Edible oil plant's commitment to clean water

Negociación Industrial Santa Lucía, S.A. de C.V., is a company in the foodstuffs sector which manufactures vegetable oils. It is situated in the city of Morelia in the state of Michoacán, Mexico.

Feb 20th, 2004

By Luis Guerrero and Javier Serafin, Kemwater de México

Feb. 16, 2004 -- Negociación Industrial Santa Lucía, S.A. de C.V., is a company in the foodstuffs sector which manufactures vegetable oils.

It is situated in the city of Morelia in the state of Michoacán, Mexico. The high production volume of the plant means that it plays an important part in the ecological balance and the environmental impact affecting the city.

The incoming raw materials to the plant are: palm oil, soya oil, sunflower oil and alimentary fat, with a total volume of approximately 10,000 tonnes/month.

The company is fully committed to the efficient use of water by minimising clean water consumption and reducing the pollution caused by process water.

Santa Lucía has a waste water treatment plant. Water from the plant is used to irrigate gardens, to wash pipes and patios and for sanitary purposes.

The influent to the plant contains 8,000 to 10,000 mg/l of emulsified vegetable fat and has an alkaline pH. These are the two main factors to be eliminated.

Treatment plant

The treatment train includes a collection and pumping system, primary chemical conditioning and separation by flotation. It also performs secondary treatment by aerobic biological oxidation with active sludge, and final cleaning by filtration with sand filters and active carbon filters.

Acidification breaks down the grease and oil emulsion, but the effect is partially reversed and some of the grease reemulsifies, producing a milky effluent which can be treated in the biological reactor.

The treatment train is a combined system involving pre-precipitation, in which PAX-XL60 is added as a coagulant and OPTIFLOC A-1638 as a flocculant.

These systems are known to achieve a considerable reduction in organic material in the feed to the biological system, in turn reducing the organic loads entering the biological reactor.

As a result, the biochemical oxygen demand will also be lower, leading to a considerable reduction in the cost of treatment, as well as offering greater stability by avoiding peaks in the organic loading in the supply to the biological reactor.

Characteristics of the water

The most important parameters to consider for this type of waste water are listed below. The stated figures apply to the entire treatment train (combined system).

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