Systems and methods for treating water using iron

Abstract

Systems and associated methods for treating contaminant-containing wastewater are provided. The systems generally include a reducing zone for reducing the oxidation-reduction potential of the water and a clean-up zone comprising zero valent iron for removing at least a portion of the contaminant from the contaminant-containing water. The systems are operable to remove one or more contaminants from the contaminant-containing water and are operable for extended durations without clogging due to the formation of iron hydroxides.

1 . An ex-situ system for treating contaminant-containing water, the system comprising:
 a first treatment zone comprising a reducing agent adapted to reduce the oxidation-reduction potential of contaminant-containing water flowing therethrough; and   a second treatment zone downstream of the first treatment zone, the second treatment zone comprising zero valent iron for removing at least a portion of contaminants contained in the contaminant-containing water.   
     
     
         2 . The system of  claim 1 , wherein the reducing agent comprises zero valent iron. 
     
     
         3 . The system of  claim 1 , wherein the first treatment zone comprises a filler. 
     
     
         4 . The system of  claim 3 , wherein the first treatment zone comprises not greater than about 10 wt % of the reducing agent. 
     
     
         5 . The system of  claim 4 , wherein the reducing agent is zero valent iron. 
     
     
         6 . The system of  claim 3 , wherein the first treatment zone is a column and wherein the column consists essentially of the reducing agent and the filler. 
     
     
         7 . The system of  claim 1 , wherein the second treatment zone comprises at least 50 wt % zero valent iron. 
     
     
         8 . The system of  claim 1 , wherein the second treatment zone consists essentially of zero valent iron. 
     
     
         9 . The system of  claim 1 , further comprising:
 a third treatment zone fluidly interconnected to an exit of the second treatment zone, the third treatment zone comprising a contaminant scavenging material.   
     
     
         10 . The system of  claim 8 , wherein the contaminant scavenging material comprises at least one of activated carbon and a biological material. 
     
     
         11 . The system of  claim 1 , wherein the contaminant-containing water exiting the second treatment zone comprises less than 30 ppb total cyanide.