Methods of treating water to remove contaminants and water treatment plants for the practice thereof

Abstract

The present disclosure relates to methods of treating water to remove contaminants, including harmful metal ions, and water treatment plants for practicing such methods. In an embodiment, the process includes adding a sulfur-containing, metal-decreasing agent; an iron (III)-containing, metalloid-decreasing agent; forming a solid precipitate from the contaminated water, wherein the solid precipitate includes a solid metal sulfide, a solid iron metalloid, a solid calcium metalloid, or a combination thereof; and separating the contaminated water from the solid precipitate to form purified water.

What is claimed is: 
     
         1 . A process for treating contaminated water comprising:
 adding at least one sulfur-containing, metal-decreasing agent to the contaminated water;   adding at least one iron (III)-containing, metalloid-decreasing agent or at least one calcium-containing, metalloid-decreasing agent to the contaminated water;   forming a solid precipitate from the contaminated water, wherein the solid precipitate includes a solid metal sulfide, a solid iron metalloid, a solid calcium metalloid, or a combination thereof; and   separating the contaminated water from the solid precipitate to form purified water.   
     
     
         2 . The process of  claim 1 , further comprising:
 adding a hardness decreasing agent to the contaminated water, wherein the hardness decreasing agent includes a sulfate, a carbonate, or a combination thereof.   
     
     
         3 . The process of  claim 1 , further comprising:
 adding a sulfate decreasing agent or a chloride decreasing agent to the contaminated water, wherein at least one of the sulfate decreasing agent and the chloride decreasing agent include a barium containing compound, a bismuth containing compound, or a combination thereof.   
     
     
         4 . The process of  claim 1 , wherein adding at least one iron (III)-containing, metalloid-decreasing agent to the contaminated water occurs during or after adding at least one sulfur-containing, metal-decreasing agent to the contaminated water. 
     
     
         5 . The process of  claim 1 , wherein the at least one sulfur-containing, metal-decreasing agent includes CH 4 N 2 S, C 2 H 5 NS, NaHS, KHS, H 2 S, or a combination thereof. 
     
     
         6 . The process of  claim 1 , wherein, provided that the contaminated water contains a metal ion selected from the group consisting of cadmium, chromium, copper, lead, mercury, zinc, nickel, any metal ion that forms a solid sulfide precipitate, or a combination thereof,
 the solid metal sulfide is selected from the group consisting of a cadmium sulfide, a chromium sulfide, a copper sulfide, a lead sulfide, a mercury sulfide, a zinc sulfide, a nickel sulfide, any metal that forms a solid sulfide precipitate, or a combination thereof.   
     
     
         7 . The process of  claim 1 , wherein the iron (III)-containing, metalloid-decreasing agent includes Fe 2 (SO 4 ) 3 , FeCl 3 , ammonium iron(III) sulfate, or a combination thereof. 
     
     
         8 . The process of  claim 1 , wherein, provided that the contaminated water contains a metalloid selected from the group consisting of an arsenate, a selenate or a selenite, a borate, a phosphate, or a combination thereof,
 the solid iron metalloid is selected from the group consisting of an iron arsenate, an iron selenite, an iron borate, a metaborate, an iron phosphate, an iron hydroxide, or a combination thereof.   
     
     
         9 . The process of  claim 2 , wherein the hardness decreasing agent includes (NH 3 ) 2 SO 4 , (NH 3 ) 2 CO 3 , NH 3 HCO 3 , Na 2 SO 4 , Na 2 CO 3 , NaHCO 3 , any metal that forms a solid sulfide precipitate, or a combination thereof; and
 wherein, provided that the contaminated water contains magnesium, calcium, or a combination thereof, the solid precipitate includes MgSO 4 , MgCO 3 , CaSO 4 , CaCO 3 , or a combination thereof.   
     
     
         10 . The process of  claim 3 , wherein the sulfate decreasing agent contains Ba(NO 3 ) 2 , BaCl 2 , Bi(NO 3 ) 3 , a bismuth oxynitrate, or a combination thereof. 
     
