IPCM n. 75 | May-June 2022

Page 80

SPECIAL ISSUE ON ARCHITECTURE & DESIGN

Table 1: Complete analysis of the waste water generated over a working week.

DATE

FLUORIDES (<12 ppm)

TOTAL PHOSPHORUS (<10 ppm)

SULPHATES (<1000 ppm)

ALUMINIUM (<1 ppm)

pH (5.5-9.5)

CONDUCTIVITY (mS/cm)

29 Nov

8.7

<2

491

0.155

7.2

2.55

30 Nov

11.2

<2

536

0.326

7.3

2.52

1 Dec

10.5

<2

482

0.115

8.1

2.66

2 Dec

6.5

<2

312

0.043

7.8

1.28

3 Dec

9.5

<2

396

0.069

7.5

1.55

Table 1 shows a complete analysis of the waste water generated over a

The waste water treatment line collects water from both plants,

working week.

with a total volume of 6 m3/h. Given the 6-ppm limit, the dosage of FLUORIDITE is about 3500 ppm, necessary to achieve a fluoride content

Case Study n. 2 Surface water discharge

of about 4-4.5 ppm in the discharge water. FLUORIDITE product can be used directly in existing waste water

The object of this second case study is another Italian company,

treatment systems, often achieving excellent results in terms of fluoride

active in the coating of aluminium profiles and sheets, which needs

removal without requiring any major plant engineering changes.

to discharge to surface water and not into the sewage system and, therefore, has to comply with a fluoride limit of 6 ppm instead of 12. This firm, which processes around 60 tonnes of aluminium per day in three eight-hour shifts, is equipped with two surface pre-treatment lines. The first one performs a degreasing/acid deoxidation phase and a non-chromium passivation phase. The second line performs three stages, namely alkaline degreasing, acid deoxidation, and nonchromium passivation.

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The depuration tanks.

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N. 75 - MAY/JUNE 2022 - international PAINT&COATING magazine