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Sustainable Drinking Water Treatment for Small Communities Using Multistage Slow Sand FiltrationCleary, Shawn A. January 2005 (has links)
Slow sand filtration is a proven and sustainable technology for drinking water treatment in small communities. The process, however, is sensitive to lower water temperatures that can lead to decreased biological treatment, and high raw water turbidity levels that can lead to premature clogging of the filter and frequent cleaning requirements, resulting in increased risk of pathogen breakthrough.
Multistage filtration, consisting of roughing filtration followed by slow sand filtration, can overcome these treatment limitations and provide a robust treatment alternative for surface water sources of variable water quality in northern climates, which typically experience water temperatures ranging down to 2°C. Prior to this study, however, multistage filtration had yet to be systematically challenged in colder climates, including testing of its performance under increased hydraulic loadings and elevated influent turbidity together with cold water conditions.
The primary goal of this research was to demonstrate the reliability of multistage filtration for small communities in northern climates with reference to the Ontario Safe Drinking Water Act. In this research, testing was conducted on two different pilot multistage filtration systems and fed with water from the Grand River, a municipally and agriculturally impacted river in Southern Ontario. One system featured pre-ozonation and post-granular activated carbon (GAC) stages, and shallower bed depths in the roughing filter and slow sand filter. The other system featured deeper bed depths in the roughing filter and slow sand filter, two parallel roughing filters of different design for comparison, and a second stage of slow sand filtration for increased robustness.
Removal of turbidity, total coliforms, and fecal coliforms under a range of influent turbidities (1 to >100 NTU), water temperatures (~2 to 20°C), and hydraulic loading rates (0. 2 to 0. 8 m/h) were investigated. In addition, the slow sand filters in each pilot system were challenged with high concentrations (~10<sup>6</sup> oocyst/L) of inactivated <i>Cryptosporidium parvum</i> oocysts.
The performance of both pilot multistage filtration systems was highly dependent on the biological maturity of the system and its hydraulic loading rate. In a less mature system operating in cold water conditions (<5°C), effluent turbidity was mostly below 0. 5 NTU during periods of stable influent turbidity (no runoff events) and a hydraulic loading of 0. 4 m/h, however, runoff events of high influent turbidity (>50 NTU), increased hydraulic loadings (0. 6 m/h), and filter cleaning occasionally resulted in effluent turbidity above 1 NTU. Furthermore, in a less mature system operating during runoff events of high turbidity, reducing the hydraulic loading rate to 0. 2 m/h was important for achieving effluent turbidity below 1 NTU.
However, in a more mature system operating in warm water conditions (19-22°C), effluent turbidity was consistently below 0. 3 NTU at a hydraulic loading rate of 0. 4 m/h, and below 0. 5 NTU at 0. 8 m/h, despite numerous events of high influent turbidity (>25 NTU). It remains to be seen whether this performance could be sustained in colder water temperatures with a fully mature filter. Removal of coliform bacteria was occasionally incomplete in a less mature multistage system, whereas, in a more mature system operating in warm water conditions (>9°C), removal was complete in all measurements. Furthermore, the average removal of <i>Cryptosporidium</i> was greater than 2. 5 logs in both systems (with hydraulic loading rates ranging from 0. 4 to 0. 8 m/h) and improved with increased filter maturity.
Each individual stage of the multistage system was an important treatment barrier in the overall process of turbidity and pathogen removal. The roughing filter was not only important for protecting the slow sand filter from solids loading and increasing its run length, but was also a significant contributor to coliform removal when the system was less mature. Removal of turbidity was significantly improved when the roughing filter was more mature, suggesting that biological treatment was an important treatment mechanism in the roughing filter. Although pre-ozonation was used mainly for the removal of organic carbon and colour, it achieved complete removal of coliform bacteria and was also suspected to be important for enhanced removal of turbidity. The second slow sand filter in series provided additional robustness to the process by reducing effluent turbidity to below 1 NTU during cold water runoff events of high turbidity and increased hydraulic loadings (0. 6 m/h), while achieving effluent below 0. 3 NTU during normal periods of operation. It also provided additional removals of coliforms under challenging operating conditions, and contributed an additional average removal of <i>Cryptosporidium</i> of 0. 8 logs, which resulted in cumulative removal of 3. 7 logs, approximately 1 log greater than all the other challenge tests.
