# US 2016/0257589 A1 · Method and apparatus for nitrogen removal in wastewater > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0257589 A1 - Document ID: US20160257589A1 - Status: Published application - Kind: A1 - Application number: 15/150,842 - Filed: 2016-05-10 - Published: 2016-09-08 - Earliest claimed: 2012-09-13 - Assignees: D.C. Water & Sewer Authority; Hampton Roads Sanitation District - Applicants: D.C. Water & Sewer Authority; Hampton Roads Sanitation District - Inventors: Bernhard Wett; Ahmed Omari; Pusker Regmi; Mark Miller; Charles B. Bott; Sudhir N. Murthy - Web page: https://patentgrep.com/patent/US20160257589A1 ## CPC - C02F 3/305: {characterised by the denitrification} - C02F 3/006: {Regulation methods for biological treatment} - C02F 3/303: {characterised by the nitrification} - C02F 3/34: characterised by the microorganisms used - C02F 3/307: {characterised by direct conversion of nitrite to molecular nitrogen, e.g. by using the Anammox process} - C02F 3/348: {characterised by the way or the form in which the microorganisms are added or dosed} - C02F 2101/16: Nitrogen compounds, e.g. ammonia - C02F 2209/14: NH3-N - C02F 2209/22: O2 - 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) ## Abstract A reactor and control method thereof for nitrogen removal in wastewater treatment achieves a measured control of maintaining high ammonia oxidizing bacteria (AOB) oxidation rates while achieving nitrite oxidizing bacteria (NOB) repression, using various control strategies, including: 1) ammonia and the use of ammonia setpoints, 2) operational DO and the proper use of DO setpoints, 3) bioaugmentation of a lighter flocculant AOB fraction, and 4) proper implementation of transient anoxia within a wide range of reactor configurations and operating conditions. ## Claims ### Claim 1 1) A reactor for biological nitrogen removal from wastewaters comprising a nitrite-shunt which targets repression of the nitrite oxidizing bacteria (NOB) under controlled transient anoxia conditions, the conditions being controlled either along the flow-path or along the process time-line, wherein a dissolved oxygen (DO) profile switches between a lower DO-setpoint of less than 0.1 mg/L and a upper DO-setpoint of greater than 1.0 mg/L, and wherein at least one of an aeration system activation interval or the upper DO setpoint are set such that an on-line measured ammonia concentration is higher than an ammonia setpoint of 1.5 mg NH4—N/L in more than 75% of the transiently aerated reactor volume (in space or time). ### Claim 2 (depends on 1) 2) The reactor of claim 1, wherein said reactor has a limited aerobic sludge retention time just sufficient to reach the ammonia setpoint by controlled extension of anoxic periods or volume and by operating a high sludge wasting rate, wherein the sludge wasting rate is controlled to maintain high DO setpoints (>1 mg/L) in the case of ammonia concentration control of aeration. ### Claim 3 (depends on 1) 3) The reactor of claim 1, wherein said reactor further includes a bioaugmentation of aerobic ammonia oxidizing bacteria (AOB) produced from a high-strength ammonia sidestream reactor, wherein the less dense and more compressible or unattached sludge fraction is selected from the high-strength ammonia sidestream reactor for the bioaugmentation by an appropriate device and fed to the reactor at a maximum rate leading to a retention time of the bioaugmentation fraction of less than 10 days in the sidestream system. ### Claim 4 (depends on 3) 4) The reactor of claim 3, wherein the appropriate device for selecting the biomass for Bioaugmentation from the high-strength ammonia sidestream reactor for the bioaugmentation comprises one of the following devices: a cyclone, centrifuge, lamella settler, sieve, or integrated biofilm process. ### Claim 5 (depends on 1) 5) The reactor of claim 1, wherein said reactor includes a bioaugmentation of anammox organisms from a sidestream reactor to the mainstream reactor in order to provide microbial competitors for nitrite which help to repress NOB. ### Claim 6 (depends on 1) 6) The reactor of claim 1, wherein a mixed liquor solids (MLSS) concentration is higher than 2 g/L, or equivalent biomass quantities in a biofilm system, in order to enhance oxygen uptake rate (OUR) to facilitate rapid transitions from aerobic to anoxic conditions. ### Claim 7 (depends on 1) 7) The reactor of claim 1, further comprising an aeration control system which is configured to maximize the frequency of transitions between aerobic and anoxic conditions. ### Claim 8 (depends on 1) 8) The