AWWA WQTC58812

Three kinetic stages were observed for the chlorine exposure-trihalomethane relationship for twoenhanced coagulated waters. There is a fast initial increase of Total Trihalomethane (TTHM) concentration for contact time (CT) < 10mg-min/L, followed by a linear increase of TTHM concentration up to a CT of 200 mg-min/Land finally followed by another slower linear increase up to a CT of 10,000 mg-min/L. Also, forboth waters the chlorine exposure - TTHM relationships were independent of chlorine dose forCT < 200 mg-min/L. For the temperature studies disinfection requirements had a greater impacton the CT than TTHM, DCAA and TCAA formed for CT < 200 mg-min/L. pH impacted the CT- THM and TCAA formation relationships for CT < 200 mg-min/L. Treatment decreased theTTHM, dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) concentrations as a function of CT. Ultraviolet absorbance (UVA) was a good indicator forthe CT-THM, DCAA and TCAA relationships for the enhanced coagulated and granular activated carbon (GAC) treatedwaters and less so for the raw water and ozonated/biotreated waters. In some cases temperature,pH and treatment had greater impacts on the CT - DBP relationship for CT > 1,000 mg-min/LThese impacts could be more important for more resistant protozoa, such as Cryptosporidiumparvum oocysts, which require higher chlorine exposures. Includes 5 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

18

File Size:

1 file , 320 KB