The fundamental element of the sludge dewatering lines from the production portfolio of VANEX is the belt press. Dewatering is continuous with the following products:

·      solid element – sludge cake, that can be transported by common transportation devices

·         liquid element – filtrate with the possibility of further processing

The requirements for the operation of the belt press are:

·         pressurized air circa 1m3/hr; 0,60 MPa;

·         pressurized water for splashing of filter belts circa 4 ÷ 10 m3/hr (VX-GORO 6 ÷ 12, VX - 6 ÷ 12), 12 - 16 m3/hr (VX-15 a 20), pressure 0,6–0,8 MPa;

·         power supply 3/N/PE/AC 400/230 V 50 Hz TN-S, installation input power of the belt press 2,25 kW (VX-GORO), 2,25 kW (VX-6, 6A, 8 a 10) and 3,00 kW (VX-15 and 20) including flocculation plant VX-FZ;

·         flocculant solution for increasing of separation efficiency of the belt press.

The sizes and informative outputs of the belt presses manufactured by VANEX are given in the table.

   The belt presses process sludge in four main interlocking technological zones:

I. Homogenizing zone. Sludge is mixed with flocculant solution, spewed and the part of the filtrate is released. This process is running in the flocculation plant VX-  

    FZ and partially in the input hopper of the belt press on the upper filter belt.

II. Gravity zone. In this zone sludge is gravitationally dewatered after its intake onto the filter belt. The gravity zone on the upper filter sieve of VX belt presses is      

    prolonged approximately up to 6m (except for the smallest belt presses). Sludge is upset from the upper sieve on to the clean bottom filter belt of the continuing  

    gravity zone. In this zone the biggest volume of the filtrate flows out with the lowest pollution.

III. Low-pressure (wedge) zone. In this low-pressure zone there is the upper belt continuously pushed to sludge resulting in further filtrate drainage.

IV. High-pressure zone. The sludge, which is closed between the filter belts, is lead hrough the roller system. As the pressure continuously increases, further filtrate      continuously drains.

     The final pressed out sludge is after passing through the press scrapped from the filter belts by plastic scrapping laths.

  The expected dry matter output of the sludge cake is 18–35% (municipal sludge).

  Another possibility of dry matter output increase is a use of high-pressure VT press, which is mainly used when processing industrial sludge. The output dry matter of sludge cake from this type of the belt press is higher by 5–20%, depending on the type of pressed medium.

  The output and quality parameters of the belt press are dependent mainly on physical properties of sludge, type of applied flocculants and the sieve as well as the quality of attendance.

  Within our delivery we optimize individual parameters including selection of appropriate flocculants.

  The construction of belt presses is backed by the long-time knowledge and skills from construction, production and usage of belt presses for pressing of different kinds of sludge.

The main construction parts of the belt presses are:

·   frame                           ·  air system                  ·   rollers, gutters

·   electricity system         ·  hoppers                     ·   filter sieves (2 pcs)

·   filtrate lead-in               ·  propulsion unit

     One of the main characteristics of VX belt presses is that corrodible material such as gutters, hoppers, covers etc. are made of polypropylene.

   The surface treatment of the press is metallized with 100micrometers of zinc. This is coated with 2 layers of two-component epoxide coating composition indurated with polyamide with high content of solid particles and low water permeability.

    The speed of filtrate sieves is regulated with the frequency converter.

    Regulation and tension of the filtrate sieves of the belt press is ensured through the air system.

   VX Belt presses have individual propulsion for bottom and upper sieve without chain gearing. This solves the problems with unequal filter belt movement and incipient "bags" of the filtrate belts, which often result in their damage.

    The connecting material of the belt press is made of stainless steel.

    If required the whole belt press can be made in stainless version.



Сonsiderable amount of fluid fibrous sludge, that is necessary to liquidate as economic as possible, rises in some processes (for example in the process of paper production). The first step in sludge liquidation is the massive reduction of its volume. For this purpose the high-pressure belt presses proved very good in the paper industry.

 Standard high-pressure belt presses produced by the company VANEX are characterized by:

·   Two gravitation sectors with total length of 6 m, where at the same time the sludge is turned down. Thanks to these long gravitation sectors sludge with low incoming dry matter (circa 1%) can be processed.

