This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the ...This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the coagulant properties are well reported, the disinfectant properties are not well studied. Literatures on low cost alternative technologies such as the application of hiocoagulants and slow sand filters are extensively reported. However, there is limited work addressing the limitations of these technologies that have restricted its widespread use to solve the global soaring water crises. Slow sand filters have a very slow filtration rate that depends on the biofilm layer which takes about 17 days to form. Moringa oleifera treated water cannot last more than 48 hours without bacteria regrowth. Investigation of the best method of isolating coagulant component continues with differing opinions over the nature of its coagulant ingredient not resolved in ongoing literature. An attempt was made in this paper to highlight the advantages of a Moringa disinfectant sand filter hybrid system that can purify water. Microbiological advantages of this system in providing a 100% removal of pathogens, and engineering considerations such as water treatment within an hour residence time, faster flow rates, less clogging and backwashing could be some of the advantages ofa Moringa sand filter system. The need to focus on integrating Moringa and sand filter systems for more practical applications is recommended.展开更多
Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particle...Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter （NOM）. For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration （MF/UF） alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation （SWTR） is not enough. MF/UF treatment processes can achieve only nominal （10 percent） removal of disinfection by-products （DBP） precursors （James, et al., 1995）. On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules （the submerged module and pressured module）. The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.展开更多
文摘This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the coagulant properties are well reported, the disinfectant properties are not well studied. Literatures on low cost alternative technologies such as the application of hiocoagulants and slow sand filters are extensively reported. However, there is limited work addressing the limitations of these technologies that have restricted its widespread use to solve the global soaring water crises. Slow sand filters have a very slow filtration rate that depends on the biofilm layer which takes about 17 days to form. Moringa oleifera treated water cannot last more than 48 hours without bacteria regrowth. Investigation of the best method of isolating coagulant component continues with differing opinions over the nature of its coagulant ingredient not resolved in ongoing literature. An attempt was made in this paper to highlight the advantages of a Moringa disinfectant sand filter hybrid system that can purify water. Microbiological advantages of this system in providing a 100% removal of pathogens, and engineering considerations such as water treatment within an hour residence time, faster flow rates, less clogging and backwashing could be some of the advantages ofa Moringa sand filter system. The need to focus on integrating Moringa and sand filter systems for more practical applications is recommended.
文摘Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter （NOM）. For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration （MF/UF） alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation （SWTR） is not enough. MF/UF treatment processes can achieve only nominal （10 percent） removal of disinfection by-products （DBP） precursors （James, et al., 1995）. On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules （the submerged module and pressured module）. The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.
