wastewater line Sompunt

Wastewater treatment process

The sewage treatment plant was dimensioned and engineerized for a 58.000 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 the maximum 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 Function diagram

water sludge Gas
     
1) inflow 11) Pre-thickener 16) gas accumulator
2) rain relief 12) Digestion chamber 17) gas torch
3) pumping station 13) Post thickeners 18) gas utilisation
4) screening plant 14) sludge press  
5) Aerated grit chamber 15) sludge disposal  
6) Preliminary clarifier    
7) Biological basin    
8) Final clarifier:    
9) drain    
10) Drau River    

Mechanical cleaning

The mechanical sewage, with a 25% organic load reduction efficiency, is assured by a spire screen[3], by aerated grit chamber [4], bar-screens and primary clarifier [5].

Mechanical cleaning

Primary clarifier, to remove settleable substances

Biological cleaning

After that, the sewage treated mechanically cross the biological tank [6] in the atmospheric oxygen is injected to permit the biodegradation of organic compounds and nitrous compounds oxidation (nitrification). On the Ara Sompunt 2 lines were converted into a so-called AAA® stage (Alternating Activated Adsorption) and are controlled accordingly. This stage achieves a higher efficiency in the preliminary clarification than in conventional preliminary clarifications.

The recycle of vented sewage, of actives sludges and the regulation of oxygen concentration, permit the creation of an ambient in which microorganisms and variousnature batteries may easily do the proper work ofdegradation of pollutant load. These microorganisms, in bow structures, are the actives sludges that are separated by sedimentation in the big secondary clarifier.

The last reduction of phosphoric compounds is obtained by simultaneous precipitation (adding chemicals agents).

Biological cleaning
<p>Activated sludge under the microscope</p>

final clarification

The water’s superior layer, now purified, flows out on toothed threshold [7], is analyzed by a measurement and metering station (for quality and flow rate), and flows out into Gader river [9].

final clarification

The clarifiers

Sludge treatment line

The sludge coming from the first clarifiers (primary sludge) [5] is thickened mechanically by a pre-thickener. The sludge is now eliminated from secondary clarifiers[7]  and thickened mechanically by screencloth. The pre-thickened sludges are now reached at a temperature of 38°C approx and digested into an anaerobic digestion chamber [11]. The sludges, now stabilized and neutrals, are dried with a screw press [13].

Sludge treatment line

screw press

Gas line

During the digestion process [11], the microorganisms transforming the organic compounds on CO2 and methane with high energetic content, available for thermal heating of digestion chambers and for factory heating. To take a solution at the gas over production is provided a storage gas tank [15].

The gas line is composed by: gasometer [15], gas flare [16], 1 heaters and 2 cogeneration groups[17].

Gas line

Combined heat and power plant (gas engine), it supplies electricity and heat for heating from the produced biogas.

Ventilation system

During Sompunt plant engineer studies, a special importance matter was the particular attenzion at stinks emossions monitoring. Exhaust air from the pre-treatment plant is transported to the scrubber using ventilators with an output of 15,000 Nm³/h where it is then chemically cleaned.

Ventilation system

Components and power

For sewerage system and sludges treatment were provided a total amount of 150 units divided into instrumentation, machineries, for a total amount of power
consumption of approx 220 kW; the same items quantity were necessary for heating system, ventilation, air treatment, lightness systems, hydro feed exc..
For power plant, control and regulation of all these plants and systems, 25 km of bundles and cables were provided.

Components and power

The control head of the plant