Turbidity measurement tool
It is an improved way of measuring turbidity (the quality of a liquid being cloudy, opaque, or thick with suspended matter) using both light intensity and time of flight measurement. This new device allows, at an affordable price, to widen the turbidity measurement range and improve the resolution.
Benefits
- Wider measurable turbidity range
- Higher resolution (x10)
- Higher sensitivity
- More robust
- Smaller probe
- Performs turbidity and flow velocity measurement at the same time
Issue
Turbidity measurement is used in many fields, for example in the food industry (beverages, dairy, cheese, etc.), in drinking water treatment, or in the production of textiles and semiconductors.
The measurement of TSS (Total Suspended Solids) concentrations is still often based on automatic sampling equipment, followed by laboratory analysis. This has multiple disadvantages:
- the representativeness of the samples is low
- often requires interventions in difficult conditions (where there is a risk of inhaling toxic gases, falling, or microbiological contamination)
- the installation and maintenance of sampling equipment requires a lot of work
Alternatively, a conventional optical turbidity measurement device can provide information on the TSS present in the water. The relationship with the TSS concentration is quite variable. In particular, the turbidity measurements are more sensitive to the presence of fine elements than to the presence of coarse elements. In addition, this method is sensitive to dissolved elements with a colouring character.
Acoustic turbidity can be applied to opaque samples, but the instrumental control necessary for its proper use makes it a rare technique.
Moreover, standard optical turbidimeters are inefficient in heavy loaded flows and need high maintenance due to fouling.
Solution
We are developing a new technology, based on time-resolved single-photon counting: a short pulse of light is injected into the sample through an optical fiber. A second fiber, placed next to the first, collects the backscattered light. The lightspeed, the intensity, and the signal shape are analyzed to find the turbidity of the sample.
This technology allows for:
- Extension of the measured turbidity range to low (<0.01 FNU) and high (>10 000 FNU) amounts with a single instrument
- Higher resolution (0,001 NTU)
- Higher sensitivity
- More robust: measurements not disturbed by probe fouling
- Smaller probe to limit sample perturbation, using optical fibers
- Perform turbidity and flow velocity measurements at the same time
The technology effectiveness was demonstrated during a dedicated test using formazine calibrated solutions.