Collectively, the entire multistage system performed well with water temperatures ranging down to 2°C, limited filter maturity, elevated raw water turbidities, and increased hydraulic loading rates. Its ability to meet the current Ontario turbidity regulations and greater than 2 log removal of <i>Cryptosporidium</i> over a range of operating conditions, with little or no process adjustment, is a testament to the robustness and minimal maintenance requirements of the process, which are desirable attributes for small water systems that are often located in rural areas. While this research demonstrated the performance of multistage filtration using pilot scale testing, it is important to note that full-scale plants tend to produce significantly better results than pilot facilities, due to long term biological maturation of the system.
Overall, multistage filtration is a sustainable and cost-effective technology that, through this research, appears to be a safe, reliable, and robust treatment alternative for small and non-municipal water systems in North America and the developing world. Further, based on its performance with challenging influent water quality and cold water conditions, multistage filtration holds particular promise for small communities in northern climates that are required to meet safe drinking water regulations, but are dependent on surface water sources of variable water quality and temperatures.
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Sustainable Drinking Water Treatment for Small Communities Using Multistage Slow Sand FiltrationCleary, Shawn A. January 2005 (has links)
Slow sand filtration is a proven and sustainable technology for drinking water treatment in small communities. The process, however, is sensitive to lower water temperatures that can lead to decreased biological treatment, and high raw water turbidity levels that can lead to premature clogging of the filter and frequent cleaning requirements, resulting in increased risk of pathogen breakthrough.
Multistage filtration, consisting of roughing filtration followed by slow sand filtration, can overcome these treatment limitations and provide a robust treatment alternative for surface water sources of variable water quality in northern climates, which typically experience water temperatures ranging down to 2°C. Prior to this study, however, multistage filtration had yet to be systematically challenged in colder climates, including testing of its performance under increased hydraulic loadings and elevated influent turbidity together with cold water conditions.
The primary goal of this research was to demonstrate the reliability of multistage filtration for small communities in northern climates with reference to the Ontario Safe Drinking Water Act. In this research, testing was conducted on two different pilot multistage filtration systems and fed with water from the Grand River, a municipally and agriculturally impacted river in Southern Ontario. One system featured pre-ozonation and post-granular activated carbon (GAC) stages, and shallower bed depths in the roughing filter and slow sand filter. The other system featured deeper bed depths in the roughing filter and slow sand filter, two parallel roughing filters of different design for comparison, and a second stage of slow sand filtration for increased robustness.
Removal of turbidity, total coliforms, and fecal coliforms under a range of influent turbidities (1 to >100 NTU), water temperatures (~2 to 20°C), and hydraulic loading rates (0. 2 to 0. 8 m/h) were investigated. In addition, the slow sand filters in each pilot system were challenged with high concentrations (~10<sup>6</sup> oocyst/L) of inactivated <i>Cryptosporidium parvum</i> oocysts.
The performance of both pilot multistage filtration systems was highly dependent on the biological maturity of the system and its hydraulic loading rate. In a less mature system operating in cold water conditions (<5°C), effluent turbidity was mostly below 0. 5 NTU during periods of stable influent turbidity (no runoff events) and a hydraulic loading of 0. 4 m/h, however, runoff events of high influent turbidity (>50 NTU), increased hydraulic loadings (0. 6 m/h), and filter cleaning occasionally resulted in effluent turbidity above 1 NTU. Furthermore, in a less mature system operating during runoff events of high turbidity, reducing the hydraulic loading rate to 0. 2 m/h was important for achieving effluent turbidity below 1 NTU.
