Water | Techniques


The main techniques used by Trevi can be divided into primary treatment (mechanical and / or physicochemical treatment), secondary treatment, tertiary treatment and sludge treatment. Depending on the composition of the waste water and the objective (discharge to sewer, discharge to surface water, reuse, closed loop, ...) a particular technique or a combination of specific purification techniques is necessary to obtain the desired final objective. Trevi builds both small and large installations and has pilot installations available for each of the techniques mentioned below. This allows each technique to be tested before full-scale is built.

Removal of solids

The mechanical pre-treatment of waste water is part of the primary treatment and is used to remove any solids, settleable solids, suspended solids and floating substances.

Physicochemical treatment

The chemical removal of contaminating components from wastewater is also one of the primary treatments. The aim is mainly detoxification: the separation of heavy metals, cyanides, hexavalent chromium, phosphates, .... 

Removal of organic pollution

The biological treatment of waste water is known as the secondary treatment. With the help of micro-organisms organic contaminations such as BOD, COD, nitrogen- and phosphate-containing compounds get converted to harmless residual substances.

Tertiairy treatment

The tertiary water treatment follows after the primary and secondary treatment, or can be applied directly to certain process waters. The aim is to extensively purify pretreated waste water (effluent polishing), for example, to meet specific conditions of discharge or to improve the quality to make reuse or closed loop possible. The components to be removed are usually in low concentrations (residues in mixed waste water), or as a specific contamination in process waters (no complex matrix). These are either residual concentrations or specific contaminations of suspended solids, metals, fluorides, phosphorus, nitrogen, hydrocarbons, pharmaceutical agents, dyes, pesticides, ...

Separation and dewatering sludge

Especially in primary and secondary waste water treatment waste sludge is produced. Solid impurities are separated, dissolved substances are insolubilized and precipitated, the excess biological sludge mass is discharged,.... For the purposes of transport as well as discharge an adequate sludge separation and concentration is necessary.