
- Van Staden, S. J., Haarhoff, J.
- Authors: Van Staden, S. J. , Haarhoff, J.
- Date: 2010
- Subjects: Water treatment plants , Carbon, Activated , Water - Purification - Membrane filtration
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16407 , uj:15770 , Van Staden, S.J., & Haarhoff, J. 2010. How to measure specific deposit washout and backwash efficiency of granular filters. In: Proceedings of the IWA Young Water Professionals Conference, 5-7 July 2010, Sydney, Australia, pC2, 11p.
- Description: Abstract: Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.
- Full Text:
- Authors: Van Staden, S. J. , Haarhoff, J.
- Date: 2010
- Subjects: Water treatment plants , Carbon, Activated , Water - Purification - Membrane filtration
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16407 , uj:15770 , Van Staden, S.J., & Haarhoff, J. 2010. How to measure specific deposit washout and backwash efficiency of granular filters. In: Proceedings of the IWA Young Water Professionals Conference, 5-7 July 2010, Sydney, Australia, pC2, 11p.
- Description: Abstract: Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.
- Full Text:
Activated carbon and ozone as supplementary water treatment options at Rietvlei Dam
- Authors: Van Staden, Andries Lodewyk
- Date: 2012-08-16
- Subjects: Carbon, Activated , Ozone , Water -- Purification , Water treatment plants -- South Africa -- Transvaal
- Type: Thesis
- Identifier: uj:9572 , http://hdl.handle.net/10210/5996
- Description: M.Ing. , Rietvlei Dam was completed in 1933, and has been utilized as a drinking water source for the City of Pretoria since then. The original process configuration operated for almost 50 years before being upgraded in 1988. This upgrading was mainly due to the eutrophication of the impoundment. The new plant worked excellently under normal conditions but certain serious problems did occur and full production could not be maintained at all times. Activated Carbon and Ozone are two possible solutions to these problems. This study was directed at investigating the possible implementation of Preozonation, Granular Activated Carbon, and Ozone and Granular Activated Carbon in combination (case study), and it was shown that: All these processes are beneficial to the final water quality. Pre-ozonation proved to be the most cost effective process, but the least effective process in improvement of the water quality. Ozone and Granular Activated Carbon in combination proved to be the least cost effective process, but should be the most effective in improvement of the water quality. Granular Activated Carbon proved to be the optimun process with regard to cost and water quality improvement. The final recommendation is the implementation of Granular Activated Carbon with an empty bed contact time of 10 minutes.
- Full Text:
- Authors: Van Staden, Andries Lodewyk
- Date: 2012-08-16
- Subjects: Carbon, Activated , Ozone , Water -- Purification , Water treatment plants -- South Africa -- Transvaal
- Type: Thesis
- Identifier: uj:9572 , http://hdl.handle.net/10210/5996
- Description: M.Ing. , Rietvlei Dam was completed in 1933, and has been utilized as a drinking water source for the City of Pretoria since then. The original process configuration operated for almost 50 years before being upgraded in 1988. This upgrading was mainly due to the eutrophication of the impoundment. The new plant worked excellently under normal conditions but certain serious problems did occur and full production could not be maintained at all times. Activated Carbon and Ozone are two possible solutions to these problems. This study was directed at investigating the possible implementation of Preozonation, Granular Activated Carbon, and Ozone and Granular Activated Carbon in combination (case study), and it was shown that: All these processes are beneficial to the final water quality. Pre-ozonation proved to be the most cost effective process, but the least effective process in improvement of the water quality. Ozone and Granular Activated Carbon in combination proved to be the least cost effective process, but should be the most effective in improvement of the water quality. Granular Activated Carbon proved to be the optimun process with regard to cost and water quality improvement. The final recommendation is the implementation of Granular Activated Carbon with an empty bed contact time of 10 minutes.
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Removal of natural organic matter from different raw waters by ion exchange resins
- Lobanga, K.P., Haarhoff, J., Van Staden, S.
- Authors: Lobanga, K.P. , Haarhoff, J. , Van Staden, S.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Water - Purification - Organic compounds removal , Carbon, Activated , Organic water pollutants
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/374006 , http://hdl.handle.net/10210/17189 , uj:15856 , Lobanga, K.P., Haarhoff, J., and Van Staden, S.J. (2011) Removal of natural organic matter from different raw waters by ion exchange resins. 2nd Young Water Professionals of Southern Africa Conference, Pretoria, South Africa, 4-5 July 2011.