·  Long passage time through the pressure sector. The length of this sector is circa 3 m. Thanks to this length and to the long passage time through the pressure sector a thick sludge layer can be created before sludge enters into the high-pressure sector. This thick sludge layer is necessary in order to achieve a high output value of dry matter.

·  The high-pressure belt press VXVT is characterized by an active high-pressure sector in which at the same time the high-pressure cylinders play the role of the driving cylinders.

   In this manner extreme high pressures can be achieved with minimum sieve tension.

   Pressure can be increased till the maximum torque of the high-pressure cylinder drive is achieved.

  The high-pressure belt presses not having designed the high-pressure sector in this way, have to increase the tension of pressing sieves together with the increasing of pressure between the two high-pressure cylinders and in this manner to avoid the slippage of separate driving cylinders.

   There is a limit in increasing the sieve tension – the sieve tensile strength.

   Since the high-pressure belt presses of the company VANEX can be operated thanks to their active high-pressure sector with minimum tension of the sieves, it is possible to use sieves with removable joints. This considerably simplifies the replacement of worn sieves in comparison with machines, that on account of using extreme sieve tension have installed endless sieves without removable joints.

   The speed synchronization of all driving mechanism is solved through frequency converters.

   The main frame and the cylinders of the belt press are made from standard steel.

   The surface of the press and of other components within the line delivered by VANEX is treated except with 100 micron zinc-metallization also with three layers of two-component polyamide hardened epoxyd coating composition, with high content of solid particles, with good wetting facility and low water permeability.

   All other components are made from stainless steel and polypropylene. Optional company VANEX can deliver the belt presses also in stainless steel version.

   Company VANEX delivers five basic types of high-pressure belt presses, their specifications are presented in the table. Values that are presented in the table are values achieved in process with standard high-pressure presses.

  These presses are constructed conceptually in the manner that enables processing of the majority sludges occurring in the paper industry and achieving maximum dry matter content and maximum performance.

    Company VANEX carries out compressibility tests of concrete sludge for concrete belt press. Following the results of these tests, the content of output dry matter and performance of the belt press, processing the tangible sludge, can be relatively exactly estimated.



   VX-GORO Belt Press is the smallest Belt Press from the production portfolio of VANEX with regards to the height and its dimensions. The Belt Press and its construction followed the requirements of smaller towns and larger communities for the plant with the parameters and economic availability that would ensure   municipal sludge dewatering for localities with cca 1000– 5000 EO.


  Sludge is fed into the Belt Press VX-GORO onto the upper sieve, which also partially acts as a gravity belt thickener.

  After passing the gravity zone on the upper sieve sludge is turned over onto the bottom sieve. The arrangement of this allows filtrate to drain from upper part of the formed sludge cake. This process enables pressing of non-homogeneous sludge with low input dry matter.

  The requirements for the operation of the belt press are:

- pressurized water for splashing of filter belts. The Belt Press VX-GORO can be set on thу filter 

- reservoir VX-FN ( also a product of VANEX ) that enables to use drained filtrate for cleaning of the belts with significant savings of clean pressurized water.

- compressed air circa 0,60Mpa, 1 m3/hr;
- power supply 3/N/PE/AC 400/230 V 50 Hz TN-S, installation input power 2.25 kW;

- flocculant solution for separation efficiency increase of the belt press.


  In case of requirement for sludge dewatering on different places the mobile plant can be used. The Belt Press VX-GORO with another line components are fixed on the trailer according to the below scheme.
  There is no need for supplementary water supply for filter belts splashing. Water for this purpose is gained from drained filtrate after its purification in the independent filter plant.

  Filter plant eliminates operation expenses of the waste water treatment plants and mainly the risk of flooding out of the small waste water treatment plants.

  Input and output places of the individual media are designed with the respect of quick commissioning of the mobile plant. Therefore sludge and splash water inputs are terminated with fast connects.

  Power supply is ensured through the socket (32A) that is a part of the main power distributor.

  Slide (extensible) low-speed conveyor takes away sludge from belt press outside of the mobile plant.

Requirements for equipment of the dewatering stand:

- sludge reservoir with a blender (accumulation of sludge when the mobile plant is not available),
- the horizontal platform circa 6 x 3 m to position the plant during operation,
- clean water supply (preferably potable) for flocculants preparation with inflow cca 0,5 m3/h,
- power supply 3/N/PE/AC 400/230 V 50 Hz TN-S, 12.0kW,
- sludge cake withdrawal and disposal (a container, render, conveyor etc.),
- joining of the pipeline for taking pressed water (filtrate) from the plant.