However, in a more mature system operating in warm water conditions (19-22°C), effluent turbidity was consistently below 0. 3 NTU at a hydraulic loading rate of 0. 4 m/h, and below 0. 5 NTU at 0. 8 m/h, despite numerous events of high influent turbidity (>25 NTU). It remains to be seen whether this performance could be sustained in colder water temperatures with a fully mature filter. Removal of coliform bacteria was occasionally incomplete in a less mature multistage system, whereas, in a more mature system operating in warm water conditions (>9°C), removal was complete in all measurements. Furthermore, the average removal of <i>Cryptosporidium</i> was greater than 2. 5 logs in both systems (with hydraulic loading rates ranging from 0. 4 to 0. 8 m/h) and improved with increased filter maturity.
Each individual stage of the multistage system was an important treatment barrier in the overall process of turbidity and pathogen removal. The roughing filter was not only important for protecting the slow sand filter from solids loading and increasing its run length, but was also a significant contributor to coliform removal when the system was less mature. Removal of turbidity was significantly improved when the roughing filter was more mature, suggesting that biological treatment was an important treatment mechanism in the roughing filter. Although pre-ozonation was used mainly for the removal of organic carbon and colour, it achieved complete removal of coliform bacteria and was also suspected to be important for enhanced removal of turbidity. The second slow sand filter in series provided additional robustness to the process by reducing effluent turbidity to below 1 NTU during cold water runoff events of high turbidity and increased hydraulic loadings (0. 6 m/h), while achieving effluent below 0. 3 NTU during normal periods of operation. It also provided additional removals of coliforms under challenging operating conditions, and contributed an additional average removal of <i>Cryptosporidium</i> of 0. 8 logs, which resulted in cumulative removal of 3. 7 logs, approximately 1 log greater than all the other challenge tests.
Collectively, the entire multistage system performed well with water temperatures ranging down to 2°C, limited filter maturity, elevated raw water turbidities, and increased hydraulic loading rates. Its ability to meet the current Ontario turbidity regulations and greater than 2 log removal of <i>Cryptosporidium</i> over a range of operating conditions, with little or no process adjustment, is a testament to the robustness and minimal maintenance requirements of the process, which are desirable attributes for small water systems that are often located in rural areas. While this research demonstrated the performance of multistage filtration using pilot scale testing, it is important to note that full-scale plants tend to produce significantly better results than pilot facilities, due to long term biological maturation of the system.
Overall, multistage filtration is a sustainable and cost-effective technology that, through this research, appears to be a safe, reliable, and robust treatment alternative for small and non-municipal water systems in North America and the developing world. Further, based on its performance with challenging influent water quality and cold water conditions, multistage filtration holds particular promise for small communities in northern climates that are required to meet safe drinking water regulations, but are dependent on surface water sources of variable water quality and temperatures.
