Negociación Industrial Santa Lucía, SA de CV, 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 10000tonnes/month.
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 8000 to 10000mg/l of emulsified vegetable fat and has an alkaline pH. These are the two main factors to be eliminated.
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 re-emulsifies, 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 flocculent. 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 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.
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).
Parameter
Unit Influent Effluent
Total suspended solids mg/l 2463 586
Sedimentable solids mg/l 12.8 0.5
Total dissolved solids mg/l 3798 2410
BOD5 mg/l 5368 12
COD mg/l 8754 22.21
Greases and oils mg/l 6387 3.5
Alkalinity mg/l 2543 137
BOD5 removal values are higher than 90percent
Dosing data: Water flow 4 litres/second; pH of influent 911; pH control 4.
Product: Dose mg/l; PAX-XL60 300; OPTIFLOC A-1638 3.
For more information, visit www.kemwater.com.mx