  Atypical belt presses are usually produced according to direct requirements of the customer who needs to separate in his technological process from each other liquid and solid components.
  The presses are usually designed direct according to customer’s requirements and according to character of the pressed medium.
  The devices are made from stainless steel.

  Washing presses are used for washing process of „semi-matter“ in the paper industry. 
  The pressing process carried out in the presses placed one after the other and the repeated thinning remove step by step chemicals from the wood pulp.
  Linen „semi-matter“ in the concrete technological line of the paper-mill OP papírna Olšany moves in succesive steps through four presses.
  After passage through the first presses the pressed material falls into the water tank that also contains bleaching components. 
  The wood pulp is in the tank destructed using a mixer equipped with special rotating screw. 
  After homogenization and repeated thinning with water in the tank this material is pumped into the next press and the process starts again.
  Via succesive pressing and repeated thinning the desired washing quality of the linen „semi-matter“ is reached.  
  Mentioned presses have to resist not only the corrosive character of water but also the chemicals, that is why they are produced form stainless steel.

  Specially designed press for pressing of herbal and liquid mixtures (spirit, water, ...).  The final product is filtrate used for further processing in cosmetics, pharmaceutical industry etc.
  These presses require higher quality of used material (stainless steel, plastics, ...) and resistance towards higher temperatures.
  To increase the process effectiveness the press has the built in high – pressure sector. The operation of this sector can be regulated from the control panel of the press.


To thicken the sludge before its entering into the belt press, it is possible to use the belt press with built in thickener. It is designated for cases with input dry matter volume lower than circa 1%.

Unit´s advantages

-    noticeably reduced hydraulic load of the press, because the sludge is thickened to 4 – 8% and only then enters into the gravitation sector
-    the sludge passes from the thickener into the press gravitationally – without necessity of a sludge pump and of an indicator for measuring the amount of the    

     thickened sludge
-    only one unit for flocculant preparation VX - FZ is sufficient for both units (before the thickener)
-    there is no necessity of the second flocculant dosage before entering into the press (floccules are not destroyed when sludge passes from the thickener into the      press and the draining process can continue with original flocculant dose) – siginificant flocculant savings
-    special construction of the belt press with included supporting surfaces for the thickener, which reduces demands for the total required area (but it is necessary        
to provide sufficient room height for sludge draining)

-    eliminated pipe connection length between unit components



  Belt thickeners are the plants for continuous thickening of different kinds of sludge.

  A free liquid compound – filtrate is released from sludge being thicken during a technological process of thickening which can be further processed.

  A recommended layout of VX-PAZA thickener within an overall technological connection scheme.

  Condensed sludge is pumped into the plant with a displacement pump. The output of this pump is continuously regulated with a frequency converter.

  In most cases it is necessary to add flocculant solution into condensed sludge before its entry into the plant. Sludge flocculates (coagulates into bigger crowds – floccules) and filtrate is being released.

  In case of variable volume of sludge that is pumped into the thickener (mainly because of variant dry matter of input sludge), it is necessary to change also the volume of added flocculant solution.

  In some cases the thickening process can run without flocculants being used. However, in such a case the parameters of thickening process are aggravated and therefore the quality of discharge filtrate is deteriorated.

   The main part of the plant is a polypropylene tank with a cover, which is divided into inflow part, drainage part, filtrate drain part and condensed sludge off-take.

Technological process of dewatering runs in two basic technological zones:

- homogenisation zone – a part of technological cycle after flocculants added into sludge, in which sludge is being mixed with organic flocculant solution, flocculated   and released. 
  When no flocculants are being used, this process is being omitted.
-  gravity dewatering zone – gravity dewatering of sludge runs in the dewatering part of the thickener on the filtrate sieve. Sludge is drifted in the mentioned zone by   the moving sieve, which is driven by the motor with a gearbox.

  If it is required to increase output dry matter of sludge at the exit of the thickener, it is possible to use a destroy slat at the end of the thickener gravity zone. The slat destroys the layer of dewatered sludge and therefore the filtrate that was blocked by the upper layer of the cake, can drain.

The filtrate sieve is being cleaned with splashing jets.

For splashing can be used either drain filtrate or cleaned water from the outlet of the wastewater treatment plant (eventually any service water).

