Zero valent iron/iron oxide mineral/ferrous iron composite for treatment of a contaminate fluid

Abstract

The present inventors have discovered a novel composition, method of making the composition, system, process for treating a fluid containing a contaminant. The fluid may be aqueous. The contaminated fluid may be in the form of a suspension. The treatment reduces the concentration of the contaminant. The reduction in concentration of a contaminant may be sufficient so as to effect remediation of the fluid with respect to the contaminant. The treatment may reduce the concentration of a plurality of contaminants. The present composition, system, and process are robust and flexible. The composition includes zero valent iron, an iron oxide mineral, and ferrous iron. The ferrous iron promotes maintenance of the iron oxide mineral. The iron oxide mineral promotes the activity of the zero valent iron. The process and system may involve multiple stages. A stage may be optimized for treatment with respect to a particular contaminant. The present composition, system, and process are effective for treating a fluid containing one or more of a variety of contaminants such as toxic metals, metalloids, oxyanions, and dissolved silica. It may be applied to treating various aqueous fluids, such as groundwater, subsurface water, and aqueous industrial waste streams.

1 . A treatment system for treating an aqueous suspension, wherein the treatment system comprises a chemical reactor system comprising a fluidized bed reactor comprising a reactive zone. 
     
     
         2 . The treatment system according to  claim 1 , wherein the chemical reactor system further comprises an internal settling zone in communication with the reactive zone. 
     
     
         3 . The treatment system according to any one of  claims 1 - 2 , wherein the internal settling zone is located in the top region of the chemical reactor system. 
     
     
         4 . The treatment system according to any one of  claims 1 - 3 , wherein the internal settling zone comprises an opening at the bottom of the internal settling zone adapted for the communication with the reactive zone. 
     
     
         5 . The treatment system according to any one of  claims 1 - 4 , wherein the internal settling zone comprises an outlet adapted for removal of effluent from the internal settling zone. 
     
     
         6 . The treatment system according to any one of  claims 1 - 5 , wherein the reactive zone comprises a conduit. 
     
     
         7 . The treatment system according to  claim 6 , wherein the conduit is central with respect to the reactive zone. 
     
     
         8 . The treatment system according to any one of  claims 1 - 7 , wherein the treatment system is a multi-stage system comprising an additional reactor system. 
     
     
         9 . The treatment system according to any one of  claims 1 - 8 , wherein the reactive zone comprises a reactive solid and a secondary reagent. 
     
     
         10 . The treatment system according to  claim 9 , wherein the reactive solid comprises iron. 
     
     
         11 . The treatment system according to any one of  claims 9 - 10 , wherein the secondary reagent comprises ferrous iron. 
     
     
         12 . The treatment system according to any one of  claims 9 - 11 , wherein the reactive solid further comprises an iron oxide mineral. 
     
     
         13 . The treatment system according to  claim 12 , wherein iron mineral comprises magnetite. 
     
     
         14 . The treatment system according to any one of  claims 1 - 13 , wherein the aqueous suspension comprises a waste influent. 
     
     
         15 . The treatment system according to any one of  claims 1 - 14 , wherein the aqueous suspension comprises a toxic material. 
     
     
         16 . The treatment system according to any one of  claims 1 - 15 , wherein the toxic material is selected from the group consisting of selenium, arsenic, mercury, aluminum, antimony, beryllium, thallium, chromium, cobalt, lead, cadmium, silver, zinc, nickel, molybdenum, nitrates, bromates, iodates, periodates, and borates. 
     
     
         17 . A process for treating an aqueous suspension, comprising feeding the aqueous suspension to the treatment system according to any one of  claims 1 - 14 . 
     
     
         18 . The process according to  claim 17 , wherein the process further comprises removing a toxic material from the aqueous suspension. 
     
     
         19 . The process according to  claim 18 , wherein the removing comprises:
 a) at least one of reacting, adsorbing, and precipitating the toxic material from the aqueous suspension so as to form removable solids in treated effluent; and   b) separating the removable solids from the aqueous suspension.   
     
     
         20 . The process according to  claim 19 , wherein the removable solids comprise at least a portion of the toxic material encapsulated in the removable solids. 
     
     
         21 . A process for treating wastewater comprising a toxic material, comprising exposing the wastewater to a reactive material system so as to remove toxic material from the wastewater, wherein the reactive material system comprises zero valent iron particles and ferrous iron, wherein the exposing comprises:
 a) at least one of reacting, adsorbing, and precipitating the toxic material from the wastewater so as to form removable solids in treated wastewater, wherein the removable solids comprise at least a portion of the toxic material encapsulated in at least a portion of an iron mineral derived from the reactive material system; and   b) separating the removable solids from the treated wastewater.   
     
     
         22 . A new and improved fluidized bed apparatus for wastewater treatment comprising a fluidized bed, a fluidized reactive zone, an internal solid/liquid separating zone in fluid communication with said reactive zone, an aerating basin, and a settling basin. 
     
     
         23 . The apparatus of  claim 22  further comprising control and metering systems for monitoring and manipulating chemical processes within said reactor. 
     
     
         24 . The apparatus of  claim 23  further comprising a sand filtration bed. 
     
     
         25 . The apparatus of  claim 22  further comprising a central conduit in the fluidized bed reactor to promote convective fluid flow enhancing mixing. 
     
     
         26 . The apparatus of  claim 25  further comprising a motorized stirrer in conjunction with said central conduit configured so fluid flow within the conduit is down and flow within the fluidized bed reactor outside the conduit is up. 
     
     
         27 . The apparatus of  claim 26  further comprising a sand filtration bed. 
     
     
         28 . The apparatus of  claim 22  further comprising at least one additional fluidized bed apparatus configured as stages in series with said first apparatus. 
     
     
         29 . The apparatus of  claim 28  further comprising control and metering systems for monitoring and manipulating chemical processes run within said reactors. 
     
     
         30 . The apparatus of  claim 29  wherein the chemical process conditions within different stages are varied to optimize results. 
     
     
         31 . The apparatus of  claim 22 , wherein the fluidized reactive zone comprises a composition comprising zero valent iron, iron oxide mineral, and ferrous iron. 
     
     
         32 . A composition for treating an aqueous suspension comprising zero valent iron, iron oxide mineral, and ferrous iron.