Device and method for controlling a microorganism content

1 . A device for controlling a content of microorganisms in a liquid, the device comprising:

a measuring unit for measuring said microorganism content,

a control unit, which is connected to the measuring unit and which is configured to determine a dosage of a biocide based on the measured microorganism content in order to achieve a predefined microorganism content,

a supply unit, which is connected to the control unit and which is configured to supply the biocide to the liquid in the dosage determined by the control unit, and

a computing unit connected to the measuring unit and the control unit,

wherein the control unit is configured to determine the dosage using a model with at least one parameter of a relationship between an amount of biocide supplied in a time interval and a change in the microorganism content caused by the supplied amount of biocide in this time interval, and

wherein the computing unit is configured to calculate the at least one parameter for use by the control unit in at least one later time interval from a recording of the microorganism content measured by the measuring unit over at least one past time interval and the amount of biocide supplied in this time interval.

2 . The device according to claim 1 , wherein said model is given by an equation

dX

dt

=

-

kB

n

⁢

X

with:

dX

dt

change in microorganism content in a time interval,

k parameter of the model,

B amount of biocide supplied in this time interval,

n dilution coefficient of the biocide and

X measured microorganism content.

3 . The device according to claim 1 , wherein said model is given by an equation

dX

dt

=

-

k

1

⁢

B

0

n

⁢

e

-

k

2

⁢

nt

⁢

X

with:

dX

dt

change in microorganism content in a time interval,

k 1 , k 2 parameters of the model,

B 0 amount of biocide supplied in this time interval at the time of supply,

n dilution coefficient of the biocide and

X measured microorganism content.

4 . The device according to claim 1 , wherein the measuring unit is a flow cytometer which is configured to measure the content of microorganisms of a predetermined type.

5 . The device according to claim 1 , wherein the computing unit is configured to calculate the at least one parameter after each time interval of a sequence of time intervals from the recording of the microorganism content measured by the measuring unit over at least one immediately preceding time interval and the amount of biocide supplied in this at least one immediately preceding time interval.

6 . The device according to claim 1 , wherein the supply unit is configured to select the biocide from one or more components according to a predetermined composition, wherein the device further comprises a control unit which is connected to the supply unit and which is configured to predetermine the composition for the supply unit.

7 . The device according to claim 6 , wherein the device comprises at least one sensor for measuring at least one measurand comprising pH, temperature, pressure and conductivity of the liquid, wherein the control unit is connected to the at least one sensor and is configured to predetermine the composition depending on at least this/these measurand/s.

8 . The device according to claim 6 , wherein the control unit is configured to predetermine a composition for the supply unit at regular time intervals.

9 . A method for controlling a content of microorganisms in a liquid, the method comprising

in a control process:

measuring said microorganism content by means of a measuring unit,

determining a dosage of a biocide with a view to achieving a predefined microorganism content based on the measured microorganism content and a model comprising at least one parameter of a relationship between an amount of biocide supplied in a time interval and a change in microorganism content caused by the supplied amount of biocide in that time interval, and

supplying the biocide in the determined dosage to the liquid; and

in a tracking process parallel or intermittent to the control process:

calculating the at least one parameter from a recording of the microorganism content measured by the measuring unit over at least one past time interval and the amount of biocide supplied in that time interval for use in the control process in at least one later time interval.

10 . The method according to claim 9 , wherein said model is given by an equation

dX

dt

=

-

kB

n

⁢

X

with:

dX

dt

change in microorganism content in a time interval,

k parameter of the model,

B amount of biocide supplied in this time interval,

n dilution coefficient of the biocide and

X measured microorganism content.

11 . The method according to claim 9 , wherein said model is given by an equation

dX

dt

=

-

k

1

⁢

B

0

n

⁢

e

-

k

2

⁢

nt

⁢

X

with:

dX

dt

change in microorganism content in a time interval,

k 1 , k 2 parameters of the model,

B 0 amount of biocide supplied in this time interval at the time of supply,

n dilution coefficient of the biocide and

X measured microorganism content.

12 . The method according to claim 9 , wherein the measuring unit measures the content of microorganisms of a predetermined type.

13 . The method according to claim 9 , wherein the tracking process is carried out after each time interval of a sequence of time intervals, wherein the at least one parameter is calculated from the recording of the microorganism content measured by the measuring unit over at least one immediately preceding time interval and the amount of biocide supplied in this at least one immediately preceding time interval.

14 . The method according to claim 9 , wherein the biocide is selected from one or more components according to a predetermined composition.

15 . The method according to claim 14 , wherein at least one sensor measures at least one measurand comprising pH, temperature, pressure and conductivity of the liquid and the composition is predetermined depending on at least this/these measurand/s.

16 . The method according to claim 14 , wherein a composition is predetermined at regular time intervals.