File Name: Turbidity.pptFeb 2001 Turbidity & Suspended Solids Overview

File Name: Turbidity.pptFeb 2001 Turbidity Definition  Turbidity in liquid is caused by the presence of suspended solids. Measurement  A Nephelometric process is used which measures the quantity of light scattered by the particles at right angles

File Name: Turbidity.pptFeb 2001 Units of Measurement  FTU = Formazine Turbidity Units  NTU = Nephelometric Turbidity Units  TUF - Turbidity Units Formazine 1 FTU = 1 NTU = 1 TUF = 2.5 ppm SiO 2 / liter

File Name: Turbidity.pptFeb 2001 Light Scatter  Small particles which are smaller than the light wavelength (approx.. 1/10) scatter light in all directions  Particles which are the same size as the light wavelength scatter light with a distinct distribution in the forward direction  Large particles (approx.. 5 x larger than the wavelength used) scatter light with a more distinct distribution in a forward direction

File Name: Turbidity.pptFeb 2001 Turbidity Sensor ISO Standard 7027  Measurement wavelength of up to 860 nm (+/- 30 nm)  Measurement angle of 90 o between the light source and receiver

File Name: Turbidity.pptFeb 2001 Comparison of Standards for Potable Water ASTM D1889 & EPA  Defines visible light source Tungsten lamp operated at color temperature between 2200 and 3000 o K  Pro Current Standard  Con Expected lamp life 1 year Affected by stray light Affected by Color Affected by air bubbles International Standard, ISO 7027  Defines wavelength The wavelength of the incident radiation shall be 860 nm  Pro Method accepted on initial review by ASTM LED life 10 years Not affected by stray light Not affected by color Only two sensors to measure from Drinking Water to Sludge  Con Affected by air bubbles in low Turbidity range

File Name: Turbidity.pptFeb 2001 Installation Options

File Name: Turbidity.pptFeb 2001 De-bubble Flow Chamber

File Name: Turbidity.pptFeb 2001 Typical Wastewater Treatment Plant