The liquid waste treatment plant is equipped with different storage areas. The plant is equipped with the following tanks: 5 tanks of 100 m3 each - usually intended for the storage of waste from chemical-physical treatment, 2 tanks of 100 m3 each for pumpable sludge, 2 tanks of 100 m3 each serving the saline solution evaporator, 2 tanks of 50 m3 each for the oily emulsion evaporator, 2 tanks of 100 m3 each and 1 tank of 60 m3 for solvent distillation waste. A new storage facility consisting of 11 tanks of 80 m3 each serving the chemical-physical treatment section has been authorised and is under construction.

This section consists of 12 batch treatment reactors (1 reactor of 30 m3, 1 reactor of 50 m3 and 10 reactors of 70 m3), four of which have yet to be built, and three continuous treatment lines. Reagents required for neutralisation, coagulation, clarification-flocculation, metal precipitation, oxidation-reduction, adsorption on activated carbon and subsequent flocculation/sedimentation can be measured out in the reactors. Clarified wastewater is fed back to the biological treatment section. The resulting sludge is sent to a continuous treatment line for conditioning and then dewatered by means of two filter presses. The dewatered sludge is then sent for disposal.

Two of the three continuous lines are fed by clarified water from batch treatments and wastewater resulting from sludge dewatering. In this section, specific treatments are carried out to enhance the purification yield of the chemical-physical section, particularly with regard to metals, hydrocarbons and solvents. Clarified water is sent for biological treatment while sludge is transferred to the conditioning line.

One of the continuous treatment lines, consisting of 3 reactors, is intended for the conditioning of pumpable sludge resulting from batch treatments to increase its filterability. In the first coagulation reactor, ferric chloride is also usually measured out. In the second precipitation/alkalinisation reactor, equipped with pH control, the measuring out of lime milk takes place. Finally, the third reactor is used for the accumulation of conditioned sludge for mechanical dewatering, which is composed of two automatic filter presses, from which semi-solid sludge results, with a dry content that generally ranges between 45 and 60%.

In this section, oily emulsions, water with high surfactant content and/or COD are treated in a multiple-effect evaporator and subsequent static concentrator. The condensed liquid (distillate) is sent to the next chemical-physical treatment, or, if no further treatment is necessary, directly to the biological treatment. The concentrator consists of a system with a solution flow rate to be concentrated of 500 kg/h for the removal of emulsion water, starting from a maximum inlet oil value of 50%. While using the evaporator, it is possible to feed a tricanter centrifuge. It separates the sludge, water and free oil that is found in the wastewater. The sludge separated from the centrifuge is sent to the storage tanks for subsequent conditioning and mechanical dewatering with a filter press. The free oil from the centrifuge is pumped into a storage tank to be sent for recovery to external plants, while the separated water is transferred to the storage tanks serving the emulsion treatment section, since the latter still contain traces of oil.

In this section, saline waste is treated in a multiple-effect evaporator and subsequently in a concentrator. The waste is then stored and sent to the triple effect vacuum evaporation plant, from which a distillate and concentrate are obtained. The condensed liquid (distillate) is sent to a degassing system and is relaunched for subsequent chemical-physical treatment, or, for biological treatment. The saline concentrate, typically with a dry content of 40%, is sent to a scraped-surface evaporator to obtain a solid material for further treatment in other plants and a distillate - which is combined with the triple effect distillate.

In this plant, low-boiling solvents are separated by treatment in a 4t/h distillation column after pre-treatment to remove salt components and heavy organic compounds. The aqueous column bottom fraction is sent for chemical-physical treatment or biological treatment, while the distillate, consisting of the solvent fraction, is sent for recovery/disposal.

The plant is composed of two parallel continuous flow treatment lines. Each line consists of an equalization phase, a pre-denitrification phase in anoxic regime for the removal of nitrates, an aerobic oxidation phase of COD and ammonia nitrogen, followed by a sludge sedimentation phase. The supernatant from the two settling tanks is fed to a second continuous flow stage for MBR-type pre-denitrification and oxidation. The water filtered by the ultrafiltration section is sent to the boron removal section, consisting of two selective resin filters in parallel, for subsequent discharge into the private sewage system, or alternatively to the reverse osmosis section, consisting of three lines in parallel, for the purpose of producing water for industrial use for the platform services. The pumpable surplus sludge extracted from the settling tanks in the first biological stage and the ultrafiltration lines in the second biological stage is sent to a post-oxidation section and then to thickening, then dewatered by centrifugation and sent for subsequent disposal/treatment.