16593 07 tủ tài liệu bách khoa
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16593 07 tủ tài liệu bách khoa
_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoaenham, Oxfordshire EnglandJames K. EdzwaldProfessor, Department of Civil and Environmental Engineering University of Massachusetts A mhersl. MassachusettsUSA.Sedimentation and flotation arc solid-liquid separation processes used in water treatment mostly to lower the solids concentration, or load, o 16593 07 tủ tài liệu bách khoan granular fillers. As a result, fillers can be operated more easily and cost effectively to produce acceptable-quality filtered water. Many sedimenta16593 07 tủ tài liệu bách khoa
tion and flotation processes and variants of them exist, and each has advantages and disadvantages. The most appropriate process for a particular appl_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoam>»nt rtf Wĩ»t#*r mislitv line lippn rxrnr’tirvari if Iinwit-7.2CHAPTER SEVENWater stored undisturbed and then poured or ladled out with little agitation will improve in quality, and this technique is used to this day.As societies developed, reservoirs and storage tanks were constructed. Although co 16593 07 tủ tài liệu bách khoanstructed for strategic purposes, reservoirs and storage tanks did improve water quality. Various examples are known that predate the Christian era. A16593 07 tủ tài liệu bách khoa
ncient surface water impounding tanks of Aden were possibly constructed as early as 600 B.c. and rainwater cisterns of ancient Carthage about 150 B.c._____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoaintended for that purpose.Modern Sedimentationrhe art of sedimentation progressed little until the industrial age and its increased need for water. Storage reservoirs developed into settling reservoirs. Perhaps the largest reservoirs constructed for this purpose were in the United Stales al Cincinna 16593 07 tủ tài liệu bách khoati. Ohio, where two excavated reservoirs held approximately 1480 ML (392 million gallons) and were designed to be operated by a fill-and-draw method,16593 07 tủ tài liệu bách khoa
though they never were used in this way (Films. 1928). The development of settling basins led to the construction of rectangular masonry settling tank_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoachanical sludge removal was introduced.Attempts to make rectangular tanks more cost-effective led to the construction of multilayer tanks. Very large diameter [60-m (200-ft)] circular tanks also were constructed al an early stage in the development of modern waler treatment. Other industries, such a 16593 07 tủ tài liệu bách khoas wastewater treatment, mineral processing, sugar refining, and water softening, required forms of sedimentation with specific characteristics, and va16593 07 tủ tài liệu bách khoa
rious designs of settling tanks particular to certain industries were developed. Subsequently, wider application of successful industrial designs were_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoafor premixing and recirculation.Ihc inclined plate settler also has industrial origins (Barham. Matherne, and Keller. 1956) (Figure 7.1), although the theory of inclined settling dales back to experiments using blood in the 1920s and 1930s (Nakamura and Kuroda. 1937: Kinosila. 1949). Closely spaced 16593 07 tủ tài liệu bách khoainclined plate systems for waler treatment have their origins in Sweden in the 1950s. resulting from a search for high-rate treatment processes compac16593 07 tủ tài liệu bách khoa
t enough to be economically housed against winter weather. InclinedFIGURE 7.1 Early patent for inclined settling. (Source:D-1.„1\SEDIMENTATION AND FLO_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoat developments have involved combining inclined settling with ballasting of floc to reduce plant footprint further (de Dianous. Pujol, and Druolon. 1990).Floc-Blanket Sedimentation and Other InnovationsHie floc-blanket process for water treatment emerged from India about 1932 as the pyramidal Candy 16593 07 tủ tài liệu bách khoasedimentation lank (Figure 7.2). A lank of similar shape was used by Imhoff in 1906 for wastewater treatment (Kalbskopf. 1970). Hie Spaulding Precipit16593 07 tủ tài liệu bách khoa
ator soon followed in 1935 (Figure 7.3) (Hartung. 1951). Other designs that were mainly solids contact clarifiers rather than true floc-blanket tanks _____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoa blankets were conceived. Hie aim was to decrease the hopper component of tanks as much as possible, yet to provide good flow distribution to produce a stable floc blanket. Development from 1945 progressed from tanks with multiple hoppers or troughs to the present flat-bottom tanks. Efficient flow d 16593 07 tủ tài liệu bách khoaistribution in flat-bottom tanks is achieved with either candelabra or lateral inlet distribution systems (Figures 7.4 and 7.5).An innovation in the 116593 07 tủ tài liệu bách khoa
970s was the inclusion of widely spaced inclined plates in the floc-blanket region (Figure 7.5). Other developments that also have led to increased su_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedme 16593 07 tủ tài liệu bách khoaThe principal centers for these developments have been in the United Kingdom. France, and Hungary.SEDIMENTATION THEORYThe particle-fluid separation processes of interest to water engineers and scientists ủrùIt tr» z'loc/'ri' hv 1I ortaltrcic moirtlvthù ntrtí/>lúC 16593 07 tủ tài liệu bách khoa_____CHAPTER 7___SEDIMENTATION AND FLOTATIONRoss GregoryWRc SwindonFrankland Road, Blagrove Swindon. WiltshireEnglandThomas F. ZabelWRc MedmenhamMedmeGọi ngay
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