Method and device for online monitoring of water quality
A method for monitoring quality of a water flow in a pipe, by diverting a flow into a laser particle counter to count particles within a particle size interval in the water, to continuously determine the number of particles within the size interval, comparing the count with a reference value and taking a sample of the water from the pipe when the count exceeds a threshold value, and also diverting a flow of water from the pipe into a unit that separates the flow into fractions, and taking a sample of at least one of said fractions when the count exceeds a threshold value, and also sending an alarm signal when the count exceeds a threshold value. When the count exceeds at threshold value, the water is treated with ozone.
1. A method for monitoring quality of water flowing in a pipe, the method comprising:
diverting a flow of water from the pipe into a laser particle counter, the laser particle counter continuously counting particles within a particle size interval S n in the diverted flow of water so as to continuously determine a number c i n of particles within the particle size interval per volume of water;
comparing c i n with a previously determined reference value c ref n for determining the number of particles per volume of water flowing in the pipe;
taking a sample of the water from the pipe when c i n exceeds a predetermined threshold value TV A n for more than a predetermined length of time t A n ;
diverting a flow of water from the pipe into a filter that separates the flow into a permeate flow and a concentrate flow;
taking a sample of at least one of the permeate flow and the concentrate flow when c i n exceeds a predetermined threshold value TV B n for more than a predetermined length of time t B n ; and
sending an alarm signal when c i n exceeds a predetermined threshold value TV C n for more than a predetermined length of time t C n .
2. The method of claim 1 , further comprising adding ozone to the water flowing in the pipe when c i n exceeds a predetermined threshold value TV D n for more than a predetermined length of time t D n so as to bring the water flowing in the pipe into contact with ozone for a period of time.
3. The method of claim 2 , wherein the water flowing in the pipe is brought into contact with the ozone at a concentration of from 0.05 to 5 mg ozone/m 3 of water for a time period of 5 minutes to 2 hours.
4. The method of claim 1 , wherein the filter is a ceramic membrane that separates the flow.
5. The method of claim 1 , wherein the particle counter continuously counts particles within a particle size interval S 1 of from 0.1 to 3 μm to provide a number c i 1 of particles within the size interval per volume of water.
6. The method of claim 5 , further comprising taking a sample of the permeate flow of the filtering unit when c i 1 exceeds a predetermined threshold value TV B 1 for more than a predetermined length of time t B 1 .
7. The method of claim 6 , wherein additionally the particle counter continuously counts particles within a particle size interval S 2 of from 3 to 25 μm to provide a number c i 2 of particles within said size interval per volume of water.
8. The method of claim 7 , further comprising taking a sample of the concentrate flow of the filtering unit when c i 2 exceeds a predetermined threshold value TV B 2 for more than a predetermined length of time t B 2 .
9. The method of claim 8 , further comprising performing at least one chemical, biochemical or microbiological analysis of a taken sample of water.
10. The method of claim 1 , wherein the laser particle counter continuously counts particles within a particle size interval S 2 of from 3 to 25 μm to provide a number c i 2 of particles within said size interval per volume of water.
11. The method of claim 10 , further comprising taking a sample of the concentrate flow of the filtering unit when c i 2 exceeds a predetermined threshold value TV B 2 for more than a predetermined length of time t B 2 .
12. The method of claim 11 , wherein additionally the particle counter continuously counts particles within a particle size interval S 1 of from 0.1 to 3 μm to provide a number c i 1 of particles within said size interval per volume of water.
13. The method of claim 1 , further comprising performing at least one chemical, biochemical or microbiological analysis of a taken sample of water.
14. The method of claim 1 , further comprising:
continuously measuring at least one physical or chemical parameter of the flow of water;
comparing a measured value P of the physical or chemical parameter with a reference value Pref of the parameter previously determined for the water; and
sending an alarm signal when P differs from Pref by more than a predetermined threshold value for more than a predetermined length of time t p .
15. The method of claim 14 , wherein the parameter is selected from total dissolved solids, ORP (oxidation reduction potential), dissolved oxygen, pH, electrical conductivity, temperature and turbidity.
16. The method of claim 5 , further comprising:
continuously measuring at least one physical or chemical parameter of the flow of water;
comparing a measured value P of the physical or chemical parameter with a reference value Pref of the parameter previously determined for the water; and
sending an alarm signal when P differs from Pref by more than a predetermined threshold value for more than a predetermined length of time t p .
17. The method of claim 1 , further comprising:
continuously measuring at least one physical or chemical parameter of the flow of water;
comparing a measured value P of the physical or chemical parameter with a reference value Pref of the parameter previously determined for the water; and
sending an alarm signal when P differs from Pr f by more than a predetermined threshold value for more than a predetermined length of time t p .