- Description: Abstract Most South African water treatment plants utilise surface water sources whose quality is continuously compromised due to high return flows and indirect reuse. The water treatment methods used by these plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins can be used to remove NOM. This paper reports this method of NOM removal. Due to the variability in the composition of NOM in natural raw water, eight surface waters were collected throughout South Africa as representative of the different water types of the country. Two resins were used for this study, a strong and a weak – base anion resins. They were chosen for their availability and competitive price at the local market. NOM removal in raw water was quantified by measuring ultraviolet absorbance at a wavelength of 254 nm (UV 254), dissolved organic carbon (DOC) and by calculating the specific ultraviolet absorbance (SUVA) at 254 nm. The Freundlich equilibrium isotherms were also fitted and the Freundlich parameters determined.
- Full Text:
- Authors: Lobanga, K.P. , Haarhoff, J. , Van Staden, S.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Water - Purification - Organic compounds removal , Carbon, Activated , Organic water pollutants
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/374006 , http://hdl.handle.net/10210/17189 , uj:15856 , Lobanga, K.P., Haarhoff, J., and Van Staden, S.J. (2011) Removal of natural organic matter from different raw waters by ion exchange resins. 2nd Young Water Professionals of Southern Africa Conference, Pretoria, South Africa, 4-5 July 2011.
- Description: Abstract Most South African water treatment plants utilise surface water sources whose quality is continuously compromised due to high return flows and indirect reuse. The water treatment methods used by these plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins can be used to remove NOM. This paper reports this method of NOM removal. Due to the variability in the composition of NOM in natural raw water, eight surface waters were collected throughout South Africa as representative of the different water types of the country. Two resins were used for this study, a strong and a weak – base anion resins. They were chosen for their availability and competitive price at the local market. NOM removal in raw water was quantified by measuring ultraviolet absorbance at a wavelength of 254 nm (UV 254), dissolved organic carbon (DOC) and by calculating the specific ultraviolet absorbance (SUVA) at 254 nm. The Freundlich equilibrium isotherms were also fitted and the Freundlich parameters determined.
- Full Text:
Comparative study for the removal of natural organic matter from different raw waters by ion exchange
- Lobanga, K.P., Haarhoff, J., Mamba, B.B., Van Staden, S.J.
- Authors: Lobanga, K.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S.J.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Organic water pollutants , Carbon, Activated , Water - Purification - Organic compounds removal
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16647 , uj:15793 , Lobanga, K.P. et al.(2011) Comparitive study for the removal of natural organic matter from different raw waters by ion exchange. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, held in Costa Mesa, USA. 27-29 July 2011, 9 p.
- Description: Abstract South African water treatment plants mainly utilise surface water sources whose quality is continuously compromised due to indirect reuse and high return flows. In general the methods used by these water treatment plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins are one way of NOM removal, reported on this paper. Due to the variability in the composition of NOM in natural raw water, eight natural raw waters were collected throughout South Africa as representative of the different water types of the country. They were collected three times during a period of eight months. The strong and weak – base anion resins used in the study were chosen for their availability and competitive price at the local market. The removal of the NOM fractions was assessed by measuring ultraviolet absorption at a wavelength of 254 nm (UV254). Freundlich equilibrium isotherms were fitted. It was observed that the Freundlich parameters K and n are related reducing the Freundlich isotherm to a single-parameter model. The two parameters cluster for some waters regardless of season. Two performance indicators, namely 65% initial UV254 removal and absolute level of 6 /m, were adopted. It was found that if the initial UV254 is less than about 15 /m the absolute level of 6 /m is reached first while when the initial UV254 is greater than 20 /m the removal of 65% of UV254 is reached first. It was also observed that the resin usage rate is not only dependent on the initial UV254 value but also on the nature and concentration of the NOM, indicating a need for a better NOM characterization.
- Full Text: false
- Authors: Lobanga, K.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S.J.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Organic water pollutants , Carbon, Activated , Water - Purification - Organic compounds removal
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16647 , uj:15793 , Lobanga, K.P. et al.(2011) Comparitive study for the removal of natural organic matter from different raw waters by ion exchange. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, held in Costa Mesa, USA. 27-29 July 2011, 9 p.
