System and methods of determining liquid phase turbidity of multiphase wastewater

Patent metadata

Field	Value
Publication number	US-10281383-B2
Application number	US-201314075613-A
Country	US
Kind code	B2
Filing date	Nov 8, 2013
Priority date	Nov 15, 2012
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

Systems and methods for determining liquid phase turbidity of multiphase wastewater. A turbidity sensor is provided with multiphase wastewater, such as by placement of the sensor in a reaction chamber, and generates a signal in response to a detected turbidity of the wastewater. The generated signal is sampled to produce a plurality of signal samples. The samples are compared to a threshold, and a turbidity of the wastewater is determined based on samples falling within the threshold. The threshold may be determined based on a statistical analysis of the plurality of samples, or may be set to a predetermined value. The wastewater may be provided by placing the turbidity sensor in a flocculation chamber, and a control signal generated based on the determined turbidity of the wastewater. This control signal may be used to adjust the amount of a chemical, such as a coagulant, introduced into the wastewater.

First claim

What is claimed:

1. A method of determining liquid phase turbidity of a multiphase wastewater consisting of:
placing a turbidity sensor consisting of a housing unit containing a light emitter and a light sensor, into the multiphase wastewater prior to any dissolved air flotation unit or clarifier;
emitting a light signal and receiving the signal at the light sensor indicative of an amount of light scattered by or transmitted through the wastewater;
sampling the signal to produce a plurality of signal sample values wherein the sample values produced by the liquid phase of the wastewater in an absence of floc particles produces a first set of sample values and wherein the sample values produced when floc particles are in a path of the signal produces a second set of values;
comparing the sample values to a threshold; wherein the threshold is based on a probability density distribution produced from the set of sample values produced from light scattered by the liquid phase without additional scattering or reflection from the floc particles; and
setting the threshold so that at least a portion of the sample values lies below the threshold;
identifying the sample values falling below the threshold; and
determining the turbidity of the liquid phase of the wastewater based on the identified sample values.

2. The method of claim 1 further comprising:
determining the threshold based at least in part on the values of the samples.

3. The method of claim 1 wherein determining the threshold further comprises:
identifying the second group of samples having values clustered around the second signal value; and
setting the threshold to a value between the first signal value and the second signal value.

4. The method of claim 3 wherein the second signal value is a value indicating a higher level of turbidity than the first signal value.

5. The method of claim 1 further comprising:
generating a control signal based on the determined turbidity of the wastewater.

6. The method of claim 5 wherein:
determining the turbidity of the wastewater includes determining a statistical value of falling below the threshold; and
comparing the statistical value to a reference value, and based on the difference between the statistical value and a reference value setting the value of the control signal;
wherein the statistical value may be an average or mean value of samples below the threshold, a median value of the samples below the threshold, a filtered value of the samples below the threshold filter, or based on the last sample obtained that was flagged as being below the threshold.

7. The method of claim 5 further comprising adjusting an amount of a chemical added to the wastewater based on the control signal.

8. The method of claim 7 wherein the chemical includes a coagulant.

9. An apparatus for treating wastewater consisting of:
a processor; and
a memory-containing program code that, when executed by the processor, causes the apparatus to:
receive a signal indicative of an amount of light scattered by the liquid phase of the wastewater or by floc particles;
sample the signal to produce a plurality of signal sample values;
compare the sample values to a threshold;
identify the sample values falling below the threshold; and
determine the turbidity of the wastewater based on the identified sample values;
wherein the threshold is based on a probability density distribution produced from the set of sample values produced from light scattered by the liquid phase without additional scattering or reflection from the floc particles.

10. The apparatus of claim 9 wherein the program code is further configured to cause the apparatus to determine the threshold based on the values of the samples by:
identifying a first group of samples having values clustered around a first signal value;
setting the threshold so that at least a portion of the first group of samples lies below the threshold.

11. The apparatus of claim 10 wherein the program code is further configured to cause the apparatus to further determine the threshold by:
identifying a second group of samples having values clustered around a second signal value; and
setting the threshold to a value between the first signal value and the second signal value, wherein
the second signal value is a value indicating a higher level of turbidity than the first signal value.

12. The apparatus of claim 9 wherein the program code is further configured to generate a control signal based on the determined turbidity of the liquid phase of a multiphase wastewater.

13. The apparatus of claim 12 wherein the program code is configured to generate the control signal by:
determining a statistical value of the samples falling below the threshold; and comparing the statistical value to a reference value, wherein the reference value is determined on the current liquid phase turbidity or light transmittance data, and based on the difference between the statistical value and a reference value setting the value of the control signal;
wherein the statistical value may be an average or mean value of samples below the threshold, a median value of the samples below the threshold, a filtered value of the samples below the threshold filter, or based on the last sample obtained that was flagged as being below the threshold.

14. The apparatus of claim 12 wherein the control signal is used to adjust an amount of a chemical added to the wastewater.

15. The apparatus of claim 9 further comprising:
a turbidity sensor configured to sample multiphase wastewater containing floc and generate the signal indicative of the amount of light scattered by the floc in the wastewater.

16. A method of controlling liquid phase turbidity of multiphase wastewater consisting of:
transmitting a beam of light from a light source into the multiphase wastewater; detecting an amount of light scattered or transmitted through the wastewater at a light sensor, wherein the light sensor generates an output signal that is proportional to the amount of scattered or transmitted light incident to the light sensor;
receiving the output signal at a processor, wherein the processor produces a plurality of signal sample values, wherein the sample values produced by the liquid phase of the wastewater in an absence of floc particles produces one set of sample values and wherein the sample values produced when floc particles are in a path of the signal produces a second set of values;
comparing the signal sample values to a threshold; wherein the threshold is based on a probability density distribution produced from a first set of sample values produced from light scattered by the liquid phase without additional scattering or reflection from the floc particles;
determining the turbidity of the liquid phase of the wastewater based on the identified sample values; and
adding a chemical additive to the wastewater system to achieve a desired turbidity.

17. The method of claim 16 , wherein the light sensor detects the amount of scattered light through the wastewater wherein the detected light is proportional to the amount of scattered light incident to the light sensor.

Assignees

• Solenis Tech Lp

Inventors

• Goldblatt Mikel E

Classifications

• C02F2209/11

  Turbidity · CPC title

• C02F1/66

  by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) · CPC title

• G01N21/532

  with measurement of scattering and transmission · CPC title

• C02F1/5245

  using basic salts, e.g. of aluminium and iron · CPC title

• C02F2209/001

  Upstream control, i.e. monitoring for predictive control · CPC title