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e-Readiness of warehouse workers : an exploratory studyMoolman, Hermanus Barend 16 May 2007 (has links)
The purpose of this research was to investigate the e-readiness of warehouse workers in a supply chain management environment. Organisations increasingly contemplate e-learning as a training option to develop their employees. Globalisation of commercial ventures increasingly demands that organisations become more competitive by introducing Information Technology (IT). e-Learning is seen as a stepping stone for empowering employees. Supply-chain management organisations use unskilled warehouse workers to perform manual duties such as registering, storing and quick location of stock for distribution. IT supports these logistic procedures – emphasising the need to introduce e-learning to warehouse workers. Questionnaires confirmed that the unit of analysis was multi-racial, mostly black, between eighteen and sixty years old and of both genders. Their limited educational qualifications are representative of many similar developing communities of work across Africa. e-Learning requires access to technology, computer literacy, self-discipline, the drive to develop and the confidence to use technology to achieve objectives. Warehouse workers as developing communities are trapped by the digital divide amidst calls to bridge the divide by introducing IT to such communities. Questions are raised whether they have the discipline, motivation, and skills to learn from such a complex learning strategy. Interviewed corporate learning experts cautioned that specific infrastructures and personal attributes are crucial. Insufficient computer experience, anxiety and technophobia, may cause warehouse workers to become unlikely candidates for e-learning. My inquiry was an interpretive, qualitative case study, intent on understanding emotional, technical, and social aspects influencing e-readiness. I collected my data in four phases. Phase one was a questionnaire to collect biographical information of the warehouse workers. During phase two, by means of a Delphi technique, I established consensus from a group of e-learning experts of what ereadiness encompasses. Phase three consisted of interviews with and observations of workers performing their daily tasks and also while completing a computer-based tutorial. In phase four I conducted interviews with warehouse managers on their perceptions of the e-readiness of their workers. From the literature I extracted Reeves’ (1999) three learner inputs, as well as six fundamental categories of e-readiness. With these nine theory codes, I followed an inductive-deductive grounded theory approach to analyse the data. I constructed six sub-questions as basis for the enquiry. I tallied the frequencies of the conceptual codes of e-readiness and created an inventory of applicable conceptual codes according to the theory codes. Patterns of technical and affective experience, aptitude, origins of motivation, access to computer infrastructure and organisation culture culminated as my seven main findings on the e-readiness of warehouse workers. I determined inter alia that warehouse workers do not suffer from technophobia, nor are they really intimidated by technology. However, they need guidance and expert facilitation to become successful e-learners. They are aware that they are dependent on the organisation’s infrastructure to develop their skills and capabilities. Therefore, the e-maturity of an organisation can greatly benefit from warehouse workers’ involvement in e-learning. / Thesis (PhD (Curriculum Studies))--University of Pretoria, 2007. / Curriculum Studies / unrestricted
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Dienslewering in die openbare biblioteek met spesiale verwysing na gebruikersleiding / Service rendering in the public library with special reference to user guidanceGericke, Elizabeth Martina 01 January 2002 (has links)
Text in Afrikaans / Die doel van die studie was om 'n model te ontwikkel vir openbare
bibiioteekdiensiewering in 'n ontwikkelende land met 'n multikulturele samelewing.
Die kernprobleem was om die teoretiese fundering van dienslewering en die
toepassing daarvan in die praktyk te ondersoek.
Die eerste subprobleem was om die eienskappe van 'n professie en professionele
dienslewering te ondersoek. Die eienskappe van die professionalis/bibiiotekaris wat
leiding aan die gebruiker moet gee, is geidentifiseer. Sleutelelemente is:
outonomie (gekoppel aan deskundigheid en opieiding), 'n altruistiese
diensorientasie en funksionele diens (volgens professionele riglyne en standaarde)
aan alle groepe in die gemeenskap, ongeag sosiale kias.
Die tweede subprobleem was om die doelstellings en funksies van die openbare
biblioteek en die roi van gebruikersleiding daarin te ontleed. Daar is gevind dat
diensleweringsfunksies in die teorie swak gefundeer is. 'n Kategorisering is
voorgestel wat onderskei tussen ondersteuningsfunksies, diensleweringsfunksies
en bestuursfunksies. Gebruikersleiding is geidentifiseer as oorkoepelende begrip en kernelement van alle diensleweringsfunksies wat gerig is op die optimalisering
van die waarde van inligting tot beswil van die samelewing.
Die derde subprobleem was om die ontstaan van 'n diensbegrip in die openbare
biblioteek te beskryf en paradigmaverskuiwings uit te wys. Professionele riglyne,
beginsels en standaarde, is ontleed. Afleidings is gemaak oor 'n heersende
diensbegrip en rol van die openbare biblioteek. Daar is bevind dat die riglyne vir die
identifisering van gebruikersgroepe en hulle behoeftes asook
diensleweringsfunksies ontoereikend is.
