Process Monitoring of Water and Wastewater Treatment

MWEA 2018 JOINT EXPO AND OPERATORS DAY

February 7, 2018

Functions of a Process Monitoring System

•Compliance / Compliance Assurance

•Early Warning / Upset Detection

•Operational Efficiency / Process Control

2

Dissolved Oxygen (DO)

Wastewater

• Compliance

• Aeration control /

Energy efficiency

Drinking Water

• Taste

• Corrosion control

3

Energy Efficiency

4Source: Blum, D., High Efficiency Aeration, Clarifier, Ilinois WEA, Summer 2013

D.O.

Polarographic DO Sensor

Oxygen diffuses through membrane

Oxygen reduced (consumed) at cathode

Electrons flow = electrical signal (mA)

Oxygen concentration proportional to signal level

O2 H2O

e-

Probe Solution

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

e-

e-e-

H2OH2O

H2O

H2O

H2O

H2O

H2O

H2O

H2OH2O

H2O

H2O

Anode

Cathode

Membrane

Measuring Dissolved Oxygen using Luminescence

6

The excitation fiber

in the sensor emits

a blue light

causing the sensing element to glow,

or luminesce red.

Measuring Dissolved Oxygen using Luminescence

7

Oxygen is constantly moving through

the Diffusion Layer, affecting the

luminescence of the sensing layer.

The amount of oxygen passing

through the sensing layer is

inversely proportional to the

lifetime of the luminescence in

the sensing layer.

The lifetime of the

luminescence is

measured by the

sensor and compared

against the reference

and a stable dissolved

oxygen concentration is

calculated.

Water Treatment Process Monitoring

8

Physico-chemical treatment

• pH

• Chlorine

• Turbidity

• Alkalinity

• Ortho-phosphate (PO4)

• Total Organic Carbon (TOC)

• Sludge level

• Nitrate

• Dissolved Oxygen (DO)

Wastewater Treatment Process Monitoring

9

Biological and Physico-chemical treatment

• Dissolved Oxygen (DO)

• Total Suspended Solids (TSS)

• Oxidation Reduction Potential (ORP)

• Sludge level

• Ammonia (NH3; N -3 valence)

• Nitrate (NO3-; N +5 valence)

• Ortho-phosphate (PO4)

• Chlorine

• pH

Process Monitoring System Components – Universal Controller

Display

System settings

Power supply

Outputs

10

Process Monitoring System Components – Sensors

Measurement

devices

Signal processing

Instrumental Methods of Analysis / Signal Types

12

Optical

Absorption Emission

Potentiometric Polarographic

Scattering

Electrochemical

Fluorimetry

Ammonia / Ammonium Measurement

Potentiometry – ion selective electrodes (ISE)

Colorimetry (absorption) – cabinet analyzers

13

Potentiometry Sensor Design

14

Reference

electrode

Ion

Selective

Electrode

MembraneJunction

(mV)

Wastewater Ammonia-Based Aeration Control

Ammonia / Ammonium Applications

15

Ortho-Phosphate Detection & Measurement by Colorimetry

reagent

sample

with PO43-

mixing photometeryellow

coloration

=420 nm

Ortho-phosphate Applications

17

Drinking water Wastewater

Control of a Ferric Chloride Dosing Pump (Phosphorus Removal from Wastewater)

light

Turbidity, Total Suspended Solids (TSS) Detection by Light Scattering

19

Backscatter

(digested sludge)

absorbance /

turbidimetry

Nephelometry

(clean water)

< 90°

(mixed liquor)

Turbidity / Total Suspended Solids Applications

20

Drinking Water (compliance)

Water or Wastewater

(non-compliance)

Turbidity Measurement Standards

21

Use of LED 860 (nm)• Weak sensitivity to very small particles

• No influence of colored samples

ISO 7027 LED 860 nm

DIN EN 27027 LED 860 nm

US EPA Method 180.1Tungsten Filament

ASTM D 1889-88 Tungsten Filament

All methods: nephelometric 90°

NTU = FNU = FTU

90°

Tungsten filament• High sensitivity to small particles

• Influence by colored samples

Wastewater Activated Sludge Solids Monitoring System

22

Immersion sensor in mixed liquor Insertion sensor in

return activated sludge

Total Organic Carbon (TOC)

Wastewater

• Surrogate parameter

• Water Reuse

Drinking Water

• Disinfection by-

products

23

Basic Building Blocks of TOC Analysis

Sample

Introduction Oxidation Detection Display

1. Syringe

2. Process/Online

3. Sample loop

4. Autosampler

5. Solids option

1. Combustion

2. Persulfate at 98 °C

3. UV/Persulfate

1. Display

2. Printout

3. Computer

4. Strip Chart Recorder

Carbon

Dioxide

1. NDIR (absorption)

2. Membrane Conductivity (electrochemistry)

TOC Analysis in the Drinking Water Treatment Process

25

Upstream Coagulant Control

26

Downstream DBP Mitigation

27

TOC Analysis – A Different Method

Sample

Introduction Oxidation Detection Display

1. Syringe

2. Process/Online

3. Sample loop

4. Autosampler

5. Solids option

1. Combustion

2. Persulfate at 98 °C

3. UV/Persulfate

1. Display

2. Printout

3. Computer

4. Strip Chart Recorder

Carbon

Dioxide

1. NDIR (absorption)

2. Membrane Conductivity (electrochemistry)

1. UV (absorption)

Direct UV Detection of TOC

TOC Monitoring for (Waste)Water Reuse

30

Control ozone dosage

Monitor treatment

performance (upstream

and downstream

sensors)

Not for compliance

Blanket Level

Wastewater

• Sludge recirculation

(ASP)

• Sludge removal

Drinking Water

• Sludge removal

31

Sludge Blanket Depth Measurement

32Optical Acoustic

Advantages:

• High resolution

• TSS profile

Disadvantages

• Moving parts

• Limited sampling

Advantages:

• Less fouling

• Continuous

• Long-term stability

Disadvantages

• Fluffy sludge /

ambiguous results

Wastewater – Activated Sludge Clarifier

33

Q + Qras

Qras

Q

MLSS

Contact YSI or Systems Specialties

34

www.YSI.com

E-mail

robert.smith@xyleminc.com

ksomsel@sysspec.com

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@YSIinc

@DrRobYSI

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https://www.youtube.com/user/YSIinc

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