FlooBelt - Belt Filter Press For Water And Wastewater Sludges

The FlooBelt technology is a multi-stage dewatering unit, which is an ideal tool for efficient dewatering of various types of sludges.

The FlooBelt unit is user friendly, because the maintenance requirements are lowered to a minimum level by using high quality components, high quality corrosion resistant materials as well as the extensive know-how of belt filter presses and their operation.

Due to possibility to choose from different length pre-dewatering zones and many different unit widths, the FlooBelt technology can handle large sludge amounts at low feed concentrations.

FlooBelt belt filter presses have three independent belts and the belts rotate over a series of rollers. Standard units are equipped with two drive motors (one in pre-dewatering table and one in pressing table) and pneumatically operated automatic belt steering and tensioning devices.

The belt curves (wrap angles) are carefully designed to obtain maximum shear and to press out all free water.

The structural frame has been designed to withstand intended loads without excessive vibration or deflection. The monocoque frame construction of the FlooBelt system enables a containment of odours within the unit. This means that the requirements of ancillary equipment for odour removal are relatively minimal compared with traditional belt filter press system, which require venting of entire dewatering room. Adequate hatches located at sides of the unit allow easy access. There is also possibility for skid mounting. An inbuilt drain pan (filtrate tray) is provided to allow all filtrate water to discharge at a single point.

Rollers are made of corrosion resistant SS 304/316 quality seam-welded stainless steel tubes. Roller shafts and end flanges are also made of SS 304/316.

Also other parts in touch with sludge are made of non-corrosive materials such as SS 304/316, GRP and plastic materials.

Pre-dewatering zone
The standard FlooBelt “multi-stage” units are always equipped with an independent pre-dewatering unit, which has its own drive unit. This will allow selecting optimal belt type and speed in accordance with the characteristics of the particular sludge. Due to this the dewatering capacity can be increased considerably. Most of the separable water will be removed in the pre-dewatering zone.

Chemically conditioned sludge from the flocculation tank will be fed onto the pre-dewatering belt by means of gravitation in such a manner as to avoid excessive turbulence and subsequently possible breaking of flocs. On-line distributor or in feed tray will spread sludge evenly over the working width of the belt in the pre-dewatering zone.

Properly treated sludge contains a lot of free water among the floc particles. In pre-dewatering section, maximum amount of water will be dewatered by gravity.

In order to minimise polymer consumption and to maximise hydraulic and solids loading rate and to boost more rapid drainage of water from the sludge, a numerous sets of special designed ploughs are installed in the pre-dewatering zone. While sludge mat on the FlooBelt belt filter is moving ahead, the ploughs will open and turn the sludge mat and release water by gravity. An optimal number of ploughs is installed in the gravity zone. Ploughs will be mounted on cross bars with adjustments to raise and lock each row in an upright position. The crossbars are of stainless steel. The DEWA ploughs are made of high-density polypropylene.

Transverse beams are located underneath of the gravity belt, where they provide downward pressure for improved filtration and prevent formation of surface tension.

Wedge zone
Pre-dewatered sludge will fed gently to the wedge zone through a guiding tray. The main task of the wedge zone is to allow sufficient pre-settling and final gravity dewatering before pressing.

In the long wedge zone, there are more horizontal scraper beams below the belt, which will remove the rest of the free water.

Low pressing zone
At the final stage of wedge zone, sludge will be fed between two belts. Units are equipped with a large perforated drum extracting more water from the sludge before the pressing with solid rollers.

Pressing forces from the pressing rollers are directed to sludge mat between the filter belts. Because of this water will be forced through numerous pinholes in the pressing belts.

Following solid rollers will give the smooth pressing against floc particles. Roller sizes and their angles are suitable for low pressuring. There are adjustable rollers, which can be used to adjust the belt tensioning according to the characteristics of the sludge.

High pressing zone
The high pressure of dewatering takes place in the end of the pressing zone. The pressing zone contains smaller pressing rollers in shorter distance and in bigger curves. This way the maximum pressing of the floc particles will be enabled. In addition, this area includes adjustable rollers, which can be located to give highest possible dewatering dryness of the cake.

Just before discharge there is a nip construction, where two rollers are positioned to be pressed towards each others, allowing high pressure on sludge mat.

Scraper blades will scrape cake away from the belts and the dewatered cake will fall down to a container or a conveyor.

Typical design parameters for FlooBelt belt filter press:

• Belt widths ranging from 1 100 to 3 100 mm
• Effective filtrate area ranging from 12,5  to 42 m2
• Feed capacity as dry solids: 150 – 2 000 kgDS/h
• Feed sludge flow capacity: 5 – 200 m3/h
• Dewatered cake dryness up to 40 % depending of the sludge characteristics

• In built pre-dewatering zone – no need for special pre-dewatering stage
• Gravity feed from flocculation to press – no pumping
• Extensive number of delivered units.
• High dry solids contents => low cost for dewatered solids disposal.
• Compact configuration => low space requirement.
• Continuous fully automated operation.
• Closed construction, which means that no separate odour cabin is required.