# US 2021/0276909 A1 · Nitrogen sparging assisted anoxic biological water treatment system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0276909 A1 - Document ID: US20210276909A1 - Status: Published application - Kind: A1 - Application number: 17/192,622 - Filed: 2021-03-04 - Published: 2021-09-09 - Earliest claimed: 2020-03-04 - Assignees: United States Government, AS Represented By the Administrator of the U.S. Epa - Applicants: United States Government, as represented by the Administrator of the U.S. EPA - Inventors: Asher Keithley; Daniel Williams; Nicholas Dugan; Darren Lytle - Web page: https://patentgrep.com/patent/US20210276909A1 ## CPC - C02F 3/305: {characterised by the denitrification} - C02F 9/00: Multistage treatment of water, waste water or sewage - C02F 1/004: {using large scale industrial sized filters} - C02F 1/20: by degassing, i.e. liberation of dissolved gases (degasification of liquids in general B01D19/00; arrangement of degassing apparatus in boiler feed supply F22D) - C02F 1/66: by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) - C02F 3/06: using submerged filters - C02F 3/26: using pure oxygen or oxygen-rich gas - C02F 3/2806: {Anaerobic processes using solid supports for microorganisms} - C02F 3/2813: {using anaerobic contact processes} - C02F 2101/163: {Nitrates} - C02F 2103/007: {Contaminated open waterways, rivers, lakes or ponds} - C02F 2103/06: Contaminated groundwater or leachate - C02F 2303/16: Regeneration of sorbents, filters - C02F 2305/06: Nutrients for stimulating the growth of microorganisms - Y02W 10/10: Biological treatment of water, waste water, or sewage - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract Systems and methods are provided for nitrogen gas sparging assisted biological treatment of water. In one example, a denitrification system may include a media-packed column or bed through which nitrogen gas is sparged to remove dissolved oxygen from water. In some examples, an external carbon source and electron donor may be added to the media-packed column or bed to facilitate biological removal of the nitrate and/or other contaminants from the water. In this way, by relying on the sparged nitrogen gas to remove the dissolved oxygen, less of the external carbon source and electron donor may be employed as compared to denitrification systems not assisted by nitrogen gas sparging. ## Claims ### Claim 1 A denitrification system for groundwater or surface water, the denitrification system comprising: a media-packed column or bed through which nitrogen gas is sparged continuously from a bottom of the media-packed column or bed to remove dissolved oxygen from the groundwater or surface water; a reaeration unit; and a polishing filter or bed. ### Claim 2 (depends on 1) The denitrification system of claim 1, wherein an external carbon source and electron donor is added to the groundwater or surface water to facilitate removal of the dissolved oxygen and nitrate from the groundwater or surface water through microbial activity. ### Claim 3 (depends on 2) The denitrification system of claim 2, wherein less of the external carbon source and electron donor is added to the denitrification system relative to an oxic denitrification system including no nitrogen gas sparging and removing a like amount of dissolved oxygen and nitrate as the denitrification system. ### Claim 4 (depends on 1) The denitrification system of claim 1, wherein nitrate is removed from the groundwater or surface water via biological reduction. ### Claim 5 (depends on 1) The denitrification system of claim 1, wherein the nitrogen gas is sparged continuously through the media-packed column or bed only when the groundwater or surface water is flowed through the media-packed column or bed during operation of the denitrification system. ### Claim 6 (depends on 1) The denitrification system of claim 1, wherein the denitrification system is operated on a continuous basis. ### Claim 7 (depends on 1) The denitrification system of claim 1, wherein nitrate nitrogen (NO3—N) in effluent groundwater or surface water is maintained below 10 mg NO3—N/L during operation of the denitrification system. ### Claim 8 (depends on 1) The denitrification system of claim 1, wherein nitrite nitrogen (NO2—N) in effluent groundwater or surface water is maintained below 1 mg NO2—N/L during operation of the denitrification system. ### Claim 9 (depends on 1) The denitrification system of claim 1, wherein no nitrate-concentrated waste brine stream is generated. ### Claim 10 (depends on 1) The denitrification system of claim 1, wherein a pH control additive is added to maintain a pH of the groundwater or surface water to between 7 and 9 and/or orthophosphate is added as an essential nutrient. ### Claim 11 (depends on 1) The denitrification system of claim 1, wherein backwashing is performed in the denitrification system at a lower backwashing frequency relative to an oxic denitrification system including no nitrogen gas sparging and removing a like amount of dissolved oxygen and nitrate as the denitrification system. ### Claim 12 A column or bed for denitrifying groundwater or surface water, the column or bed comprising: a packing of discrete media, wherein the column or bed is fluidically coupled to a nitrogen gas source, and wherein nitrogen gas from the nitrogen gas source is continuously sparged through the column or bed to remove dissolved oxygen from the groundwater or surface water. ### Claim 13 (depends on 12) The column or bed of claim 12, wherein the column or bed is fluidically coupled to each of a reaeration unit and a discrete media filter, column, or bed. ### Claim 14 (depends on 12) The column or bed of claim 12, wherein the column or bed is fluidically coupled to a carbon and electron donor additive source, the carbon and electron donor additive source feeding an external carbon source and electron donor to the column or bed to facilitate removal of the dissolved oxygen and nitrate. ### Claim 15 (depends on 12) The column or bed of claim 12, wherein the column or bed has less biomass and less nitrogen gas accumulation relative to an oxic dual-media filter including no nitrogen gas sparging and removing a like amount of dissolved oxygen and nitrate as the column or bed. ### Claim 16 A method for treating water containing dissolved nitrate and other oxidized inorganic contaminants amenable to biological conversion, the method comprising: feeding the water as influent into an anoxic contactor packed with media; feeding additives to the water to facilitate biological conversion of the dissolved nitrate and the other oxidized inorganic contaminants; introducing nitrogen gas through a diffuser positioned at a bottom of the anoxic contactor to sparge and remove dissolved oxygen from the water; establishing colonies of microorganisms to convert the dissolved nitrate to additional nitrogen gas within the anoxic contactor; introducing air or oxygen gas to the water in a reaeration unit; establishing colonies of microorganisms assimilating residual dissolved nitrate and consuming residual dissolved organic carbon within an aerobic filter or bed; removing particulates from the water via the aerobic filter or bed; and expelling an effluent from the aerobic filter or bed, the effluent including a lower nitrate concentration than the water fed into the anoxic contactor as the influent. ### Claim 17 (depends on 16) The method of claim 16, wherein sparging with the nitrogen gas in the anoxic contactor lowers a concentration of the dissolved oxygen in the water. ### Claim 18 (depends on 16) The method of claim 16, wherein sparging with the nitrogen gas in the anoxic contactor to remove the dissolved oxygen lowers an amount of an external carbon source and electron donor included in the additives necessary to facilitate the biological conversion of the dissolved nitrate relative to an oxic denitrification system not sparged with nitrogen gas which reduces a like amount of dissolved oxygen and nitrate. ### Claim 19 (depends on 16) The method of claim 16, wherein the water is flowed through the anoxic contactor, the reaeration unit, and the aerobic filter in sequence. ### Claim 20 (depends on 16) The method of claim 16, wherein the additives include an external carbon source and electron donor to facilitate the removal of residual dissolved oxygen not removed by sparging with the nitrogen gas and the biological conversion of the dissolved nitrate.