Anaerobic suspended growth treatment of contaminated water

Abstract

A system may include a reactor, in which an anaerobic environment exists, that includes a slurry of at least contaminated water and a mixed bacterial culture of facultative bacteria and anaerobic bacteria. The mixed bacterial culture may be suspended within the slurry. The contaminated water may include contaminants associated with a non-metal, a metal, or a metalloid. The mixed bacterial culture may react with the contaminated water to reduce or remove the contaminants from the contaminated water to create a treated slurry. The reactor may output the treated slurry. The system may also include a filtration device to receive the treated slurry; remove, from the treated slurry, the mixed bacterial culture and the contaminants, reduced or removed from the contaminated water, to create treated water; and output the treated water. The system may also include an aeration device to add dissolved oxygen to the treated water, and output the treated water. The system may also include a reaction device where iron or aluminum salts are added to remove phosphorous, selenite, arsenate, or other contaminants which adsorb onto iron or aluminum oxyhydroxide solids. The system may also include a filtration device to remove the solids from the water, and output the treated water.

What is claimed is: 
     
         1 . An anaerobic treatment system to treat contaminated water, the treatment system comprising:
 a reactor consisting of one or more chambers providing an anaerobic environment, the one or more reactors comprising:
 a slurry of contaminated water comprising one or more contaminants selected from the group consisting of a perchlorate, a metal, or a metalloid; and 
 a mixed bacterial culture suspended within the slurry and not attached to a physical substrate associated with attached growth technology, wherein the mixed bacterial culture comprises:
 metal-reducing bacteria; and 
 a mixing system that mixes the slurry to maintain the mixed bacterial culture and/or other solids within the one or more reactors in suspension; and 
 
   a means for adding separately to the one or more reactors or to the influent contaminated water an organic material selected from the group consisting of a low molecular weight organic acid, and a simple carbohydrate wherein the organic material acts as an electron donor for the mixed bacterial culture and thus enables the mixed bacterial culture to react with the contaminated water to biologically and/or chemically reduce and precipitate the contaminants in the contaminated water;   wherein biological and/or chemical reduction and precipitation of the contaminants occurs in the anaerobic environment in the one or more reactors; and   a filtration device that retains the mixed bacterial culture.   
     
     
         2 . The system of  claim 1  wherein the filtration device:
 removes the mixed bacterial culture and the precipitated contaminants including precipitated metals and metalloids if present; and 
 outputs treated water from which the precipitated contaminants have been removed. 
 
     
     
         3 . The system of  claim 1  wherein the filtration device is external to the reactor. 
     
     
         4 . The system of  claim 1  wherein the filtration device is inside the reactor. 
     
     
         5 . The system of  claim 1  wherein at least a portion of the retained mixed bacterial culture is returned to the one or more reactors. 
     
     
         6 . The system of  claim 1  wherein at least one of the contaminants is selected from the group consisting of mercury, lead, copper, and selenium. 
     
     
         7 . The system of  claim 5  further comprising a means for increasing the rate of flow of the recovered mixed bacterial culture back to the reactor. 
     
     
         8 . A method for treating contaminated water in an anaerobic environment, the method comprising:
 providing an anaerobic treatment system comprising:
 a reactor consisting of one or more chambers housing an anaerobic environment, the one or more reactors comprising:
 a slurry of contaminated water comprising contaminants wherein at least one of the contaminants is a perchlorate, a metal, or a metalloid; and 
 a mixed bacterial culture suspended within the slurry and not attached to a physical substrate associated with attached growth technology, wherein the mixed bacterial culture comprises metal-reducing bacteria that biologically and/or chemically reduce one or more of the contaminants, 
 
 delivering the contaminated water to the anaerobic environment in the one or more reactors; 
 mixing the slurry under anaerobic conditions to keep the mixed bacterial culture in suspension; 
 providing separately to the one or more reactors or to the influent contaminated wastewater an organic material selected from the group consisting of a low molecular weight organic acid, and a simple carbohydrate, wherein the organic material acts as an electron donor to enable the mixed bacterial culture to react with the contaminated water to biologically and/or chemically reduce and precipitate the contaminants in the contaminated water, while maintaining the anaerobic environment; and 
 producing a treated slurry comprising the organic material, the mixed bacterial culture, and the contaminated water from which the contaminants have been precipitated, reduced or removed; and 
 retaining at least a portion of the mixed bacterial culture with a filtration device. 
   
     
     
         9 . The method of  claim 8  further comprising:
 recovering at least a portion of the retained mixed bacterial culture; and 
 returning at least a portion of the recovered mixed bacterial culture to the one or more reactors. 
 
     
     
         10 . The method of  claim 8  wherein the filtration device:
 removes, from the treated slurry, the mixed bacterial culture and the precipitated metals and metalloids if present; and 
 outputs, treated water from which the biologically and/or chemically reduced contaminants have been removed. 
 
     
     
         11 . The method of  claim 8  wherein the filtration device is external to the reactor. 
     
     
         12 . The method of  claim 8  wherein the filtration device is inside the reactor. 
     
     
         13 . The method of  claim 9  further comprising increasing the rate of the biological and chemical reactions in the reactor by increasing the rate of flow of the recovered mixed bacterial culture back to the reactor. 
     
     
         14 . The method of  claim 8  wherein at least one of the contaminants is selected from the group consisting of mercury, lead, copper, and selenium. 
     
     
         15 . A method for treating contaminated water, the method comprising:
 providing an anaerobic environment comprising a suspended mixed bacterial culture of metal reducing bacteria, wherein the mixed bacterial culture is not attached to a physical substrate associated with attached growth technology;   providing a slurry of contaminated water, wherein the contaminated water comprises one or more contaminants selected from the group consisting of a perchlorate, a metal, and a metalloid;   providing an organic material, wherein the organic material is selected from the group consisting of a low molecular weight organic acid and a simple carbohydrate, wherein the organic material acts as an electron donor for the mixed bacterial culture;   biologically and/or chemically reducing the contaminants in the contaminated water by delivering the contaminated water and organic material to the anaerobic environment, wherein the organic material mediates the biological and/or chemical reduction and precipitation of the contaminants in the contaminated water by the metal reducing bacteria and wherein the biological and/or chemical reduction and precipitation takes place in the anaerobic environment; and   removing the reduced and precipitated contaminants from the contaminated water to produce treated water; and   retaining at least a portion of the mixed bacterial culture with a filtration device.   
     
     
         16 . The method of  claim 15  further comprising:
 recovering at least a portion of the mixed bacterial culture from the treated water; and 
 returning at least some of the recovered mixed bacterial culture to the anaerobic environment. 
 
     
     
         17 . The method of  claim 15  wherein the mixed bacterial culture is suspended via a mixing system. 
     
     
         18 . The method of  claim 15  wherein the organic material is added to the contaminated water prior to delivery of the contaminated water to the anaerobic environment. 
     
     
         19 . The method of  claim 16  further comprising increasing the rate of the biological and chemical reactions in the reactor by increasing the rate of flow of the recovered mixed bacterial culture back to the reactor. 
     
     
         20 . The method of  claim 15  wherein at least one of the contaminants is selected from the group consisting of mercury, lead, copper, and selenium.