AWWA ACE95255

The Britannia Water Purification Plan in Ottawa, Canada, which treats a low alkalinity, colored water, currently practices prechlorination and low pH coagulation (pH 5.8) at full scale. However, with a view to overall process optimization the utility is examining a number of treatment alternatives. This paper reports on a pilot scale comparison of enhanced alum coagulation, as currently practiced, to acid enhanced alum coagulation with and without pre-sedimentation ozone. Because of sludge handling considerations, reduced alum dosages were investigated in the experiments involving pre-sedimentation ozonation. Process performance was assessed on the basis of nonpurgeable organic carbon (NPOC), UV absorbance, turbidity and color reduction. During this study it was observed that a minimum alum dose of 30 to 35 mg/L had to be applied (regardless of coagulation pH) before floc formation occurred. This was attributed to the elevated humic fraction of the raw water.

Product Details

Published:

01/01/1995

ISBN(s):

089867834X

Number of Pages:

22

File Size:

1 file , 890 KB