Filterpress

Filterpress "AKFA"

The sludge produced during the primary and secondary treatment of liquid waste is very watery and cannot be deposited in tanks and treated in a drier. Therefore, sludge of any type and volume is treated with the “AKFA” filterpress which is able to remove most of the water enclosed in the sludge.

The final product of the procedure has a lower content of water compared to the primary sludge and is relatively solid (solid content 25% w/w) and can be carried if necessary with a belt. When there is need of a less watery waste product, the waste experiences a further dehydration through the use of vacuum pumps. The “AKFA” filterpress is designed to concentrate and dehydrate sludge, when the latter is passed through two filter presses in three stages.

1. Coagulation stage
2. Cuneiform stage
3. Compressed stage

Coagulation stage

The sludge is pumped and it is driven into a tank where a polyelectrolyte solution is added. The tank is also equipped with a stirrer to promote the formation of solid aggregates.  When the coagulation is completed the sludge is transferred to the upper filter press for further treatment.

Cuneiform stage

At this stage the coagulated sludge is gradually compressed between two filter presses. This  stage is crucial as the “pitta” is produced.

Compressed stage

The coagulated sludge is compressed between several cylinders which are shaped like an S.  The Pitta is turned upside down as it moves from one cylinder to another, thus, dehydration is achieved on both sides of the pitta ensuring a homogenous result. The first cylinder in the row has several gaps in order to ensure the discharge of most of the residue.  The stage of compression is accomplished in the last three cylinders which exert high pressure on the pitta before it is discharged for further treatment into a drier.

Movement mechanism

A motor equipped with a shaft gear box is responsible for the movement of the belts and of the cylinders. The adjustment of speed is accomplished manually from the control panel.

Belt alignment

The alignment of belts is achieved with an automated device. In case of a device breakdown, an alarm is activated and movement ceases. All belts have a mechanism responsible for stretching and it is controlled automatically.

All the residue is collected and stored in a tank for further treatment.