     
         11 . The process of  claim 3 , wherein, provided that the contaminated water contains chloride, sulfate, or a combination thereof,
 the solid precipitate includes barium chloride, barium sulfate, bismuth oxychloride, bismuth sulfate, or a combination thereof.   
     
     
         12 . The process of  claim 1 , wherein the purified water contains a fertilizer selected from the group consisting of NH 2 CN, NaNO 3 , KNO 3 , NH 3 NO 3 , or a combination thereof. 
     
     
         13 . The process of  claim 1 , further comprising a desalinization step. 
     
     
         14 . The process of  claim 1 , wherein one or both of the at least one sulfur-containing, metal-decreasing agent or the at least one iron (III)-containing, metalloid-decreasing agent is added as a solid. 
     
     
         15 . The process of  claim 1 , further comprising:
 measuring a level of metal ion or metalloid in the contaminated water.   
     
     
         16 . A water treatment plant configured to perform the process of  claim 1  comprising:
 one reaction vessel; or two or more reaction vessels, the two or more of the reaction vessels being interconnected. 
 
     
     
         17 . The water treatment plant of  claim 16 , configured to perform the following steps, in order:
 adding at least one sulfur-containing, metal-decreasing agent to the contaminated water;   adding at least one iron (III)-containing, metalloid-decreasing agent or adding at least one calcium-containing, metalloid-decreasing agent to the contaminated water; and   adding a sulfate decreasing agent to the contaminated water, wherein the sulfate decreasing agent includes a barium containing compound, a bismuth containing compound, or a combination thereof; and   providing a purified water containing a fertilizer.   
     
     
         18 . The water treatment plant of  claim 16  comprising:
 a water inlet; 
 a water outlet; and 
 one or more reaction vessels, wherein at least one of the reaction vessels is connected to the water inlet and at least one of the reaction vessels is connected to the water outlet, 
 wherein the water treatment plant is configured to add the at least one sulfur-containing, metal-decreasing agent or the at least one iron (III)-containing, metalloid-decreasing agent to at least one of the reaction vessels. 
 
     
     
         19 . The water treatment plant of  claim 18 , wherein the water treatment plant is configured to add a hardness decreasing agent to the contaminated water, wherein the hardness decreasing agent includes a sulfate, a carbonate, or a combination thereof. 
     
     
         20 . A process for treating contaminated water comprising:
 adding one or both of at least one sulfur-containing, metal-decreasing agent or at least one iron (III)-containing, metalloid-decreasing agent to the contaminated water;   forming a solid precipitate, wherein the solid precipitate includes a solid metal sulfide, a solid iron metalloid, or a combination thereof; and   removing the contaminated water from the solid precipitate to form purified water, wherein the purified water contains a fertilizer.   
     
     
         21 . A process for treating contaminated or ion-containing water comprising:
 adding at least one sulfur-containing, metal-decreasing agent, at least one iron (III)-containing, metalloid-decreasing agent, a hardness decreasing agent, at least one sulfate reducing agent, and adding a sulfate decreasing agent, or a combination thereof, simultaneously or in any order,   removing ion-contaminants identified or quantified from the contaminated water.   
     
     
         22 . The process claim of  20 , further comprising:
 adding at least one sulfur-containing, metal-decreasing agent or at least one iron (III)-containing, metalloid-decreasing agent into one, two or more tanks individually, in sequence, or in a combination.   
     
     
         23 . The process claim of  21 , further comprising:
 transferring fluid from tank to tank, filtering after each tank.   
     
     
         24 . The process claim of  23 , further comprising:
 removing of a solid precipitate before, after, or during any reagent addition steps by filtering or settling.   
     
     
         25 . The process of  claim 23 , further comprising:
 collecting the solid precipitate.   
     
     
         26 . The process of  claim 23 , further comprising:
 concentrating or drying the solid precipitate before disposal.