Effect of copper(II) on natural organic matter removal during drinking water coagulation using aluminum-based coagulants.
Coagulation has been proposed as a best available technology for controlling natural organic matter (NOM) during drinking water treatment. The presence of heavy metals such as copper(II) in source water, which may form copper-NOM complexes and/or interact with a coagulant, may pose a potential challenge on the coagulation of NOM. In this work, the effect of copper(II) on NOM removal by coagulation using alum or PAX-18 (a commercial polymerized aluminum chloride from Kemiron Inc., Bartow, Florida) was examined. The results show that the presence of 1 to 10 mg/L of copper(H) in the simulated waters improved the total organic carbon (TOC) removal by up to 25% for alum coagulation and by up to 22% for PAX-18 coagulation. The increased NOM removal with the presence of copper(II) in the waters can most likely be ascribed to the formation copper-NOM complexes that may be more adsorbable on aluminum precipitates and to the formation of copper(II) co-precipitates that may also adsorb NOM. The presence of 1 to 5 mg/L of copper(I) in the waters containing 3 mg/L NOM as carbon was reduced below the maximum contaminant level goal (1.3 mg/L as copper) using either coagulant. The results suggest that the presence of copper(H) in source water may not adversely affect the NOM removal by coagulation. A good linear correlation was observed between the TOC removal efficiency and the log-total moles of the precipitated metals, which include the metal ion from a coagulant and the divalent metal ion(s) in source water.
Liu
Guojing
G
Department of Civil Engineering and Geological Sciences, University of Notre Dame, Indiana 46556, USA.
Zhang
Xiangru
X
Talley
Jeffrey W
JW
D000534:Alum Compounds / Q000737:chemistry; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D000534:Alum Compounds; D017607:Aluminum Compounds; D002712:Chlorides; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D014867:Water; C041524:aluminum sulfate; D000077410:Aluminum Chloride; D003300:Copper