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The compact preatreatment unit ENVIROSTEP are designed for urban and industrial raw effluents.
Such simple and efficient solution fits perfectly with projects looking after minimizing the concrete and  reducing the preatreatment operating costs of urban and industrial sewage treatment plants.


The compact preatreatment unit ENVIROSTEP  are  machine-welded in stainless steel with three fucntions, screening, sand removal, and fat removal of raw effluents. ENVIROSTEP units are designed to accept flows from 10 up to 500 m3/hr, but several units can be installed in parrallel to accept flow variation due to seasonality or to higher flow. An efficient screening is performed with a SPIRASCREEN adapted to each model. Sand and fat removal  is performed inside a longitudinal tank  in  continuation to the screening phase.


Screening and compacting

The solids are retained by the grid and then extracted and conveyed by the screw to the compaction zone. The compaction can be integrated into the screening machine, or carried out by an ENVIROPRESS transversal compactor equipped with an innovative and specific back pressure system to adjust the dryness.

Sand and fat removal

The bubbles formed by an air insufflation ensure the separation of the fat by flotation and separate the organic materials stuck to the sand. The sand and fat removing tank is designed by modules of identical lengths. This modularity offers a great flexibility. It is thus possible to vary, at the origin or later on, the length of the tank to adapt to the desired hydraulic speeds.

Sand extraction

The decanted sand is collected by a first horizontal screw installed at the bottom of the tank, and is transferred to  an extraction and draining screw for evacuation towards storage systems  before final disposal.

Fat Extraction

The extraction of fat takes place over the entire length of the machine by means of a longitudinal box.
The accumulation of fat in this zone is favored by the movement created by the insufflation of air.
The fat is recovered and evacuated by a surface scraper.