Belt Filter Press

A Belt Filter Press is a Bio-solids / sludge dewatering equipment that is used to remove water from the residues of liquid wastewater and forms a non-liquid material (known as cake). The dewatering residuals or cake vary in consistency from that of custard to moist soil. The dewatering application serves the following objectives –

• Shrinking the volume, thereby reducing the cost of storage and transportation.
• Eliminating the free liquids before landfill disposal.
• Reduced requirements of fuel, if the residuals are to be incinerated or dried.
• Producing a material that will have adequate volatile solids and void space for composting when mixed with a bulking agent.
• Avoiding the possibility of bio-solids pooling and runoffs that are associated with liquid land application.
• Optimizing subsequent phases such as thermal drying.

A belt filter press functions by applying the mechanical pressure to chemically conditioned slurry that is sandwiched between two tensioned belts through a serpentine of reducing diameter rolls. The device can be divided into three zones –

• Gravity zone – In this zone, the free draining water is drained by gravity via a porous belt.
• Wedge zone – In the wedge zone, the solids are prepared for pressure application.
• Pressure zone – In the pressure zone, the high pressure is applied to the conditioned solids.

Generally, a belt filter press receives a slurry that may range from 1 - 4 % feed solids and forms a final product of 12 - 35 % cake solids. The performance of a belt filter press depends on the nature of the solids that are being processed.

Applications
Typically the applications of a belt filter press can be divided into two prime categories –

• Municipal applications
• Typical applications

Brief description of these two types of applications is given below –

Municipal

Raw	Anaerobically Digested	Aerobically Digested	Potable Water Plant
Primary Primary & trickling filter Primary & WAS WAS Contact Stabilization Primary & RBC	Primary Primary & trickling filter Primary & WAS Primary & RBC	Oxidation ditch Primary & activated Contact stabilization Extended aeration Primary & RBC WAS	Alum sludge Lime softening sludge River water silt

Industrial

• Food processing wastes
• Chemical sludges
• Pulp & paper wastes
• Industrial waste processing sludges
• Pharmaceutical wastes
• Petrochemical wastes

Advantages
Some of the important advantages of a belt filter press include –

• Low staffing requirements, especially in the case, the equipment is big enough to process the solids in one shift.
  
  
• Simple and easy to maintain, the belt filter presses can usually be completed by a wastewater plant maintenance crew. Belt can be easily replaced that is a major maintenance cost.
  
  
• These presses can be started and shut down quickly as compared to centrifuges that may require up to an hour to build up speed.
  
  
• Belt filter presses produce less noise as compared to centrifuges.