The type of the filtrate sieve affects quality of the filtrate and plant output and this is selected according to sludge properties and used flocculants.

Filtrate drains through the filtrate sieve into a drainage part, then into further technology. This is done in most cases gravitationally.

Filtrate can be also pumped automatically if required. The pump can be switched on with the level probes that scan the amount of filtrate in the drainage part of the thickener.

After passing the gravity zone sludge drains into further process (belt press, centrifuge, digestion tower etc.) in most cases gravitationally.

Similarly like filtrate, condensed sludge can be pumped with the pump and this can be operated with the level probes and regulated by the frequency changer.

For the operation of the thickener are required power supply system 3/N/PE AC, 400/230 V, 50 Hz, TN-S, with the demand of power according to the following table.


   The great environmental problem of modern Ukraine is the utilization of waste from production and consumption, including sewage sludge from urban wastewater treatment plants, sludge, industrial waste and processing enterprises.
   The bulk of the sediment is accumulated on sludge sites and dumps, creating technological problems in the treatment of sewage. Their storage conditions lead to pollution of surface and underground waters, soils, vegetation, reducing our chances of providing ourselves with clean and pleasant to taste with drinking water now and in the near future.
   Problems of the processing and use of sewage sludge are of particular importance, since it has not only ecological but also economic value, contributes to the restoration of raw materials and material resources, energy supply (biogas), reduces the cost of compensation for land abandonment for sediment storage.
   Mechanical dewatering of sediment is the initial and obligatory stage in the process of preparing sludge for further use, regardless of the chosen method, the main task of which is a reasonable reduction of moisture and sediment volume, pure filtrate, obtaining a product convenient for transportation, storage, utilization .
   For more than 20 years now, with success in the European market, such problem is solved by the Slovak company Vanex spol.s.r.o., Liptovsky Hradok, which designs, produces and supplies components of lines for dewatering and condensation of sediment for wastewater treatment plants, industrial enterprises and processing industries.

VANEX in the stated areas offers:
- Consultations

- Projects and proposals

- Products deliveries

- static and mobile classic and high-pressure belt presses for dewatering of municipal, industrial and other kind of sludge
- slot and belt thickeners,
- other components of the sludge terminations (chemical preparation plants, distributors, sludge pumps, compressors, hygenization, belt conveyors, service      

  platforms etc.).

- Installation, commissioning and attendant training

- Service of the given plants

- Accomplishes maintenance and reconstruction of the belt presses produced by different manufacturers


VANEX since its beginning (1992), based on 15 years experience and practise, has been developing and continuously improving belt presses and other additional components of the lines.
VANEX up to the end of the year 2016 manufactured and commissioned more than 500 technological lines with belt presses and supplied plants to more than 700 localities.
The philosophy of the company is an immediate introduction of knowledge from belt press operation into the construction and production.
The ideal way of achieving this is launching of the technological lines into operation direct by the constructers of the company VANEX. This is one of the main principals of our company.
While improving the level of the technological lines with belt presses, VANEX is also focusing on economy of the operation by the optimal power, flocculants and other media consumption.


Type of Belt Press

The Belt Press size 
(l x w x h), m

Weight, kg

Filter belt width, m

Informative output of the Belt Press

kg D.S./h


Typ of 
High-Pressure Belt Press

Filter Belt Width, m

Informative Performance of the Belt Press,

Dry Matter Content of Incoming Sludge, %

Dry Matter Content of Outgoing Sludge from the Press for Sludge with Negligible Ash сontent

Dry Matter Content of Outgoing Sludge from the Press for Sludge with Ash and Fibre Content in Relation (1:1), %

Power Consumption,


VX –GORO Belt Press dimensions (l x w x h), m

2,53 х 1,40 х 1,50

The mobile plant dimensions (l x w x h), m

3,8 х 2,7 х 2,8 + shaft 1,6

Input dry matter, %


Belt Press output (m3/h-1)


Output dry matter, %


Flocculants consumption, g/kg-1 a.s.



Type of Belt Press

The Belt Press size
(l x w x h), m

Weight, kg

Filter belt

width, m

Informative output of the Belt Press

kg a.s./h

m3/h while 4% inlet thickening





Length, m

Width, m

Height, m

Weight, kg








Dry matter

Input, %

Output, %


g/kg a.s.