'n Kategorisering van potensiele gebruikersgroepe en hul behoeftes is gedoen en 'n
model vir openbare biblioteekdiensiewering ontwikkel om die leemte in
teoretisering te vul. Die model onderskei 'n diensparadigma van dienslewering aan alie individue en groepe in die gemeenskap en missie van ontwikkeling; die primere
doeiltelling opvoeding; beginsels van gemeenskapskontak; behoeftebepaling en
toegang lot inligting; diensfunksies en uitreikaktiwiteite; die professionalis-klientverhouding;
wetgewing, organisatoriese strukture en omgewingsfaktore.
Die model is in 'n vraelysopname in die Suid-Afrikaanse openbare biblioteekpraktyk
getoets. Daar is bevind dat die doelsteliings nagestreef en diensfunksies toegepas
word. Die grootste probleme word in organisatoriese strukture en finansiering
ondervind. Hierdie sake moet dringend aandag kry om die gestelde missie, naamlik
om 'n wesenlike rol te speel in die ontwikkeling van die hele Suid-Afrikaanse
samelewing, te verwesenlik. / The purpose of the study was to develop a model for public library service rendering
in a developing and multicultural society. The core problem was to investigate the
theoretical foundation of service rendering and the application thereof in practice.
The first subproblem was to examine the characteristics of a profession and
professional service rendering. The characteristics of the professional/ librarian who
has to provide guidance to the user were identified. Key elements are: autonomy
(linked to expertise and training), an altruistic service orientation and functional
service (according to professional guidelines and standards) to all groups in the
community irrespective of social class.
The second subproblem was to analyse the aims and functions of the public library
and the role of user guidance in it It was found that service rendering functions are
not theoretically well grounded. A categorisation is proposed which distinguishes
between supporting, service rendering and management functions. User guidance
is identified as an umbrella concept and core element of all service rendering
functions which is directed at optima/isirtg the value of information to the benefit of
society.
The third subproblem was to describe the origins of a service concept in the public
library and to expose paradigm shifts. Professional guidelines, principles and
standards were analysed. Conclusions were drawn about a predominant service
concept and the role of the public library. It was found that guidelines for the
identification of user groups and their needs as well as service rendering functions
are inadequate.
A categorisation of potential user groups and their needs was compiled and a
model for public library service rendering was developed to bridge the gap in XXtheorisation.
The model distinguishes a paradigm of service to all Individuals and
groups in the community and a developmental mission; the primary aim of
education; service principles of community networking, needs assessment and
information access; service functions and outreach activities; the professionalclient-
relationship; legislation, organisational structures and environmental factors.
The model was tested in South African public library practice by means of a
questionnaire survey. It was found that aims are pursued and service functions are
applied. The greatest problems are experienced In organisational structures and
financing. These issues must be urgently addressed to realise the public library's
declared mission, namely to play a substantial role in the development of the South
African society as a whole. / Information Science / D. Litt. et Phil. (Information Science)
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Dienslewering in die openbare biblioteek met spesiale verwysing na gebruikersleiding / Service rendering in the public library with special reference to user guidanceGericke, Elizabeth Martina 01 January 2002 (has links)
Text in Afrikaans / Die doel van die studie was om 'n model te ontwikkel vir openbare
bibiioteekdiensiewering in 'n ontwikkelende land met 'n multikulturele samelewing.
Die kernprobleem was om die teoretiese fundering van dienslewering en die
toepassing daarvan in die praktyk te ondersoek.
Die eerste subprobleem was om die eienskappe van 'n professie en professionele
dienslewering te ondersoek. Die eienskappe van die professionalis/bibiiotekaris wat
leiding aan die gebruiker moet gee, is geidentifiseer. Sleutelelemente is:
outonomie (gekoppel aan deskundigheid en opieiding), 'n altruistiese
diensorientasie en funksionele diens (volgens professionele riglyne en standaarde)
aan alle groepe in die gemeenskap, ongeag sosiale kias.
