AWWA ACE56165

High rate treatment processes were evaluated as alternatives that would allow more cost effective expansion and treatment upgrades for the Passaic Valley Water Commission, located in northern New Jersey. The existing facility is located on a site with limited additional area for added structures, thereby favoring technologies that have a small footprint. The applicability of ballasted flocculation as a high rate/high efficiency process for meeting project goals was demonstrated using a treatment unit that was rated for a capacity up to 210 gpm/sq. ft. Water quality at this location exhibits significant variations that include changes in turbidity, TOC, alkalinity, hardness, temperature, and algal blooms. Operation and evaluation in the demonstration testing program covered a twelve-month period that allowed performance to be assessed for a full range of raw water quality conditions. The process met treatment objectives for all water quality conditions at normal loading rates of 30 gpm/sq. ft. and sustained peak loading rates up to 45 gpm/sq. ft. Key operating parameters included pH, coagulant dose, microsand dose, and polymer type and dose. Ferric chloride was applied as the coagulant to obtain a higher level of TOC removal as compared with alum and polyaluminum chloride that have been applied in the existing plant. Results indicated significant increase in TOC removal and a corresponding reduction in the level of THM and HAA5 formation that resulted from this approach in combination with a downstream ozone/biological filtration sequence. These modifications are key to meeting new goals for microbial and disinfection byproduct regulations. Includes figures.

Product Details

Edition:

Vol. - No.

Published:

06/16/2002

Number of Pages:

11

File Size:

1 file , 370 KB