Method for detecting a concentration of chlorate-ions in an aqueous solution, apparatus for detecting a concentration of chlorate-ions and control unit

1. A method for determining an actual concentration of chlorate ions in an aqueous solution, comprising:

detecting a total concentration of chlorine, chlorite, and chlorine dioxide in a defined volume of the aqueous solution;

applying energy to the defined volume of the aqueous solution to transform substantially all chlorine species therein to chloride and chlorate;

detecting a concentration of chlorate ions in the defined volume after the energy is applied; and

subtracting the total concentration of chlorine, chlorite, and chlorine dioxide from the detected concentration of chlorate ions contained in the defined volume after the energy is applied to determine the actual concentration of chlorate ions in the aqueous solution.

2. The method of claim 1 , wherein the aqueous solution is flowing in a water treatment facility.

3. The method of claim 2 , wherein the concentration of chlorate ions in the defined volume is detected downstream of an energy source.

4. The method of claim 3 , wherein the energy is applied by exposing the defined volume to ultraviolet radiation for an exposure time.

5. The method of claim 4 , further comprising adjusting an intensity of the ultraviolet radiation to promote the transformation to chloride and chlorate.

6. The method of claim 4 , further comprising adjusting the exposure time to promote the transformation to chloride and chlorate.

7. The method of claim 6 , wherein the exposure time is adjusted by adjusting a flow rate of the aqueous solution.

8. The method of claim 7 , wherein the flow rate is adjusted prior to applying energy to the defined volume.

9. The method of claim 5 , wherein the intensity of the ultraviolet radiation is adjusted by adjusting a power or wavelength parameter of a source of the ultraviolet radiation.

10. The method of claim 1 , wherein a target concentration of chlorate ions in the aqueous solution is lower than 5 mg/L.

11. The method of claim 1 , wherein the concentration of chlorate ions in the aqueous solution is measured online as part of a water treatment process.

12. The method of claim 1 , wherein the energy is applied consecutively to a plurality of defined volumes.

13. The method of claim 12 , wherein the concentration of chlorate ions in the plurality of defined volumes is detected after the energy is applied.

14. The method of claim 13 , wherein the actual concentration of chlorate ions in the aqueous solution is determined based on the detected concentration of chlorate ions in the plurality of defined volumes.

15. The method of claim 14 , wherein the actual concentration of chlorate ions in the aqueous solution is determined continuously.

16. The method of claim 1 , wherein the total concentration of chlorine, chlorite, and chlorine dioxide is continuously detected before the energy is applied.

17. The method of claim 13 , wherein the actual chlorate concentration is based on the total concentration of chlorine, chlorite, and chlorine dioxide and the detected chlorate concentration for the same defined volume or the same plurality of defined volumes.

18. The method of claim 17 , wherein a location of a defined volume of the aqueous solution is tracked based on a flow rate of the aqueous solution or a known reference point for the defined volume.

19. The method of claim 9 , wherein the wavelength parameter is between about 100 nm and about 400 nm, and wherein the power is between about 20 W and about 100 W.

20. The method of claim 11 , wherein the concentration of chlorate ions in the aqueous solution is measured with an amperometric sensor.