reactor of claim 1, further comprising an aeration control system which is configured to increase the upper DO-setpoint in correspondence with load increase. ### Claim 9 (depends on 1) 9) The reactor of claim 1, wherein said reactor can be any one of a sequencing batch reactor, a completely mixed reactor, an oxidation ditch or a plug flow process, wherein at least one of the oxic and anoxic steps or DO setpoints is controlled either in time or in space. ### Claim 10 (depends on 1) 10) The reactor of claim 1, wherein said reactor includes one of a suspended growth process, a granular process or a biofilm process or a hybrid combination of these processes. ### Claim 11 (depends on 1) 11) The reactor of claim 1, wherein the separation process can occur using a settler, a dissolved air flotation device, a filter or a membrane. ### Claim 12 (depends on 1) 12) The reactor of claim 1, wherein said reactor maintains a high oxygen uptake rate to allow for a rapid transition to anoxia from an aerated state. ### Claim 13 (depends on 12) 13) The reactor of claim 12, wherein said reactor feeds a minimum mass-flow of organic carbon to the reactor to enhance heterotrophic growth for more rapid transition to anoxia from an aerated state and for additional competition for nitrite for improved NOB-repression. ### Claim 14 14) A method of controlling a reactor for biological nitrogen removal from wastewaters comprising a nitrite-shunt which targets repression of the nitrite oxidizing bacteria (NOB) under controlled transient anoxia conditions, the conditions being controlled either along a flow-path or along a process time-line, wherein a dissolved oxygen (DO) profile switches between a lower DO-setpoint of less than 0.1 mg/L and an upper DO-setpoint of greater than 1.0 mg/L, and wherein at least one of an activation of an aeration system of the reactor or the upper DO setpoint is dependent on an on-line measured ammonia concentration being higher than an ammonia setpoint of 1.5 mg NH4—N/L in more than 75% of transiently aerated reactor volume (in space or time). ### Claim 15 (depends on 14) 15) The method of claim 14, further comprising controlling said reactor to have a limited aerobic sludge retention time just sufficient to reach the ammonia setpoint by controlled extension of anoxic periods or volume and by operating a high sludge wasting rate, wherein the wasting rate is controlled to maintain high DO setpoints (>1 mg/L) in the case of ammonia concentration control of aeration. ### Claim 16 (depends on 14) 16) The method of claim 14, further comprising said reactor receiving a bioaugmentation of aerobic ammonia oxidizing bacteria (AOB) produced from a high-strength ammonia sidestream reactor, wherein the less dense and more compressible or unattached sludge fraction is selected from the high-strength ammonia sidestream reactor for the bioaugmentation by an appropriate device and fed to the main reactor system at a maximum rate leading to a retention time of the bioaugmentation fraction of less than 10 days in the sidestream system. ### Claim 17 (depends on 16) 17) The method of claim 16, wherein the appropriate device is one of a cyclone, centrifuge, lamella settler, sieve, or integrated biofilm process. ### Claim 18 (depends on 14) 18) The method of claim 14, wherein a bioaugmentation of anammox organisms from a sidestream reactor to the mainstream reactor is provided in order to provide microbial competitors for nitrite which help to repress NOB. ### Claim 19 (depends on 14) 19) The method of claim 14, wherein the reactor is controlled to achieve a mixed liquor solids (MLSS) concentration of higher than 2 g/L, or equivalent biomass quantities in a biofilm system, in order to enhance oxygen uptake rate (OUR) to facilitate rapid transitions from aerobic- to anoxic conditions. ### Claim 20 (depends on 14) 20) The method of claim 14, wherein controlling said reactor further comprises controlling an aeration control system to maximize the frequency of transitions between aerobic and anoxic conditions. ### Claim 21 (depends on 14) 21) The method of claim 14, wherein controlling said reactor further comprises controlling an aeration control system to increase the higher DO-setpoint in correspondence with load increase. ### Claim 22 (depends on 14) 22) The method of claim 14, wherein said reactor controlled by the method can be any one of a sequencing batch reactor, a completely mixed reactor, an oxidation ditch or a plug flow process, and wherein at least one of the oxic and anoxic steps or DO setpoints are controlled in time or in space.