The sand and microfiltration of algae in water supplies
The following was observed in early work on the sand filtration of algal suspensions (1961): · Three genera of algae (Scenedesmus, Ankistrodesmus, Anabaena) easily penetrated sand filters even at low filtration rates (0.2 to 2gpm/ft2) and using filters containing small media when no chemical pretreatment was used. · Coagulant addition prior to filtration substantially improved the removal of all algal genera. Chemical pretreatment with a coagulant was found to be essential for effective algal filtration Recent research (2008) on the microfiltration of three genera of algae (Scenedesmus, Microcystis,Asterionella) and of natural organic matter from the Great Dismal Swamp in Virginia, U.S.A led to thefollowing conclusions: · Microfiltration could easily remove the algal cells without chemical pretreatment. However, under certain conditions, fouling was extensive. Fouling by the algal cells was relatively small and easily reversible hydrauhcally.Fouling by exocellular algal organic matter could be extensive and was hydrauhcally irreversible · Pretreatment of the algal suspensions with a coagulant removed much the algal organic matter and significantly reduced membrane fouling. In summary, pretreatment of algal-laden waters with a chemical coagulant was necessary toaccomphsh algal removal by sand filtration and to control fouling by algal organic matter in microfiltration.Coagulant dose was critical to achieve these results.
Charles R.OMELIA
Johns Hopkins University,Baltimore,MD 21218 U.S.A
国际会议
西安
英文
3
2008-05-15（万方平台首次上网日期，不代表论文的发表时间）