- Description: Abstract South African water treatment plants mainly utilise surface water sources whose quality is continuously compromised due to indirect reuse and high return flows. In general the methods used by these water treatment plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins are one way of NOM removal, reported on this paper. Due to the variability in the composition of NOM in natural raw water, eight natural raw waters were collected throughout South Africa as representative of the different water types of the country. They were collected three times during a period of eight months. The strong and weak – base anion resins used in the study were chosen for their availability and competitive price at the local market. The removal of the NOM fractions was assessed by measuring ultraviolet absorption at a wavelength of 254 nm (UV254). Freundlich equilibrium isotherms were fitted. It was observed that the Freundlich parameters K and n are related reducing the Freundlich isotherm to a single-parameter model. The two parameters cluster for some waters regardless of season. Two performance indicators, namely 65% initial UV254 removal and absolute level of 6 /m, were adopted. It was found that if the initial UV254 is less than about 15 /m the absolute level of 6 /m is reached first while when the initial UV254 is greater than 20 /m the removal of 65% of UV254 is reached first. It was also observed that the resin usage rate is not only dependent on the initial UV254 value but also on the nature and concentration of the NOM, indicating a need for a better NOM characterization.
- Full Text: false
How to measure specific deposit washout and backwash efficiency of granular filters
- Van Staden, S.J., Haarhoff, J.
- Authors: Van Staden, S.J. , Haarhoff, J.
- Date: 2011
- Subjects: Water - Purification - Membrane filtration , Water treatment plants , Carbon, Activated
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/16971 , uj:15830 , Van Staden, S.J. & Haarhoff, J. (2011) How to measure the specific deposit washout and backwash efficiency of granular filters. Water Practice and Technology 6 (1) DOI:10.2166/WPT. 2011.014.
- Description: Abstract Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.
- Full Text:
- Authors: Van Staden, S.J. , Haarhoff, J.
- Date: 2011
- Subjects: Water - Purification - Membrane filtration , Water treatment plants , Carbon, Activated
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/16971 , uj:15830 , Van Staden, S.J. & Haarhoff, J. (2011) How to measure the specific deposit washout and backwash efficiency of granular filters. Water Practice and Technology 6 (1) DOI:10.2166/WPT. 2011.014.
- Description: Abstract Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.
- Full Text:
Activated carbon from maize tassels and polymer composites for water decontamination
- Olorundare, Oluwasayo Folasayo
- Authors: Olorundare, Oluwasayo Folasayo
- Date: 2014-07-15
- Subjects: Carbon, Activated , Water - Purification - Adsorption , Agricultural wastes , Composite materials
- Type: Thesis
- Identifier: uj:11657 , http://hdl.handle.net/10210/11380
- Description: Ph.D. (Chemistry) , This study presents work on the preparation, characterisation and application of agricultural waste residue, maize tassel in the production of activated carbon (AC) using both physical and chemical methods of activation in their production. The activated carbon produced from maize tassel (MTAC) or steam-produced activated carbon (STAC) were later added as a filler – together with beta-cyclodextrin (β-CD), and raw tassel (RT) – in the production of polyurethane composite adsorbent (PUCAD) material for the removal of selected inorganic (such as Cd2+, Cr3+, Pb2+) and organic pollutants (phenolic compound - bisphenol A (BPA), ortho-nitrophenol (O-NTP), para-chlorophenol (PCP), polychlorinated biphenyl (PCB), and methylene blue (MB) as adsorbate/analytes from aqueous medium. Both batch and solid-phase extraction adsorption methods (SPE), were used for separation and preconcentration. The investigations included reactivity using Fourier transform infrared (FT-IR) spectroscopy, surface morphology analysis using scanning electron microscopy (SEM), thermal stability using thermogravimetric analysis (TGA), heat flow using differential scanning calorimetry (DSC), and crystallinity using X-ray diffraction (XRD) coupled with energy dispersive X-ray spectrometry (EDX). The FT-IR analysis revealed that there was interaction between the polymeric material and all the fillers. The hydrogen bonding and N-H group interaction between all the materials and the polyurethane polymer composite (PCAD) showed compatibility between the polymeric materials and the fillers.
- Full Text:
- Authors: Olorundare, Oluwasayo Folasayo
- Date: 2014-07-15
- Subjects: Carbon, Activated , Water - Purification - Adsorption , Agricultural wastes , Composite materials
- Type: Thesis
- Identifier: uj:11657 , http://hdl.handle.net/10210/11380
- Description: Ph.D. (Chemistry) , This study presents work on the preparation, characterisation and application of agricultural waste residue, maize tassel in the production of activated carbon (AC) using both physical and chemical methods of activation in their production. The activated carbon produced from maize tassel (MTAC) or steam-produced activated carbon (STAC) were later added as a filler – together with beta-cyclodextrin (β-CD), and raw tassel (RT) – in the production of polyurethane composite adsorbent (PUCAD) material for the removal of selected inorganic (such as Cd2+, Cr3+, Pb2+) and organic pollutants (phenolic compound - bisphenol A (BPA), ortho-nitrophenol (O-NTP), para-chlorophenol (PCP), polychlorinated biphenyl (PCB), and methylene blue (MB) as adsorbate/analytes from aqueous medium. Both batch and solid-phase extraction adsorption methods (SPE), were used for separation and preconcentration. The investigations included reactivity using Fourier transform infrared (FT-IR) spectroscopy, surface morphology analysis using scanning electron microscopy (SEM), thermal stability using thermogravimetric analysis (TGA), heat flow using differential scanning calorimetry (DSC), and crystallinity using X-ray diffraction (XRD) coupled with energy dispersive X-ray spectrometry (EDX). The FT-IR analysis revealed that there was interaction between the polymeric material and all the fillers. The hydrogen bonding and N-H group interaction between all the materials and the polyurethane polymer composite (PCAD) showed compatibility between the polymeric materials and the fillers.
