AWWA ACE54470

Large municipalities are requiring that delivered bleach (9 to 16 wt% NaOCl) have between 0.1 - 0.4 wt% excess caustic, 1,500 mg/L CIOS-, 0.5 mg/L iron and 0.05 mg/L nickel and copper. Important considerations for minimizing C103- formation include: pH (i.e. excess caustic); dilution (decomposition is 2nd order with respect to OCl-); and, temperature control. Bleach filtering produces stable, high quality bleach by removing inert sediments which impart off-color and turbidity to the bleach. Filtration with the proper filter-aid materials can be used to precipitate soluble metal ion species. This process removes sub-micron particles of the various species of Fe, Ni, and Cu and helps to reduce the coating of pumps/piping and the accumulation of heavy metal sludge on tank bottoms. It also reduces the potential for the catalytic formation of oxygen and pressure build-up in bleach containers. The analysis of 15 % bleach before and after filtration shows a reduction of iron from 2-3 ppm to 0.3 mg/L. The same kind of reduction was observed for nickel ion (0.5 to 0.01 ppm). Includes 5 references.

Product Details

Edition:

Vol. - No.

Published:

06/01/2001

Number of Pages:

9

File Size:

1 file , 690 KB