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Wastewater line Tobl

Wastewater treatment process

The sewage treatment plant was dimensioned and engineerized for a 200.000 inhabitants equivalent capacity, in the way to satisfy the needs of population in local areas, of tourism, of industry and artisan shipment, guarantying in the meanwhile higher levels in quality, with themaximum efficiency in organic pollutant load knocking down and phosphoric and nitrogen components strong reduction.

The target of sewage treatment is reached with physical, biological, chemical and biochemical processes.

Legend wastewater line

water	sludge	turbid water

1) inflow	5) to the sludge line	10) turbid water inlet
2) rain relief		11) turbid water basin
3) screening plant		12) DEMON-System
4) aerated grit chamber
6) preliminary clarifier
7) biological basin
8) final clarifier
9) drain
13) Rienz river

Mechanical pre-cleaning, screens

In the first section of the sewage treatment plant, the mechanical cleaning [3], the waste water is freed from coarse contamination. Automated screens extract coarse materials from the wastewater, such as..: Toilet paper, food scraps, articles of monthly hygiene, wet wipes, packaging materials, etc.

Aerated grit chamber

A sand trap [4] is an aerated settling tank with the task of removing coarse, settleable impurities from the wastewater, such as sand, small stones or glass splinters. In the grease trap, fats and oils reach the water surface where they are removed by a scraper.

Preliminary clarifier

The mechanically cleaned waste water now flows slowly through the primary clarifier [6]. Undissolved colloidal substances (faeces, fibres, etc.) settle. The excess water is fed to the further purification process of the sewage treatment plant, the settled sludge is pumped into the digestion tower for subsequent treatment.

Biological cleaning

This is the heart of the treatment plant. In biological wastewater treatment [7], billions of microorganisms work by absorbing the substances contained in water as food, degrading or reducing carbon compounds and nitrogen compounds. The phosphorus is also biologically degraded and the excess phosphorus is chemically precipitated. The entire cleaning process is controlled with a lot of measuring technology. Measuring probes control the oxygen concentration, the temperature, the sludge concentration and the pH value. The controller and computer use the measured values to optimize and document the cleaning process.

Final clarifier

In the final clarifier [8], which forms a process unit with the activated sludge tank, the activated sludge is separated. To concentrate the biomass, some of it is pumped back into the biology. The biologically purified wastewater is then returned to the receiving water.
The sewage treatment plants cause a reduction of carbon compounds of up to 99 %, nitrogen of up to 84 % and phosphorus of more than 90 % to be removed from the water.

DEMON-System

The resulting filtrate water and vapour condensate [10] is collected in a basin [11]. The DEMON® technology [12] uses a biological process to remove large amounts of ammonium from wastewater. The innovative technology requires 60 percent less energy than conventional processes and, unlike these, no chemical additives.