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oF'Dfc <br /> � �9� <br /> V � 7Co <br /> �:1:� <br /> '/[LINO�`' <br /> April 19, 1999 <br /> PUBLIC WORKS MEMORANDUM <br /> NO. 99 - 11 <br /> MEMORANDUM TO: Honorable Mayor and City Council <br /> I FROM: James L. Williams, Jr., Ci Mana er <br /> �Y g <br /> � <br /> Bruce A. McNabb Director of Public Works <br /> , <br /> John A. Smith, Water Production Manager <br /> SUBJECT: Nitrate Treatment Cost Study <br /> City Project 9852 <br /> The City of Decatur may have to install nitrate treatment (removal) process equipment at the ' <br /> South Water Treatment Plant(SWTP) in order to be in compliance with the 10 mg/1 nitrate MCL I'� <br /> (maximum contaminant level) as set by U.S.E.P.A. There are two primary treatment processes <br /> used to remove nitrates from drinking water: ion exchange (IX) and reverse osmosis (RO). <br /> Each removal process has advantages and disadvantages. IX is lower in initial capital cost <br /> and is probably lower in operating costs than RO. However, IX is a single use process--it only <br /> removes nitrates and does not add any additional benefits to the quality of the water. RO is <br /> higher in capital costs and probably much higher in operating costs, but has other advantages: <br /> • Disinfection by-product removal <br /> • Taste and Odor control <br /> • Credit for cryptosporidium removal <br /> � Turbidity removal <br /> • Atrazine (farm chemicals) removal <br /> The installation of RO may eliminate the need for future expensive treatment process <br /> equipment for disinfection by-product control. <br />