- Full Text:
Natural organic matter removal from surface waters by enhanced coagulation, granular activated carbon adsorption and Ion exchange
- Authors: Lobanga, Kaluka Paul
- Date: 2014-09-17
- Subjects: Water - Purification - Adsorption , Water - Purification - Organic compounds removal , Carbon, Activated , Organic water pollutants
- Type: Thesis
- Identifier: uj:12322 , http://hdl.handle.net/10210/12109
- Description: M.Ing. (Civil Engineering) , Natural organic matter (NOM) is a complex mixture of organic compounds resulting from the decay of plants and animals. When not properly removed, NOM reacts with disinfectants to form disinfection by-products, of which some are known to be carcinogenic. Regulations have become more and more stringent about the maximum level of NOM in drinking water. Different water treatment processes can be applied to remove NOM. However, because each process targets specific fractions of NOM, this results in the existence of recalcitrant NOM fractions that are not removed, for each treatment process. The main objective of the study was thus to investigate NOM removal by using three advanced water treatment processes alone and in combination. The processes used were enhanced coagulation, granular activated carbon adsorption and ion exchange resin processes. Strong and weak base ion exchange resins were used. Although NOM removal methods have been investigated intensively, little attention is given to a so-called “multi-barrier” approach of NOM removal through enhanced coagulation, granular activated carbon adsorption and ion exchange resin that could be applied in practice. In order to take the seasonal and geographical variability of NOM into account, water samples were collected at eight geographical areas over five to seven seasons from 2010 to 2013. Results showed that different treatment processes remove different NOM fractions with different efficiency. Results also confirmed that EC performs better than the adsorptive treatment processes. But the literature shows that NOM removal by EC is difficult for water with high alkalinity and low SUVA values, which is common with SA waters. The adsorptive processes used for NOM removal revealed that they are not viable options, because even low percentage of NOM removal would require high adsorbent dosages, which removes this approach as a practical option.
- Full Text:
- Authors: Lobanga, Kaluka Paul
- Date: 2014-09-17
- Subjects: Water - Purification - Adsorption , Water - Purification - Organic compounds removal , Carbon, Activated , Organic water pollutants
- Type: Thesis
- Identifier: uj:12322 , http://hdl.handle.net/10210/12109
- Description: M.Ing. (Civil Engineering) , Natural organic matter (NOM) is a complex mixture of organic compounds resulting from the decay of plants and animals. When not properly removed, NOM reacts with disinfectants to form disinfection by-products, of which some are known to be carcinogenic. Regulations have become more and more stringent about the maximum level of NOM in drinking water. Different water treatment processes can be applied to remove NOM. However, because each process targets specific fractions of NOM, this results in the existence of recalcitrant NOM fractions that are not removed, for each treatment process. The main objective of the study was thus to investigate NOM removal by using three advanced water treatment processes alone and in combination. The processes used were enhanced coagulation, granular activated carbon adsorption and ion exchange resin processes. Strong and weak base ion exchange resins were used. Although NOM removal methods have been investigated intensively, little attention is given to a so-called “multi-barrier” approach of NOM removal through enhanced coagulation, granular activated carbon adsorption and ion exchange resin that could be applied in practice. In order to take the seasonal and geographical variability of NOM into account, water samples were collected at eight geographical areas over five to seven seasons from 2010 to 2013. Results showed that different treatment processes remove different NOM fractions with different efficiency. Results also confirmed that EC performs better than the adsorptive treatment processes. But the literature shows that NOM removal by EC is difficult for water with high alkalinity and low SUVA values, which is common with SA waters. The adsorptive processes used for NOM removal revealed that they are not viable options, because even low percentage of NOM removal would require high adsorbent dosages, which removes this approach as a practical option.
- Full Text:
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