Aerator mixer upgrades industrial wastewater treatment

Sulzer submersible aerator mixer improves wastewater treatment in a cardboard mill

Europac is a paper, cardboard, and packaging company with mills in Spain, France, and Portugal. The French site near Rouen specializes in corrugated cardboard and has a production of more than 300’000 tons per year. In the cardboard production process, Sulzer pumps and agitators are widely used. The mill has its own biological wastewater treatment plant with a total capacity of 350’000 population equivalent. Once treated, the water is recycled in the mill or restored to the natural environment. The WWTP has been modernized regularly during the past years.

Aerial view of Europac cardboard mill
OKI 2000  submersible aerator mixer
The OKI 2000 submersible aerator mixer is ideal for demanding industrial wastewater applications.

The challenge

The efluents from the paper mill contain a high amount of organic matter. In the wastewater treatment plant, the efluents go through an anaerobic tower reactor prior to being aerobically treated in an activated sludge process. The aeration of the wastewater is done in successive basins - frst in a circular tank with external bottom jet aerators and then in a rectangular lagoon with surface aerators. With the increase of the WWTP capacity, the oxygenation of both basins, especially the frst one, had become insuffcient. Therefore, Europac decided to upgrade the aeration performance of the existing installation with minimum capital expenditure in 2014.

OKI 2000 E-37AM with air hose
The OKI 2000 E-37AM with air hose at the bottom of a circular aeration tank.

The solution

Sulzer, together with the local contractor Eco-Tech, came up with the solution to add an aerator mixer OKI 2000 in the middle of the circular tank. The OKI is fed by compressed air distributed through a lexible hose. Despite the high tank depth, no air cooling is needed. The OKI runs in parallel with the fve bottom jet aerators, and the total oxygen transfer rate is now more than tripled. Thanks to its effcient mixing capacity, the OKI eliminates all types of sedimentation that used to occur in the middle of the tank earlier.
The OKI aerator mixer is a problem solver and it has helped us improve the overall eficiency of the wastewater treatment plant. Joel Bruwaert, Technical and Projects Director Europac

Customer benefit

For the aeration and mixing of harsh industrial wastewaters, the OKIs have a justi- fed reputation of steady performance, robustness, and reliability. These features have been confrmed at the Europac WWTP. After an easy installation, the OKI 2000 E-37AM has been running smoothly with no degradation of the aeration eff- ciency with time. In addition, the machine is liftable for quick and practical mainte- nance without emptying the tank.
Product specification

OKI 2000 E-37AM

  • One OKI 2000 E-37 AM with air hose, lifting cable, and electrical cables
  • The OKI is installed at the bottom and in the middle of a circular tank (diameter 19 meters, depth 9 meters).
Power 37 kW
Protection type IP68
Voltage 500 V / 50 Hz
Temperature control Thermal switch 130°C
OKI dimensions (diameter x height) 2'252 mm x 2'195 mm
Unit weight 2'070 kg
SOTR 276 kg O₂/h
Air lowrate 3'005 Nm3/h
Product
  • OKI aerator mixer
    The submersible OKI aerator mixer is a heavy-duty, non-clogging, gentle mixing unit which can operate both as an aerator and as a mixer.
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