There are four levels of treatment: pretreatment, primary treatment, secondary treatment and tertiary treatment.

Pretreatment
The pre-treatment or primary treatment aims at removing coarse solids from water or separate excessive amounts of organic liquids such as oils and greases.

It is done through a retaining device, often through the railing. But there are other methods such as static screens and mobile screens. The removal of oils and greases can be made through grease traps (at home or collective), an adaptation of a device remover fats into settling tank or aerated oil separator ..


Primary Treatment
Is the removal of inorganic pollutants, heavy metals and other items through various processes such as sedimentation, flocculation and sedimentation. The main objective of this phase is to obtain a clarified effluent. This process generates a sludge, which must be handled properly through the process of adhesive mud.

It is used to remove suspended solids and fatty material (oil and grease). It is also considered a primary treatment for the conditioning of the eviction order after its release in the receiving body or unit of the subsequent treatment (treatment secondary / tertiary).