Method and arrangement for a water treatment
View Patent ↗The invention relates to a water treatment using an UV AOP. The invention combines an UV AOP ( 11 ) applied to a water containing a free chlorine species ( 8 ) with a chemical post treatment ( 14 ), a quenching. The quenching ( 14 ) is applied to said water ( 9 ) after the UV AOP ( 11 ) able to reduce a remaining content of said free chlorine species in said water ( 9 ).
1. A method for treating water comprising:
adding a chlorine species to a water to be treated in an amount to provide a dissolved chlorine species having a weight ratio in the water to be treated relative to contaminants of the water to be treated in a range of about 1,000:1 to about 10,000:1;
irradiating the water with ultraviolet irradiation to degrade-a first portion of the dissolved chlorine species; and
quenching the water to reduce a second portion of the dissolved chlorine species.
2. The method of claim 1 , wherein the chlorine species is one of chlorine and chlorine dioxide.
3. The method of claim 1 , further comprising measuring a concentration of the dissolved chlorine species at at least one of a time before and after irradiating the water with the ultraviolet irradiation to provide a measured concentration of the dissolved chlorine species.
4. The method of claim 3 , further comprising controlling the quenching based on the measured concentration of the dissolved chlorine species.
5. The method of claim 1 , wherein quenching comprises adding a quenching agent to the water.
6. The method of claim 1 , wherein the water to be treated comprises 2 μg/l or less of water contaminants.
7. The method of claim 1 wherein the weight ratio of the dissolved chlorine species in the water to be treated and contaminants of the water to be treated is in a range of about 3,000:1 to about 8,000:1.
8. The method of claim 7 , wherein the weight ratio of the dissolved chlorine species in the water to be treated and contaminants of the water to be treated is about 6,000:1.
9. The method of claim 1 , wherein irradiating comprises irradiating at a wavelength of about 100 nm to 400 nm.
10. The method of claim 1 , wherein irradiating comprises irradiating at a dose of about 400 J/m 2 to 4000 J/m 2 .
11. The method of claim 1 , wherein the water to be treated is from a source of one of municipal water, potable water, waste water, industrial water, process water and ultrapure water.
12. The method of claim 3 wherein measuring a concentration of the dissolved chlorine species comprises measuring a concentration of the second portion of the dissolved chlorine species.
13. The method of claim 5 wherein quenching comprises reacting the quenching agent with the second portion of the dissolved chlorine species.
14. The method of claim 5 wherein quenching comprises adsorbing of the second portion of the dissolved chlorine species by the quenching agent.
15. The method of claim 5 wherein quenching comprises forming ions and water.
16. The method of claim 5 wherein the quenching agent comprises one of hydrogen peroxide, thiosulphate, thiosulphate salts and activated carbon.