Systems and methods for controlling nitrous oxide production in wastewater treatment facilities
Methods and systems for controlling nitrous oxide production in a wastewater treatment facility in which wastewater is treated with microbes in a biological reactor. Nitrous oxide production can be controlled by determining an amount of two or more nutrients in the biological reactor, calculating a value that represents a comparison of the values, comparing the calculated value to a threshold value, and optionally taking a corrective action to reduce nitrous oxide production based on the comparison. In one aspect, nitrous oxide production can be controlled by determining an amount of ammonium in the biological reactor, determining an amount of a nitrogen compound that can include nitrite, nitrate, and/or hydroxylamine, calculating a value that compares the amount of ammonium to the amount of the nitrogen compound, and taking a corrective action that changes a system parameter to reduce the nitrous oxide production if the calculated value surpasses a threshold limit.
1 . A method for controlling nitrous oxide production in a wastewater treatment facility in which wastewater is treated with microbes in an anoxic zone and an aerobic zone, the method comprising:
determining an amount of ammonium in the aerobic zone;
determining an amount of at least two nitrogen compounds in the aerobic zone, the at least two nitrogen compounds including nitrite and hydroxylamine;
determining an amount of at least one of total organic carbon (TOC) and chemical oxygen demand (COD) in the aerobic zone;
calculating a first value that represents a comparison of the determined amount of ammonium and the determined amount of the nitrite such that the first value is indicative of relative amounts of the ammonium and the nitrite in the aerobic zone;
comparing the calculated first value to a first threshold value;
calculating a second value that is indicative of relative amounts of (a) the at least one of TOC and COD and (b) the hydroxylamine in the aerobic zone;
comparing the calculated second value to a second threshold value;
based on both the comparing steps, performing at least one of (a) displaying a notification on a display; and (b) taking one or more corrective actions to change a system parameter of the wastewater treatment facility.
2 . The method according to claim 1 , wherein the calculated first value is a ratio of the determined amount of ammonium and the determined amount of nitrite.
3 . The method according to claim 1 , wherein the one or more corrective actions are performed, and wherein the one or more corrective actions are effective to reduce an amount of nitrous oxide that is produced in the wastewater treatment facility.
4 . The method according to claim 1 , wherein the one or more corrective actions are performed, and wherein the one or more corrective actions are selected from the group consisting of (i) changing an amount of chemical oxygen demanded added to the anoxic zone; (ii) changing an amount of dissolved oxygen in the aerobic zone; and (iii) changing an amount of ammonium in the wastewater in an influent to either the anoxic zone or the aerobic zone.
5 . The method according to claim 1 , wherein the one or more corrective actions are performed and wherein the one or more corrective actions includes increasing a hydraulic retention time of the anoxic zone.
6 . The method according to claim 1 , wherein the step of determining the amount of the at least two nitrogen compounds in the aerobic zone includes determining an amount of nitrate in the aerobic zone, and further comprising calculating a ratio of the determined amount of ammonium and the determined amount of nitrate.
7 . The method according to claim 1 , wherein the one or more corrective actions includes at least one of adding COD to the anoxic zone and decreasing an amount of dissolved oxygen in the aerobic zone.
8 . The method according to claim 1 , further comprising determining an amount of ammonium in an influent to either the anoxic zone or the aerobic zone, and comparing the measured amount of ammonium in the influent to a third threshold value.
9 . The method according to claim 1 , wherein the one or more corrective actions are performed and include changing a hydraulic retention time of the aerobic zone.
10 . The method according to claim 1 , wherein the one or more corrective actions are performed and include changing a hydraulic retention time of the anoxic zone.
11 . The method according to claim 1 , wherein (i) the at least two nitrogen compounds includes nitrate, (ii) the method further includes calculating a ratio that is indicative of relative amounts of the ammonium and the nitrate in the aerobic zone, and (iii) based on the comparison of the ratio to the threshold value, the one or more corrective actions are performed to increase a hydraulic retention time of the anoxic zone.