Apraitz WwTS

Apraitz WwTS -wastewater treatment”

Apraitz Wastewater Treatment Station, in Elgoiba, in the Spanish Basque Country, treats the wastewater for 90,027 equivallent inhabitants in the townships of Mallabia, Ermua, Eibar, Soraluze , Elgoibar, and Mendaro.

One of the special features of this plant, which has a treatment capacity of 29,894 m3/day, is that its a Sequencing Batch Reactor (SBR) biological treatment system.

In these SBR tanks, Aquasystems Installed 4 ADMC 1500 decanters and 4 MIX-SL units of 30kW combined with 60m³/h FRMD floatable pumps.

When the aeration system is stopped, the 30kW mixers ensure an efficient mixing of the activated sludge to prevent settling and ensure a good denitrification.

After the settling period, the decanters will evacuate the clean supernatant at a flow rate up to 2000m²/h. The mechanical closing system on the decanters will ensure that no sludge enters the weir during the Aeration and mixing phase. As soon as the sludge is settled sufficiently low below the decanter level, the weir will open and evacuate the clean water without risk of aspirating sludge or floatables.

During the aeration and mixing phase, the FRMD units that are installed on top of the floating mixers will aspirate the floatables and the filamentous bacteria that are responsible for the formation of foam.