Die tweede subprobleem was om die doelstellings en funksies van die openbare
biblioteek en die roi van gebruikersleiding daarin te ontleed. Daar is gevind dat
diensleweringsfunksies in die teorie swak gefundeer is. 'n Kategorisering is
voorgestel wat onderskei tussen ondersteuningsfunksies, diensleweringsfunksies
en bestuursfunksies. Gebruikersleiding is geidentifiseer as oorkoepelende begrip en kernelement van alle diensleweringsfunksies wat gerig is op die optimalisering
van die waarde van inligting tot beswil van die samelewing.
Die derde subprobleem was om die ontstaan van 'n diensbegrip in die openbare
biblioteek te beskryf en paradigmaverskuiwings uit te wys. Professionele riglyne,
beginsels en standaarde, is ontleed. Afleidings is gemaak oor 'n heersende
diensbegrip en rol van die openbare biblioteek. Daar is bevind dat die riglyne vir die
identifisering van gebruikersgroepe en hulle behoeftes asook
diensleweringsfunksies ontoereikend is.
'n Kategorisering van potensiele gebruikersgroepe en hul behoeftes is gedoen en 'n
model vir openbare biblioteekdiensiewering ontwikkel om die leemte in
teoretisering te vul. Die model onderskei 'n diensparadigma van dienslewering aan alie individue en groepe in die gemeenskap en missie van ontwikkeling; die primere
doeiltelling opvoeding; beginsels van gemeenskapskontak; behoeftebepaling en
toegang lot inligting; diensfunksies en uitreikaktiwiteite; die professionalis-klientverhouding;
wetgewing, organisatoriese strukture en omgewingsfaktore.
Die model is in 'n vraelysopname in die Suid-Afrikaanse openbare biblioteekpraktyk
getoets. Daar is bevind dat die doelsteliings nagestreef en diensfunksies toegepas
word. Die grootste probleme word in organisatoriese strukture en finansiering
ondervind. Hierdie sake moet dringend aandag kry om die gestelde missie, naamlik
om 'n wesenlike rol te speel in die ontwikkeling van die hele Suid-Afrikaanse
samelewing, te verwesenlik. / The purpose of the study was to develop a model for public library service rendering
in a developing and multicultural society. The core problem was to investigate the
theoretical foundation of service rendering and the application thereof in practice.
The first subproblem was to examine the characteristics of a profession and
professional service rendering. The characteristics of the professional/ librarian who
has to provide guidance to the user were identified. Key elements are: autonomy
(linked to expertise and training), an altruistic service orientation and functional
service (according to professional guidelines and standards) to all groups in the
community irrespective of social class.
The second subproblem was to analyse the aims and functions of the public library
and the role of user guidance in it It was found that service rendering functions are
not theoretically well grounded. A categorisation is proposed which distinguishes
between supporting, service rendering and management functions. User guidance
is identified as an umbrella concept and core element of all service rendering
functions which is directed at optima/isirtg the value of information to the benefit of
society.
The third subproblem was to describe the origins of a service concept in the public
library and to expose paradigm shifts. Professional guidelines, principles and
standards were analysed. Conclusions were drawn about a predominant service
concept and the role of the public library. It was found that guidelines for the
identification of user groups and their needs as well as service rendering functions
are inadequate.
A categorisation of potential user groups and their needs was compiled and a
model for public library service rendering was developed to bridge the gap in XXtheorisation.
The model distinguishes a paradigm of service to all Individuals and
groups in the community and a developmental mission; the primary aim of
education; service principles of community networking, needs assessment and
information access; service functions and outreach activities; the professionalclient-
relationship; legislation, organisational structures and environmental factors.
The model was tested in South African public library practice by means of a
questionnaire survey. It was found that aims are pursued and service functions are
applied. The greatest problems are experienced In organisational structures and
financing. These issues must be urgently addressed to realise the public library's
declared mission, namely to play a substantial role in the development of the South
African society as a whole. / Information Science / D. Litt. et Phil. (Information Science)
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