Filtration Equipment

How Filtration Equipment Work

The basis of any filtration system is that a membranous screen with very small pores allows liquid to pass through while blocking larger particles like bacteria. As a result, a filter with smaller pores is more likely to prevent more objects from passing through it. If the pores of a filter are small enough, they ought to be able to block the passage of all living creatures- including microscopic organisms like microbes, bacteria, and viruses.

Types of Filtration Equipment

Gravity Filtration Equipment

The filtrate flow (liquid that has flowed through a filter) is produced by gravity filtration equipment using hydrostatic pressure. Hydrostatic pressure is the pressure exerted by a fluid in a confined space. In this case the pressure is due to a pre-filter column above the filter surface. Sand filters, gravity nutsche filters, and bag filters are typical examples of gravity filtration equipment.

Bag Filter

Bag filters are felt or woven fabric filters in the form of bags. It is not advised to use bag filters where extensive filtering is required.

Gravity Nutsche

A tank, or closed vessel, with a permeable or porous filtered bottom is referred to as a gravity nutsche. This equipment works by using pressure or a vacuum to drive contaminants into the filter.

Sand Filter

The sand filter is the most popular kind of gravity filter. It is made of a tank filled with layers of filtering material like gravel, sand, or crushed anthracite (coal). The size of the filtering bed material diminishes from the bottom of the bed to the top. Sand filters are a type of filtering apparatus that produces a cake of accumulated filtered material on the surface. Sand filters are mostly used for water conditioning.

Clarifying Equipment

Clarifying equipment includes suction clarifiers, and reverse osmosis (RO) clarifiers. They work to “clear” liquids by separating suspended solids from a liquid. This equipment is often used to handle both industrial and household garbage.

Suction Clarifiers

Suction clarifiers operate on the settling principle of gravity where heavier materials settle at the bottom of a liquid. Through this process, chemicals are used to coagulate smaller contaminants into a larger, heavier mass which then settles to the bottom of the “clarification zone.” This mass then settles into a filter to be removed; in some instances, the settled solids may be swept away with the aid of moving scraper blades.

Reverse Osmosis

The reverse osmosis (RO) water treatment method eliminates impurities from water by applying pressure to drive water molecules through a semipermeable membrane. Any impurities are filtered out and flushed away during this procedure, leaving behind a clean liquid.

Centrifugal Separators

Centrifugal separators use centrifugal force to separate solid particles from a liquid solution. Both hydrocyclones and centrifuges act as centrifugal separators, albeit through different processes. A centrifuge separates particles from a solution based on the size, shape, density, medium viscosity, and rotor speed of the particles. A hydrocyclone separates particles of various sizes, shapes, and densities using centrifugal force.

Sedimentation Equipment

Sedimentation equipment uses either gravity or a chemical reaction to force particles to sink to the bottom. Sedimentation equipment includes machinery that uses flocculation and gravity sedimentation as filtration processes.

Flocculation: Flocculation is the development of a cake or aggregate, typically produced through a chemical reaction; however iron-containing particles may also be gathered when subjected to a magnetic field. Flocculation is an essential step in the treatment of wastewater used to filter out dangerous, harmful agents to one’s health.

Gravity Sedimentation: This process is used to lower a liquid’s solid- material content through gravity. The heavier particles in a gravity sedimentation process descend to the bottom due to gravity. The difference in density between the liquid and the solids within it affects the pace of settling.

Vacuum Filtration Equipment

Vacuum filtration is a subcategory of liquid-solid separation equipment, and there are numerous variations of this sort of filtration equipment. There are two types of vacuum filters: batch (vacuum-nutsche and vacuum-leaf filters) and continuous (drum, disk, and horizontal filters).

Batch Vacuum Filters: Batch vacuum filters were developed from gravity filters and added a vacuum-type element to the filtration process. Nutsche-type filters are used in industrial applications and are similar to gravity filters except that they have a vacuum pump or some other vacuum-generating equipment to reduce the pressure under the filter. Vacuum leaf filters are another type of batch vacuum filtration system. Again, the cloth filter is dipped into a slurry. A vacuum draws the slurry material through the filter. The filtered liquid (filtrate) passes through and the filter collects solid material until a cake forms on it. The cake is washed off the filter and removed by reversing the airflow/vacuum pressure direction.

Continuous Vacuum Filters: Also known as rotary-drum filters, these filters are largely used in industrial settings to remove a high content of solid matter from a semi-liquid slurry to purify a liquid. The bottom of the drum is partially submerged into the slurry and begins to spin. A vacuum draws the liquid through a filter located on the drum which traps the solids until they form a cake. The cake coating is removed and the filter is either removed, or not, depending on the thickness of any remaining coating and the process is repeated.

Choosing the Right Filtration Equipment Supplier

To ensure you have the most positive outcome when purchasing filtration equipment from a filtration equipment supplier, it is important to compare several companies using our directory of filtration equipment suppliers. Each filtration equipment supplier has a business profile page highlighting their areas of experience and capabilities, along with a contact form to directly communicate with the supplier for more information or request a quote. Review each filtration equipment business website using our proprietary website previewer to quickly learn what each company specializes in. Then, use our simple RFQ form to contact multiple filtration equipment companies with the same form.