AWWA WQTC60798

Magnetic ion-exchange (MIEX®) has been shown to be effective forreducing the concentration of dissolved organic carbon (DOC) from water.MIEX® is a high capacity ion exchange resin that is used as a continuousfeed suspension in a stirred contactor. The magnetic component of thisresin aids in settling by aggregating particles for more rapid settling. Inthis investigation, MIEX® was evaluated for removal of several endocrinedisrupting chemicals (EDCs) and pharmaceuticals. Both static benchscaleand dynamic pilot-scale tests were completed using Colorado Riverwater spiked with over 60 different EDCs and pharmaceuticals, whichinclude compound classes such as antibiotics, steroids, flame-retardants,analgesics, pesticides, and x-ray contrast media. For bench-scale testing,MIEX® was dosed at 5, 10, 15, and 20 mL/L with contact times of 10 and20 minutes. Bench-scale results show, in general, that removal is relatedto polarity (log Kow) with higher removal related to lower polarity (higherlog Kow). For instance, most compounds with log Kow values greaterthan 3.5 were removed by greater than 40% (i.e., oxybenzone, triclosan,polycyclic aromatic hydrocarbons, and some organochlorine pesticides).However, some exceptions were noted. For instance, the pharmaceuticaldiclofenac has a log Kow of only 0.7, yet it was well removed by MIEX®(>70%). The removal of diclofenac is dominated by ion exchange since itexists as an anion at ambient pH. Furthermore, excellent dose responsecurves were obtained, showing that removal is directly related to MIEX®dose. Contact time seemed to be less important as the 20 minute contact timegenerally improved removal by only 20% or less. Pilot-scale tests wereconducted at 10 gallons per minute with a spike feeding 100 ng/L of thetarget compounds. For pilot-scale tests, a MIEX® dose of 20 mL/L with acontact time of 20 minutes was utilized. Results from the pilot-scale weresimilar to results from the bench-scale. MIEX® proved to be of limiteduse for the removal of EDCs and pharmaceuticals, as most compoundswere not well removed. However, for specific compounds and multibarrierprocesses, MIEX® may be applicable. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

7

File Size:

1 file , 280 KB