Turbidity measurement

TURBIDITY MEASUREMENT

BY – PRAFUL HANMANTE

CONTENTS

• Basics about turbidity

• Measurement units

• measurement techniques

• Calibration

• Application

TURBIDITY

• Turbidity is the amount of cloudiness in the

water.

• It is indicator of water quality.

INFERENCES

• Particle size

• Bubbles

• Stray light

• Absorbing particles

• Contamination

CLASSIFICATION OF DEVICES

3 Factors affecting design of device

• Light source

• Detection angle

• Number of detector

LIGHT SOURCE

3 most commonly used light sources

• Incandescent

• LED

• Laser based

LIGHT SOURCES

Source Wavelength Application

Incandescent light 400-600nm Shorter wavelength for

short particles

LED 830-890 nm Not effected by color in

sample

LASER 660nm Sensitive to smaller

changes,

Most effective for

filtration

DETECTION ANGLES

90 degree Most commonly used,

180 degree High turbidity application

Backscatter detection

angle

High turbidity application

Multiple detection

angle

Colour compensation

Dual light source

detector

Correction for color absorption and optics fouling

SIGNAL ON 180

DEGREES DETECTOR

What are we measuring ?

Robert Lagrange Sli

de

12

Concentration

Intensity

SIGNAL ON 90

DEGREES DETECTOR

What are we measuring ?

Robert Lagrange Sli

de

13

Concentration

Intensity

CALIBRATION

Two point calibration

-Zero point calibration- distilled water

-Spanning the instrument

Primary standard –formazin

COMPARISON

SURFACE SCATTER

HACH TURBIDITY

METER

GENERAL GUIDELINES

• Drinking water should have a turbidity of 5 NTU/JTU or

less.

• • Where water is chlorinated, turbidity should be less than

5 NTU/JTU and preferably less than 1 NTU/JTU for

chlorination to be effective.