AWWA ACE91070

In looking at building a filtration plant to comply with the Surface Water Treatment Rule, the New York City Department of Environmental Protection evaluated three processes: ozone-diatomaceous earth, direct filtration, and dissolved air flotation. This paper discusses DAF, used with polyaluminum chloride as a coagulant. A comparison between direct filtration and DAF showed that DAF removes solids and organic material from the water to the same degree as direct filtration and that the DAF process produced approximately twice as much filtered water and direct filtration. Thus, the combination of DAF and polyaluminum chlorides was found to be effective and economical for the Croton water supply. Although ferric chloride outperformed the polyaluminum chlorides for DAF water production, the ferric chloride doses were much higher. Significantly less sludge is produced by the polyaluminum chlorides, and because sludge disposal is a major concern, the difference in sludge volume would result in significant savings; also, the overall cost of polyaluminum chloride was less than ferric chloride, when the difference in dosages is taken into account.

Product Details

Published:

01/01/1991

ISBN(s):

0898675901

Number of Pages:

17

File Size:

1 file , 580 KB