## Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

## If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

# Calcium Phosphate Precipitation at Slightly Alkaline pH Values

John F. Ferguson, David Jenkins and John Eastman
Journal (Water Pollution Control Federation)
Vol. 45, No. 4 (Apr., 1973), pp. 620-631
Stable URL: http://www.jstor.org/stable/25037801
Page Count: 12
Preview not available

## Abstract

A calcium phosphate precipitation process was found which could reduce chemical costs from one-half to one-sixth of the $20 to$50/mil gal ($5.30 to$13.20/1,000 cu m) projected for current methods using alum, lime, or iron salts. This process can be operated simultaneously with the activated sludge process because it is conducted in a reactor of similar dimensions and residence time distribution and at a pH between 7 and 9. The process is applicable and should be considered as a viable alternative in wastewater with alkalinity of less than 350 mg/l as ${\rm CaCO}_{3}$ and magnesium concentrations less than 24 mg/l as Mg. Laboratory scale, continuous-flow studies produced phosphate residuals ranging from 3.3 to 1.2 mg/l, representing removals from 63 to 87 percent of an initial 10 mg/l as P.

• 620
• 621
• 622
• 623
• 624
• 625
• 626
• 627
• 628
• 629
• 630
• 631