Waste Water Analysis Online TOC Analysis of Vegetable Oils and Animal Fats in Waste Water

Author / Editor: Piet Broertjes / Dr. Jörg Kempf

The continuous online analysis of oils and fats in waste water is known to be one of the most toughest applications. Many oil-in-water analysers have trouble handling this highly contaminated oily and fatty waste water. Not so for the QuickTOC (Total Organic Carbon) analyser from LAR.

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View of an oil and fat separator. The influent water is warm and contains a high load of mainly oils and fats.
View of an oil and fat separator. The influent water is warm and contains a high load of mainly oils and fats.
(Picture: LAR)

Oils and fats are extracted from raw materials, like seeds, seeds leafs and animal fats, by the way of mechanical treatment, drying and heating, extraction with use of a solvent and steam, concluding with separation via evaporation. During these processes quite a bit of the dissolved and emulsified oils can leak into the warm process water and finally end up in the sewer system.

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How Oil Becomes Fat ...

Basically oil and water are immiscible. Oil can be present as free oil, as an oil sheen and as mixed droplets, but at an increased temperature, and in turbulent conditions, it can be dissolved or get emulsified. When some process solvents also leak into the waste water, oils become even more soluble or/and emulsified. As the water temperature slowly drops, the unctuous emulsified oil starts to separate, thickens, hardens and solidifies. Oils become fats. The typical solidification range depends on the type of oil, e.g. palm oil 41 to 31 ºC. As a consequence, a layer of fat builds up in process pipes or/and sewer systems, restricting the waste water flow.

Oil Pest in Waste Water?

Should an incident arise where some of the costly raw oil products are spillt, an organic shock load would be caused, leading to severe problems in the waste water treatment installation. To prevent this, a reliable online oil-in-water analyser is needed. It continuously measures and reports the organic load of the discharged waste water. By monitoring the operation of the oil production process operators can take prompt action, therefore preventing the loss of products and breakthroughs in the oil-and-water separation systems, whilst protecting the biology in the aerobe and/or anaerobe waste water treatment tank.

Why indirect measurement sometimes just isn't enough... on page 2!