J Water SRT - Aqua 52 443-454 (2003)

Activated carbon adsorption of chloroacetanilide herbicides and their degradation products from surface water supplies

David I. Gustafson, Katherine H. Carr, David B. Carson, John D. Fuhrman, Amy G. Hackett, Thomas J. Hoogheem, Vernon L. Snoeyink, Mike Curry, Bas Heijman, Sunmao Chen, Peter Hertl and Ian van Wesenbeeck

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Monsanto Company, 800 N. Lindbergh Blvd, St Louis, MO 63167, USA Tel: +1 314/694-2698 Fax: +1 314/694-8774 E-mail: david.i.gustafson@monsanto.com

Department of Civil and Environmental Engineering, University of Illinois, Urbana, IL 61801, USA

Curry & Associates Engineers, Inc., 243 East Elm, P.O. Box 246, Nashville, IL 62263, USA

Kiwa N.V., Water Research, Postbox 1072, 3430 BB Nieuwegein, The Netherlands

Syngenta Crop Protection, Inc., P.O. Box 18300, Greensboro, NC 27419, USA

Syngenta Crop Protection, Inc., P.O. Box 18300, Greensboro, NC 27419, USA

Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, USA

A recent (1995 - 2001) 175-site surface drinking water monitoring programme in the United States showed that one community water system (Nashville, Illinois) was particularly successful at removing chloroacetanilide herbicides and their degradation products from source water. Nashville adds powdered activated carbon (PAC) just prior to a clarifier in which settled solids are recirculated, increasing the PAC residence time. We conducted bench-scale studies to quantify the effects of PAC dose and contact time on removal efficiency. Results indicate that 90% of the parent herbicides and 40 - 45% of the acetanilide degradation products are removed for a contact time of 60 min and a PAC dose of 20 mg/l, from Nashville, IL, source water. Removal of these compounds by the same PAC dose and contact time was even higher in three other US water sources (Idaho, Kansas, Missouri) and a European (Dutch) water source, generally 60 - 80% for the degradation products and over 95% for the parent compounds. Removal percentages substantially increased with higher PAC dose and contact time, fell slightly with decreasing pH or higher NOM, but remained constant when the inlet concentration was raised from 2 to 10 µg/l.

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