The aim of physical pre-treatments is to extract waste water, solid waste (sand, refuse) and grease. The techniques used are fine screening by sieving and degritting by decantation respectively. The aim of physico-chemical treatments is to speed up the separation of solid waste by injecting chemical reagents (iron, aluminium salts and polymers).

NANTAISE DES EAUX INGÉNIERIE offers varied procedures for physico-chemical pre-treatments and treatments of waste water:

• Screening, degreasing, sand removal and sand washing
• External feeding sieve
• Internal feeding sieve
• Screw sieve
• Dissolved air flotation (DAF)
• Primary settling tank
• Buffer tank