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Home> | Plant, Process & Control | >Sensors and instrumentation | >Satron's VOD optical sensors improve utilisation and performance at dairy |
Satron's VOD optical sensors improve utilisation and performance at dairy
06 October 2023
A LARGE dairy which produces numerous types of white cheese has improved their ultrafiltration and reverse osmosis systems using Satron’s optical sensors. The innovative VOD sensor measures the purity of the permeate, (the liquid that has passed through a filter or filtrate) and thus the effectiveness of the filtration.

The Satron VOD optical sensor measures the absorption of light by the liquid as it passes the sensor. The absorption is measured with light of different wavelengths depending on the desired application. Its ability to detect remnants of fat, protein or lactose in a liquid, means that it can monitor if there are milk residues in water.
Therefore, Satron is trusted to protect quality and productivity by providing 24/7 monitoring and immediate detection of the non-optimal operation of either the ultrafiltration or reverse osmosis processes. A process operator will be alerted to resolve any problems that arise to quickly optimise the membrane filtration, and resume full capacity. The sensors protect against product loss and also have environmental benefits, helping to ensure more sustainable production.
"An O ring seal may fail in the Ultra Filtration system, causing a leak, so that the efficiency of the whole system decreases. This is detected by the sensor immediately and gives an alarm to the process operator who can get the O-ring changed, and then the membrane filtration system can get back to full production again," explained a continuous improvement engineer at the plant.
"Since the sensor measures the purity in the permeate, then registers it immediately if the permeate contains fat or protein - and that's just fat and protein collected in the retentate. Without the sensor, the valuable fat and protein would run into the permeate and be lost, thereby the yield of membrane filtration would be significantly reduced."
Filter efficiency decreases with time
Four Satron VOD optical sensors are installed on the various membrane systems. As the membranes gradually become worn, their capacity decreases until it is time to change the membranes. When the membranes are worn, small amounts of fat, protein or lactose enter the permeate, which the Satron sensor detects.
With the information from the sensors and analysis of the permeate, the dairy can change the membranes at an optimal time.
Recycling water for CIP
The dairy also fitted one Satron VOD sensor on their reverse osmosis system, because the permeate from the ultrafiltration plant contains valuable lactose that is not filtered out.
Reverse osmosis is a filtration technology, where the incoming liquid is pressed through a very fine membrane, typically as fine as 0.001 to 0.0001µm, which can filter both ions and dissolved substances, for example, lactose.
The dairy's reverse osmosis plant therefore captures the lactose and an income stream is now provided by supplying the extracted lactose to other dairies for further processing. Improving the utilisation of all of the milk’s constituents enables more sustainable operation of the dairy. After the reverse osmosis treatment, the permeate is now clean enough to be used instead of fresh water, significantly reducing the dairy’s water consumption.
Satron has a range of optical sensors to provide optimal solutions to many applications and are trusted in many dairies, creameries and food and beverage plants.
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