Vacuum Belt Filter
The vacuum belt filter (VBF) is used for the filtration of liquids by means of filter cloth (geotextiles). In comparison to hydrostatic filters, the VBF has the advantage of a vacuum assisted filtration. Therefore a higher throughput and a better drainage of the filter cake can be achieved.
The filtration is done with a self-sealing filter fleece, chosen for the individual application. The filter fleece is transported and coiled by a gear motor. A float switch controls the fleece transport and the filter cake is stripped off into a dirt tank.
Function
The wastewater is fed into the filter from above, and gets evenly distributed over the entire fleece width through a cascade box. The filter fleece is fed into the water chamber from the bottom. The filtration is performed on an inclined plane, whereas the actual filtration happens in the lower part of the fleece, and a post-dewatering of the filter cake takes place in the upper part.
The gear motor is switched on once a certain water level is exceeded. The filter fleece together with the filter cake is then pulled upward, the cake is stripped off and the fleece is taken up by a take up spool. At the same time, new fleece is drawn into the chamber at the bottom end of the fleece. Due to the now lower flow resistance, the water level decreases and the motor stops.
A lateral channel compressor constantly sucks air out of the filter chamber, thus creating a slight vacuum at the filtrate side.
Fields of Application
Vacuum belt filters can be used, for example, for continuous treatment of cooling lubricants or for degreasing baths. Further fields of application are the filtration of wash waters, fish ponds, wastewater (e.g. after precipitation/flocculation) as well as other process waters.
Other applications are wastewaters which are difficult to treat, as they tend to cake or clog the fleece, as for example wastewater with paint residues or landfill leachates.
Further examples and applications can be found in our references:
Advantages
Advantages of the vacuum belt filter:
- Filter fleece supply from bottom -> the fleece is loaded with sediment first
- Flotation tailing is extracted together with the sediment at the discharge side -> optimal use of fleece
- Filter cake is removed from the fleece -> requirements of the cycle economy-law are fulfilled by the separate disposal of fleece and mud.
- The filter fleece lies flat on the inclined filter ->optimal use of the entire filter width
- Lateral sealing of fleece -> no leakage of unfiltered medium into the clean water tank
- Reusability of the filter fleece when used in grinding processes -> low operating costs
- Filter made of stainless steel -> long life
- Vacuum support -> higher throughput and a better drainage of the filter cake in comparison to hydrostatic filters
