AWWA ACE59903

An effective means of providing a greater level of disinfection without increasingdisinfection byproducts is to improve chlorine contact chamber flow characteristics. Thequestion of the most efficient geometric design of a chlorine contact chamber has beenstudied in the past. A circular basin is more economical than a rectangular basin, buttypical baffle wall arrangements are difficult to fit into a circular shape. The mostcommon baffle designs are serpentine patterns or other combinations of straight chambers,which typically achieve disinfection efficiencies (T10/T) of 70% or less.A new spiral baffle design combines the economics of a circular contact chamber withthe extremely high disinfection efficiency and low headloss inherent in a spiral bafflewall arrangement. Although spiral baffle designs have been designed and built in thepast, the actual construction of a spiral is often mistakenly thought to be difficult. Mostprevious designs relied on concentric circular walls inside the outer shell, with a radialwall intersecting the concentric circles. This design is essentially a hybrid of a spiral anda serpentine pattern, and although more efficient than a straight-walled serpentinearrangement, the discontinuity of the circular walls due to the gaps along the radial wallmake for difficult analysis, and a substantial boundary member. The spiral design wascomposed entirely of circular semi-circles or partial circles, of varying radii. Thiseliminated all sharp corners, allowing the water to always flow in circular pattern,thereby considerably reducing turbulence and head losses. By placing the inlet at theedge of the circular tank and the outlet in the center, concerns of cross connection wereeliminated. Includes figures.

Product Details

Edition:

Vol. - No.

Published:

06/17/2004

Number of Pages:

12

File Size:

1 file , 810 KB