Preventing mobilization of trace metals in subsurface aquifers due to the introduction of oxygenated water

Abstract

A method for providing the recharge of water into underground aquifers while preventing the mobilization of trace metals. The recharge water may be used for storage and subsequent withdrawal, or to regain or increase the long term beneficial use of an aquifer. The recharge water may be also be used to influence the groundwater flow in the aquifer. Water is treated and recharged by the addition of a small amount of a sulfide compound to remove dissolved oxygen and prevent dissolution of negative valence sulfur bearing minerals, such as pyrite, in the subsurface. The recharged water may increase the pressure head in the aquifer, alter the groundwater flow pattern to prevent the encroachment of objectionable quality water, or to segregate water of different quality. The recharge water may be fresh or brackish depending on the specific objectives of the application.

1 . A method to remove dissolved oxidants from water introduced into a subsurface aquifer and to resist trace metal mobilization in said subsurface aquifers due to the dissolution of minerals containing sulfur comprising the steps of:
 providing a recharge conveyance system to allow said water to reach the aquifer;   recharging said water to said aquifer while measuring the flow rate of said water being recharged;   forming a treated recharged water by adding a measured amount of sulfide compound into said recharge water based on said flow rate and chemical composition of said recharge water; and   storing said recharged water in said underground aquifer   
     
     
         2 . The method of  claim 1 , further comprising the step of: allowing said water to remain in said underground aquifer to increase the hydraulic head in the aquifer or for subsequent withdrawal 
     
     
         3 . The method according to  claim 1 , wherein said sulfide compound is a compound selected from the group consisting of Group Ia and Group IIa metal sulfides, hydrosulfides (bisulfides), and hydrogen sulfide. 
     
     
         4 . The method according to  claim 1 , wherein said sulfide compound is sodium hydrosulfide. 
     
     
         5 . The method according to  claim 1 , wherein said aquifer has strata containing arsenic and other trace metals. 
     
     
         6 . The method according to  claim 1 , wherein said the water is recharged into said aquifer increasing the hydraulic head pressure in said aquifer and changing the groundwater flow direction in said aquifer. 
     
     
         7 . The method according to  claim 1 , wherein said recharge conveyance is a recharge aquifer system. 
     
     
         8 . The method according of  claim 1 , wherein said recharge conveyance is selected from the group consisting of a well, recharge basin, infiltration gallery, infiltration trench, infiltration pit, and infiltration shaft. 
     
     
         9 . The method according to  claim 1 , wherein said water reaches said aquifer via gravity flow or applied head pressure. 
     
     
         10 . The method according to  claim 1 , wherein the water quality of said aquifer is controlled by changing groundwater flow patterns laterally or vertically within or to said aquifer. 
     
     
         11 . The method of  claim 1 , wherein said introduction of said water limits migration of water containing undesirable chemical constituents within a USDW. 
     
     
         12 . The method according to  claim 1 , wherein said introduction of said water limits the introduction of salt into a USDW 
     
     
         13 . The method according to  claim 1 , wherein said aquifer is a USDW. 
     
     
         14 . The method according to  claim 1 , wherein said sulfur is in a formal negative oxidation state. 
     
     
         15 . The method according to  claim 14 , wherein said mineral is pyrite.